METHODS
Sampling Design
Sampling stations were located within a 300-ft study corridor aligned with the proposed
WBB location (Figure 1). In the field a differential global positioning system (DGPS) was used
to navigate the survey vessel to the pre-plotted station locations. Temperature, conductivity, and
dissolved oxygen (DO) were measured near bottom with a portable Hydrolab to determine if
anomalous temperature, salinity, or dissolved oxygen conditions existed during field surveys.
Hypoxic (DO < 2.0 mg/L) conditions were not detected during the field surveys. Physical
parameters at each station are presented in Table 1.
Table 1. Depth, salinity, and dissolved oxygen (DO) concentration at benthic stations in Wolf Bay, November 2
Depth
Salinity
DO
Depth
Salinity
DO
Station
Station
ft
ppt
mg/L
ft
ppt
mg
1-B1
4.0
10.97
5.54
7-B
15.4
21.14
4.3
1-S
0.7
10.46
5.93
7-M
7.6
11.18
6.8
2-B
8.6
11.23
5.12
7-S
0.3
10.83
7.6
2-M
4.3
10.78
7.37
8-B
1.5
10.94
7.6
2-S
0.5
10.67
7.66
9-B
4.0
11.13
7.8
3-B
14.2
20.57
4.31
9-S
0.3
10.96
7.8
3-M
6.5
11.06
7.07
10-B
8.6
11.18
6.0
3-S
0.4
10.81
7.66
10-M
4.5
10.77
7.3
4-B
1.8
11.01
7.77
10-S
0.4
10.70
7.5
5-B
4.7
11.03
6.17
11-B
4.2
10.98
4.6
5-S
0.4
10.50
6.32
11-S
0.5
10.46
5.4
6-B
8.7
11.62
5.05
12-B
11.5
17.76
4.3
6-M
4.2
10.75
7.23
12-M
5.3
11.05
7.1
6-S
0.6
10.63
7.53
12-S
0.5
10.82
7.5
1
Key: B=bottom; M=mid-column; S=surface
1
Figure 1. Station locations for the November 2007 benthic survey in Wolf Bay
2
Sediments
A sample (about 250 grams) of sediment for grain size analyses and total organic carbon
(TOC) was removed from one grab sample per station, placed in a labeled plastic bag, and stored
on ice. In the laboratory, grain size analyses were conducted using combined sieve and
hydrometer methods according to recommended American Society for Testing Materials
(ASTM) procedures. Samples were washed in demineralized water, dried, and weighed. Coarse
and fine fractions (sand/silt) were separated by sieving through a U.S. Standard Sieve Mesh No.
230 (62.5 µm). Sediment texture of the coarse fraction was determined at 0.5-phi intervals by
passing sediment through nested sieves. Weight of materials collected in each particle size class
was recorded. Boyocouse hydrometer analyses were used to analyze the fine fraction (<62.5
µm). Percentages of gravel, sand, silt, and clay were recorded for each sample. TOC was
measured by drying a sediment sample of at least 5 g wet-weight at 60 °C for 48 hours. The dry
weight was then recorded. Dried sediments were then transferred to a porcelain mortar and
ground with a pestle. Approximately 20 to 30 mg of the dried and ground sediment was then
placed into a small glass beaker and acidified to remove inorganic fragments, and then was dried
for an additional 2 hr at 100 °C. Sediments were then combusted at ~ 950 °C and exposed to a
pre-combusted stream of oxygen. The CO2 evolved was measured by an infrared gas analyzer
and compared to a standard curve to convert to organic carbon.
Infauna
Three replicate samples were collected at each station using a petite Ponar benthic grab
(0.023 m2). Sample contents were sieved through a 0.5-mm sieve for macroinfaunal analyses.
Infauna were preserved in 10% formalin with rose bengal stain. In the laboratory, organisms
were identified and counted to lowest practical identification level (LPIL).
Univariate summary statistics including number of taxa, number of individuals, density,
Shannon’s index of diversity (H’), Pielou’s index of evenness (J’), and Margalef’s index of
species richness (D) were calculated for each replicate. Station means of these summary
statistics were then calculated based on the three station replicates.
Spatial patterns in the macroinfaunal assemblage were examined using multivariate cluster
analysis. The cluster analysis was performed on a similarity matrix constructed from a raw data
matrix consisting of taxa and samples (station replicates). To weight the contributions of
common and rare taxa, raw counts of each taxon in a sample (n) were transformed to logarithms
[log10 (n+1)] prior to similarity analysis. Species accounting for observed assemblage
differences among groups and within groups of samples determined by normal cluster analysis
were identified using a similarity percentage breakdown (SIMPER) procedure. SIMPER
determines the average contribution of each species to characterizing a sample group or
discriminating between pairs of sample groups that are resolved by multivariate technique such
as cluster analysis. These analyses (cluster analysis, SIMPER) were performed with PRIMER
v5 software.
3
RESULTS
Sedimentary Habitat
Sediments at shallower stations nearest the northern (Stations 4, 8, and 9) and southern (Stations
1, 5, and 11) shorelines had sand bottoms. Stations in deeper water had greater amounts of silt
and clay, with over 90% at Stations 2 and 6. Percent TOC was greatest at stations with the
highest amounts of silt and clay (Table 2).
Table x. results of sediment analysis for Stations 1 through 12, sampled 11-2-07 at Wolf Bay.
% Fines
Station
% Sand
% Gravel
Description
% TOC
(silt+clay)
1
92.05
7.95
0.00
Sand
0.09
2
7.23
92.77
0.00
Mud
3.17
3
43.32
55.16
1.52 Sandy mud
1.12
4
95.99
3.98
0.03
Sand
0.08
5
94.95
4.89
0.15
Sand
0.16
6
2.77
97.23
0.00
Mud
2.90
7
19.39
80.32
0.28 Sandy mud
0.79
8
93.63
6.37
0.00
Sand
0.08
9
94.92
5.08
0.00
Sand
0.06
10
60.85
39.06
0.09 Sandy mud
2.99
11
95.79
4.21
0.00
Sand
0.08
12
27.14
72.86
0.00 Sandy mud
2.12
Infauna
Univariate summary statistics, including number of taxa, number of individuals, density,
Shannon’s index of diversity (H’), Pielou’s index of evenness (J’), and Margalef’s index of
species richness (D) were calculated for each replicate. Station means of these summary
statistics were then calculated based on the three station replicates.
Table 2 provides summary statistics for Wolf Bay stations. The total number of taxa ranged
from 1 (Station 6) to 11 (Station 8). Total number of individuals ranged from 4 (Stations 6 and
10) to 70 (Station 12). Diversity (H') ranged from 0.00 (Station 6) to 1.87 (Station 8). Evenness
(J') ranged from 0.11 (Station 12) to 0.96 (Station 7). Species richness (D) ranged from 0.00
(Station 6) to 2.89 (Station 8).
Figure 2 presents the results of cluster analysis grouping of stations due to similarities in species
composition and relative abundance. Three groups of stations (Groups A, B, and C) were
resolved by the cluster analysis (see Appendix X). Group A included Stations 2, 3, 6, and 12,
which had mud or sandy mud habitat and yielded low numbers of taxa, and low measures of
4
diversity and species richness. Group B included the sand bottom stations (1, 4, 5, 8, 9, 11),
which yielded the greatest numbers of taxa of the stations surveyed. Group C stations (7, 10)
had sandy mud that yielded low abundances of infauna.
Table y. Infaunal summary statistics for Stations 1 through 12, sampled 11-2-07 at Wolf Bay.
Mean
Mean
H'
J'
D
Total No. No. of Taxa Total No.
Density
Station
Shannon Pielou
Margalef
Taxa
per Replicate Individuals (Individuals/m2)
Diversity Evenness Richness
(Std Dev.)
(Std. Dev.)
1
7
4.0(1.0)
36
521.7(217.5)
1.36
0.70
1.67
2
2
1.3(0.6)
31
449.3(109.2)
0.14
0.21
0.29
3
2
1.3(0.6)
15
217.3(43.5)
0.39
0.57
0.37
4
8
3.3(2.1)
15
217.3(199.6)
1.81
0.87
2.58
5
8
4.0(2.6)
26
376.7(175.8)
1.46
0.70
2.15
6
1
0.7(0.6)
4
57.7(66.2)
0.00
0.00
7
4
1.3(1.2)
5
72.3(66.2)
1.33
0.96
1.86
8
11
4.3(1.5)
32
463.7(223.3)
1.87
0.78
2.89
9
5
2.0(2.0)
11
159.3(205.3)
1.39
0.86
1.67
10
4
1.3(1.5)
4
57.7(66.2)
1.39
1.00
2.16
11
7
4.0(1.0)
47
681.3(295.9)
1.17
0.60
1.56
12
2
1.3(0.6)
70
1,014.7(654.1)
0.07
0.11
0.24
Table z presents the SIMPER results that identified the taxa most responsible for station
groupings resolved by cluster analysis. Strebloso contributed to station similarities in four of the
five station groups, an indication of the ubiquity of this taxon in the Lagoon. Trough stations
(Groups A and C) were distinguished by species Paraprionospio pinnata (Group A) and
Prionospio perkinsi, M. ambiseta, and Lysilla sp. B (Group C). The gastropod Acteocina
canaliculalta, the bivalve Tellina (LPIL), and Mediomastus ambiseta typified Group B (Stations
D4 through D9).
Table z. Average abundance of macroinfaunal species predominantly responsible for the within
group similarity in Station Groups A through C, sampled 11-2-07 at Wolf Bay.
Group
Species
Average Abundance
Average Similarity
A
Streblospio benedicti
2.98
61.52
B
Streblospio benedicti
Mediomastus ambiseta
Nuculana acuta
Mulinia lateralis
Tubulanus (LPIL)
Capitella (LPIL)
2.60
1.14
0.66
0.83
0.35
0.35
23.56
8.93
3.69
2.77
1.54
1.45
C
Streblospio benedicti
0.69
23.30
5
Figure 2. Station groups A through E resolved by cluster analysis
6