White Paper
Benthic Infauna at the Mouth of the Columbia River
Prepared for
Institute for Natural Resources at Oregon State University
Prepared by
Gary M. Braun
12100 NE 195th St., Suite 200
Bothell, WA 98011
May 2005
TABLE OF CONTENTS
1.0
ABSTRACT AND SUMMARY .................................................................................................... 3
2.0
INTRODUCTION.......................................................................................................................... 3
2.1 COLUMBIA NEARSHORE BENEFICIAL USE PROJECT BACKGROUND ...................................................... 4
2.2
PURPOSE AND SCOPE OF THIS WHITE PAPER ................................................................................ 6
3.0
OVERVIEW OF GENERAL BENTHIC BIOLOGY AT THE MCR AND IN THE
PROPOSED DEMONSTRATION AREA ................................................................................................. 6
3.1
SUMMARY AND DESCRIPTION OF AVAILABLE MCR BENTHIC STUDIES ....................................... 6
4.0
DISTRIBUTION AND ABUNDANCE OF BENTHIC INFAUNA IN AND AROUND THE
AREA OF INTEREST ................................................................................................................................. 9
4.1
4.2
4.3
5.0
5.1
5.2
5.3
5.4
5.5
6.0
6.1
6.2
6.3
SYNTHESIS OF RESULTS ............................................................................................................... 9
POTENTIAL FOR CONTINUED RECENT EROSION ......................................................................... 12
RAZOR CLAMS ........................................................................................................................... 14
DREDGED MATERIAL DISPOSAL IMPACTS TO BENTHIC INFAUNA ....................... 16
GENERAL IMPACTS..................................................................................................................... 16
SHORT-TERM IMPACTS .............................................................................................................. 17
LONG-TERM IMPACTS ................................................................................................................ 19
SITE-SPECIFIC IMPACTS ............................................................................................................. 20
EFFECTS OF SILTATION ON RAZOR CLAMS ................................................................................. 21
MONITORING PROGRAM DESIGN ...................................................................................... 22
PROPOSED GENERAL MONITORING APPROACH .......................................................................... 23
ISSUES TO CONSIDER WHEN DEVELOPING SPECIFIC MONITORING PLAN.................................... 24
MONITORING PLAN DETAILS ..................................................................................................... 25
7.0
CONCLUSIONS .......................................................................................................................... 25
8.0
LITERATURE CITED................................................................................................................ 25
9.0
APPENDICES .............................................................................................................................. 31
Appendix 4 – Braun
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1.0 Abstract and Summary
As part of the collaborative effort between state and federal agency staff and local
stakeholders to explore the use of dredge disposal material from the Columbia River to
renourish the nearshore environment in the Columbia River littoral cell, this White Paper
examines the existing benthic infauna biology, distribution, and abundance in and around
the mouth of the Columbia River (MCR); identifies known dredge disposal impacts; and
provides recommendations for a general approach to monitoring these impacts.
Based on the overview of the general biology, diversity, distribution, and abundance of
benthic infauna found around the area of interest, and a review of the research regarding
known dredge and disposal impacts to local benthic infauna documented through
historical monitoring that is provided in this White Paper, the following conclusions can
be drawn that are relevant to the proposed demonstration project:
•
The benthic community composition in areas located off the MCR and south of
the south jetty indicate a community adapted to the unstable and erosive sediment
conditions associated with the high energy current and wave regime in this area.
•
The relative stability of the dominant taxa and their associated life history traits in
this area indicate that the infaunal community will continue to adapt to the
changing conditions and should not be significantly impacted by a continuing
erosive condition.
Past monitoring of disposal impacts shows that vertical migration and horizontal
migration are main methods of recolonization; reduced abundances in disposal
areas generally occur for less than 1 year; and some larval recruitment occurs, but
is not the main mechanism in this environment.
Demonstration project disposal should not have a large impact on shallow benthic
community.
Long-term disposal in the nearshore area also should not have a large impact on
shallow benthic community.
•
•
•
2.0 Introduction
The Institute for Natural Resources (INR) at Oregon State University works to provide
Pacific Northwest decision-makers with ready access to scientific information and
methods to better understand resource management challenges and develop solutions.
INR is helping to coordinate and synthesize scientific information for the Columbia
Nearshore Beneficial Use Project, a collaborative effort involving state and federal
agency staff, and local stakeholders such as port officials, fishermen, and
conservationists. This project is exploring the use of dredge disposal material from the
Columbia River to renourish the nearshore environment in the Columbia River littoral
cell. Specifically, the group is working toward development of a two-phase
demonstration project in the nearshore area off the south jetty of the Columbia River in
the Clatsop Plains region of Oregon.
Appendix 4 – Braun
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As part of this effort, INR agreed to develop a number of scientific and technical White
Papers on various topics of interest to the Nearshore Project group. One topic of interest
identified by the group is:
•
Benthic infauna biology, distribution, and abundance in and around the
demonstration project area; known dredge disposal impacts; and
recommendations for monitoring these impacts.
This White Paper was developed to address the need for more information on this topic.
This section explains the background of the Columbia Nearshore Beneficial Use Project
and describes the purpose and scope of this White Paper. Section 3 provides an overview
of the general biology and diversity of benthic infauna at the MCR and in the proposed
demonstration project area. Section 4 describes the distribution and abundance of benthic
infauna in and around the area of interest and includes a summary of results from
research and monitoring to date, a discussion of the potential for continued erosion in the
project area to impact distribution and abundance based on known biological/life history
and habitat needs, and a description of the razor clam fishery. Section 5 describes known
dredge impacts to benthic infauna, including potential mortality associated with various
amounts of sediment accumulations, if known. It also describes potential dredge impacts
on razor clams. Section 6 presents the recommended monitoring program design, and
Section 7 presents some preliminary conclusions regarding the proposed demonstration
project’s effects on benthic infauna.
2.1 Columbia Nearshore Beneficial Use Project Background
Since October 2003, a group of public and private sector participants has engaged in a
collaborative process to explore the use of lower Columbia River maintenance dredge
material to address the depletion of the natural sand volumes in the nearshore
environment off of the south jetty of the Columbia River.
Chronic erosion to the Columbia River north spit and along the Clatsop Plains has
increased, along with the potential for a breach at the south jetty. The objective of the
proposed supplementation of dredged sediments would be for these sediments to rebuild
the offshore sands and, in the long term, to better protect the jetty from the impacts of
waves coming from the southwest.
A recent White Paper titled “Columbia River Littoral Cell – Technical Implications of
Channel Deepening and Dredge Disposal,” by the Oregon Department of Geology and
Mineral Industries (DOGAMI) (Allan 2002), describes the changes to the system over the
past century. The DOGAMI study summarizes a body of research regarding the erosion
that has resulted due to the reduction in sediment in the littoral system from the Columbia
River. The Mouth of the Columbia River (MCR) navigation project consists of a onehalf-mile-wide navigation channel extending for about 6 miles through a jettied entrance
(3 miles seaward and shoreward of the tip of the north jetty) between the Columbia River
and the Pacific Ocean. The channel was deepened to its present depths in 1984 and has
been maintained at those depths to date. The northerly 2,000 feet of the channel is
maintained at 55 feet and the southerly 640 feet is maintained at 48 feet, with an
additional 5 feet of depth allowed for advanced maintenance. In its present
Appendix 4 – Braun
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configuration, the entrance channel has required annual dredging of 4 to 5 million cubic
yards on average of fine- to medium-grained sands to maintain the authorized depths.
Studies indicate that there is a loss of offshore sediment to the mid-continental shelf and
nearshore region offshore from the Clatsop Plains, and that the sediment is being
transported northwards along the coast and into the lower Columbia River estuary. The
deepening of the bathymetry offshore from the Clatsop coastline has subsequently
resulted in greater wave energy being focused on the jetty and the ocean shore.
The ongoing erosion offshore from the south jetty and adjacent areas has prompted
concern by the U.S. Army Corps of Engineers (Corps) that the south jetty may eventually
be undermined through toe erosion. The jetty is constructed on a sandbar, making it
susceptible to erosion. There is long-standing concern that the more narrow northern end
of the spit could be breached, resulting in the formation of a second river mouth. The
placement of Columbia River dredge material in the nearshore area off the south jetty
may help to slow this process and prevent further damage to the jetty and erosion of the
ocean shore beach. Accordingly, the Corps has recently re-introduced an option to
dispose of dredged sediments in the nearshore, offshore from Clatsop Spit (U.S. Corps of
Engineers Public Notice, 21 December 2001). It is expected that these sediments will
then move onshore to re-nourish beaches along the northern Clatsop Spit.
The Columbia Nearshore Beneficial Use Project team has identified an iterative approach
to accomplishing the objective to rebuild the offshore sands and, in the long term, to
better protect the jetty from the impacts of waves. This approach will involve at least two
demonstration projects. The purpose of these projects is to demonstrate and evaluate the
technical feasibility, effectiveness, and environmental impacts of dispersal methods likely
to be used in the longer-term efforts to mitigate the erosion of nearshore sands off the
south jetty of the Columbia River.
•
The area targeted for the demonstration project will be the nearshore area off the
south jetty of the Columbia River. The area identified would be approximately
9,000 feet by 7,000 feet, and would be approximately one mile offshore in water
depths between 12 meters (40 feet) and 18 meters (60 feet).
•
A small-scale (30,000 cubic yards) test of the enhanced dumping method of
dispersal will occur in summer 2005. The key objective of this study is to
determine the feasibility of “thin-layer” dispersal of dredged sediments in the
nearshore area.
•
A subsequent demonstration would occur using larger volumes (150,000 cubic
yards) to determine the degree and direction of migration of deposited sediments
in the nearshore environment.
•
The team would then undertake modeling and measurement of biological impacts
and navigational safety (wave) impacts prior to any long-term large-scale
dispersal of dredged sediments in the nearshore environment.
Appendix 4 – Braun
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2.2
Purpose and Scope of this White Paper
Given this background information, this White Paper has been developed to address the
potential impacts and effects to benthic infauna communities associated with both the
proposed demonstration and the long-term project. Specifically, the following sections
present:
•
General discussion of the benthic infauna biology in and around the proposed
demonstration area;
o Distribution and abundance of benthic infauna in and around the
demonstration project area including the potential for recent erosion in the
project area to impact distribution and abundance of benthic infauna and
razor clams, based on known habitat needs;
•
Known dredge disposal impacts to benthic infauna and razor clams; and
•
Recommendations for monitoring these potential impacts to benthic infauna.
3.0 Overview of General Benthic Biology at the MCR and
in the Proposed Demonstration Area
Benthic infauna are organisms that live in the sediments by either attaching to the
substrate, living in tubes, or burrowing through the sediments. Infaunal communities are
commonly used for ecological assessments because they tend to be more stable (less
motile) than epifaunal species such as crabs or bottom fish. Infaunal assemblages
(groups of different taxa and species living together) generally consist of worms,
amphipods, small clams, anemones, and small crustaceans. They also serve as important
prey items for larger organisms (e.g., crabs, flatfish).
The sedentary nature of the infauna makes sampling quantifiable and therefore aids in the
sample-to-sample (between sample) and habitat-to-habitat (between habitat) assessment
of ecological change, and aids in determining impact assessment. Despite their generally
small size and seasonal abundance cycles, some species are often long lived and are
known to be good indicators of the health of their habitat. Because they cannot easily
move away, the infaunal assemblages have been shown to provide a good indicator of
changes in the health of an ecosystem.
This section provides a summary and description of available MCR benthic studies
followed by specific descriptions of infaunal assemblages near the MCR.
3.1 Summary and Description of Available MCR Benthic
Studies
In an effort to provide an evaluation of benthic infaunal communities in the proposed
demonstration area, available MCR studies regarding the benthos were reviewed. Six
studies were found that collected benthic data in the area of interest (Emmett and Hinton
1996; Hinton and Emmett 1994, 1996; Richardson et al. 1977; Sanborn 1975; Hinton
1998) The review conducted by Hancock (1997) was used as a basis for this summary
because no new studies were located that had not been reviewed in that synthesis. Table
Appendix 4 – Braun
6
1 identifies the individual studies reviewed, the period the sampling occurred, the
equipment used, and other pertinent information used to compare the results. Although
many of the research studies were performed with somewhat different goals and
objectives, each of the studies have some elements in common, which allows for some
comparisons. Similarities of past studies that allow comparisons are:
•
Each study focused on baseline benthic information or dredge material disposal,
either for site location or monitoring of specific disposal areas or projects.
•
All but Richardson et al. (1977) used the identical quantitative sampler.
•
All but Richardson et al. (1977) used the same mesh size.
•
The same group of professional taxonomists made the identifications for all
studies.
•
Sampling areas are all within the overall MCR area.
•
All studies report areal concentrations in numbers of organisms (or density) and
are directly comparable (except for Richardson et al. [1977] which is
approximately comparable).
•
All had sample replication information (estimate of variability).
All abundance information was converted to number of organisms per meter square
(no./m2). Other community level measures such as diversity, species richness,
equitability, and clustering results were used as presented in the original studies.
Physical and biological resources in the vicinity of the MCR have been investigated since
the mid 1970s, with the most recent benthic infauna data reviewed and collected in 1996
(Hinton 1998). Most studies were conducted to evaluate placement or impacts associated
with dredge disposal sites and were not designed to document benthic communities in the
proposed demonstration project area. However, the benthic community attributes from
the shallow-water stations (i.e., <30 meters) from each study, provide a basis for
assessing the potential conditions in the proposed demonstration area. These attributes
are discussed below in the following section.
The area off the mouth of the Columbia River is a productive biological environment that
is influenced by a variety of complex physical processes. The major short-term processes
that affect the area are tides, local winds, and currents. River flow also has a major
seasonal impact on the area. The nearshore areas are subjected to high current and wave
energy and populated by biological organisms adapted to this high-energy environment.
The offshore area is less active and populated by organisms adapted to more stable
environments (Corps 1999).
3.2
General Synthesis of Infaunal Assemblages near the MCR
As summarized by Hancock (1997), the offshore area closely resembles the nearshore
shallow-water sand-bottom communities typical of the Oregon and Southern Washington
coast (Carey 1972; Jumars and Banse 1989). The infauna are characterized by species
whose evolutionary history has adapted them to high-energy environments. These
environments typically contain high wave energy, which produces high fluxes of
Appendix 4 – Braun
7
sediment deposition, erosion, and transport of sand. Large storms with large waves occur
off the MCR which, when combined with the large fresh water output from the Columbia
River and the semi-diurnal tides, produce suspended material containing both sediment
and organic particulates. The bottoms of high-energy environments tend to exhibit sand
waves or ripples caused by bottom transport of sand. Organisms have adapted to these
high-energy environs by being highly motile rapid burrowers, quick tube builders, or
rapid colonizers.
Richardson et al. (1977) described five major species assemblages of benthic
invertebrates in the area of the MCR (Figure 1). The influence of the Columbia River,
primarily sediment deposition, probably accounts for the differences noted between
benthic assemblages in the study site and the rest of the Oregon-Washington coast.
Seasonal variations of benthic community structure and species composition were
considerable, especially at inshore locations exposed to sediment movement due to winter
storms and at locations affected by sedimentation from the river. Yearly variations in
benthic communities are probably related to yearly fluctuations in the intensity of winter
storms and in the output of water from the Columbia River.
In general, the studies reviewed indicate that invertebrate densities increased with
distance from shore. The nearshore shallow-water benthos tends to have fewer taxa and
lower densities than quieter offshore habitats, especially in areas with sediments of finer
grain size and higher organic content. The association of benthic community with bottom
type (for example, sand, silt or clay) has been recognized for almost 100 years (Gray
1981; Levinton 1995; Snelgrove and Butman 1994; Raffaelli and Hawkins 1996). This
correlation is apparently driven by the dynamics of sediment movement rather than static,
easily measurable variables like sediment grain size (Nowell and Jumars 1984; Peterson
1991; Snelgrove and Butman 1994; Hall 1994).
With one exception, the nearshore wave-swept zone exhibits the lowest densities,
seasonal variability, and patchiness. The exception was in 1994, when the nearshore
shallow-water stations exhibited both the highest and lowest densities. The two shallowwater stations with the highest densities were low in diversity and dominated by two
species, Diastylopsis spp. (very mobile cumacean) and Owenia fusiformis (an
opportunistic polychaete). These species are rapid colonizers and highly tolerant of
disturbed areas such as those caused by currents, wave surges, and shifting sediments.
The combined results of the studies indicate the benthic assemblages immediately off the
MCR are the most variable and exhibit community patchiness, year-to-year variations in
density and species composition, seasonal variability, and responses to disposal impacts.
Such characteristics of the infauna are typical of areas of high disturbances and the
species found in these habitats tend to be rapid colonizers, high energy tube dwellers, and
rapid burrowers. Variations in the densities of benthic infauna as reported in the
individual studies reviewed are consistent with observations reported from other highenergy nearshore shallow sandy environments (Oliver et al. 1980; Hancock 1997).
Sandy shallow-water marine systems typically exhibit larger spatial and temporal
variations than deeper-water, low-energy areas that tend to have more stable
hydrography. The lessening of wave and current action allows finer-grained sediments to
settle and produces muddier bottoms (Sternberg et al. 1977). Evidence of this trend is
Appendix 4 – Braun
8
documented in the multi-season and multi-year studies reviewed. Richardson et al.
(1977) noted that the structure and distribution of benthic assemblages were related to
depth. Depth is probably a composite of several environmental factors, including
reduced intensity of winter storms with depth, increased organic content of sediment with
depth, and an increase in finer-grained sediment with depth. However, superimposed on
this general trend is the influence of the Columbia River outflow variations, and largerscale changes in oceanic conditions (e.g., primary production, upwelling, storm events)
that can cause variations in abundances and species composition (Richardson et al 1977;
Hancock 1997; Hinton and Emmett 1996).
The area south of the river (Assemblage C of Richardson et al 1977) is predominantly
well-sorted sand and does not vary seasonally. Species composition changes little in this
region. The major seasonal change noted by Richardson et al. (1977) was the increase of
the polychaete Spiophanes bombyx in June and September. The high-energy area inshore
is less productive and generally has lower density and diversity. This is likely due to the
instability of the sediments and lack of input of silt and organics.
4.0 Distribution and Abundance of Benthic Infauna in
and around the Area of Interest
As discussed above, in general, the high-energy inshore area is less productive and
generally has lower densities and diversity of benthic infauna, likely due to sediment
instability. The studies (Richardson et al. 1977; Hinton and Emmett 1994, 1996; Emmett
and Hinton 1995) indicate that the benthic community structure in the area of interest
immediately off the MCR is the most variable because it is exposed to considerable
seasonal changes in sediment type from deposition of Columbia River silts and winter
storms. Benthic assemblages show considerable seasonal and spatial changes in species
composition. In winter, the area has predominantly sand substrate with low species
density and biomass. Near inshore areas are dominated by the snail Olivella biplicata
and Magelona sacculata, a polychaete. Following spring deposition of fine-grained
sediment with presumably more organics, the density and biomass values increase and
dominant species change to cumaceans, clams (Siliqua patula), and occasionally a
polychaete and amphipods (Richardson et al. 1977).
In contrast to this pattern, the substrate at stations located inshore and to the south of the
MCR are characterized by a well-sorted sand that does not vary with season. Species
composition also changes little with season in this region. The major seasonal change is
an increase or decrease in abundance of the polychaete Spiophanes bombyx.
This section presents a synthesis of each reviewed study’s identification, classification,
and description of the species in the nearshore benthic communities; explains the
potential for continued recent erosion near the MCR; and discusses the razor clam fishery
and this species life history.
4.1
Synthesis of Results
The studies conducted in the vicinity of the MCR were not directed at assessing and
documenting only the nearshore (<30 m) benthic communities. However, each study
Appendix 4 – Braun
9
collected benthic community data from shallow-water stations that can be used to assess
the attributes of the benthic community in the area of the proposed demonstration project.
As part of this review, an attempt was made to assemble the benthic community
parameters for individual stations located in <30 meters of water from each of these
studies (Figure 2; Appendix A). Most of the studies did not present community structure
data (i.e., individual species abundances) from individual stations, but most did present
densities, diversity and equitability indices, and dominant taxa based on cluster groups.
These data are presented in Tables 2 and 3.
Study Comparability
The infaunal studies reviewed conducted sampling utilizing accepted sampling protocols,
accepted sampling replication (five replicates), and organism extraction and preservation
techniques. Richardson et al. (1977) used a 0.1m2 Smith McIntyre grab sampler and a
1.0 mm mesh screen, while the other studies used a 0.1m2 Gray O’Hare box corer and a
0.5 mm mesh screen to collect the benthic infauna. Thus, the results of the Richardson et
al. (1977) study underestimates the population density compared to the other studies
because the smaller organisms were retained and counted on the 0.5 mm screen. In
addition, the number of taxa may also be biased low. Thus, direct comparisons between
the Richardson et al. (1977) study and the other studies cannot be made. However,
comparisons of the benthic infauna community patterns and indices of community
structure can be made. Five replicate grab samples were taken at most stations during
each sampling period.
Summary of Benthic Indices for Inshore Areas
Table 2 presents the benthic infaunal community structure indices summarized from the
stations located in < 30 meters of water from the reviewed studies. The indices include
the number of taxa, abundance (no./m2), diversity, and equitability. As discussed above,
the results of the most comprehensive study (Richardson et al. 1977) and the other studies
are not directly comparable, so the summaries of the benthic indices are presented
separately in the table. The number of taxa at inshore stations varied from 12 to 57 with
a mean of 32.9 +/- 10.6 for data collected from December 1974 to January 1976 by
Richardson et al. (1977). In those same studies, the infaunal abundances were variable,
ranging from 56/m2 to 43,802/m2, and averaged 1,716 +/- 3,997/m2. The other benthic
community measures of diversity and equitability also varied and tended to reflect the
variability of the abundances. The other studies conducted from 1992 to1996
documented similar patterns. The number of taxa at inshore stations varied from 11 to
119 with a mean of 68.8 +/- 20.4 for data collected from 1992 to 1996 by Hinton and
Emmett (1994; 1996), Emmett and Hinton (1995) and Hinton (1998). In those same
studies, the infaunal abundances were extremely variable, ranging from 844/m2 to
165,105/m2, and averaged 22,537.5 +/- 35,967/m2. The other benthic community
measures of diversity and equitability also varied and tended to reflect the variability of
the abundances, with the lowest diversity and equitability values associated with the
highest abundances. Figures 3 to 6 show the variability of the benthic community indices
at several inshore stations from 1992 to 1994. The rapid changes (increases) in
abundances between stations or seasonally, which were reported on several occasions,
Appendix 4 – Braun
10
can be correlated with natural population fluctuations such as mass recruitment. For
example, in 1992 some of the highest densities ever observed in Oregon and Washington
coasts were due to a large set of juvenile razor clams. In 1994, Diastylopsis spp. (a very
mobile cumacean) and Owenia fusiformis were found in very high densities at two
inshore stations that normally have lower density than the offshore stations.
The data from Richardson et al. (1977) were collected consistently from many inshore
stations from December 1974 through July 1976 to assess baseline conditions in the
vicinity of dredge disposal sites. Their data were used in this report to compare benthic
community parameters at stations located directly off the mouth of the Columbia River
with those located to the south of the south jetty in the approximate area of the proposed
demonstration project. These data are plotted and shown in Figures 7 to 12. The data for
the stations located south of the south jetty show remarkable consistency among the
stations sampled for both number of taxa and abundances. In contrast, the stations
located directly off the MCR exhibit greater variability in both number of taxa and
abundances, likely reflecting the variable nature of inputs and outflow of the Columbia
River. An increase in abundance was noted for all sites regardless of location in the
September 1975 samples, suggesting a response to a broad-scale change (e.g., upwelling).
Dominant Taxa at Inshore Areas
The area off the mouth of the Columbia River is a productive biological environment that
is influenced by a variety of complex physical processes. The major short-term processes
that affect the area are tides and local winds and currents. River flow also has a major
seasonal impact on the area. The nearshore areas are subjected to high current and wave
energy and populated by biological organisms adapted to this high-energy environment.
The offshore area is less active and populated by organisms adapted to more stable
environments (U.S. Army Corps of Engineers 1999).
Each study also summarized the dominant taxa associated with each cluster grouping.
Table 3 lists the dominant taxa (defined as the top three most abundant taxa in associated
cluster groups identified in each study) found across all stations in the inshore area.
Several polychaetes, cumaceans, amphipods, and molluscs were re-occurring dominants
throughout the time period observed and are generally consistent with the Shallow-Water
Sand Community from the Washington Coast (Jumars and Banse 1989). Table 4 lists the
35 taxa that were represented as dominants based on the cluster groupings from 1974 to
1996. Compared to the total number of taxa identified in all samples over these same
years (425 taxa in the Richardson et al. study; 338, 361, 348, 571, and 502 in 1992, 1993,
1994, 1995, and 1996, respectively), this represents a very short list and indicates that
these taxa are very well adapted to the variable conditions in this area..
Areas off the MCR tended to have a more variable group of dominant taxa than those
located south of the MCR. In June and September 1975 and again in July 1992, juvenile
razor clams (Siliqua patula) dominated areas directly off the MCR, but were not among
the dominant taxa at other times.
Table 3 also documents the consistency of the dominant taxa from the area south of the
south jetty in the area near the proposed demonstration project. Spiophanes bombyx and
Magelona saculata were the top dominant taxa for the sampling events between
Appendix 4 – Braun
11
December 1974 and June 1976 at stations south of the south jetty (K-1 thru K-31, R-1, R10, R-19, R-24, and R-27 through R-33). Later studies had fewer stations in these areas,
but those stations that were nearby also were dominated by Spiophanes bombyx.
Life Histories of Dominant Taxa
This section presents a brief description of some of the most dominant taxa found at
inshore stations (see Table 4). These species are adapted to the high-energy
environments by being highly mobile rapid burrowers, quick tube builders, or rapid
colonizers and are highly tolerant of disturbed areas such as those caused by currents,
wave surges, and shifting sediments.
Spiophanes bombyx, a small, slender bristleworm (5 to 6 cm long by 0.15 cm wide), is
found in clean sand from the low water mark to about 60 meters. Spiophanes bombyx is
regarded as a typical 'r' selecting species with a short life span, high dispersal potential,
and a high reproductive rate (Kröncke 1980; Niermann et al. 1990). It is often found at
the early successional stages of variable, unstable habitats that it is quick to colonize
following perturbation (Pearson & Rosenberg 1978). Its larval dispersal phase may allow
the species to colonize remote habitats. Tube building worms, including Spiophanes
bombyx, modify the sediment making it suitable for later colonization and succession
(Gallagher et al., 1983).
Magelona spp. typically burrows in fine sand at low water and in the shallow sublittoral.
It does not produce a tube. Magelona spp. is adapted for life in highly unstable sediments,
characterized by surf, strong currents, and sediment mobility.
Owenia fusiformis is a thin, cylindrical, segmented worm, up to 10 cm long, that lives in
a tough, flexible tube buried in the sand with its anterior end just protruding from the
surface. It is found buried in sand or muddy sand, at or below low water, on fairly
sheltered beaches.
Spio filicornis is found in clean sand, from the low water mark into the shallow
sublittoral. It inhabits a tube made of sediment grains and detritus stuck together with
mucus. Tube-building worms, including Spio filicornis, modify the sediment, making it
suitable for later colonization and succession (Gallagher et al. 1983).
Hippomedon denticulatus is a lysianassid amphipod. They are scavengers on muddy and
sandy sediments in bays, the continental shelf, and the deep sea where they clean up the
carcasses of dead fishes and invertebrates. This species of lysianassid amphipod is large
(14 mm), shiny, and white, with a pair of fat antennae attached to the front of the head
and a small hook on the last side-plate of the abdomen.
4.2
Potential for Continued Recent Erosion
Background
A recent white paper titled “Columbia River Littoral Cell – Technical Implications of
Channel Deepening and Dredge Disposal,” by the Oregon Department of Geology and
Mineral Industries (DOGAMI)(Allan 2002), describes the changes to the system over the
past century. The DOGAMI study summarizes a body of research regarding the erosion
Appendix 4 – Braun
12
that has resulted due to the reduction in sediment in the littoral system from the Columbia
River.
Studies indicate that there is a loss of offshore sediment to the mid-continental shelf and
nearshore region offshore from the Clatsop Plains, and that the sediment is being
transported northwards along the coast and into the lower Columbia River estuary. The
deepening of the bathymetry offshore from the Clatsop coastline has subsequently
resulted in greater wave energy being focused on the jetty and the ocean shore.
The ongoing erosion offshore from the south jetty and adjacent areas has prompted the
Corps to be concerned that the south jetty may eventually be undermined through toe
erosion. The jetty is constructed on a sandbar, making it susceptible to erosion. There is
long-standing concern that the more narrow northern end of the spit could be breached,
resulting in the formation of a second river mouth. Sand eroded from the Clatsop Plains,
nearshore, and mid-shelf regions may now constitute a significant source of beach
sediment to the Columbia River littoral system. Without further analyses and ongoing
monitoring of the Clatsop Plains, it is not clear whether the present erosion will continue,
accelerate, or even expand farther south along the coast (Allan 2002).
Potential Impacts of Continued Erosion to the Benthic Infaunal
Community
The placement of Columbia River dredge material in the nearshore area off the south
jetty (the subject of the demonstration project) is suggested to help prevent further
damage to the jetty and to slow erosion of the ocean shore beach. However, if the
demonstration project does not happen or the predicted benefits do not occur and the
existing situation persists, we have been asked to evaluate the potential impacts to the
benthic community from further erosion in this area.
Sediment movement is a natural phenomenon. Waves and tides move sand, and the rates
of movement are greatly modulated by the wind and weather (Miller and Sternberg 1988;
Hall 1994; Sherwood et al. 1994). The most severe agents of sediment movement on the
Oregon-Washington coast are winter storms. Seasonally, the ocean shoreline erodes
during the winter and accretes in the summer. Ripples on the sandflat at low tide attest to
the power of water to erode and transport sand grains even in relatively sheltered
environments. From the intertidal zone to the subtidal zone, sands, silts, and clays are
continually subject to the action of waves and tidal currents to transport them along and
across the shoreline.
These sediments are inhabited by a variety of marine benthic organisms, which display a
range of adaptations to deposition and erosion of the sea bottom. Benthic fauna survive
intense storm events that control and shape the coastlines (Bock and Miller 1995). Many
are surprisingly resilient to “sand-blasting” by sediment transport (Miller et al. 1992; Hall
1994). Infauna can burrow up and down in the sediment to maintain contact with the
sediment-water interface, and this implies that certain species or functional groups, even
certain community assemblages, are adapted to frequent, natural sediment movement,
burial, and erosion (Miller, Muir, and Hauser 2002). In fact, it is likely that susceptibility
to sediment movement and burial will vary considerably among taxa (Jumars and Nowell
1984; Snelgrove and Butman 1994; Hall 1994). For example, large and deep-dwelling
Appendix 4 – Braun
13
deposit feeders may be tolerant to deposition and erosion because of their size and
burrowing ability (Tuck et al.2000). Because coastal storms occur most frequently in the
winter, winter populations may be more tolerant to sedimentation events than summer
populations (Tettelbach et al. 1998).
There are virtually no observations of organisms under realistically simulated conditions
of sediment erosion, deposition, and transport (Jumars and Banse 1989). Animals that
experience daily bedload transport show striking behavioral adaptations (Nowell et al. in
press). The effects of erosion and deposition might be expected to be most severe in the
inshore silt-to-sand transition zone. Because zone shifts occur on a seasonal basis, any
sessile organism will experience an annual cycle of changing grain size (Nittrouer 1978).
Work cited by Jumars and Banse (1989) suggests that meiofauna may often be
transported passively along with sediments of similar settling velocity. Local (Oregon
shelf) evidence that meiofauna is redistributed by winter storms comes from observed
homogenization of the small-scale distributions (Hogue and Miller 1981; Hogue 1982).
Hogue (1982) further found a marked faunal boundary in nematode species composition
at 25-meter water depth, which appears from bottom photographic evidence to be a depth
below which wave disturbance becomes much less frequent. His conclusion regarding
the cause for this faunal change also is supported by morphological adaptations in the
shallower-zone species, apparently for gaining or retaining purchase on the grains
surrounding interstices. According to Jumars and Banse (1989), the large spatial extent
of the shelf affected during storm events argues for the efficacy of planktonic larvae. An
interesting but undocumented strategy would be to have larval dispersal coincide with the
late fall/winter transport season. Besides affording the usual benefits of dispersal, such a
strategy could serve as insurance against adult mortality due to erosion and deposition.
Conversely, adults that release larvae after the winter storm season must have effective
protection from these sediment transport events (Jumars and Banse 1989).
Based on the synthesis and analysis of the nearshore data collected to date and discussed
above, some predictions can be offered:
•
The benthic community composition in areas located off the MCR and south of the
south jetty indicate a community adapted to the unstable and erosive sediment
conditions associated with the high energy current and wave regime in this area.
•
The relative stability of the dominant taxa and their associated life history traits in this
area indicate that the infaunal community will continue to adapt to the changing
conditions and should not be significantly impacted by a continuing erosive
condition.
4.3
Razor Clams
Because there is concern that the demonstration project and possible long-term action
could affect the razor clam fishery near the MCR, the fishery and the species are briefly
described here. In addition, potential impacts of dredging and sediment deposition on
razor clams are discussed in Section 5.5.
Appendix 4 – Braun
14
Razor Clam Fishery
Over 90 percent of Oregon’s razor clams are dug in the intertidal zone along the 18-mile
stretch of Clatsop Beach on the northern Oregon coast. The razor clam has been referred
to as the “finest food clam available on Pacific beaches” and is the basis of economically
important commercial and recreational fisheries throughout its range in the Pacific
Northwest (Figure 13). Commercial fishing for razor clams has existed since before the
turn of the century but has been largely replaced by recreational digging. Millions of
clams are taken annually from Oregon and Washington beaches (Lassuy and Simons
1989).
Characteristics and Life History of the Razor Clam
The Pacific razor clam (Siliqua patula) ranges from California to Alaska. It is abundant
on low gradient surf-pounded ocean beaches, but also occurs in sheltered areas along the
coast. Razor clams are found primarily on the intertidal coastal beaches (those that are
exposed at low tide) from a +3 foot level to a -2 foot tide level (Nickerson 1975; Lassuy
and Simons 1989; http://wdfw.wa.gov/fish/shelfish/razorclm/razorclm.htm). Limited
diving observations have indicated some adult razor clams (S.patula) offshore for up to
one-half mile. Razor clams dredged in water deeper than 30 feet, although similar to the
beach clam, are typically a different species (Siliqua sloati).
In Oregon and Washington waters, the razor clam grows to a maximum length of 6
inches, although this size class is seldom found. The life expectancy for Pacific
Northwest clams is approximately 5 years. They suffer from a high degree of mortality
due to predation by Dungeness crabs, shore birds, numerous species of fish, and of course
thousands of clam diggers. A disease was also discovered in the early 1980s that caused
mass mortalities of large numbers of clams. It is unknown how long this disease has
affected clam populations. In contrast, razor clams found in Alaska may grow to 11
inches in length and live to be 15 years old, due to colder water temperatures and slower
growth rates.
Razor clams are characterized by a long siphon, a prominent muscular foot, and brittle
elongated valves. They are noted for their unusual ability to dig very rapidly through the
subsurface sand. Razor clams can burrow at rates exceeding 20 cm per minute and are
found up to 25 cm deep in the sand. Adults left on the surface of the beach will quickly
reburrow. Lateral movement of adults is believed to be small, although juvenile clams
have been found to move because of substrate instability (Nickerson 1975). Juvenile
clams burrow to a lesser depth and may be washed out and moved because of scouring of
the substrate. Although there have been numerous studies of intertidal populations, little
is known about the subtidal populations in the vicinity of major razor clam beaches
(Bourne 1969 as cited in Lassuy and Simons 1989).
Razor clams have separate sexes and are broadcast spawners. Age and size at sexual
maturity varies, but most clams are sexually mature at 2 to 4 years of age and 9.7 to 10.3
cm in length. Time of spawning generally occurs in late spring and early summer in the
Pacific Northwest with recruit to flat, sandy beaches in late summer. Spawning can be
influenced by temperature, upwelling, tidal cycles, currents, food availability, and gonad
maturity. The life history follows a common bivalve pattern of release of gametes into
Appendix 4 – Braun
15
the surrounding water, fertilization, development as a free-swimming pelagic larvae,
settlement to the bottom as “spat,” and finally development as a sedentary organism. The
razor clam larval period is estimated to be about 8 to 10 weeks in the Pacific Northwest.
Survival of intertidal razor clams is likely affected by availability of food (e.g., diatoms),
predators, and natural occurrences such as storms or disease. Predators on razor clams
include gulls, ducks, crabs, and a few fish species (Lassuy and Simons 1989).
5.0 Dredged Material Disposal Impacts to Benthic
Infauna
This section addresses general, short-term, and long-term impacts of dredged material
disposal on benthic infauna near the MCR. It also identifies potential site-specific
impacts. The section concludes with a brief description of potential impacts of dredged
material disposal on razor clams.
5.1
General Impacts
Benthic community distributions and characteristics often mirror the physical sediment
regime, reflecting, among other factors, sediment type, sedimentation rate, and intensity
of disturbance (Rhoads et al. 1985; Alongi 1989; Lopez-Jamar et al. 1992; Aller and
Stupakoff 1994). For example, sedimentary environments impacted by frequent and
severe physical disturbances tend to have reduced numbers, diversity, and sizes of
benthic macroinfauna and are dominated by opportunistic surface-dwelling pioneering
species and reduced numbers of sexually mature individuals (Harkantra et al. 1980;
Hanson et al. 1981; Thistle et al. 1985; Rhoads and Boyer 1982; Thayer 1983; Rhoads et
al. 1985; Yingst and Rhoads 1985; Aller and Aller 1986; Alongi 1989; Alongi et al.
1992). On shelves immediately off the mouths of large rivers like the Amazon and
Changjiang (East China Sea), periodic erosional/depositional events, fluid muds, and
unstable seabeds can contribute to significantly reduced infaunal populations (Rhoads et
al. 1985; Aller and Aller 1986). In contrast, decreasing gradients in physical disturbance
in mid-shelf regions farther offshore, coupled with the potential of increased inputs of
water-column primary productivity to the seabed, typically allow for the development of
denser populations with diverse feeding and life habits among the macrobenthos. As
discussed above, the benthic community distributions and characteristics in the vicinity of
the MCR are consistent with the distributions and characteristics described in the cited
references.
Benthic organisms are adapted to the natural processes of sediment movement, erosion,
and deposition. Laboratory studies have cataloged the range of responses to flow and
sediment movement that allow benthos to survive, and even thrive, under intense, stormdriven sediment movement. Extreme sedimentation events also result from man’s
modifications of the nearshore environment, and the scale and magnitude of these
alterations can often greatly exceed that of natural occurrences. In an attempt to
counteract natural forces, we rebuild beaches, deepen channels for navigation, and restore
habitat with dredge materials placement (National Research Council 1995). These efforts
alter otherwise natural patterns of deposition and erosion by protecting the shore from
wave action and interrupting longshore transport. To be effective, dredging projects
Appendix 4 – Braun
16
typically must move sediment at rates that far exceed those typical in nature. Large
amounts of sediment must be moved over the lifetime of a funded project in order to
counter the more gradual but persistent, longer-term transport driven by natural forces.
Dredging, dredge material disposal, and beach nourishment have all become
commonplace management practices and such projects will continue to be employed to
foster economic development (Kester et al. 1983; National Research Council 1995; Clark
1996). While these projects have many positive societal benefits, they also may cause the
disruption of coastal benthic habitats and living resources (National Research Council
1995).
Sediment transport itself is not detrimental to most benthic organisms. Erosion does not
necessarily result in defaunation of the bottom, just as disposal of dredged material does
not always result in burial and smothering of the benthic community (Miller et al. 2002).
Dredging and disposal of dredged material may have an adverse effect on marine benthic
communities, but the level of impact depends on the scale of the operation, type of
organism affected, time of year in which the disturbances occur, as well as the hydrology
(Engler et al. 1991; Qian et al. 2003; Newell et al. 1998).
5.2
Short-Term Impacts
Disposal operations will deposit a sediment blanket over established bottom communities
at the disposal site with dredged material that may or may not resemble bottom sediments
at the disposal site. Dredging and disposal operations have immediate localized effects
on the benthos, which generally involve burial and smothering. The recovery of the
affected sites occurs over periods of weeks, months, or years, depending on the biology
of the organisms affected, the type of environment, and the quantity and quality of the
deposited materials.
Recolonization after Initial Burial
After the initial mortality that occurs immediately following deposition of sediments,
initial recolonization of the newly deposited dredged material begins via migration from
surrounding areas (McLusky et al. 1983; Oliver et al. 1977; Richardson et al. 1977),
larval recruitment, and vertical migration (Maurer et al. 1981, 1981, 1982; Maurer et al.
1978). The first organisms to recolonize dredged material usually are not the same as
those that originally occupied the site. They consist of opportunistic species whose
environmental requirements are flexible enough to allow them to occupy the disturbed
areas. Trends toward re-establishment of the original community are often noted within a
year or two (Blanchard and Feder 2003). The general recolonization pattern is often
dependent upon the nature of the adjacent undisturbed community, which provides a pool
of replacement organisms capable of recolonizing the site by adult migration, passive
advection, or larval recruitment.
Organisms have various capabilities for moving upward through newly deposited
sediments, such as dredged material, to reoccupy positions relative to the sediment-water
interface that are similar to those maintained prior to burial by the disposal activity.
Defaunation and mortality due to dredge material disposal was addressed by Maurer and
his coworkers in laboratory deposition experiments on Delaware Bay benthos (Allan
2002; Maurer et al. 1985; Maurer et al. 1981, 1981, 1982; Maurer et al. 1978; Maurer et
Appendix 4 – Braun
17
al. 1986). These authors conclude that because a fraction of buried animals do return
alive to (or near) the surface, some degree of upward mobility and recolonization of
dredged material is expected from the vertical migration of buried organisms. Maurer’s
studies are still cited because they represent one of only a few such projects to document
the burrowing abilities of benthic fauna through differing depths and types of deposited
sediments.
Vertical migration ability is greatest in dredged material similar to the existing substrate
and is minimal in sediments of dissimilar particle-size distribution. Benthic organisms
with morphological and physiological adaptations for crawling through sediments are
able to migrate vertically through several inches of overlying sediment. However,
physiological status of the organism and environmental variables are of great importance
to vertical migration ability. Organisms of similar lifestyle and morphology react
similarly when covered with an overburden. For example, most surface-dwelling forms
are generally killed if trapped under dredged material overburdens, while subsurface
dwellers migrate to varying degrees. Maurer’s lab studies suggest that vertical migration
may be an important mechanism for recolonization at some disposal sites. His work also
indicates that vertical migration abilities are highly variable among species.
Factors Affecting Severity of Short-Term Impacts
The severity of potential impacts on benthic infauna and their ability to recolonize after
deposition depend on several factors including the variability of the physical environment
where sediment is deposited; the rate, timing, and thickness of the deposition; and the
type of material deposited (similar versus dissimilar to existing conditions).
The more naturally variable the physical environment, especially in relation to shifting
substrate due to waves or currents, the less effect dredged material disposal will have.
Organisms common to such areas of unstable substrates are adapted to physically
stressful conditions and have life cycles that allow them to withstand the stresses imposed
by disposal activities. Dredged material discharged at disposal sites that have a naturally
unstable or shifting substrate due to wave or current action tends to be more quickly
dispersed and does not cover the area to substantial depths. This natural dispersion,
which usually occurs most rapidly and effectively during the stormy winter season, can
be assisted by conducting the disposal operation so as to maximize the spread of dredged
material, producing the thinnest possible overburden. The thinner the layer of
overburden, the easier it is for mobile organisms to survive burial by vertical migration
through dredged material.
Exotic sediments (those that are different from the sediments that the existing organisms
live in) are likely to have more severe effects when organisms are buried than sediments
similar to the disposal site. Generally, physical impacts are minimized when sand is
placed on a sandy bottom. When disposed sediments are dissimilar to site sediments,
recolonization will probably be slow and carried out by organisms whose life habits are
adapted to the new sediment. The new community may be different from what originally
existed at the site (Maurer et al. 1986; Miller, Muir, and Hauser 2002).
Maurer’s studies suggested that some individual organisms (molluscs and polychaetes)
would be capable of migrating through 0.9 meters of overburden similar in sediment type
Appendix 4 – Braun
18
to their indigenous sediment (Maurer et al. 1978). Richardson et al (1977) reported that
most of the species that were not significantly affected by dredged material disposal were
active, motile species capable of recolonization by horizontal migration and burrowing up
through dredged material. They emphasized vertical migration as the principal means of
recolonization, which supports the conclusions of Maurer’s studies that under certain
conditions vertical migration is one of several mechanisms of recolonization operating at
disposal sites. Miller et al. (2002) also conducted burial testing of two polychaetes and a
gastropod. Experiments using the gastropod involved increments of thinner layers of
sediment (for example, four 5-cm layers at 2-hour intervals) in comparison with a layer
of the same thickness deposited at one time. These experiments showed that snails
emerge from the thin layers quickly enough to better tolerate incremental deposition.
Thus, total layer thickness in addition to the frequency of deposition has a role in the
snail’s tolerance to sedimentation. The burrowing polychaete (Marenzelleria viridis)
tested with changes of 5 cm had little effect on tube building and feeding. The sessile,
suspension-feeding polychaete (Sabellaria vulgaris) tested showed a lethal effect with 2
cm of deposition.
Results of the National Demonstration Program for Thin-layer Dredged Material
Disposal (Corps 1999) demonstrated that there was no evidence of thin-layer placement
causing total defaunation of any of the disposal areas. The response of the macrobenthic
community to thin-layer disposal is dependent upon the initial sedimentary characteristics
and thus the existing community type, the sedimentary characteristics of the dredged
material, and the time of the placement operation. At no time, however, did the thinlayer placement result in the total defaunation of the disposal area. Evidence of
migration upward through the thin layer of material was evident in all studies. In
addition, the environment of the newly placed dredged material was suitable for
recolonization by organisms migrating inward from adjacent areas as well as
recolonization through larval settlement and growth. Placement of dredged material with
different sedimentary characteristics from that of the disposal site may cause a shift in the
faunal composition. Depending upon the time of placement, recovery may be slow
initially, mediated by upward and inward migration of adult forms. This was evident
when placement was accomplished in the fall and total recovery was not noted until after
the spring larval recruitment event. Although the specific results of this demonstration
project cannot be applied to the MCR, the patterns and trends can provide a perspective
on the potential impacts that the proposed placement techniques at the MCR will have on
the benthic community.
5.3
Long-Term Impacts
Whereas the immediate impacts of dredged material disposal are expected to result in the
mortality of benthic organisms caused by material burying organisms as it hits the ocean
floor, the longer-term impacts on the benthic community can include changes in
substrate; sediment instability, and changes in hydrodynamic regimes. These physical
changes can result in long-term shifts in community structure.
Changes in substrate composition are likely to occur because the dredged material being
deposited at a disposal site may not match the existing substrate distribution. Several
studies have discussed the potential impacts to the benthic communities from these
Appendix 4 – Braun
19
substrate changes (Blanchard and Feder 2003; Flemer et al. 1997; Levings et al. 1985;
Maurer et al. 1986; Miller et al. 2002; Qian et al. 2003; Richardson, Carey, and Colegate
1977). As discussed above, the response of the macrobenthic community to disposal is
dependent upon the initial sedimentary characteristics and thus the existing community
type, the sedimentary characteristics of the dredged material, and the time of the
placement operation. Placement of dredged material with different sedimentary
characteristics from that of the disposal site may cause a shift in the faunal composition
and, depending upon the time of placement, recovery may be impacted (Corps 1999).
Dredge material disposal operations likely result in the formation of changes to existing
topography of the existing disposal site (e.g., mounding, berms, and swales). These
topographic modifications will affect the hydrodynamic regime in the area, which in turn
may influence the stability of the sediments and the type of benthic assemblages that are
able to recolonize the newly deposited dredged material (Flemer et al. 1997; Miller et al.
2002; Qian et al. 2003; Richardson et al. 1977; Corps 1999).
5.4
Site-Specific Impacts
This section reviews the results from investigations and evaluations conducted in the
immediate MCR area. Several reports relating to dredged material disposal site
designation and monitoring were reviewed (Allan 2002; Richardson et al. 1977;
Sternberg et al. 1977; Corps 2003, 1999, 1987). The best site-specific study and data on
the potential effects of dredged material disposal in shallow water at the mouth of the
Columbia River are presented by Richardson et al. (1977).
Experimental Site G Disposal Site Monitoring
The objectives of the Richardson et al. (1977) study were to identify and determine the
significance of physical, chemical, and biological factors that govern the rate at which
open-water dredged material disposal sites are colonized by benthic assemblages. One
aspect of the study was the monitoring and documentation of dredged material disposal at
Experimental Site G. From July 9, 1975 to August 26, 1975 approximately 600,000
cubic yards of sand was dredged from the mouth of the Columbia River and deposited at
Experimental Site G (located south of Disposal Site A and the south jetty in relatively
shallow water, 25 to 30 meters). The substrate prior to disposal was a well-sorted sand
(median phi ~ 3.0). The dredged material deposited on the experimental site was a
coarser sand than the ambient substrate with a higher percentage of 2.0-2.5 phi size
particles. The deposited material formed a circular deposit with a radius of 456 meters
and a maximum elevation of 1.5 meters above the ambient substrate (Sternberg et al.
1977).
The area in the disposal site was sampled three times prior to disposal and five times after
disposal. The station groups calculated from species abundance values were similar to
station groups derived from the external parameters that define the extent and magnitude
of the dredged material disposal. These data include Corps records on the disposal
operations, observations of pre-disposal and post-disposal bathymetry, and textural
analysis of pre- and post-disposal sediments.
Appendix 4 – Braun
20
The stations exposed to direct disposal of dredged material had significantly higher
diversity and evenness values and significantly lower density of macrofauna when
compared to unaffected stations. The significant differences in diversity and evenness
persisted for at least 8 months after disposal and the significant difference in density of
macrofauna persisted for the duration of the sampling program (10 months after
disposal). There was also a significant reduction in the abundance of 11 of the 33 most
abundant taxa at stations exposed to dredged material disposal when compared to
unaffected stations. In general, the species affected by dredged material disposal were
tube-dwelling polychaetes and amphipods and species that have limited ability to burrow
through the sediments (e.g., Spiophanes bombyx, Nothria iridescens, Pharphoxus
vigitegus, Eohaustorius sencillus, Ampelisca macrocephela, Amphiodia urtica). Many of
the species were primarily restricted to the inshore sand sediments south of the mouth of
the Columbia River. The species not affected by dredged material disposal were shelled
gastropods and molluscs (Olivella pycna, Olivella baetica, Olivella biplacata, Macoma
modesta alaskana), nontube-dwelling polychaetes (Magelona saculata, Haploscolopolos
elongates, Thalenessa spinosa), and cumacea (Diastylopsis dawsoni, Hemilamprops
californiensis). All of these species are active burrowers who migrated considerable
distances over the sediment. These species generally have a wide distribution and are
abundant on the Columbia River delta as well as south of the river.
The effects of dredged material disposal on benthos was probably related to direct burial
of benthos and changes in sediment characteristics, and not increased turbidity from the
disposal operations or introduction of pollutants or organic matter.
Repopulation of the benthos into the affected area was probably accomplished primarily
by benthos burrowing up through the dredged material, by passive advection, or active
migration into the area and, to a lesser extent, by reproduction and recruitment of benthos
from outside the affected area. There was very little evidence of transportation of benthic
infauna to the experimental disposal site via the dredged material.
5.5
Effects of Siltation on Razor Clams
Relatively little is known about environmental factors contributing to survival of razor
clams during the vulnerable larval and early juvenile stage of their life history. However,
Nickerson (1975) discussed the apparent effects of substrate and exposure on razor clam
survival and density. This study reports that in 1958 the Orca Inlet (popular razor clam
beach in Alaska) razor clam populations experienced heavy mortalities. The cause of the
mortalities was attributed by local clam diggers to heavy “siltation” from spring breakup
of the Copper River. Nickerson (1975) investigated the Copper River silt discharges and
concluded that “discharge of an inordinately large volume of clayey silt material along
the Copper River Delta during spring 1958 may well have occurred and may well have
been linked with the clam mortalities.” In this study, Nickerson attempted to determine
the relationship among razor clam densities, substrate, and tide level exposure. He used
the densities of 1- and 2-year-old clams as the density measure and examined several
beaches with high and low densities. He also collected and evaluated the substrate
distributions at each site. He found a relationship between density and the amount of clay
fractions within the top 4 inches of the substrate surface. Therefore, on the basis of this
correlation, he concluded that a critical region for lethal level of fine substrate particles
Appendix 4 – Braun
21
<0.005 mm in diameter may be approximately 2.2 percent of the total substrate
composition, and that levels of clay fractions in this proportion may cause suffocation in
early life stages of razor clams.
Based on the Nickerson (1975) study, other authors have extrapolated his conclusions to
raise concern over dredging activities near razor clam beaches (Lassuy and Simons
1989). The authors indicate that silt-generating activities should be avoided in the
vicinity of razor clam beaches, particularly during the time of setting, because juveniles
are susceptible to suffocation (Nickerson 1975; Lassuy and Simons 1989). No references
to the impacts of dredging in relation to juvenile razor clam suffocation and mortality are
raised by Nickerson (1975). Rather, his report states the “substrates containing 2.2
percent or more of clay fractions may cause mortalities in early life stages of razor
clams.” There have been no additional studies pertaining to dredging and disposal
activities directly offshore of razor clam beaches and there have been no evaluations of
potential disposal impacts (turbidity/siltation) in areas farther offshore in deeper waters
(e.g., >20 m). Thus, this remains a data gap. However, for the two phases of the
demonstration project, timing of the disposal activity should consider the razor clam life
history, in particular the timing of juvenile setting. In addition, data from the Corps
indicates that only 1.4% fines are contained in the maintenance dredge material that will
be used for the demonstration project. The distribution of clayey materials from the
dredged material should be monitored and evaluated. Based on the size of the proposed
phases of the demonstration projects (i.e., 30,000 and 150,000 cy), the amount of
potential deposition on the inshore intertidal beaches is assumed to be negligible and
unlikely to affect even the newly settled juveniles. Given the rates at which adults can
move up and down within the intertidal sands, it is also unlikely that the amount of or rate
of newly deposited material would impact adult razor clams.
6.0 Monitoring Program Design
The Columbia Nearshore Beneficial Use Project team has identified an iterative approach
to accomplishing the objective to rebuild the offshore sands and, in the long term, to
better protect the jetty from the impacts of waves. At a minimum, this approach will
involve a two-phase demonstration project. The purpose of this project is to demonstrate
and evaluate the technical feasibility, effectiveness, and environmental impacts of
dispersal methods likely to be used in the longer-term efforts to mitigate the erosion of
nearshore sands off the south jetty of the Columbia River. The proposed demonstration
is composed of a minimum of two phases, each with its own unique objectives. The
recommended monitoring program should address the objectives of each phase.
•
The first phase involves a small-scale (30,000 cubic yards) testing of the
enhanced dumping method of dispersal in summer 2005. The key objective of
this study is to determine the feasibility of “thin-layer” dispersal of dredged
sediments in the nearshore area.
•
For the subsequent demonstration (second phase), a larger volume (150,000 cubic
yards) of sediment would be dumped to determine the degree and direction of
migration of deposited sediments in the nearshore environment.
Appendix 4 – Braun
22
The following subsections describe the general proposed monitoring approach and
identify considerations that will need to be addressed in developing the final specific
monitoring plan. The details regarding specific monitoring methods/analyses to be used,
locations for control and treatment sites, timing of the monitoring, and other specific
monitoring issues will be addressed at a later date after review and discussion about the
general approach.
6.1
Proposed General Monitoring Approach
Monitoring plans should be developed using a tiered approach; simple techniques for
monitoring of physical characteristics occupy the lowest tier, while more complex
chemical monitoring techniques occupy higher tiers (Zeller and Wastler 1986).
Biological effects testing of oceanic processes occupy the highest tier. Work at the
higher tiers is undertaken only when the need is demonstrated by the results of
monitoring techniques at the lower tiers. Therefore, only the level of monitoring needed
to address specific management decisions is undertaken. Each monitoring plan addresses
the specific or unique aspects of a particular site and contains triggers, unacceptable
impacts, and indications for management action or additional testing depending on the
management needs (Zeller and Wastler 1986).
In the tiered approach, the decision rules indicating the need for further testing or
remedial action are to be defined in advance (Fredette et al. 1986; Fredette et al. 1990;
Segar and Stamman 1986). Specifying the decision rule alone is not enough. One should
also specify potential actions to be taken for the specific outcomes of applying the
decision rule to the monitoring results. In establishing tiers and triggers, concern for a
resource is not sufficient. Quantitative changes in the resource or other variables that
indicate an unacceptable impact are to be predefined and must be testable.
For the purpose of developing this plan, the null hypothesis to be tested is that regardless
of deposition depth, most of the benthic organisms living in the areas used for placement
will be destroyed. In fact, based on past studies at disposal sites at the MCR and
especially the type of organisms living in the high energy, nearshore areas, many
organisms are likely to survive disposal, and affected areas are expected to recolonize
following use. Unfortunately, given the large natural fluctuations in population
composition and density, it would be very expensive and difficult to conclusively
demonstrate this through classic impact monitoring studies. Instead, specialized studies
focused on determining the physical aspects of the demonstration project should be
implemented.
Tier 1. The focus for monitoring at this level should be on determining the physical
behavior of the disposed material in relation to the disposal techniques (“enhanced”
disposal versus traditional disposal) to determine whether the deposited material is
behaving as expected. This could generally be done by bathymetric surveys (highresolution multibeam) and use of the sediment profile camera in conjunction with
periodic sediment characterization. Collection and archiving of limited traditional
benthic community samples could also be a cost-effective approach to gathering the
maximum amount of data for the minimum cost.
Appendix 4 – Braun
23
The sediment profile imaging camera (SPI) was developed to address some of the
shortcomings of traditional benthic community sampling methodology. The SPI design
allows undisturbed in-situ profile images of the top 15 to 20 cm of sediment to be
obtained rapidly. In addition, organism-sediment relationships are preserved, and the
system is never affected by water turbidity, allowing images to be obtained anywhere.
Recent advances in understanding the dynamics of infaunal community structure have
lead to the development of a theory of image interpretation, making SPI a powerful
benthic sampling tool. Using SPI, one can deduce the dynamics of biological and
physical seafloor processes from imaged structures. Features such as sediment grain size,
depth of the apparent redox potential discontinuity, and infaunal successional stage can
be measured, mapped, and interpreted within a few weeks of the field work. The SPI
camera has been used extensively to monitor dredged material disposal sites throughout
the United States.
In addition to the physical and SPI monitoring at the specific disposal location, Oregon
Department of Fish and Wildlife should continue the annual razor clam population
monitoring that they are conducting on area beaches. This will assist in documenting any
changes tot eh razor clam fishery that may be related to the demonstration project.
Tier 2. Monitoring at this level can include more intensive physical or sediment
monitoring (limited chemistry and/or minimal biological monitoring) with the extent of
each component determined by the outcome of the Tier 1 activities.
Tiers 3 and 4. If necessary, these additional monitoring efforts could include intensive
studies directed at specific problems.
6.2
Issues to Consider when Developing Specific Monitoring Plan
Prior to implementation of the proposed demonstration project, the Columbia Nearshore
Beneficial Use Project team will need to identify a specific plan for assessing pre-and
post-project conditions for aquatic life and benthic organisms. While benthic organisms
(the smaller organisms living in the sediment of the nearshore environment) likely are
acclimated to rapid changes in sediment from natural wave and current action, they could
be affected by accumulations of sediment. Initially, the team will need to assess the
potential impacts to both aquatic life and the benthic community of thin-layer disposal in
the nearshore environment and answer a series of questions related to monitoring the
effects of the demonstration project on benthic organisms:
o What additional baseline information is needed to ensure proper postplacement evaluation?
o What are the ranges of natural sediment deposition/erosion events that the
existing community is adapted to?
o What rates and frequencies of sediment deposition/erosion are detrimental
to representative benthic species? What are the threshold/triggers?
o What is the best and most cost-effective way of measuring impacts to the
benthic community?
o What specific methods should be used to monitor impacts to the biological
community?
Appendix 4 – Braun
24
6.3
Monitoring Plan Details
(To be developed after further peer review and discussion.)
Methods/Analyses
Monitoring Locations
Timing
Data Gaps
7.0 Conclusions
Based on the overview of the general biology, diversity, distribution, and abundance of
benthic infauna found around the area of interest, and a review of the research regarding
known dredge and disposal impacts to local benthic infauna documented through
historical monitoring that is provided in this White Paper, the following conclusions can
be drawn:
•
•
•
•
The existing benthic community in the shallow area is adapted to sediment
deposition and instability.
Past monitoring of disposal impacts shows that vertical migration and horizontal
migration are main methods of recolonization; reduced abundances in disposal
areas generally occur for less than 1 year; and some larval recruitment occurs, but
is not the main mechanism in this environment.
Demonstration project disposal should not have a large impact on shallow benthic
community.
Long-term disposal in the nearshore area also should not have a large impact on
shallow benthic community.
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9.0 Appendices
Compiled tables of shallow water benthic data are provided in this section.
Appendix 4 – Braun
31
Figure 1.
Benthic Assemblages and Station Groups off the Mouth of the Columbia River
(Richardson et al. 1977)
Appendix 4 – Braun
32
Appendix 4 – Braun
33
No. Taxa 1992-1994
120
100
Station 12
Station 15
# Taxa
80
Station 32
60
Station 33
40
Station 39
Station 42
20
0
Jul-92
Jul-93
Jul-94
Date
Figure 3. Number of Taxa 1992 – 1994 (Hinton and Emmett)
Abundance 1992-1994
50,000
No. Individuals/m2
45,000
40,000
Station 12
Station 15
Station 32
Station 33
35,000
30,000
25,000
20,000
Station 39
Station 42
15,000
10,000
5,000
0
Jul-92
Jul-93
Jul-94
Date
Figure 4. Abundance of Benthic Invertebrates 1992 - 1994(Hinton and Emmett)
Appendix 4 – Braun
34
Diversity (H) 1992-1994
6
Diversity (H)
5
Station 12
Station 15
Station 32
Sttaion 33
Station 39
Station 42
4
3
2
1
0
Jul-92
Jul-93
Jul-94
Date
Figure 5. Diversity of Benthic Invertebrates 1992 – 1994 (Hinton and Emmett)
Equitability (E) 1992-1994
0.9
0.8
Equitability (E)
0.7
Station 12
Station 15
Station 32
Station 33
Station 39
0.6
0.5
0.4
0.3
Station 42
0.2
0.1
0
Jul-92
Jul-93
Jul-94
Date
Figure 6. Equitability of Benthic Invertebrates 1992 – 1994 (Hinton and Emmett)
Appendix 4 – Braun
35
No. Taxa
No. Taxa 1975-1976
South of South Jetty
60
50
40
30
20
10
0
M Apr- M JunS Oct- Nov- D Jan- F
ep- 75 75 ec- 76 eb- ar- 76 ay- 76
76
76 76
75
75
Station K11
Station K-16
Station K-18
Station K-22
Station K-26
Staiton K-31
Station K-7
Series8
Date
Figure 7. Number of Taxa 1975 – 1976 at locations South of the South Jetty (Richardson et al.
1977)
3500
3000
2500
2000
1500
1000
500
0
Se
p7
O 5
ct
-7
No 5
vDe 75
c7
Ja 5
n7
Fe 6
bM 76
ar
-7
Ap 6
rM 76
ay
-7
Ju 6
n76
Abundance (no./m2)
Abundance (no./m2) Sep 1975 - Jan 1976
South of South Jetty
Station K-11
Station K-16
Station K-18
Station K-22
Station K-26
Station K-31
Station K-7
Date
Figure 8. Abundance 1975 – 1976 at locations South of the South Jetty (Richardson et al.
1977)
Appendix 4 – Braun
36
No. T axa Dec 1974 - Jun 1976
South of South Jetty
60
Station
Station
Station
Station
Station
Station
Station
Station
50
No. Taxa
40
30
20
10
n-
76
6
Ju
r-7
76
Ap
b-
5
Fe
-7
ec
-7
5
D
ct
75
O
g-
Au
n-
75
5
Ju
r-7
Ap
bFe
D
ec
-7
4
75
0
R-24
R-27
R-28
R-31
R-33
R-1
R-10
R-29
Date
Figure 9. Number of Taxa 1974 – 1976 at locations South of the South Jetty (Richardson et al.
1977)
Abundance (no/m2) Dec 1974 - Jun 1976
South of South Jetty
Abundance (no/m2)
7000
6000
5000
4000
3000
2000
1000
D
ec
-7
Fe 4
b7
Ap 5
r-7
Ju 5
n7
Au 5
g7
O 5
ct
-7
De 5
c7
Fe 5
b7
Ap 6
r-7
Ju 6
n76
0
Station R-24
Station R-27
Station R-28
Station R-29
Station R-31
Station R-33
Station R-1
Station R-10
Date
Figure 10. Abundance 1974 – 1976 at locations South of the South Jetty (Richardson et
al. 1977)
Appendix 4 – Braun
37
5
Au
g75
O
ct
-7
5
D
ec
-7
5
Station R-12
Station R-11
Station R-13
Station R-20
Station R-21
Station R-22
Station R-23
Station R-25
Station R-26
Ju
n7
Ap
r-7
5
60
50
40
30
20
10
0
De
c74
Fe
b75
No. Taxa
No. Taxa Dec 1974 - Jan 1976
West of MCR
Date
Figure 11. Number of Taxa 1974 – 1976 at locations West of MCR (Richardson et al. 1977)
30000
25000
20000
Station R-12
15000
10000
Station R-13
Station R-20
Station R-21
Station R-22
Station R-23
Station R-25
Station R-26
Station R-11
Jan-76
Dec-75
Nov-75
Oct-75
Sep-75
Aug-75
Jul-75
Jun-75
May-75
Apr-75
Mar-75
Feb-75
Jan-75
5000
0
Dec-74
Abundance (no/m2)
Abundance (no/m2) Dec 1974 - Jan 1976
West of MCR
Date
Figure 12. Abundance 1974 – 1976 at locations West of MCR (Richardson et al. 1977)
Appendix 4 – Braun
38
Figure 13. Distribution of the Pacific razor clam in the Pacific Northwest Region
(Lassuy and Simons 1989)
Appendix 4 – Braun
39
Table 1. Benthic Studies Included in Shallow Water Assessment.
Reference
Richardson et al. 1977
Number of
shallow water
Sites (<30 m)
Number of
shallow
water
samples
Year Sampled
Number of Sites in Study
Number of Samples
1974, 1975, 1976
12 Cruises
25 stations for distribution
and density, 20 stations for
benthic assemblages
2190 total
1657 infauna
74
1974
5
6 replicates
2
Sanborn 1975
Reporting
Information
Navigation
Sampling Gear/Screen size
171
Del Norte &
LORAN A
Smith McIntyre (0.1m2)
1.0 mm screen
Density, diversity
equitability, SR,
Cluster analysis
4
Visual and
Van Veen grab (0.2m2)
Density
compass
1.0 mm screen
at each station
Hinton and Emmett 1994
1992
51 infauna
45 infauna singles
30 replicates at 6 stations
26
26
GPS
Gray O'Hara Box Core (0.1 m2)
0.5 mm screen
Density diversity
Cluster analysis
Emmett and Hinton 1995
1993
28
140
6
6
GPS
Gray O'Hara Box Core (0.1 m2)
0.5 mm screen
Density diversity
Cluster analysis
Hinton and Emmett 1996
1994
29
145
6
6
GPS
Gray O'Hara Box Core (0.1 m2)
0.5 mm screen
Density diversity
equitability
Cluster analysis
1995, 1996
39
Five replicates
for 75 samples
11
25
GPS
Gray O'Hara Box Core (0.1 m2)
0.5 mm screen
Density diversity
equitability
Cluster analysis
Hinton 1998
Appendix 4 – Braun
40
Table 2. Benthic Indices
1974 - 1976 Richardson et al.
1992 - 1996 Hinton and Emmett
Appendix 4 – Braun
Mean
SD
# Taxa
33
11
# /m2
1,716
3,997
H'
3.0
0.9
E
0.6
0.2
Mean
SD
69
20
22,538
35,967
3.3
0.9
0.5
0.2
41
Table 3. Dominant Taxa at Inshore Stations 1974-1994 (based on Cluster Groupings)
Date of Study
Cluster "name"
Study
Station Sample Date
Richardson et. al. 1977
1974-1976
R-21
Apr-75
Sanborn 1975
April - August 1974
10
1974
discrete site
Richardson et. al. 1977
1974-1976
R-11
Jun-75
Richardson et. al. 1977
1974-1976
R-12
Jun-75
Richardson et. al. 1977
1974-1976
R-23
Jun-75
Richardson et. al. 1977
1974-1976
R-22
Dec-74
Hinton 1998
Oct/Nov 1995, June 1996
1
10/31/1995
A (1,7,11)
Hinton and Emmett, March 1996 Aug 1994 Study
39
8/9/1994
39, 54 (G)
Emmett and Hinton, Oct 1995
July 1993 Study
39
7/20/1993
39,54 (E)
Richardson et. al. 1977
1974-1976
R-13
Apr-75
Richardson et. al. 1977
1974-1976
K-18
Jan-76
F3
Richardson et. al. 1977
1974-1976
D1
1974-1976 D1 (59, 121, 124, 125)
Richardson et. al. 1977
1974-1976
K-7
Apr-76
F4
Richardson et. al. 1977
1974-1976
R-13
Dec-74
Sanborn 1975
April - August 1974
7
1974
discrete site
Richardson et. al. 1977
1974-1976
R-11
Sep-75
Richardson et. al. 1977
1974-1976
D2
1974-1976
D2 (25 stations)
Hinton and Emmett, March 1996 Aug 1994 Study
12
8/8/1994
12,15 (E)
Hinton and Emmett, Oct 1994
July 1992 Study
3
7/15/1992
2,3,7,8,10,13-15
Hinton and Emmett, Oct 1994
July 1992 Study
5
7/20/1992
5,9,31
Hinton and Emmett, Oct 1994
July 1992 Study
21
7/20/1992
20,21
Richardson et. al. 1977
1974-1976
K-16
Jun-76
F5
Richardson et. al. 1977
1974-1976
R-13
Jun-75
Richardson et. al. 1977
1974-1976
R-22
Sep-75
Richardson et. al. 1977
1974-1976
R-25
Sep-75
Richardson et. al. 1977
1974-1976
R-13
Sep-75
Richardson et. al. 1977
1974-1976
R-22
Jun-75
Richardson et. al. 1977
1974-1976
R-26
Jun-75
Richardson et. al. 1977
1974-1976
R-26
Sep-75
Hinton and Emmett, Oct 1994
July 1992 Study
51
7/22/1992
16,51
Richardson et. al. 1977
1974-1976
111
1974-1976
E (5 stations)
1 dominant
Archeomysis grebnitzkii*
Diastylopsis dawsoni
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Diastylopsis spp.
Diastylopsis spp.
Diastylopsis tenuis
Lamprops sp #1*
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata*
Mandibulophoxus uncirostratus
Olivella biplicata*
Olivella pycna
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Paraphoxus obtusidens major
Siliqua patula*
Siliqua patula*
Siliqua patula*
Siliqua patula*
Siliqua patula*
Siliqua patula*
Siliqua patula*
Siliqua spp.
Spio filicornis
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Hinton and Emmett, Oct 1994
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Hinton 1998
Hinton 1998
Richardson et. al. 1977
Hinton and Emmett, Oct 1994
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Hinton 1998
Spio filicornis*
Spio filicornis*
Spio filicornis*
Spiochaetopterus costarum
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx*
Spiophanes bombyx*
Spiophanes bombyx*
Spiophanes bombyx*
Spiophanes bombyx*
Spiophanes bombyx*
Spiromoellaria quadrae
Appendix 4 – Braun
1974-1976
1974-1976
1974-1976
July 1992 Study
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
Oct/Nov 1995, June 1996
Oct/Nov 1995, June 1996
1974-1976
July 1992 Study
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
1974-1976
Oct/Nov 1995, June 1996
R-21
R-12
R-21
12
C1
K-16
K-1
K-16
K-9
K-11
K-11
R-19
R-24
R-24
K-11
1
2
R-19
22
R-1
R-20
R-23
R-24
R-24
R-24
4
Jun-75
Sep-75
Dec-74
7/20/1992
1974-1976
Oct-75
Sep-75
Sep-75
Sep-75
Oct-75
Jan-76
Jan-76
Oct-75
Apr-76
Jun-76
6/3/1996
6/3/1996
Jun-75
7/20/1992
Sep-75
Jun-75
Jan-76
Jun-75
Sep-75
Jan-76
10/31/1995
C1 (11 stations)
F2
H1
F1
G1
G2
G3
I3
I2
I4
I5
A (1,4,7,37ABC)
B (2,5,8,11,12)
fig C40
22,23,27,42,43,50
B (4)
2 dominant
Paraphoxus obtusidens major*
Olivella baetica
Anisogammarus confervicolus*
Spio filicornis*
Spiophanes bombyx*
Paraphoxus obtusidens
Monoculodes spinipes*
Siliqua patula*
Magelona sacculata
Owenia fusiformis
Diastylopsis spp.
Diastylopsis dawsoni*
Chaetozone setosa
Olivella pycna
Paraphoxus obtusidens major
Spiophanes bombyx
Diastylopsis tenuis
Prionospio lighti
Monoculodes spinipes*
Paraphoxus obtusidens major
Archeomysis grebnitzkii
Chaetozone setosa
Paraphoxus obtusidens
Spio filicornis*
Magelona sacculata
Diastylopsis tenuis
Siliqua spp.
Siliqua spp.
Spiochaetopterus costarum
Spiophanes bombyx
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Spio filicornis*
Monoculodes spinipes
Nephtys californienses*
Diastylopsis dawsoni
Diastylopsis dawsoni
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Paraphoxus milleri*
Owenia fusiformis
Hippomedon denticulatus
Dendraster excentricus
Mandibulophoxus uncirostratus
Eteone sp # 6, Capitellidae sp # 1,
Nemertea sp # 5*
Archeomysis grebnitzkii*
Siliqua patula*
42
3 dominant
Spiophanes bombyx
Eohaustorius sencillus
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Owenia fusiformis
Paraphoxus obtusidens major
Spiochaetopterus costarum
Magelona sacculata*
Owenia fusiformis
Magelona sacculata
Chaetozone setosa
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Paraphoxus obtusidens major
Rhepoxynius vigitegus
Tellina spp.
Magelona sacculata
Chaetozone spinosa
Mytilidae
Photis macinerneyi
Table
Table 4.
4. Dominant
DominantBenthic
BenthicInvertebrates
Invertebratesfrom
fromInshore
InshoreStations
Stations1974-1996
1974-1994
Nemertea
Nemertea sp # 5
Polychaeta
Capitellidae sp # 1
Chaetozone setosa
Chaetozone spinosa
Eteone sp # 6
Magelona sacculata
Nephtys californienses*
Prionospio lighti
Owenia fusiformis
Spio filicornis
Spiochaetopterus costarum
Spiophanes bombyx
Mollusca
Olivella biplicata*
Olivella pycna
Siliqua patula*
Siliqua spp.
Spiromoellaria quadrae
Tellina spp.
Crustacea
Anisogammarus confervicolus*
Archeomysis grebnitzkii*
Diastylopsis dawsoni
Diastylopsis spp.
Diastylopsis tenuis
Eohaustorius sencillus
Hippomedon denticulatus
Lamprops sp #1*
Mandibulophoxus uncirostratus
Mytilidae
Monoculodes spinipes*
Paraphoxus milleri*
Paraphoxus obtusidens
Paraphoxus obtusidens major
Photis macinerneyi
Rhepoxynius vigitegus
Echinodermata
Dendraster excentricus
Appendix 4 – Braun
43
APPENDIX A
Appendix 4 – Braun
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Sample
Date
Station
3
7/15/1992
4
7/15/1992
5
7/20/1992
Re
f
Depth
(m)
24.1
14.9
27.4
Depth
(ft)
79
49
90
Latitud
e
46 23.0
46 23.0
46 22.0
Longitud
e
124 8.0
124 6.0
124 10.0
Numbe
r of
Taxa
80
NA
119
#
indv/m2
74,680
NA
43,702
Std
Dev
Study
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Date of Study
Jul-92
Jul-92
Jul-92
Hinton and Emmett, Oct 1994
Jul-92
7
7/20/1992
26.2
86
46 21.0
124 10.0
70
34,490
3
Hinton and Emmett, Oct 1994
Jul-92
8
7/20/1992
20.1
66
46 21.0
124 8.0
68
77,962
2.22
Hinton and Emmett, Oct 1994
Jul-92
9
7/20/1992
13.7
45
46 21.0
124 6.0
97
79,744
Hinton and Emmett, Oct 1994
Jul-92
10
7/20/1992
14
46
46 20.0
124 6.0
57
103,283
Hinton and Emmett, Oct 1994
Jul-92
12
7/20/1992
36.6
120
46 19.0
124 12.0
75
29,780
2.89
Hinton and Emmett, Oct 1994
Jul-92
13
7/20/1992
26.8
88
46 19.0
124 10.0
68
68,261
2.41
Hinton and Emmett, Oct 1994
Jul-92
14
7/20/1992
20.7
68
46 19.0
124 8.0
70
64,323
1.72
Hinton and Emmett, Oct 1994
Jul-92
15
7/20/1992
13.1
43
46 19.0
124 6.0
68
152,455
1.86
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Jul-92
Jul-92
17
21
7/20/1992
7/20/1992
13.4
27.4
44
90
46 18.0
46 17.0
124 6.5
124 10.0
NA
54
NA
11,868
Hinton and Emmett, Oct 1994
Jul-92
22
7/20/1992
98
14
1
13.4
44
46 17.0
124 8.0
49
8,617
2.3
Hinton and Emmett, Oct 1994
Jul-92
23
7/20/1992
10.7
35
46 17.0
124 6.5
42
3,730
3.49
Hinton and Emmett, Oct 1994
Jul-92
26
7/20/1992
20.4
67
46 16.0
124 10.0
83
13,846
Hinton and Emmett, Oct 1994
Jul-92
27
7/20/1992
11.3
37
46 16.0
124 0.8
47
6,638
Hinton and Emmett, Oct 1994
Jul-92
32
7/27/1992
21
69
46 15.0
124 10.0
63
6,556
Hinton and Emmett, Oct 1994
Jul-92
33
7/27/1992
14
9
10
1
10
2
10
3
94
13.4
44
46 15.0
124 9.0
11
844
2.28
Hinton and Emmett, Oct 1994
Jul-92
38
7/27/1992
16.5
54
46 14.3
124 10.7
35
2,813
3.41
Hinton and Emmett, Oct 1994
Jul-92
39
7/27/1992
11
7
64
21
69
46 14.0
124 9.5
37
6,247
3.67
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Jul-92
Jul-92
42
43
7/22/1992
7/22/1992
58
59
25.9
16.2
85
53
46 12.0
46 12.0
124 6.5
124 2.5
47
32
4,679
11,129
3.36
1.34
Hinton and Emmett, Oct 1994
Jul-92
47
7/22/1992
60
16.5
54
46 9.0
124 0.5
66
37,043
2.45
Appendix 4 – Braun
15
1
15
2
NA
8,541
46,19
3
NA
4,304
H'
2.56
NA
2.98
1.96
1.92
NA
4.01
2.68
2.74
1,377
3.55
E
0.4
NA
0.4
3
0.4
9
0.3
6
0.3
0.3
3
0.4
6
0.4
0.2
8
0.3
1
NA
0.7
0.4
1
0.6
5
0.4
2
0.4
9
0.5
9
0.6
6
0.6
6
0.7
1
0.6
0.2
7
0.4
1
Median
Grain
(mm)
0.11
0.12
0.1
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
3.3
0.5
1.6
0.9
9.1
0.9
Classification
Silty Sand
Silty Sand
Silty Sand
0.1
4.2
0.8
Silty Sand
0.13
2.5
0.7
Silty Sand
0.14
1.1
0.8
0.1
3.6
1.1
Poorly graded sand with
silt
Silty Sand
20.7
Silty Sand
0.09
8.8
1
Silty Sand
0.12
5.5
0.5
Silty Sand
0.13
1.8
0.7
Silty Sand
0.12
0.09
0.4
18.4
0.7
1.3
Silty Sand
Silty Sand
0.15
0.4
0.6
Silty Sand
0.17
0.3
4.3
Silty Sand
0.1
2.6
0.8
Silty Sand
0.16
0.5
0.7
0.12
9.3
1
Poorly graded sand with
silt
Silty Sand
0.15
3.4
0.8
0.21
1.2
0.6
0.21
4.5
0.6
0.17
0.18
0.5
0.4
0.5
0.6
Poorly graded sand with
silt
Poorly graded sand
Poorly graded sand
0.12
0.5
0.3
Silty Sand
A-1
Poorly graded sand with
silt
Poorly graded sand
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Sample
Date
Station
50
7/22/1992
Re
f
50
Depth
(m)
27.7
Depth
(ft)
91
Latitud
e
46 6.0
Longitud
e
124 1.0
Numbe
r of
Taxa
71
#
indv/m2
13,202
61
13.7
45
46 6.0
123 58.5
64
165,105
Std
Dev
Study
Hinton and Emmett, Oct 1994
Date of Study
Jul-92
Hinton and Emmett, Oct 1994
Jul-92
51
7/22/1992
Emmett and Hinton, Oct 1995
Jul-93
12
7/19/1993
23.5
77
46 18.98
124 8.98
89
13,171
7,645
2.7
Emmett and Hinton, Oct 1995
Jul-93
15
7/19/1993
12.2
40
46 18.98
124 6.00
80
3,239
942
4.8
Emmett and Hinton, Oct 1995
Jul-93
32
7/19/1993
20.4
67
46 15.02
124 10.03
107
7,613
1,950
4.17
Emmett and Hinton, Oct 1995
Jul-93
33
7/19/1993
13.7
45
46 15.00
124 9.00
79
5,145
1,406
4.71
Emmett and Hinton, Oct 1995
Jul-93
39
7/20/1993
22.2
73
46 14.00
124 9.46
81
5,937
1,214
4.14
Emmett and Hinton, Oct 1995
Jul-93
42
7/21/1993
25.9
85
46 12.03
124 6.47
65
1,392
318
4.74
Aug 1994
12
8/8/1994
24.7
81
46 18.98
124 8.98
81
7,857
3,227
2.01
Aug 1994
15
8/8/1994
12.8
42
46 18.98
124 6.00
73
10,395
2.13
Aug 1994
32
8/8/1994
23.2
76
46 15.02
124 10.03
69
6,416
11,20
4
2,726
3.61
Aug 1994
33
8/9/1994
14.6
48
46 15.00
124 9.00
72
2,748
509
4.45
Aug 1994
39
8/9/1994
23.2
76
46 14.00
124 9.46
55
47,034
1.81
Aug 1994
42
8/10/1994
25
82
46 12.03
124 6.47
73
2,299
24,10
3
521
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
1
10/31/199
5
6/3/1996
15.2
50
46 24.00
124 6.50
56
1,861
380
4.56
15.2
50
46 24.00
124 6.50
49
1,884
325
4.02
10/31/199
5
6/3/1996
25.3
83
46 24.00
124 9.50
86
8,855
3,244
3.13
25.3
83
46 24.00
124 9.50
96
6,363
1,131
3.91
10/31/199
5
6/3/1996
14.3
47
46 22.00
124 6.50
58
4,304
2,053
3.72
14.3
47
46 22.00
124 6.50
48
2,238
428
3.74
10/31/199
5
6/3/1996
24.7
81
46 22.00
124 9.50
85
13,886
4,072
2.9
24.7
81
46 22.00
124 9.50
88
7,638
1,648
3.97
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Appendix 4 – Braun
1
2
2
4
4
5
5
H'
3.91
1.99
3.68
E
0.6
4
0.3
3
0.4
2
0.7
6
0.6
2
0.7
5
0.6
5
0.7
9
0.3
2
0.3
4
0.5
9
0.7
2
0.3
1
0.5
9
0.7
9
0.7
2
0.4
9
0.5
9
0.6
3
0.6
7
0.4
5
0.6
1
Median
Grain
(mm)
0.13
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
0.4
0.6
Silty Sand
0.12
0.3
0.7
Silty Sand
0.1
11.7
0.8
Silty Sand
0.13
3.4
0.7
Silty Sand
0.08
36.3
3.3
Silty Sand
0.14
7.3
1
0.13
36.4
3.4
0.17
1.7
0.6
0.1
9.1
0.6
Poorly graded sand with
silt
Silty Sand
0.11
6.5
0.7
Silty Sand
0.11
12
0.7
Silty Sand
0.15
5.9
0.9
0.06
50.9
1.6
Poorly graded sand with
silt
Silty Sand
0.21
1.6
0.7
0.130
3
0.6
Poorly graded sand with
silt
Fine Sand
0.120
5.2
0.6
Fine Sand
0.120
6.3
0.7
Fine Sand
0.110
6.9
0.7
Fine Sand
0.130
4.6
0.7
Fine Sand
0.120
6.6
0.9
Fine Sand
0.110
9.9
0.6
Fine Sand
0.110
12.7
0.7
Fine Sand
A-2
Poorly graded sand with
silt
Silty Sand
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Study
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Date of Study
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Oct 1995, June
1996
Depth
(m)
16.5
Depth
(ft)
54
Latitud
e
46 20.00
Longitud
e
124 7.00
Numbe
r of
Taxa
65
#
indv/m2
3,751
Std
Dev
1,080
H'
3.78
16.5
54
46 20.00
124 7.00
53
2,440
488
3.75
10/31/199
5
6/3/1996
28
92
46 20.00
124 10.75
89
12,840
2,818
3.25
28
92
46 20.00
124 10.75
106
7,442
771
4.48
10/31/199
5
6/5/1996
19.5
64
46 18.00
124 8.25
65
3,616
641
4.33
19.5
64
46 18.00
124 8.25
80
4,983
1,306
3.7
12
10/31/199
5
28.3
93
46 18.00
124 10.00
100
10,660
1,147
3.8
12
6/5/1996
28.3
93
46 18.00
124 10.00
89
5,062
1,117
4.29
37A
6/5/1996
15.2
50
46 17.00
124 8.44
55
2,209
567
4.00
37B
6/6/1996
15.2
50
46 16.00
124 9.69
64
3,034
264
4.11
37C
6/6/1996
15.2
50
46 15.00
124 9.41
54
2,255
501
3.97
Sample
Date
Station
7
10/31/199
5
7
6/3/1996
8
8
11
11
Re
f
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
50
51
Dec-74
Dec-74
18-29
18-29
45
36
392
496
4.628
4.155
Richardson et. al. 1977
1974-1976
58
Dec-74
18-29
32
362
4.037
Richardson et. al. 1977
1974-1976
59
Dec-74
16-26
19
230
3.363
Richardson et. al. 1977
1974-1976
61
Dec-74
18-29
27
604
3.721
Richardson et. al. 1977
1974-1976
62
Dec-74
13-27
22
518
2.576
Richardson et. al. 1977
1974-1976
63
Dec-74
13-27
22
328
2.945
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
77
79
Dec-74
Dec-74
13-27
13-27
16
12
220
360
2.453
1.793
Richardson et. al. 1977
1974-1976
80
Dec-74
13-27
25
262
2.991
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
81
83
Dec-74
Dec-74
13-27
13-27
21
20
348
346
2.392
2.835
Appendix 4 – Braun
E
0.6
3
0.6
5
0.5
0.6
7
0.7
2
0.5
8
0.5
7
0.6
6
0.6
9
0.6
9
0.6
9
0.8
4
0.8
0.8
1
0.7
9
0.7
8
0.5
8
0.6
6
0.6
1
0.5
0.6
4
0.5
5
0.6
Median
Grain
(mm)
0.120
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
6.3
0.6
Fine Sand
0.110
8.6
0.7
Fine Sand
0.110
6.9
0.7
Fine Sand
0.110
10.7
0.6
Fine Sand
0.120
5.0
1.0
Fine Sand
0.100
9.5
1.0
Fine Sand
0.096
10.2
0.9
Fine Sand
0.092
17.0
1.2
Fine Sand
0.140
4.3
0.4
Fine Sand
0.120
4.8
0.8
Fine Sand
0.160
6.5
0.7
Fine Sand
A-3
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Station
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
86
92
Dec-74
Dec-74
13-27
13-27
20
25
244
780
2.428
1.872
Richardson et. al. 1977
1974-1976
93
Dec-74
13-27
28
394
3.634
Richardson et. al. 1977
1974-1976
94
Dec-74
13-27
25
264
3.619
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
102
104
Dec-74
Dec-74
13-27
18-29
23
38
678
366
3.189
4.208
Richardson et. al. 1977
1974-1976
105
Dec-74
18-29
48
520
4.324
Richardson et. al. 1977
1974-1976
106
Dec-74
18-29
38
504
4.133
Richardson et. al. 1977
1974-1976
107
Dec-74
18-29
34
458
4.017
Richardson et. al. 1977
1974-1976
111
Dec-74
13-20
29
826
2.678
Richardson et. al. 1977
1974-1976
113
Dec-74
13-20
12
94
2.938
Richardson et. al. 1977
1974-1976
114
Dec-74
13-20
21
280
3.595
Richardson et. al. 1977
1974-1976
119
Dec-74
13-27
22
280
3.173
Richardson et. al. 1977
1974-1976
122
Dec-74
18-29
35
560
3.488
Richardson et. al. 1977
1974-1976
123
Dec-74
18-29
29
334
3.334
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
124
125
Dec-74
Dec-74
16-26
16-26
21
14
340
218
2.702
3.026
Richardson et. al. 1977
1974-1976
128
Dec-74
13-27
36
380
3.983
Richardson et. al. 1977
1974-1976
129
Dec-74
13-27
23
254
3.245
Richardson et. al. 1977
1974-1976
130
Dec-74
13-27
22
280
3.18
Richardson et. al. 1977
1974-1976
131
Dec-74
13-27
19
250
3.156
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
132
133
Dec-74
Dec-74
13-27
13-27
23
23
406
496
2.914
2.272
Appendix 4 – Braun
Depth
(m)
Depth
(ft)
Latitud
e
Longitud
e
#
indv/m2
Date of Study
Study
Re
f
Numbe
r of
Taxa
Sample
Date
Std
Dev
H'
E
6
0.5
6
0.4
0.7
6
0.7
8
0.7
1
0.8
0.7
7
0.7
9
0.7
9
0.5
5
0.8
2
0.8
2
0.7
1
0.6
8
0.6
9
0.6
2
0.8
0.7
7
0.7
2
0.7
1
0.7
4
0.6
4
0.5
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
A-4
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Station
Richardson et. al. 1977
1974-1976
134
Dec-74
13-27
24
246
3.062
Richardson et. al. 1977
1974-1976
135
13-27
36
324
Richardson et. al. 1977
1974-1976
C1
Richardson et. al. 1977
1974-1976
D1
Richardson et. al. 1977
1974-1976
D2
Dec-74
19741976
19741976
19741976
4.198
3.334.6
2.73.36
1.794.2
Richardson et. al. 1977
1974-1976
K-1
Sep-75
Richardson et. al. 1977
1974-1976
K-11
Sep-75
Richardson et. al. 1977
1974-1976
K-11
Oct-75
Richardson et. al. 1977
1974-1976
K-11
Jan-76
Richardson et. al. 1977
1974-1976
K-11
Apr-76
Richardson et. al. 1977
1974-1976
K-11
Jun-76
Richardson et. al. 1977
1974-1976
K-14
Sep-75
Richardson et. al. 1977
1974-1976
K-16
Sep-75
Richardson et. al. 1977
1974-1976
K-16
Oct-75
Richardson et. al. 1977
1974-1976
K-16
Apr-76
Richardson et. al. 1977
1974-1976
K-16
Jun-76
Richardson et. al. 1977
1974-1976
K-18
Sep-75
Richardson et. al. 1977
1974-1976
K-18
Oct-75
Richardson et. al. 1977
1974-1976
K-18
Jan-76
Richardson et. al. 1977
1974-1976
K-18
Apr-76
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
K-18
K-20
Jun-76
Sep-75
Appendix 4 – Braun
22
3
23
0
31
0
33
2
36
8
39
1
23
8
24
6
31
2
36
9
38
6
24
8
31
3
33
5
37
0
38
7
24
Depth
(m)
Depth
(ft)
Latitud
e
Longitud
e
#
indv/m2
Date of Study
Study
Re
f
Numbe
r of
Taxa
Sample
Date
18-29
<96
334-888
16-26
<90
196-340
13-27
<90
220-780
Std
Dev
H'
E
0.6
7
0.8
1
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
Sand
Sand
Sand
25-30
46 11.25
124 06.33
44
2968
1.803
25-30
46 11.68
124 05.76
43
2918
1.653
25-30
46 11.68
124 05.76
29
1406
1.89
25-30
46 11.68
124 05.76
28
526
3.073
25-30
46 11.68
124 05.76
30
308
4.14
25-30
46 11.68
124 05.76
44
896
3.997
25-30
46 11.59
124 06.22
41
1380
2.559
0.3
3
0.3
1
0.3
9
0.6
4
0.8
4
0.7
3
0.4
8
25-30
46 11.56
124 06.02
40
752
3.749
0.7
25-30
46 11.56
124 06.02
22
242
3.578
25-30
46 11.56
124 06.02
26
286
3.874
25-30
46 11.56
124 06.02
39
488
3.785
0.8
0.8
2
0.7
2
25-30
46 11.58
124 05.88
49
1472
3.03
25-30
46 11.58
124 05.88
22
396
3.078
25-30
46 11.58
124 05.88
19
222
3.155
25-30
46 11.58
124 05.88
25
198
3.709
25-30
25-30
46 11.58
46 11.60
124 05.88
124 05.58
34
40
496
3092
3.933
1.543
0.5
0.6
9
0.7
4
0.8
0.7
7
0.2
A-5
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
K-22
Sep-75
Richardson et. al. 1977
1974-1976
K-22
Oct-75
Richardson et. al. 1977
1974-1976
K-22
Jan-76
Richardson et. al. 1977
1974-1976
K-22
Apr-76
Richardson et. al. 1977
1974-1976
K-22
Jun-76
Richardson et. al. 1977
1974-1976
K-26
Sep-75
Richardson et. al. 1977
1974-1976
K-26
Oct-75
Richardson et. al. 1977
1974-1976
K-26
Jan-76
Richardson et. al. 1977
1974-1976
K-26
Apr-76
Richardson et. al. 1977
1974-1976
K-26
Jun-76
Richardson et. al. 1977
1974-1976
K-27
Sep-75
Richardson et. al. 1977
1974-1976
K-28
Sep-75
Richardson et. al. 1977
1974-1976
K-31
Sep-75
Richardson et. al. 1977
1974-1976
K-31
Oct-75
Richardson et. al. 1977
1974-1976
K-31
Jan-76
Richardson et. al. 1977
1974-1976
K-31
Apr-76
Richardson et. al. 1977
1974-1976
K-31
Jun-76
Richardson et. al. 1977
1974-1976
K-34
Sep-75
Richardson et. al. 1977
1974-1976
K-36
Sep-75
Richardson et. al. 1977
1974-1976
K-38
Sep-75
Richardson et. al. 1977
1974-1976
K-40
Sep-75
Study
Appendix 4 – Braun
Re
f
0
25
1
31
5
34
3
37
1
38
5
24
2
31
6
33
6
37
2
38
9
24
1
25
3
25
6
31
9
34
5
37
3
38
4
25
9
26
6
26
4
26
2
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
25-30
46 11.47
124 06.24
48
1464
2.738
25-30
46 11.47
124 06.24
29
422
3.189
25-30
46 11.47
124 06.24
25
202
3.735
25-30
46 11.47
124 06.24
28
302
4.078
25-30
46 11.47
124 06.24
37
754
3.698
25-30
46 11.55
124 05.76
46
2970
1.883
25-30
46 11.55
124 05.76
33
1348
2.049
25-30
46 11.55
124 05.76
23
338
3.464
25-30
46 11.55
124 05.76
28
278
4.149
25-30
46 11.55
124 05.76
43
712
4.105
25-30
46 11.54
124 05.62
43
3892
1.567
25-30
46 11.43
124 06.36
52
3070
2.252
25-30
46 11.45
124 06.00
41
660
3.844
25-30
46 11.45
124 06.00
25
370
3.168
25-30
46 11.45
124 06.00
22
148
3.165
0.4
0.7
2
0.6
8
0.7
1
25-30
46 11.45
124 06.00
30
228
3.901
0.8
25-30
46 11.45
124 06.00
40
642
3.708
25-30
46 11.45
124 05.77
52
3378
1.741
25-30
46 11.33
124 06.26
57
3950
2.064
25-30
46 11.35
124 05.99
42
2350
2.409
25-30
46 11.35
124 05.66
49
3338
1.921
0.7
0.3
1
0.3
5
0.4
5
0.3
4
Depth
(m)
Depth
(ft)
Std
Dev
H'
E
9
0.4
9
0.6
6
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
0.8
0.8
5
0.7
1
0.3
4
0.4
1
0.7
7
0.8
6
0.7
6
0.2
9
A-6
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
K-5
Sep-75
Richardson et. al. 1977
1974-1976
K-7
Sep-75
Richardson et. al. 1977
1974-1976
K-7
Oct-75
Richardson et. al. 1977
1974-1976
K-7
Jan-76
Richardson et. al. 1977
1974-1976
K-7
Apr-76
Richardson et. al. 1977
1974-1976
K-7
Jun-76
Richardson et. al. 1977
1974-1976
K-9
Sep-75
Richardson et. al. 1977
1974-1976
R-1
Dec-74
Richardson et. al. 1977
1974-1976
R-1
Apr-75
Richardson et. al. 1977
1974-1976
R-1
Jun-75
Richardson et. al. 1977
1974-1976
R-1
Sep-75
Richardson et. al. 1977
1974-1976
R-1
Jan-76
Richardson et. al. 1977
1974-1976
R-10
Dec-74
Richardson et. al. 1977
1974-1976
R-10
Apr-75
Richardson et. al. 1977
1974-1976
R-10
Jun-75
Richardson et. al. 1977
1974-1976
R-10
Sep-75
Richardson et. al. 1977
1974-1976
R-10
Jan-76
Richardson et. al. 1977
1974-1976
R-11
Dec-74
Richardson et. al. 1977
1974-1976
R-11
Apr-75
Richardson et. al. 1977
1974-1976
R-11
Jun-75
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
R-11
R-12
Sep-75
Dec-74
Study
Appendix 4 – Braun
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
25-30
46 11.77
124 05.65
37
2308
1.692
25-30
46 11.64
124 06.50
50
2708
2.002
25-30
46 11.64
124 06.50
33
932
2.591
25-30
46 11.64
124 06.50
19
350
2.966
25-30
46 11.64
124 06.50
24
176
4.07
25-30
46 11.64
124 06.50
39
750
3.847
25-30
46 11.67
124 05.98
42
1196
3.188
17-20
46 09.0
124 00.5
34
544
3.768
17-20
46 09.0
124 00.5
26
578
3.728
17-20
46 09.0
124 00.5
39
800
4.12
17-20
46 09.0
124 00.5
39
3118
1.934
17-20
46 09.0
124 00.5
23
606
2.858
15-17
46 12.0
124 02.5
19
230
3.363
15-17
46 12.0
124 02.5
25
234
4.062
15-17
46 12.0
124 02.5
30
478
3.968
15-17
46 12.0
124 02.5
37
892
2.676
15-17
46 12.0
124 02.5
22
344
3.56
11-13
46 15.5
124 07.5
18
208
3.452
11-13
46 15.5
124 07.5
22
374
3.647
11-13
46 15.5
124 07.5
35
1500
3.028
11-13
15-16
46 15.5
46 15.2
124 07.5
124 09.4
36
22
2786
234
1.9
2.789
Re
f
22
8
23
4
30
8
33
0
36
7
38
8
23
2
Depth
(m)
60
16
3
20
6
27
1
34
9
59
16
4
20
3
27
2
34
8
11
5
17
3
18
5
27
3
11
Depth
(ft)
Std
Dev
H'
E
0.3
3
0.3
6
0.5
1
0.7
0.8
9
0.7
3
0.5
9
0.7
4
0.7
9
0.7
8
0.3
7
0.6
3
0.7
9
0.8
8
0.8
1
0.5
1
0.8
0.8
3
0.8
2
0.5
9
0.3
7
0.6
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
2.03
sand
2.84
sand
1.78
sand
1.24
sand
2.31
sand
1.21
sand
NS
sand
1.12
sand
1.15
sand
1.23
sand
3.65
sand
1.21
sand
5.27
sand
1.33
1.73
sand
sand
A-7
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
R-12
Apr-75
Richardson et. al. 1977
1974-1976
R-12
Jun-75
Richardson et. al. 1977
1974-1976
R-12
Sep-75
Richardson et. al. 1977
1974-1976
R-12
Jan-76
Richardson et. al. 1977
1974-1976
R-13
Dec-74
Richardson et. al. 1977
1974-1976
R-13
Apr-75
Richardson et. al. 1977
1974-1976
R-13
Jun-75
Richardson et. al. 1977
1974-1976
R-13
Sep-75
Richardson et. al. 1977
1974-1976
R-19
Jun-75
Richardson et. al. 1977
1974-1976
R-19
Sep-75
Richardson et. al. 1977
1974-1976
R-19
Jan-76
Richardson et. al. 1977
1974-1976
R-20
Dec-74
Richardson et. al. 1977
1974-1976
R-20
Apr-75
Richardson et. al. 1977
1974-1976
R-20
Jun-75
Richardson et. al. 1977
1974-1976
R-20
Sep-75
Richardson et. al. 1977
1974-1976
R-20
Jan-76
Richardson et. al. 1977
1974-1976
R-21
Dec-74
Richardson et. al. 1977
1974-1976
R-21
Apr-75
Richardson et. al. 1977
1974-1976
R-21
Jun-75
Richardson et. al. 1977
1974-1976
R-21
Sep-75
84
17
9
19
0
27
8
19
7
23
6
35
6
12
1
16
7
19
6
22
2
34
7
11
2
15
8
18
4
28
3
Richardson et. al. 1977
1974-1976
R-22
Dec-74
91
Study
Appendix 4 – Braun
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
15-16
46 15.2
124 09.4
26
644
3.159
15-16
46 15.2
124 09.4
42
2128
2.88
15-16
46 15.2
124 09.4
35
2896
2.11
15-16
46 15.2
124 09.4
25
218
3.677
18-20
46 14.0
124 09.0
20
398
2.729
18-20
46 14.0
124 09.0
35
8968
1.273
18-20
46 14.0
124 09.0
38
7826
1.388
18-20
46 14.0
124 09.0
26
1580
2.448
25-30
46 11.7
124 06.3
52
820
4.513
25-30
46 11.7
124 06.3
45
2714
1.532
25-30
46 11.7
124 06.3
29
750
3.071
22-24
46 12.5
124 06.5
16
196
3.232
22-24
46 12.5
124 06.5
30
194
4.345
22-24
46 12.5
124 06.5
35
556
3.731
22-24
46 12.5
124 06.5
36
1682
1.952
22-24
46 12.5
124 06.5
14
184
2.56
17-21
46 14.5
124 05.6
22
580
1.855
17-21
46 14.5
124 05.6
23
300
3.739
17-21
46 14.5
124 05.6
16
832
2.355
17-21
46 14.5
124 05.6
14
56
3.611
E
3
0.6
7
0.5
4
0.4
1
0.7
9
0.6
3
0.2
5
0.2
7
0.5
2
0.7
9
0.2
8
0.6
3
0.8
1
0.8
9
0.7
3
0.3
8
0.6
7
0.4
2
0.8
3
0.5
9
0.9
5
22-33
46 14.5
124 10.0
40
20488
0.518
0.1
Re
f
6
17
4
19
1
28
2
36
6
Depth
(m)
Depth
(ft)
Std
Dev
H'
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
2.15
sand
8.13
sand
4.13
sand
2.12
sand
3.46
sand
14.91
sand
87.75
clayey silt
39.28
silty sand
1.06
sand
1.02
sand
5.16
sand
1.14
sand
0.97
sand
1.63
sand
1.32
sand
16.91
silty sand
6.95
sand
stratified sand with silt and
clay
10.82
A-8
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
R-22
Apr-75
Richardson et. al. 1977
1974-1976
R-22
Jun-75
Richardson et. al. 1977
1974-1976
R-22
Sep-75
Richardson et. al. 1977
1974-1976
R-22
Jan-76
Richardson et. al. 1977
1974-1976
R-23
Dec-74
Richardson et. al. 1977
1974-1976
R-23
Apr-75
Richardson et. al. 1977
1974-1976
R-23
Jun-75
Richardson et. al. 1977
1974-1976
R-23
Sep-75
Richardson et. al. 1977
1974-1976
R-23
Jan-76
Richardson et. al. 1977
1974-1976
R-24
Dec-74
Richardson et. al. 1977
1974-1976
R-24
Apr-75
Richardson et. al. 1977
1974-1976
R-24
Jun-75
Richardson et. al. 1977
1974-1976
R-24
Sep-75
Richardson et. al. 1977
1974-1976
R-24
Oct-75
Richardson et. al. 1977
1974-1976
R-24
Jan-76
Richardson et. al. 1977
1974-1976
R-24
Apr-76
Richardson et. al. 1977
1974-1976
R-24
Jun-76
Richardson et. al. 1977
1974-1976
R-25
Dec-74
Richardson et. al. 1977
1974-1976
R-25
Apr-75
Richardson et. al. 1977
1974-1976
R-25
Jun-75
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
R-25
R-26
Sep-75
Dec-74
Study
Appendix 4 – Braun
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
22-33
46 14.5
124 10.0
45
43802
0.172
22-33
46 14.5
124 10.0
41
14556
2.378
22-33
46 14.5
124 10.0
23
2266
1.593
22-33
46 14.5
124 10.0
28
716
2.618
27-31
46 18.0
124 10.0
46
1126
4.104
27-31
46 18.0
124 10.0
50
1086
4.328
27-31
46 18.0
124 10.0
52
2802
3.428
27-31
46 18.0
124 10.0
43
4392
2.222
27-31
46 18.0
124 10.0
36
910
3.759
24-27
46 11.0
124 05.0
29
334
3.334
24-27
46 11.0
124 05.0
33
348
4.335
24-27
46 11.0
124 05.0
42
802
4.215
24-27
46 11.0
124 05.0
46
2692
2.075
25-30
46 11.0
124 05.0
34
2242
1.587
24-27
46 11.0
124 05.0
33
978
2.033
25-30
46 11.0
124 05.0
49
1654
2.73
25-30
46 11.0
124 05.0
47
1446
3.382
15-18
46 13.9
124 08.0
22
302
2.702
15-18
46 13.9
124 08.0
37
1144
3.362
15-18
46 13.9
124 08.0
42
9454
1.267
15-18
20-22
46 13.9
46 14.0
124 08.0
124 09.5
36
27
3126
562
2.75
2.862
Re
f
17
7
19
4
27
9
36
2
14
5
16
8
21
5
28
7
36
5
12
3
16
5
20
2
26
8
30
0
35
3
37
4
38
1
Depth
(m)
82
18
0
18
6
27
4
85
Depth
(ft)
Std
Dev
H'
E
0.0
3
0.4
4
0.3
5
0.5
5
0.7
4
0.7
7
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
11.69
silty sand
76.69
sandy silt
27.4
silty sand
14.01
sand
29.23
silty sand
19.39
silty sand
0.6
0.4
1
0.7
3
0.6
9
0.8
6
0.7
8
0.3
8
0.3
1
17.06
silty sand
26.99
silty sand
10.13
silty sand
1.75
sand
1.51
sand
1.68
sand
1.68
sand
0.4
0.4
9
0.6
1
0.6
1
0.6
2
0.2
4
0.5
3
0.6
1.73
sand
1.66
sand
3.54
sand
28.22
silty sand
38.22
1.34
silty sand
sand
A-9
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
R-26
Apr-75
Richardson et. al. 1977
1974-1976
R-26
Jun-75
Richardson et. al. 1977
1974-1976
R-26
Sep-75
Richardson et. al. 1977
1974-1976
R-27
Jun-75
Richardson et. al. 1977
1974-1976
R-27
Sep-75
Richardson et. al. 1977
1974-1976
R-27
Oct-75
Richardson et. al. 1977
1974-1976
R-27
Apr-76
Richardson et. al. 1977
1974-1976
R-27
Jun-76
Richardson et. al. 1977
1974-1976
R-28
Jun-75
Richardson et. al. 1977
1974-1976
R-28
Sep-75
Richardson et. al. 1977
1974-1976
R-28
Oct-75
Richardson et. al. 1977
1974-1976
R-28
Jan-76
Richardson et. al. 1977
1974-1976
R-28
Apr-76
Richardson et. al. 1977
1974-1976
R-28
Jun-76
Richardson et. al. 1977
1974-1976
R-29
Jun-75
Richardson et. al. 1977
1974-1976
R-29
Sep-75
Richardson et. al. 1977
1974-1976
R-29
Oct-75
Richardson et. al. 1977
1974-1976
R-31
Jun-75
Richardson et. al. 1977
1974-1976
R-31
Sep-75
Richardson et. al. 1977
1974-1976
R-31
Oct-75
Richardson et. al. 1977
Richardson et. al. 1977
1974-1976
1974-1976
R-31
R-31
Jan-76
Apr-76
Study
Appendix 4 – Braun
Re
f
17
8
18
9
27
7
19
9
24
9
29
9
37
8
38
3
20
4
26
9
30
2
35
2
37
5
38
0
20
5
27
0
30
3
20
1
26
1
29
8
35
4
37
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
20-22
46 14.0
124 09.5
26
2368
1.383
20-22
46 14.0
124 09.5
34
2346
1.895
20-22
46 14.0
124 09.5
27
2894
1.761
25-30
46 11.50
124 06.00
47
942
4.232
25-30
46 11.50
124 06.00
39
572
4.067
25-30
46 11.50
124 06.00
24
270
3.544
25-30
46 11.50
124 06.00
23
168
4.017
25-30
46 11.50
124 06.00
40
748
3.694
25-30
46 10.00
124 04.00
40
970
3.068
25-30
46 10.00
124 04.00
46
4362
1.42
25-30
46 10.00
124 04.00
36
3648
1.313
E
0.2
9
0.3
7
0.3
7
0.7
6
0.7
7
0.7
7
0.8
9
0.6
9
0.5
8
0.2
6
0.2
5
25-30
46 10.00
124 04.00
34
1588
2.038
0.4
25-30
46 10.00
124 04.00
45
2088
2.211
25-30
46 10.00
124 04.00
43
968
3.97
25-30
46 09.00
124 03.50
40
1188
2.753
25-30
46 09.00
124 03.50
51
6950
1.197
25-30
46 09.00
124 03.50
44
4202
1.292
25-30
46 11.50
124 05.50
37
626
3.818
25-30
46 11.50
124 05.50
50
3306
1.937
0.4
0.7
3
0.5
2
0.2
1
0.2
4
0.7
3
0.3
4
25-30
46 11.50
124 05.50
41
2428
1.599
25-30
25-30
46 11.50
46 11.50
124 05.50
124 05.50
33
42
1618
908
1.802
3.056
Depth
(m)
Depth
(ft)
Std
Dev
H'
0.3
0.3
6
0.5
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
16.1
sand
45.09
silty sand
52.37
silty sand
1404.8
2640.5
A-10
Table A-1. Benthic Invertebrate Samples at Mouth of Columbia River with depth <30m (98 ft)
Date of Study
Station
Sample
Date
Richardson et. al. 1977
1974-1976
R-31
Jun-76
Richardson et. al. 1977
1974-1976
R-32
Jun-75
Richardson et. al. 1977
1974-1976
R-32
Sep-75
Richardson et. al. 1977
1974-1976
R-33
Jun-75
Richardson et. al. 1977
1974-1976
R-33
Sep-75
Richardson et. al. 1977
1974-1976
R-33
Oct-75
Richardson et. al. 1977
1974-1976
R-33
Jan-76
Richardson et. al. 1977
1974-1976
R-33
Apr-76
Richardson et. al. 1977
Sanborn 1975
Sanborn 1975
1974-1976
Apr-Aug 1974
Apr-Aug 1974
R-33
7
10
Jun-76
1974
1974
Study
Latitud
e
Longitud
e
Numbe
r of
Taxa
#
indv/m2
25-30
46 11.50
124 05.50
52
1286
4.108
25-30
46 11.70
124 06.00
46
874
3.815
25-30
46 11.70
124 06.00
43
2586
1.581
25-30
46 11.25
124 06.00
47
876
4.079
25-30
46 11.25
124 06.00
57
3736
1.816
25-30
46 11.25
124 06.00
36
1246
2.517
25-30
46 11.25
124 06.00
33
554
3.241
25-30
46 11.25
124 06.00
39
746
3.844
46 11.25
124 06.00
54
17
39
1182
328
1,130
4.304
Depth
(m)
25-30
<30
Depth
(ft)
<90
<125?
Std
Dev
H'
Cluster "name"
2,3,7,8,10,13-15
1 dominant
Owenia fusiformis
2 dominant
Siliqua spp.
3 dominant
Spiophanes bombyx
Avg #
/m2
77,210
5,9,31
2,3,7,8,10,13-15
2,3,7,8,10,13-15
5,9,31
2,3,7,8,10,13-15
Siliqua spp.
Siliqua spp.
Siliqua spp.
Siliqua spp.
Siliqua spp.
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Owenia fusiformis
56,639
77,210
77,210
56,639
77,210
19,946
2,3,7,8,10,13-15
2,3,7,8,10,13-15
2,3,7,8,10,13-15
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Spiochaetopterus
costarum
Owenia fusiformis
Owenia fusiformis
Owenia fusiformis
Siliqua spp.
Siliqua spp.
Siliqua spp.
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
77,210
77,210
77,210
20,21
Owenia fusiformis
Spiophanes bombyx
15,093
22
22,23,27,42,43,50
Spiophanes bombyx
Chaetozone spinosa
7,999
23
22,23,27,42,43,50
Spiophanes bombyx
Spiochaetopterus
costarum
Spiochaetopterus
costarum
Spiochaetopterus
costarum
Chaetozone spinosa
7,999
Study
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Station
3
4
5
7
8
9
10
12
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
13
14
15
17
21
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Appendix 4 – Braun
Re
f
6
38
2
19
8
22
6
20
0
26
7
29
7
34
6
37
7
39
0
E
7
0.7
2
0.6
9
0.2
9
0.7
3
0.3
1
0.4
9
0.6
4
0.7
3
0.7
5
Median
Grain
(mm)
Silt/Clay Volatil
(%
e Solids
Fines)
(%)
Classification
2111
Fine Sand
Fine Sand
A-11
Study
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Station
Cluster "name"
26
27
22,23,27,42,43,50
1 dominant
2 dominant
3 dominant
Avg #
/m2
Spiophanes bombyx
Spiochaetopterus
costarum
Chaetozone spinosa
7,999
Spiochaetopterus
costarum
Spiochaetopterus
costarum
Chaetozone spinosa
7,999
Chaetozone spinosa
7,999
Chaetozone spinosa
7,999
Dendraster excentricus
267,28
3
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
32
33
38
39
42
22,23,27,42,43,50
Spiophanes bombyx
Hinton and Emmett, Oct 1994
43
22,23,27,42,43,50
Spiophanes bombyx
Hinton and Emmett, Oct 1994
Hinton and Emmett, Oct 1994
47
50
22,23,27,42,43,50
Spiophanes bombyx
Hinton and Emmett, Oct 1994
51
16,51
Siliqua spp.
Spiochaetopterus
costarum
Owenia fusiformis
Emmett and Hinton, Oct 1995
Emmett and Hinton, Oct 1995
Emmett and Hinton, Oct 1995
Emmett and Hinton, Oct 1995
Emmett and Hinton, Oct 1995
Emmett and Hinton, Oct 1995
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton and Emmett, March
1996
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
12
15
32
33
39
42
12
39,54 (E)
Diastylopsis tenuis
Diastylopsis spp.
Prionospio lighti
6,538
12,15 (E)
Owenia fusiformis
Diastylopsis tenuis
Diastylopsis dawsoni
9,126
12,15 (E)
Owenia fusiformis
Diastylopsis tenuis
Diastylopsis dawsoni
9,126
39, 54 (G)
Diastylopsis spp.
Owenia fusiformis
Diastylopsis tenuis
47,663
A
A
Diastylopsis spp.
Spiophanes bombyx
Magelona sacculata
Magelona sacculata
Spiophanes bombyx
Rhepoxynius vigitegus
3,076
2,344
B
B
A
Spiophanes bombyx
Spiromoellaria quadrae
Spiophanes bombyx
Owenia fusiformis
Mytilidae
Magelona sacculata
Tellina spp.
Photis macinerneyi
Rhepoxynius vigitegus
6,297
4,304
2,344
B
A
A
Spiophanes bombyx
Diastylopsis spp.
Spiophanes bombyx
Owenia fusiformis
Magelona sacculata
Magelona sacculata
Tellina spp.
Spiophanes bombyx
Rhepoxynius vigitegus
6,297
3,076
2,344
B
Spiophanes bombyx
Owenia fusiformis
Tellina spp.
6,297
Appendix 4 – Braun
15
32
33
39
42
1
1
2
2
4
4
5
5
7
7
8
8
A-12
Study
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Hinton 1998
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Station
11
11
12
12
37A
37B
37C
50
51
58
59
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
61
62
63
77
79
80
81
83
86
92
93
94
102
104
105
106
107
111
113
114
119
122
123
124
Richardson et. al. 1977
125
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
128
129
130
131
132
133
134
Appendix 4 – Braun
Cluster "name"
A
B
1 dominant
Diastylopsis spp.
Spiophanes bombyx
2 dominant
Magelona sacculata
Owenia fusiformis
3 dominant
Spiophanes bombyx
Tellina spp.
Avg #
/m2
3,076
6,297
B
A
A
A
C1 (11 stations)
C1 (11 stations)
C1 (11 stations)
D1 (59, 121, 124,
125)
C1 (11 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
C1 (11 stations)
C1 (11 stations)
C1 (11 stations)
C1 (11 stations)
E (5 stations)
E (5 stations)
E (5 stations)
D2 (25 stations)
C1 (11 stations)
C1 (11 stations)
D1 (59, 121, 124,
125)
D1 (59, 121, 124,
125)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
D2 (25 stations)
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Owenia fusiformis
Magelona sacculata
Magelona sacculata
Magelona sacculata
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Olivella pycna
Tellina spp.
Rhepoxynius vigitegus
Rhepoxynius vigitegus
Rhepoxynius vigitegus
Magelona sacculata
Magelona sacculata
Magelona sacculata
Archeomysis grebnitzkii
6,297
2,344
2,344
2,344
467
467
467
246
Spiophanes bombyx
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spio filicornis
Spio filicornis
Spio filicornis
Olivella pycna
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Eohaustorius sencillus
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Hippomedon denticulatus
Hippomedon denticulatus
Hippomedon denticulatus
Magelona sacculata
Eohaustorius sencillus
Eohaustorius sencillus
Olivella pycna
Magelona sacculata
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Mandibulophoxus uncirostratus
Mandibulophoxus uncirostratus
Mandibulophoxus uncirostratus
Diastylopsis dawsoni
Magelona sacculata
Magelona sacculata
Archeomysis grebnitzkii
467
366
366
366
366
366
366
366
366
366
366
366
366
467
467
467
467
378
378
378
366
467
467
246
Magelona sacculata
Olivella pycna
Archeomysis grebnitzkii
246
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Olivella pycna
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
366
366
366
366
366
366
366
A-13
Study
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Station
Cluster "name"
135
D2 (25 stations)
C1
C1 (11 stations)
D1
D1 (59, 121, 124,
125)
D2
D2 (25 stations)
K-1
H1
K-11 H1
K-11 G2
K-11 G3
K-11 F4
1 dominant
Olivella pycna
Spiophanes bombyx
Magelona sacculata
2 dominant
Magelona sacculata
Eohaustorius sencillus
Olivella pycna
3 dominant
Diastylopsis dawsoni
Magelona sacculata
Archeomysis grebnitzkii
Avg #
/m2
366
467
246
Olivella pycna
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Chaetozone setosa
366
3385
3385
1233
473
243
Paraphoxus obtusidens major
Diastylopsis dawsoni
Diastylopsis dawsoni
Chaetozone setosa
Chaetozone setosa
1156
1572
661
340
243
Magelona sacculata
656
Magelona sacculata
Magelona sacculata
Chaetozone setosa
Paraphoxus obtusidens
major
Spiophanes bombyx
Diastylopsis dawsoni
Chaetozone setosa
Paraphoxus obtusidens major
Chaetozone setosa
1572
340
231
243
Magelona sacculata
656
Magelona sacculata
Magelona sacculata
Magelona sacculata
Chaetozone setosa
Paraphoxus obtusidens
major
Spiophanes bombyx
Diastylopsis dawsoni
Diastylopsis dawsoni
Chaetozone setosa
Paraphoxus obtusidens major
Chaetozone setosa
3385
1572
340
231
243
Magelona sacculata
656
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Chaetozone setosa
3385
1233
473
243
Magelona sacculata
656
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Chaetozone setosa
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Chaetozone setosa
Paraphoxus obtusidens major
3385
3385
661
340
231
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-11
K-14
K-16
K-16
K-16
I5
G1
F1
F2
F4
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Richardson et. al. 1977
K-16
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-18
K-18
K-18
K-18
G1
F2
F3
F4
Paraphoxus obtusidens
major
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Magelona sacculata
Richardson et. al. 1977
K-18
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-20
K-22
K-22
K-22
K-22
H1
G1
F2
F3
F4
Richardson et. al. 1977
K-22
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-26
K-26
K-26
K-26
H1
G2
G3
F4
Richardson et. al. 1977
K-26
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-27
K-28
K-31
K-31
K-31
H1
H1
F1
F2
F3
Appendix 4 – Braun
Paraphoxus obtusidens
major
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
A-14
Study
Richardson et. al. 1977
Station
Cluster "name"
K-31 F4
Richardson et. al. 1977
K-31
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-34
K-36
K-38
K-40
K-5
K-7
K-7
K-7
K-7
H1
H1
G1
H1
H1
H1
G2
F3
F4
Richardson et. al. 1977
K-7
F5
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
K-9
R-1
R-1
R-1
R-1
R-1
R-10
R-10
R-10
R-10
R-10
R-11
R-11
R-11
G1
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-11
R-12
R-12
R-12
R-12
R-12
R-13
R-13
R-13
R-13
R-19
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-19
R-19
R-20
Appendix 4 – Braun
1 dominant
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Avg #
/m2
243
2 dominant
Paraphoxus obtusidens
major
Spiophanes bombyx
3 dominant
Chaetozone setosa
Magelona sacculata
656
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Chaetozone setosa
Paraphoxus obtusidens
major
Spiophanes bombyx
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Diastylopsis dawsoni
Eohaustorius sencillus
Paraphoxus obtusidens major
Chaetozone setosa
3385
3385
1572
3385
3385
3385
1233
231
243
Magelona sacculata
656
Magelona sacculata
Diastylopsis dawsoni
1572
Spiophanes bombyx*
Magelona sacculata*
Spiophanes bombyx*
Magelona sacculata*
Diastylopsis dawsoni*
Olivella biplicata*
Anisogammarus
confervicolus*
Spio filicornis*
Diastylopsis dawsoni*
Spio filicornis*
Spio filicornis*
Siliqua patula*
Siliqua patula*
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Monoculodes spinipes*
Paraphexus milleri*
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
887
Diastylopsis dawsoni
Eohaustorius sencillus
3385
1234
fig C40
Magelona sacculata*
Lamprops sp #1*
Siliqua patula*
Siliqua patula*
Spiophanes bombyx
H1
I3
Spiophanes bombyx
Spiophanes bombyx
Monoculodes spinipes*
Nephtys californienses*
A-15
Study
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Station
R-20
R-20
R-20
R-20
R-21
R-21
Richardson et. al. 1977
R-21
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-21
R-22
R-22
R-22
R-22
R-22
R-23
R-23
R-23
R-23
R-23
R-24
R-24
R-24
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Cluster "name"
1 dominant
2 dominant
Avg #
/m2
Spiophanes bombyx*
Spiophanes bombyx*
Spio filicornis*
Archeomysis
grebnitzkii*
Spio filicornis*
Paraphoxus obtusidens
major*
Archeomysis grebnitzkii* Eteone sp # 6, Capitellidae sp #
1, Nemertea sp # 5*
Diastylopsis dawsoni*
Siliqua patula*
Siliqua patula*
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Diastylopsis dawsoni*
Spiophanes bombyx*
Spiophanes bombyx*
Spiophanes bombyx*
fig C40
Spiophanes bombyx*
R-24
R-24
R-24
R-24
R-24
R-25
R-25
R-25
R-25
R-26
R-26
R-26
R-26
R-27
H1
I2
I3
I4
I5
Spiophanes bombyx*
Spiophanes bombyx
Spiophanes bombyx*
Spiophanes bombyx
Spiophanes bombyx
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Siliqua patula*
Siliqua patula*
Diastylopsis dawsoni*
Spio filicornis*
fig C40
Siliqua patula*
Siliqua patula*
Spiophanes bombyx
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-27
R-27
R-27
F1
F2
F4
Spiophanes bombyx
Spiophanes bombyx
Magelona sacculata
Richardson et. al. 1977
R-27
F5
Richardson et. al. 1977
R-28
fig C40
Paraphoxus obtusidens
major
Spiophanes bombyx
Appendix 4 – Braun
3 dominant
Magelona sacculata
887
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Paraphoxus obtusidens major
3385
3130
1234
1349
1156
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Spiophanes bombyx
Magelona sacculata
887
Diastylopsis dawsoni
Chaetozone setosa
Chaetozone setosa
661
340
243
Magelona sacculata
656
Paraphoxus obtusidens
Magelona sacculata
887
A-16
Study
Station
Cluster "name"
1 dominant
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-28
R-28
R-28
R-28
R-28
R-29
H1
I2
I3
I4
I5
fig C40
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-29
R-29
R-31
H1
I2
fig C40
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
R-31
R-31
R-31
R-31
R-31
R-32
H1
I2
I3
I4
I5
fig C40
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Richardson et. al. 1977
Richardson et. al. 1977
R-32
R-33
H1
fig C40
Spiophanes bombyx
Spiophanes bombyx
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Richardson et. al. 1977
Sanborn 1975
R-33
R-33
R-33
R-33
R-33
7
H1
G2
G3
I4
I5
discrete site
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Spiophanes bombyx
Mandibulophoxus
uncirostratus
Diastylopsis dawsoni
2 dominant
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphoxus obtusidens
major
Magelona sacculata
Paraphoxus obtusidens
major
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Magelona sacculata
Paraphexus obtusidens
Sanborn 1975
10
discrete site
Olivella baetica
Notes:
E = Equitability (E) from Hinton and Emmett studies and Eveness (JPR2) from Richardson et al. 1977.
H' = Diversity (H) from Hinton and Emmett studies and Diversity (HPR2) from Richardson et al 1977.
Latitude and Longitude are in degrees decimal minutes
Ref. = This is a reference number for the same station, different sample. Hinton and Emmett Oct 1994 references
a DMRP for certain stations. Richardson et al 1977 uses multiple sample numbers at the same station over time.
Appendix 4 – Braun
3 dominant
Avg #
/m2
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Paraphoxus obtusidens major
Magelona sacculata
3385
3130
1234
1349
1156
887
Diastylopsis dawsoni
Eohaustorius sencillus
Magelona sacculata
3385
3130
887
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Paraphoxus obtusidens major
Magelona sacculata
3385
3130
1234
1349
1156
887
Diastylopsis dawsoni
Magelona sacculata
3385
887
Diastylopsis dawsoni
Eohaustorius sencillus
Eohaustorius sencillus
Eohaustorius sencillus
Paraphoxus obtusidens major
Monoculodes spinipes
3385
1233
473
1349
1156
328
Paraphexus obtusidens
1,130
A-17