GCE-LTER NSF Progress Report
Year 9 (2009)
GCE Annual Report Research Findings
September 2009
Context
The central paradigm of GCE-II is that variability in estuarine ecosystem processes is primarily
mediated by the mixture of fresh and salt water flows across the coastal landscape. The project
is focused on 5 main, inter-related questions:
Q1: What are the long-term patterns of environmental forcing to the coastal zone?
Q2: How do the spatial and temporal patterns of biogeochemical processes, primary production,
community dynamics, decomposition, and disturbance vary across the estuarine
landscape, and how do they relate to environmental gradients?
Q3: What are the underlying mechanisms by which the freshwater-saltwater gradient drives
ecosystem change along the longitudinal axis of an estuary?
Q4: What are the underlying mechanisms by which proximity of marshes to upland habitat
drives ecosystem change along lateral gradients in the intertidal zone?
Q5: What is the relative importance of larval transport versus the conditions of the adult
environment in determining community and genetic structure across both the longitudinal
and lateral gradients of the estuarine landscape?
Q1: What are the long-term patterns of environmental forcing to the coastal zone?
Coastal ecosystems are influenced by the characteristics of the upstream watershed (e.g. land
use, slope), by those of the ocean (e.g. wave climate, sea level), and by those of the atmosphere
(e.g. temperature, precipitation). Each of these external forcing functions is expected to
experience substantial changes over the coming decades due to factors such as climate change,
sea level rise, and human alterations of the landscape. The GCE project collects data on local
climate (temperature, precipitation, wind speed and direction), on watershed characteristics, and
on the water chemistry of the tributaries that discharge into the Altamaha River.
Climate signals
We continue to collaborate with the Sapelo Island National Estuarine Research Reserve and
USGS National Water Information System to maintain comprehensive climate and hydrographic
monitoring stations on Sapelo Island (Marsh Landing) and the Georgia mainland (Hudson Creek
at Meridian Landing), with near-real-time data telemetry. W. Sheldon (UGA) has developed
programs to automatically harvest data on an hourly basis and display weekly weather plots and
daily tide predictions for Sapelo on the GCE web site home page to provide current information
about site conditions. Both near-real-time and historic data and plots from these and other
relevant climate stations are also publicly accessible on the GCE Data Portal website (http://gcelter.marsci.uga.edu/portal/monitoring.htm).
At the site level, A. Burd (UGA) and J. Sheldon (UGA) continue their work to evaluate
variability in freshwater delivery to the GCE domain in relation to various climate indices: the
Southern Oscillation Index (SOI), the North Atlantic Oscillation (NAO) and the Bermuda High
Index (BHI). This past year, they completed a project that compared monthly standardized
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Year 9 (2009)
anomalies of river discharge and climate indices to multi-decadal time series of Altamaha
watershed precipitation. They used empirical orthogonal function (EOF) analysis to describe the
precipitation patterns at 7-13 stations. The first EOF mode (65% of the variance) was spatially
uniform with temporal variability at the monthly scale. The second mode (11% of the variance)
showed a spatial gradient along the long axis of the watershed (NW-SE) whereas the third mode
(6% of the variance) showed an onshore-offshore pattern with higher variability during JuneSeptember. There were no consistent relationships between NAO and precipitation. The SOI
showed correlations with discharge and weak correlations with modes 1 and 2 of the
precipitation. The BHI is correlated with May-January discharge with a 0-1 month lag, and is
also strongly correlated with EOF mode 1 of precipitation. These results were presented at the
2009 LTER All Scientists Meeting and will be presented at the upcoming Coastal and Estuarine
Research Federation (CERF) conference in November 2009.
At a broader scale, M. Alber (UGA) has been involved in a network-level effort to evaluate the
effects of climate change on coastal systems. The LTER provides a network of coastal sites that
differ in their biophysical vulnerability to various aspects of climate change, with some being
more affected by sea level rise and storm surge (e.g. VCR, FCE) and others by acidification (e.g.
MCR), loss of sea ice (e.g. PAL), changes in temperature (e.g. CCE), or changes in freshwater
inflow (e.g. PIE, GCE). Coastal LTER sites also differ in their gradients of human vulnerability,
with differences arising from coastal population densities and demographic compositions (e.g.
FCE vs. VCR) and also from the location and resilience of their built infrastructure (e.g. BES vs.
SBC). Alber and C. Hopkinson (UGA) led a working group at the 2009 Science Council
meeting in May 2009 to discuss these issues, and have put together a prospectus describing our
approach to the question of how human and natural templates interact to affect vulnerability to
climate change. Alber also gave talks on coastal climate effects at both the NSF LTER minisymposium in February 2009 and the Science Council meeting.
Watershed inputs
G. Kaufman (M.S. student, UGA) and Alber have completed an estimate of nitrogen inputs to
the Altamaha River estuary using a combination of observations and literature values. Sources
of nitrogen examined were atmospheric deposition, downstream advection of river water, flux
from the marshes, flux from the subtidal sediments, and upstream tidal mixing of ocean water.
Overall nitrogen input to the Altamaha River estuary is strongly dominated by riverine loading,
which accounts for 95% of the input. Approximately 60% of the input is organic material, which
is primarily dissolved. This work was done in preparation for a modeling study to link riverine
input of nitrogen to estuarine nitrogen distributions.
The GCE project is also involved in a cross-site initiative (Maps and Locals) led by R. Pontius
(PIE), G. Kofinas and N. Sayles (JRN) to use spatial representation of land cover and land use to
identify patterns of landscape change in regions in and around LTER sites. Specifically, we are
comparing land cover within the GCE domain from 5 time points (1974, 1985, 1991, 2001, and
2005). This analysis will allow us to address several immediate questions: 1. Where and when
did landscape changes occur, and at the expense of what type of land? 2. Has the process of land
transformation been consistent across more than one time interval? 3. What are the differences
in the landscape (and in landscape change) in the different watersheds? 4. Are there associations
between landscape change and potential driving variables (e.g. slope, the location of roads and
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Year 9 (2009)
protected areas)? 5. Can differences in the watersheds be linked to observations in response
variables (e.g. estuary nutrient concentration, salt marsh primary production)?
We are particularly interested in the process of development and how that influences the
receiving water. For example, an inspection of Figure 1 reveals build-out in the landscape,
particularly in the towns of Doctortown and Darien. If we can find a relationship between
impervious surface and water quality then we can use that to evaluate the effects of potential
future development scenarios.
Figure 1. Landcover in the GCE domain in 1974 and 2005.
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Year 9 (2009)
River delivery of dissolved and suspended material
S. Joye (UGA) continues to work with J. Sandow (Aquatic Research South) to monitor nutrients
in the river water entering the GCE domain via the Altamaha River and its tributaries. The Joye
lab (under the guidance of K. Hunter, UGA) receives approximately 8 samples per month and
has analyzed about 600 samples to date. Samples are analyzed to determine concentrations of
dissolved inorganic nutrients (DIN, DIP, and DSi species), dissolved organic nutrients (DOC,
DON, and DOP) and total suspended solids. A paper describing temporal variations in
concentration, nutrient and dissolved organic matter loading rates, and an evaluation of the
watershed evolution over time was published this year (Weston et al. 2009) and another paper on
nutrient delivery variability (Hunter and Joye) is in preparation.
Q2: How do the spatial and temporal patterns of biogeochemical processes,
primary production, community dynamics, decomposition, and disturbance vary
across the estuarine landscape, and how do they relate to environmental
gradients?
Variability in external forcing (see Q1) is manifest as environmental gradients (e.g., in salinity or
nutrients) within the coastal landscape. We collect data on physical oceanographic conditions,
nutrients and organisms in the water column; groundwater hydrology and biogeochemistry; and
intertidal marsh soil, plant, microbial and animal dynamics. Although data are collected
throughout the domain, we primarily focus on conditions in the Duplin River, which is at the
heart of our system. The variables of interest to us span all five of the LTER core research areas.
Water Column
Salinity structure
Long-term measurements of conductivity, temperature, and sub-surface pressure are collected
every 30 minutes at 8 moorings distributed across the GCE domain (see http://gcelter.marsci.uga.edu/public/research/mon/sounds_creeks.htm). MicroCAT sondes are cleaned and
inspected biweekly to minimize data loss due to fouling, and logged data are manually
downloaded on a bimonthly to quarterly basis by GCE field technicians (J. Shalack, D. Saucedo,
UGA Marine Institute). Data are processed by W. Sheldon and D. Di Iorio (UGA).
This past year, M. Ait Amrouche (undergraduate, U. Toulon, France) worked with Di Iorio on
applying empirical orthogonal function (EOF) analysis to the sonde data in order to study salinity
variability and the relative influences of freshwater and oceanic inputs across the GCE domain.
(GCE 7 was excluded because it is almost always fresh water and GCE 1 was excluded because
it responds primarily to rainfall). For the remaining 6 sites they found that the first EOF mode
explains 85.6% of the variability and the second mode an additional 8.7%. The temporal
variability for the first mode is negatively correlated with river discharge, with time lags
increasing from 1-3 d to 6-8 d as one moves from Altamaha to Doboy and Sapelo Sounds,
respectively (Figure 2). The coherence shows that variability over yearly time scales dominates.
For the second mode there is a correlation with sea surface height (SSH) but there is a phase
difference between the sounds: In the Altamaha River, salinity increases when SSH increases,
whereas for Doboy and Sapelo Sounds, salinity decreases when the SSH increases. For this
mode the coherence indicates a more seasonal time scale of variability. Over these seasonal time
scales when SSH increases during Nor’easter storms, Altamaha River water may be forced
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Year 9 (2009)
Figure 2. Results of EOF analysis of salinity in the GCE domain. The first mode is strongly correlated
with Altamaha River discharge, while the second mode is moderately correlated with sea surface height.
through the Intracoastal Waterway or other channels moving freshwater north, or may recirculate
back in through the Sounds from the ocean. Further investigation is needed to test this
hypothesis.
Patterns of dissolved and suspended material
Monthly cruises to monitor surface water quality in the sounds continued during 2008 (Saucedo,
Shalack). During the past year, the Joye lab processed 4800 samples from the monitoring
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Year 9 (2009)
cruises: 496 samples for determination of concentrations of dissolved inorganic nutrients (NO2-,
NO3-, NH4+, HPO42-, and H2SiO42-) and dissolved organics (DOC, TDN, DON, TDP, and DOP);
1488 chlorophyll a samples; and 1488 total suspended sediment and particulate CN samples.
These analyses are in various phases of completion.
As observed in previous years, spatial and temporal variations in biogeochemical parameters
among the study sites were significant. The highest NOx concentrations were present in
Altamaha Sound at GCE 7 and 8. Surface and bottom NOx concentrations were comparable at
all the stations. At all of the study sites, concentrations of dissolved organic nitrogen equaled
(Altamaha stations) or exceeded (all others) concentrations of dissolved inorganic nitrogen.
Ammonium concentrations were highest in Doboy Sound, followed by Sapelo and Altamaha
Sounds. Concentrations of dissolved organic phosphorus were comparable to concentrations of
dissolved inorganic phosphorus at all stations during all samplings; no depth variation in
phosphorus availability was observed. As noted in previous years, DOC concentrations were
highest in Sapelo Sound, followed by Doboy and Altamaha Sounds.
Microbial Dynamics
Starting in July 2008, M. Booth (UGAMI) has collected bacterioplankton samples during GCE
cruises for analysis of bacterial cell numbers, leucine incorporation, and viral numbers. Samples
for extraction of bacterial DNA and RNA were also collected and stored for later processing.
We have also received supplement funds to conduct a survey of prokaryotic and small eukaryotic
(<5 µm) diversity over 1-2 annual cycles to determine whether prokaryotic and/or eukaryotic
diversity vary spatially and temporally within the GCE domain, and if they are related to one or
more biotic or abiotic factors. Microbial prokaryotes and eukaryotes will be sampled at four
sites concurrent with the GCE sampling routine over 12 months. The ribosomal RNA genes will
be sequenced using high-throughput sequencing technology, e.g. 454 pyrosequencing.
Groundwater inputs
The groundwater wells within the GCE domain (Moses Hammock, Visitor Center) are sampled
quarterly (April, July, October and January) by the Joye lab, but most of our efforts have
concentrated on groundwater inputs to Moses Hammock, where wells are located across a
Figure 3. The Moses Hammock transect. Black rectangles represent approximate relative well locations and depths
and are labeled with their respective well ID numbers. The black circles represent locations where sediment samples
were collected.
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Year 9 (2009)
Figure 4. Comparison of redox metabolites in wells at Moses Hammock at spring and neap tides for April 2002
through April 2009. (left) DON, (center) NH4, (right) NOx.
gradient from the freshwater upland, across the upland-marsh transition, and into the ringing
marsh (Figure 3). The well field captures the transition from freshwater to saltwater in the
aquifer; the redox interface lies between these wells and physical exchange between the upland
and marsh is modulated in this area by a strong gradient in hydraulic conductivity. A minimum
in permeability is located in this area, which generates an amplification/focusing effect as the
aquifer is forced by pressure variations resulting from tidal (diurnal and spring-neap) variations.
Concentrations of many redox metabolites, including DOC, NH4, H2S, Fe, and DON, vary
substantially across the well field (Figure 4). The degradation of dissolved organic nitrogen is
enhanced during neap tides, and there is evidence for nitrification (accumulation of nitrate)
during neap tide as well.
Marshes
Soil processes
We continue to measure vertical
accretion and sedimentation
using sedimentation-erosion
tables (SETs) and feldspar
marker layers to evaluate the
effects of freshwater pulsing on
long-term stability of tidal
marshes. Under the direction of
C. Craft (IU), we measure
changes in marsh surface
elevation and sediment
deposition every six months at
the ten GCE domain sites and at
three sites of a directed study on
Figure 5. Marsh surface elevation changes at GCE 6 since 2001. Timing
Dean Creek. Results from 6+
of salt marsh dieback and recovery noted with arrows.
years of data collection indicate
no clear trends in marsh surface elevation across the ten core sites of the GCE domain.
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Year 9 (2009)
The SET at GCE 6, which was installed in 2001, is in an area that experienced marsh dieback.
At the height of the dieback (2004), the plot was completely bare and the marsh surface elevation
had decreased by 20 mm relative to the pre-dieback elevation (Figure 5). By 2006 vegetation
began to re-colonize the site, and by 2008 the surface recovered to its pre-disturbance elevation.
Plant dynamics
S. Pennings (UH) and his lab continue to monitor plant biomass with the goal of testing the
hypothesis that end-of-year biomass varies as a function of freshwater discharge from the
Altamaha (especially in low-marsh plots), local rainfall (especially in high-marsh plots), and
average sea level. In 2000 they set up permanent plots at all 10 GCE monitoring sites. Plots
were established at creekbank and mid-marsh zones (8 plots/zone/site). Most sites are dominated
by Spartina alterniflora, but some zones at some sites are dominated by Juncus roemerianus,
Spartina cynosuroides, or Zizaniopsis miliacea. An additional set of high marsh Juncus plots
was established at site 10 in 2005 to increase replication of sites dominated by Juncus. Plants
have been non-destructively monitored (stem counts, heights, flowering status) in October of
every year since 2000.
A preliminary analysis of data for S. alterniflora
(means and SE averaged over sites dominated by
S. alterniflora) from 2000-2006 shows that endof-year biomass in creekbank plots varied more
than two-fold among years (Figure 6). The two
years with highest biomass (2003 and 2005) were
years with high discharge from the Altamaha
River during the spring months, which reduced
water column salinities and provided superior
growing conditions. End-of-year biomass in the
mid-marsh plots varied slightly less than two-fold
Figure 6. End-of-year biomass at GCE monitoring
among years and did not vary in synchrony with
biomass in the creekbank plots (in particular, mid- sites dominated by Spartina alterniflora, 2000-2006.
Data are means and SE of creek bank (solid circles)
marsh plots showed no peak in biomass in 2003,
and mid-marsh (open circles) sites.
Figure 6). Variation in biomass in mid-marsh
plots is likely driven by variation in sea level and
local precipitation, rather than Altamaha River discharge. A rigorous analysis of these data
leading to a publication will be conducted once several more years of data have been collected.
These plots are also proving useful in documenting spatial and temporal variation in disturbance
from physical (floating dead plant material called wrack) and biotic sources. Wrack disturbance
is high in creekbank plots at some sites and low in mid-marsh plots. Biotic damage from snail
grazing and pig digging is high in some mid-marsh plots at some sites. (Disturbed plots were
omitted from above analyses of annual variation in biomass).
In a separate set of plots, Pennings is testing the hypothesis that annual variation in high-marsh
plant species composition is driven by variation in rainfall. Salt marsh vegetation often consists
of discrete stands with abrupt borders between different species or associations. Pennings has
monitored mid-summer plant composition at permanent plots located on 3 types of vegetation
borders (Spartina alterniflora-Juncus roemerianus, S. alterniflora-meadow, meadow-Juncus
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Year 9 (2009)
roemerianus), at two sites each, since 1996. Vegetation composition in these plots is dynamic
and appears to be related to variation in rainfall, although more years of data will be needed to
test this hypothesis rigorously.
Finally, Pennings is conducting parallel experiments in GA and AL to examine 1) how rapidly
marsh vegetation can recover from disturbance, and 2) the role of competition in secondary
succession. In 3 vegetation zones (Spartina alterniflora-meadow border, meadow-Juncus
roemerianus border, J. roemerianus zone) at each of 2 marshes in each state, replicate 3 x 3 m
plots were cleared using herbicide and clipping and maintained free of vegetation for 2 years.
Control plots were marked but unmanipulated. In
2000, individual plots were divided into halves or
quadrants, depending on the diversity of the vegetation
in each zone, with one section allowed to recover
without further manipulation and the other section(s)
treated by periodically removing 1 or 2 dominant plant
species occurring in each zone. To date, succession
has been fastest in plots on the Spartina alterniflorameadow border, which have already converged on
control plot values, and slowest in the J. roemerianus
plots, which are still early in the successional
trajectory. Removal treatments indicate that
competition plays a strong role in mediating the
composition of the vegetation in each zone.
Animal Dynamics
Fall annual monitoring of animal populations in the
salt marsh continued this year. One of the striking
patterns since monitoring began in 2000 is that
densities of the periwinkle snail, Littoraria irrorata,
are lower in the Altamaha than in the other sounds.
This may be a result of the inability of larvae to recruit
upstream, or else reduced survival of the new recruits.
Another striking pattern is that snail densities are
higher at barrier island sites (GCE 3, 6, 9) than at
mainland sites on the same estuaries (GCE 1, 4 and 7).
We are currently investigating mechanisms creating
these patterns (see Q5).
In addition, Pennings and his lab collect annual data on
grasshopper abundance to test the hypothesis that it
varies as a function of site characteristics and
angiosperm production. An initial analysis of temporal
variation in grasshopper densities (means and SE
averaged over the three sites with highest densities)
from 2000 through 2006 shows that densities have
varied more than five-fold among years (Figure 7, top).
The two years with highest biomass (2004 and 2006)
Figure 7. Grasshopper abundance at GCE
monitoring sites over time (top), compared with
creekbank Spartina biomass in the previous
year (middle), and compared across sites
(bottom).
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Year 9 (2009)
followed years (2003 and 2005) of high creekbank Spartina biomass. More generally, there is a
strong trend (P=0.07) for grasshopper densities to be correlated with the previous year’s biomass
of creekbank Spartina (Figure 7, middle); this trend is driven by two “bumper years” in plant
biomass followed by years with high grasshopper populations. We hypothesize that vigorous
growth of creekbank Spartina in one year leads to high egg production by grasshoppers, leading
to high grasshopper population densities the following year. A rigorous analysis of these data
leading to a publication will be conducted once several more years of data have been collected.
An analysis of spatial variation in grasshopper densities (means and SE averaged over years)
from 2001-2008 found that densities (all species combined) differed more than ten-fold among
sites (Figure 7, bottom). Grasshoppers were common on barrier island sites, moderately
abundant at mainland sites, and almost absent at mid-estuary sites. Several mechanisms might
explain these spatial patterns in grasshopper population density, and experiments to address these
hypotheses are planned (see Q5).
This past year, B. Silliman (UF) and his lab conducted a one-time survey of densities of mud
snails and ribbed mussels at all GCE sites. (Our routine monitoring protocol does not include
mud snails and samples ribbed mussels poorly.) Densities of these two species roughly mirrored
each other: Both were rare at some sites (7, 8, 9), present at others (2, 3, 4, 5, 6) and most
abundant at site 10. Both species also displayed a highly patchy distribution. These data
provided a good baseline for long-term monitoring and shed insight into the patchy nature of the
animals, but lacked sufficient replication to rigorously test whether there was a pattern in
densities across the barrier island – mid-estuary – mainland gradient. To assess this possibility,
we will enumerate densities of these species and the other dominant marsh invertebrates in a
highly replicated transect with 8 barrier island marshes, 8 mid-estuary marshes, and 8 mainland
marshes. Sampling is planned for fall 2009.
We are also conducting short-term studies of animal dynamics. Graduate students C. Ho and J.
Jimenez (both Ph.D. students at UH), in collaboration with Pennings, are investigating top-down
and bottom-up control of arthropod food webs. It is generally believed that the diverse and
reticulate interactions promoted by omnivory will tend to reduce strong trophic cascades. In
both laboratory and field experiments, however, Ho found that an omnivorous crab suppressed
both predator and herbivore populations on the shrub Iva frutescens, releasing plants from
herbivore pressure and promoting plant performance. Ho graduated in 2008, and a manuscript
based on this work was published in Ecology in 2008. A similar experiment, but focusing on the
arthropod food web of Spartina alterniflora, was conducted by Jimenez, who graduated in 2009.
A publication based on Jimenez’s work is planned in the near future.
At a larger spatial scale, Pennings is also working with Ho to evaluate whether high-latitude
plants are better food for herbivores than low-latitude plants by conducting growth experiments
in the greenhouse. Preliminary results support this hypothesis, but suggest that the results may
vary among feeding guilds. To the extent that superior foods lead to larger body sizes, highquality plants at high latitudes could be one mechanism behind Bergmann’s rule (animals are
larger at high latitudes). A manuscript discussing this idea is in press at the American Naturalist.
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Table 1. Population density of A. mississippiensis
J. Nifong (MS student, UF) and Silliman are
working on a project to assess population densities in tidal creeks of Sapelo Island in 2007.
of the American alligator on Sapelo Island. They Creek Name
Alligators km-1
have found that alligators spend significant time
Dean Creek
1.21
feeding and moving in marine waters and can be
Southend Creek
1.05
abundant in marsh creeks with full strength salt
Oakdale Creek
4.29
water (Table 1). T-tests (P<0.05) revealed three
Bighole Creek
1.36
categories of alligator density: high (Oakdale),
Post Office Creek
1.3
low (Factory, Blackbeard to Cabretta, Duplin),
Factory
Creek
0.33
and medium (all others). They hypothesize that
Cabretta Creek
1.19
alligators cope with osmotic stress by moving
Blackbeard Creek NW END
1.36
every week or two into freshwater to drink and
rest, and then move back into marine waters to
Blackbeard Creek S to Cabretta
0.25
feed. Nifong and Silliman plan to sample alligator Duplin River
0.43
density across the entire domain and use isotopic
data to better understand their feeding habits and role in the marsh food web.
Duplin River estuary
The Duplin River estuary continues to be a core focus of our efforts to produce an integrated
understanding of both water and marsh processes in estuaries. The 12.5 km tidal inlet is part of
the Sapelo Island National Estuarine Research Reserve and at the geographic center of the GCE
domain. It represents a defined “tidal-shed” in which we can couple water column and marsh
processes at a spatial scale that is more manageable than our entire study system. Our efforts this
past year have focused on obtaining and analyzing remote sensing data collected for the area.
Remote sensing
We obtained aerial, hyperspectral AISA imagery (http://calmit.unl.edu/champ/) for the Duplin
River watershed in June 2006. This past year, C. Hladik (Ph.D. student, UGA) worked with J.
Schalles (Creighton) to classify two of the flight lines using both the Maximum Likelihood
Classification (MLC) and Spectral Angle Mapper (SAM) supervised classification algorithms in
Environment for Visualization Images (ENVI). The following salt marsh plant classes were used
in the classification based on ground data obtained in 2006 and 2007: Batis maritima, Borrichia
frutescens, Salicornia virginica, Spartina alterniflora (short, medium and tall forms) and Juncus
roemerianus. Nonvegetated cover classes (mud, creek bank, salt pan) were also included. The
best overall classification accuracies for the two flight lines were 75% and 66% and were
obtained using the MLC algorithm after a land and water mask had been applied. The classes
most often confused were short and medium Spartina, short Spartina and Salicornia, and short
Spartina and mud. Continued improvement of the classification is planned using advanced
hyperspectral procedures and analysis of training data. A paper on this effort is currently in
preparation. Hladik will also present this work at the CERF conference in Fall 2009.
The GCE project contracted with the National Center for Airborne Laser Swath Mapping
(NCALM) to acquire LIDAR data for both the Duplin River and Blackbeard Island in March
2009 (Figure 8). NCALM processed and filtered the data to produce a Digital Elevation Model
(DEM) with vegetation removed (bare earth interpolated from the last return) and a canopy DEM
(from the first return). Approximate vertical and horizontal accuracies of the geolocated laser
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return points are 7-10 cm and 20-30 cm,
respectively. In order to enhance this
data set, C. Alexander (SKIO) is working
to classify the LIDAR intensity data,
which is part of the data return that is not
used to obtain elevation, and to evaluate
the correlations between intensity and the
physical and biological characteristics of
the study area (e.g. LIDAR elevation
data, National Wetland Inventory plant
classifications, observations that can be
obtained from aerial imagery, such as the
presence of manmade structures). This
work will advance the field as the
interpretation of LIDAR intensity data in
these types of applications is currently
the subject of on-going research by
scientific users of LIDAR data.
Hladik is currently in the process of
performing an accuracy assessment of the
LIDAR and DEM models. In summer
and fall 2009, she worked with C.
Connor (undergraduate, UGA) and K.
Anstead (UGAMI technician) to do a
field survey of marsh platform elevation
Figure 8. LIDAR image of the Duplin River.
using a Real Time Kinematic (RTK)
GPS. At least 100 ground LIDAR points
were selected and surveyed for each of the major vegetation classes found in these marshes (S.
alterniflora, J. roemerianus, S. patens, Batis maritima, Salicornia virginica, and Borrichia
frutescens) as well as nonvegetated classes (mud, creekbank, salt pan). In addition to the RTK
data, a preliminary sampling of vegetation characteristics (plant composition, height, percent
cover and density) were done to groundtruth the imagery, with more planned for the upcoming
year. LIDAR and RTK data will be analyzed using ArcGIS (version 9.3, ESRI) and ENVI
(version 4.5, ITT Visual Information Solutions) software packages. Once this is complete,
Hladik will be in a position to use the LIDAR information on elevation in conjunction with the
hyperspectral information on plant species to model the relationship between observed salt marsh
species distributions and potential controlling factors, including elevation, proximity to tidal
creeks, and proximity to uplands.
Q3: What are the underlying mechanisms by which the freshwater-saltwater
gradient drives ecosystem change along the longitudinal axis of an estuary?
To predict how future changes in salinity distributions might affect the ecosystem, it is necessary
to understand the mechanisms that drive these patterns. In particular, we are interested in
separating the effects of salt from that of sulfate on ecosystem processes, given that these factors
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are correlated across the estuarine gradient. This portion of the project is under the direction of
Joye, with involvement from co-PIs Pennings, Craft, C.
Meile (UGA), and Alber.
In 2009 we hired a technician to manage this portion of
the project. In summer 2010 we will set up a field
experiment at a freshwater site along the Altamaha
River about 30 km from the ocean (in the vicinity of
GCE 7). The experiment will consist of four treatments
(control, salinity-amended, sulfate-amended and
salinity+sulfate-amended) in which freshwater
sediments will be amended with increasing salinity
(from 0 to 10) and/or sulfate (proportional increases,
from 0 to 9 mM) in an orthogonal design over 12
months. In addition to the field experiment, the effect of
short-term variations in substrate concentrations, ionic
strength, pH, and H2S on potential rates of nitrification,
denitrification, methane oxidation, methanogenesis and
sulfate reduction will be evaluated in slurry experiments
in the laboratory.
In addition to the core experiment, we are also
addressing this question with leveraged funding from an
EPA grant (PD: Craft, co-PIs: Pennings and Joye).
Pennings, H. Guo (PhD student, UH) and K. Wieski
Figure 9. Plant species richness in three
salinity zones for sites (top) and plots (bottom).
Figure 10. Plant height, standing biomass,
carbon, nitrogen, and phosphorus in three
salinity zones.
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GCE-LTER NSF Progress Report
Year 9 (2009)
(UH) are examining factors creating plant community structure along the estuarine salinity
gradient. They sampled plant biomass and diversity at replicate fresh, brackish and marine tidal
marshes on the Satilla, Altamaha and Ogeechee Rivers. A total of 109 plant species were found,
but 11 species dominated the plant communities. Site-level species richness decreased across the
salinity gradient and did not differ among rivers (Sa=11.3, A=13.0, O= 12.2). Plot-level richness
showed a similar pattern (Figure 9).
Standing biomass was greatest at brackish sites (Figure 10) and in both brackish and fresh sites
tended to decrease away from the creekbank, whereas in the salt marsh sites biomass was
greatest in the mid-marsh zones dominated by Juncus roemerianus (data not shown). Standing
stocks of C, N and P were estimated based on total biomass, the relative abundance of different
plant species, and the elemental composition of each plant species. Total carbon stocks
paralleled patterns of biomass in that they were greatest at the brackish sites and lowest at the
salt marsh sites. Nitrogen stocks decreased across sites as salinity increased and were greatest in
the creekbank zone. Phosphorus stocks did not differ between fresh and brackish sites, but were
lower at salty sites (Figure 10). An overview of the results of this collaborative project were
published in Frontiers in Ecology and the Environment in 2009, and a more detailed manuscript
describing vegetation patterns is in review.
In collaboration with Pennings, Guo is also conducting a series of transplant experiments to
explain these patterns. This work is described in detail below (Question 5).
Q4: What are the underlying mechanisms by which proximity of marshes to
upland habitat drives ecosystem change along lateral gradients in the intertidal
zone?
The GCE project is investigating the underlying mechanisms by which proximity of marshes to
upland habitat drives ecosystem change along lateral gradients in the intertidal zone. Our
approach to this question involves taking advantage of marsh hammocks as a natural laboratory
for evaluating the influence of landscape structure and freshwater input on marsh processes. The
hammock research includes basic characterization of groundwater flow as well as physical and
biological characteristics at selected sites, experiments designed to understand the effects of
manipulating water flow on marsh processes, and modeling. In 2007 we did a survey of 55
hammocks representing a range of sizes and origin, and these data are still being analyzed. Our
activities this past year included processing geological samples; collecting data from
instrumented hammocks; and continuing archeological studies. We also continued our analysis
of the plant community associated with hammocks and initiated field and greenhouse studies to
support our modeling efforts. This portion of the project is under the direction of Alber and
Alexander, with involvement from co-PIs Pennings, Joye, Burd, Meile, B. Moore (USC), and V.
Thompson (Ohio State).
Geology
Geologic characterization of marsh hammocks within the GCE domain, under the direction of
Alexander, continued along several fronts in the past year. The Alexander lab completed textural
analyses of the hammocks sampled in summer 2007 and showed that there are distinct textural
differences between hammocks based on origin. Holocene hammocks contain the greatest
amount of sand, followed by Pleistocene hammocks and GCE monitoring sites (as would be
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GCE-LTER NSF Progress Report
Year 9 (2009)
expected from their locations on Pleistocene upland bodies), followed by ballast stone
hammocks, which accumulate a wide range of materials from the water column, and lastly,
dredge spoil hammocks, which are created from an indiscriminant mixture of flocculant muds
and sands rapidly deposited in channels over time. During the last year, we also assessed the
textural preferences of the focus salt marsh plants in our study. Results indicate that Borrichia
prefers sandy sediments (75-95% sand) with little mud (4-30%), as is expected from its tendency
to grow on the eroding flanks of sandy hammocks and in environments where the texture does
not change dramatically with depth. Juncus is found in zones of somewhat greater mud content
(7-40%) and in a wider range of sand contents (60-95%). Spartina grows in more variable
settings, with a wide range of sand (5-90%) and mud (7-90%), suggesting that other factors are
more important than sediment type for constraining this species.
Coring throughout the region behind Sapelo Island has revealed that stiff, Pleistocene-aged
marsh mud discontinuously underlies many of the Pleistocene hammocks and the open marshes
surrounding them. This layer, observed from <1 m to >5 m below the surface, is impermeable
and widespread and must have significant impact on the hydrologic pathways both from
hammocks to marshes and within marshes as well. This linkage between marsh ecosystems,
stratigraphy and hydrology will be pursued in the coming year, and the distribution of this
impermeable layer will be mapped with greater detail. To start this process, we have collected
transects and targeted cores near Marys Hammock (10 cores), Jacks Hammock (1 core) and
PNi12 (e.g., Fishing Hammock, 4 cores). These cores have been subsampled for texture and
AMS C-14 where material was available; samples will be analyzed in the coming year.
Archeological studies
J. Turck (Ph.D. student, UGA) and Alexander used a vibracorer to take six sediment cores from
the marsh near one of our study hammocks (Marys Hammock, a Pleistocene hammock on the
west side of the Duplin R.) in an attempt to locate former ground surfaces and understand the
depositional history of the marsh surrounding the hammock as related to changes in sea level.
The cores were split in half, photographed, X-rayed, and visually inspected. Three sets of
sediment samples were taken from the cores at 10-cm intervals for stratigraphic and geochemical
analyses. Particle size analysis was performed on one set of samples, to locate buried B soil
horizons and stratigraphic discontinuities showing breaks in sedimentation. Loss on ignition was
performed on the second set of samples to estimate organic matter, which can be used to locate
buried A soil horizons. The third set of samples has been saved for a future pollen study.
Thompson and Turck also published a paper on the response of hunter-gatherer groups to
changes in sea level and resource distribution. They suggest that, despite major destabilizing
forces in the form of sea level lowering and its concomitant effects on resource distribution,
cultural systems rebounded to a structural pattern similar to the one expressed prior to
environmental disruption. They propose, in part, that the ability for people to return to similar
patterns was the result of the high visibility of previous behaviors inscribed on the landscape in
the form of shell middens and rings from the period preceding environmental disruption.
Finally, despite a return to similar cultural formulations, hunter-gatherers experienced some
fundamental changes resulting in modifications to existing behaviors (e.g., ringed villages) as
well as the addition of new ones in the form of burial mound construction. This work was
published in the American Antiquity (2009).
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GCE-LTER NSF Progress Report
Year 9 (2009)
Intensive hammock research
In 2008 two hammocks were selected for more detailed study: HNi1 is of Holocene origin and is
located west of and adjacent to Blackbeard Island to the north of Sapelo; PCi29 was thought to
be of Pleistocene origin and is located adjacent to the south end of Sapelo Island. These two
hammocks are of similar size, with similar vegetation zones in the high marsh. We set up
transects that run from the nearby upland (Blackbeard and Sapelo Islands, respectively), through
the marsh, and up and over each hammock to the marsh adjacent to the Sound (Sapelo and
Doboy, respectively) and took cores at each site. Information from the stratigraphic data was
used as a guide to install wells across a hydrologically connected sand layer.
The cores from HNi1 generally exhibit profiles consistent with a sand body deposited onto backbarrier marsh by storm processes. A single, continuous marsh deposit, dated by AMS C-14 at
about 3500 y BP, underlies HNi1. Sedimentary structures in the cores suggest that energetic
forces washed beach sand back onto the marsh, creating a shore-parallel, linear sand body that
has been modified over the past few thousand years (see core 5 detail in Figure 11). This
Holocene hammock consists of clean medium- to fine-grained sands that contain parallel to
cross-bedded laminations. Cores from PCi29, along with AMS C14 and OSL dating, suggest
Figure 11. Core 5 from Holocene hammock HNi1 west of Blackbeard Island. Panels show stratigraphic
interpretation; average grain size; percent sand, silt and clay; photographs; and core location.
16
GCE-LTER NSF Progress Report
Year 9 (2009)
that this hammock has had a
complicated history spanning multiple
environments of deposition.
Each hammock has eight wells
installed from the upland, across the
marsh-upland interface, and into the
marsh. Water levels recorded in the
wells placed along the transect from
Blackbeard over HNi1 and into the
marsh show features that suggest
significant hydrologic interaction on
some timescales and very little at
others (Figure 12, top). Tidal
signatures are evident in all records;
dominant and subordinant tides can be
recognized at spring and neap tides for
the wells in Spartina and Juncus zones
(wells 2, 3, 7 and 8), whereas both
daily tides can be identified only at
spring tides in Borrichia and upland
zones (wells 1, 4, and 5). Large
rainfall events are easily recognized in
the record, with events on 10, 13 and
25 October creating abrupt increases
in well water level.
Salinity recorders are present in 3 of
the wells on HNi1 (Figure 12, bottom).
Significant freshening in the hammock
well (5), where salinities are 13-15,
can be observed in comparison to well
4, in the Borrichia zone some tens of
meters away and several meters lower
in elevation, where salinities are 30-35.
form a focus for the coming year.
Figure 12. Water levels (top) and salinities (bottom) in wells on
hammock HNi1. Water level results for well 8 in the Spartina
zone are problematic at this time.
Interactions between these closely adjacent wells will
Monthly monitoring of wells at the two hammocks began in August 2008. It is unclear at this
point how hydrologically connected the wells actually are. Chemical constituents are at least an
order of magnitude higher in the groundwater than in surface water collected from the sites.
Concentrations of dissolved organic carbon (DOC) as high as 15 mM have been observed in the
groundwater, and DOC in nearby surface water (~2 mM) exceeds that in open sound water
(hundreds of µM). Concentrations of dissolved inorganic nitrogen tend to be dominated by
ammonium, which is not surprising since the groundwater is anoxic and sulfidic.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Halo Area (hectares)
Plant Community
25
In the hammock survey of 2007, we
y = 0.326x - 0.0637
R2 = 0.97
used sub-meter accuracy GPS units
to map the hammock upland border
20
and the extent of the upper marsh
(from the hammock border to the
15
upper edge of Spartina alterniflora,
i.e. the marsh “halo”). Plants within
10
the halo were also characterized.
Analyses of these observations by
Hladik and Alber showed that the
5
Pleistocene
area of the high marsh plant
Holocene
community adjacent to the upland
Ballast Stone
0
area of the hammocks was
0
10
20
30
40
50
60
70
positively related to hammock area
Hammock Area (hectares)
(Figure 13), and was larger in
Figure 13. Area of high marsh plant community adjacent to the
Holocene and Pleistocene
upland area of hammocks (“halo”) compared with hammock area.
hammocks than those of other
origins. Borrichia frutescens and Juncus roemerianus were most often the dominant plants in
these areas, but there were differences related to hammock size and origin. This work will be
presented at the LTER ASM and the 2009 CERF meeting.
In order to help parameterize the plant model for Burd, Pennings and Anstead collected data on
high marsh plant communities and associated soils. In 2009 we collected light profiles and
associated data on plant heights and densities in stands of S. alterniflora, J. roemerianus, and B.
frutescens. These data will provide information on how stands of different plant species at
different densities affect the light environment for other plants (one mechanism of competition
among plants). We also collected data on soil porewater content and porewater salinity from
stands of the same three plant species. These data will provide information on how the physical
environment experienced by each plant species varies over space and time. To determine if
plants are in fact rooting in the soils that we are sampling, we collected pre-dawn xylem pressure
potential readings on all three species of plants. (In theory, pre-dawn XPP readings are in
equilibrium with soil water potentials).
Pennings and Anstead are also conducting a greenhouse experiment to evaluate the sensitivity of
three common salt marsh plants, S. alterniflora, J. roemerianus, and B. frutescens, to varying
levels of shade (0 to 80% of light blocked) and salinity (0 to 60). Monthly measurements of
plant size and photosynthetic rate over the course of the 2009 growing season will help inform
the model about how the three plant species respond to competition for light (as simulated by
shade cloth) and salinity. This information will also be used in plant modeling efforts.
Q5: What is the relative importance of larval transport versus the conditions of
the adult environment in determining community and genetic structure across
both the longitudinal and lateral gradients of the estuarine landscape?
We have documented a variety of distribution patterns of different species across the GCE
domain. These include 1) a close correlation with salinity (most plants, marine invertebrates), 2)
18
GCE-LTER NSF Progress Report
Year 9 (2009)
Juncus roemerianus
80
A
60
A
40
20
0
700
600
500
400
300
200
100
0
BC C
B
C
Zizaniopsis miliacea
A
Relative Interaction Intensity (RII)
100
1.0
Juncus roemerianus
.5
0.0
-.5
-1.0
1.0
Zizaniopsis
Zizaniopsis miliacea
miliacea
.5
0.0
-.5
N/A N/A
C C
Salt
Brackish
B
-1.0
gh) dium ) t(Low ) ckish Fresh
t(Hi
Bra
Sa l
Sal alt(M e
S
Fresh
Salinity zone
Salinity zone
Figure 14. Results from 2007 transplant experiments of salt (Spartina
alterniflora), brackish (Juncus roemerianus), and fresh (Zizaniopsis
milacea) marsh plants into different salinity zones, with or without
neighbors.
100
1.0
Batis maritima
80
A
Batis maritima
.5
Without neighbor
With neighbor
60
20
0
300
B
BC
CD
BCD
D
Schoenoplectus americanus
250
A
200
150
100
50
N/A N/A
0
100
B
B C
Pontederia cordata
80
A
60
Relative Interaction Intensity (RII)
0.0
40
Aboveground biomass (g)
Mechanisms explaining
plant distributions
Guo and Pennings are
conducting a series of transplant
experiments to explain patterns
of vegetation composition,
diversity and productivity in the
GCE domain (see above, Q3).
Over the years 2007, 2008 and
2009, Guo transplanted three
salt marsh plants, Spartina
alterniflora, Batis maritima and
Salicornia virginica; three
brackish marsh plants, Juncus
roemerianus, Spartina
cynosuroides, and
Schoenoplectus americanus;
and three fresh marsh plants,
Pontederia cordata, Zizaniopsis
miliacea, and an unidentified
species, to replicate fresh,
brackish and saline sites, with
and without competition. Plants
were transplanted in March of
each year and harvested, dried,
and weighed each October after
7 months of growth. Sites were
categorized into 5 regions of
salinity (fresh, brackish, low
salinity, medium salinity, and
high salinity) based on GCE
water column monitoring and
porewater salinity data collected
by Guo. The strength of
competition among transplanted
plants and background
Aboveground biomass (g)
densities decreasing from the barrier island to the mainland (most marine invertebrates), 3)
densities low at mid-estuary sites (grasshoppers), and 4) no systematic spatial variation (beetles).
We are using a combination of recruitment studies, transplant studies, and genetic approaches to
begin to understand these
400
1.0
Spartina alterniflora
Spartina alterniflora
patterns. This portion of the
Without
neighbors
.5
300
project is being led by Pennings
With neighbors
A
0.0
200
in conjunction with Silliman, J.
-.5
B
Wares (UGA), and D. Bishop
100
C
D
E
E
(UGA).
-1.0
0
-.5
-1.0
1.0
Schoenoplectus americanus
.5
0.0
-.5
-1.0
1.0
Pontederia cordata
.5
0.0
40
-.5
20
0
N/A N/A
N/A N/A
Salt
Brackish
B
-1.0
Fresh
Salinity zone
)
)
)
igh dium lt (low ackish Fresh
e
t (h
Br
Sa
Sal alt (m
S
Salinity zone
Figure 15. Results from 2008 transplant experiments of salt (Batis
maritima), brackish (Schoenoplectus americanus), and fresh (Pontederia
cordata) marsh plants into different salinity zones, with or without
neighbors.
19
GCE-LTER NSF Progress Report
Year 9 (2009)
vegetation was calculated for each salinity zone as Relative Interaction Intensity (RII), which is
calculated as (Biomass with neighbor - Biomass without neighbor)/(Biomass with neighbor +
Biomass without neighbor).
Results from 2007 (S. alterniflora, J. roemerianus and Z. miliacea, Figure 14) and 2008 (B.
maritima, S. americanus and P. cordata, Figure 15) indicate that the freshwater plants were
excluded from saltier sites by physical stress (they died with or without neighbors, indicated in
figures by “N/A”), and that the intensity of competition increased at less-saline sites, excluding
salt marsh species. There were hints of facilitation of some plant species by background
vegetation (positive values of RII) at the saltiest sites. The third set of transplants in 2009 is
underway and appears to show similar results.
Mechanisms explaining animal distributions
In 2008, the Silliman lab surveyed the GCE domain
and found that densities of both periwinkles and
barnacles were highest in the barrier-island marshes
followed by mid-estuary and then mainland marshes
(P < 0.01, all cases, Figure 16). The pattern was
consistent across both species and life stages (adults
and recruits). There was also a strong main effect of
zone (P < 0.01, all cases), but no interaction between
zone and site. Adult snail density was always higher
in the short zone, whereas barnacle and snail recruits
were always most abundant in the tall zone. These
patterns suggest a strong recruitment shadow effect, Figure 16. Locations of sampling sites along an
off-shore on-shore gradient. Barrier island sites
where larval supply to marshes is highest closest to
are in the orange box, mid-estuary sites are in the
the ocean source and trails off toward the mainland. white box, and mainland sites are in the blue box.
Combined with our tethering experiments (ongoing),
which suggest strong predation in the tall zones at all sites but lower predation rates in the short
zones, these data suggest that high densities of marsh invertebrates occur in areas where
recruitment is high enough to overcome losses due to high predation, i.e., short Spartina zones
on barrier islands.
To further assess the relative effects of habitat quality, larval transport, and predation in
governing invertebrate densities along the off-shore, on-shore gradient, the Silliman lab is
assessing recruitment rates (using integrative methods) and adult densities (using quadrats) for
all major marsh invertebrates at all sites. Ongoing work includes transplanting tethered
periwinkle snails, ribbed mussels and mud snails with animals of each species in paired uncaged
and caged areas across the GCE domain, both with and without predator/competitor access
(2009-2010). We will use a multiple regression model to compare separate and combined effects
of recruitment rates and predation rates as assessed by tethering all invertebrates at all sites.
When completed, this work will be integrated with work by the Pennings laboratory on
grasshopper distributions to compare drivers of distribution between marine and terrestrial
invertebrate taxa.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Genetic structure across the GCE domain
The Wares lab conducted a survey of the genetic structure of organisms in the GCE domain. The
results illustrate the importance of examining processes of site diversity and diversification at
multiple scales and levels of biological organization. Spartina alterniflora showed no significant
pattern across the domain. As might be predicted based on the larval life history of most of the
invertebrate species, there is little to no significant differentiation of marine invertebrates across
GCE sites. Figure 17 shows the distribution of pairwise estimates of Wright’s Fst from
mitochondrial data in the invertebrate species; only a few pairs of populations have statistically
significant results, but these results are neither consistent across taxa nor reliable when you
consider the effect of multiple comparisons (i.e. after Bonferroni correction). Contrasts of Fst >
0.10 are summarized below with the initials of each species and the pair of populations
exhibiting that value (Li = Littoraria irrorata; Up = Uca pugnax; Mb = Melampus bidentatus)
Although there was little genetic differentiation among sites, detailed examination of the data
revealed two interesting patterns. First, examination of nucleotide diversity (a measure of the
amount of polymorphism harbored in a DNA sequence data set) indicated that populations closer
to the ocean side of the domain were more than twice as diverse on average as populations in the
interior or mainland regions of the domain. This preliminary result suggests that even if sites in
the GCE domain were not evolutionarily differentiated from one another (and thus adaptation
was not driving ecological differences), some element of larval recruitment or other effect of the
environment on diversity at a site was important. Second, the spatial pattern of nucleotide
diversity across all sites and eight species, including the invasive porcelain crab Petrolisthes
armatus, was strongly correlated with site species diversity (using previous GCE data for
molluscan and plant diversity at each site). Although the pattern was only marginally significant
for Geukensia demissa and a couple of other species, the combined analysis suggested a highly
significant relationship between genetic and taxonomic diversity at GCE sites (as well as
between appropriate measures of genetic and species richness when only the molluscan species
data were included). These results were published in Estuaries and Coasts (Robinson et al.
2009).
Figure 17. Distribution of pairwise estimates of Wright’s Fst from mitochondrial data
in invertebrate species (see text for details).
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GCE-LTER NSF Progress Report
Year 9 (2009)
Project Management
GCE administration
Day-to-day project administration is shared by Alber and Pennings, with support from the GCE
Executive Committee (J.T. Hollibaugh (UGA), Joye, W. Sheldon, Burd). Project management
involves submitting supplementary proposals, overseeing the core budget (including setting up
subcontracts, approving purchase orders, travel, etc.), taking care of routine reporting,
supervising core project personnel, and writing letters of support for collaborative projects. We
also continue to provide GCE support for leveraged projects.
We conducted our annual GCE-LTER meeting in January 2009 in Athens, GA. The meeting was
attended by the following members of our scientific advisory committee: Iris Anderson
(VIMS/VCR), Jane Caffrey (UWF), Wim Kimmerer (SFSU), Cathy Pringle (UGA) and Mark
Hay (Georgia Tech). George Jackson (TAMU) was unable to attend the meeting but continues
to serve on the committee.
Pennings continued administrative duties related to field efforts, including supervising field
technicians at Sapelo Island and overseeing repair and maintenance of boats and field
instruments.
Network interactions
GCE scientists are active at the network level:

Pennings continues his term on the LTER Executive Board.

Alber served on the planning committee for the LTER Science Council Meeting in San,
Diego, CA (May 2009). Pennings and Craft also attended the meeting.

Burd served on the planning committee for the LTER All Scientists Meeting in
September 2009.

Alber gave a talk at the NSF LTER mini-symposium in February 2009 on coastal climate
change. She also gave a plenary talk on this topic at the Science Council Meeting in
May, which she co-chaired with C. Hopkinson (PIE). Alber and Hopkinson also helped
to organize a working group on this topic at ASM and have taken the lead on developing
a prospectus for NSF.

Alber participated in the Social-Ecological Systems cross-site workshop in Puerto Rico in
December 2008. She contributed to the synthesis document that came out of that effort
(“The Common Denominator”) and is also participating in the “Maps and Locals”
initiative.

Pennings is a member of an LTER cross-site synthesis group examining whether the
traits of plant species can predict different responses by different taxa in fertilization
experiments. This work will enhance our ability to predict the impacts of anthropogenic
inputs of nitrogen into natural systems. The group has published five manuscripts based
on this work, one in PNAS, one in Ecology Letters, two in Ecology and one in Oikos.
They have another manuscript in review and several more in preparation.
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GCE-LTER NSF Progress Report
Year 9 (2009)

Hollibaugh chaired a workshop at the ASM meeting on microbial diversity and
ecosystem dynamics across sites. He and Booth are also collaborating with L. AmaralZettler (MBL) on the MIRADA project.

Shalack collected samples for Josh Heward (Brigham Young University) and Mark
Williams (Colorado University) for cross-site comparisons.
We also have a strong network presence in terms of information management, through the
activities of W. Sheldon and J. Carpenter (UGA). Over the past year GCE IM staff served the
network in the following capacities:

Sheldon served as co-chair of the LTER Network Information System Advisory
Committee, which is developing a cyber-infrastructure implementation plan for the
LTER network.

Sheldon chaired a working group on CI implementation at the 2009 LTER IM committee
meeting.

Sheldon collaborated with the LNO Network Information System team to develop and
test a data access server (DAS) architecture to log access to LTER site data centrally
through proxy data URLs in EML metadata.

Sheldon continues to host the USGS Data Harvesting Service for HydroDB (see
http://gce-lter.marsci.uga.edu/public/im/tools/usgs_harvester.htm). Data from 57 USGS
stream flow gauging stations are automatically harvested on a weekly basis for 11 LTER
sites (AND, BES, CWT, FCE, GCE, KBS, KNZ, LUQ, NTL, PIE, SBC) and one USFS
site.

Sheldon continues to provide near-real-time USGS streamflow data harvesting for the
CWT site
(http://coweeta.ecology.uga.edu/ecology/hydrologic_data/hydrologic_data.html),
including automated plots and metadata generation for acquired data sets for 5 stations.

Sheldon served as a lead software developer for an LTER research project database
working group, and designed XQueries, XSLT stylesheets and example XHTML code to
support embedding project search and display forms on any LTER site’s web page.

Sheldon participated in a working group that is developing a controlled vocabulary of
keywords for annotating LTER metadata documents.

Sheldon and Carpenter provided training and consultation to the new CWT IM team to
help them leverage GCE-developed software, databases and approaches for enhancing
their information system to support new data collection activities.

Carpenter served as a lead developer of a cross-site, web-based mapping application for
the LTER GIS working group, and coordinated collection of GIS data describing research
areas for all 26 LTER sites.
23
GCE-LTER NSF Progress Report
Year 9 (2009)
Information Management
Overview
Information Management at the GCE site is led by W. Sheldon (UGA); J. Carpenter (UGA)
assists Sheldon and serves as our GIS specialist. A major focus of our Information Management
effort during the past year has been updating the GCE information system to support more
comprehensive management of research project information linked to over-arching research
questions, personnel, LTER core areas and research products (data, publications, reports,
imagery). We also developed interactive mapping applications for the GCE web site to provide
geospatial context for study sites and data sets and to support map-based data search and
retrieval. In addition, we have actively participated in several LTER working group initiatives to
improve standardization of data search and access across LTER sites through adoption of
controlled vocabularies and common interfaces.
IT Infrastructure
We currently manage three production servers to support GCE research and operations,
including a general database server (running SQL Server 2000), web server (running IIS 6 and
Apache 2.2) and enterprise geodatabase server (running ESRI ArcSDE 9.2, SQL Server 2000
and license servers for ArcGIS and GPS software). We also operate an additional server running
Apache 2.2, Subversion 1.6.5 and eXist 1.2.6 (a native XML database) to support GCE software
development and testing. All servers are equipped with RAID-5 hard drive configurations and
uninterruptible power supplies to provide fault tolerance, and are backed up daily to disk and
weekly to tape to protect against data loss. We added an additional 3 TB of storage to the
geodatabase server this year, expanding available storage for GIS data and disk-to-disk backups
to over 4 TB in the RAID-5 array.
We manage four high performance workstations and several field computers to support core
GCE information management activities. We also provide ArcGIS software and licenses to GCE
investigators, staff, students and affiliates in the UGA Dept. of Marine Sciences and the UGA
Marine Institute on Sapelo Island to support working with data in GCE geodatabases and general
GIS analyses.
Spatial Data Management and GIS
We continue to provide mapping and geo-analytical support for all GCE projects, maintain the
ArcSDE server, edit content for GIS-based web pages, manage spatial data for GCE personnel
use, post-process all GPS data, and create reference maps of study sites for GCE publications
and presentations.
The primary focus of spatial data management activities this year was developing an interactive
Internet mapping application to enable users to search for GCE data geographically (http://gcelter.marsci.uga.edu/public/gis/gcewebmap.html). We used the Google Maps™ Application
Programming Interface (API) to develop this web application based on performance, seamless
satellite imagery, lack of cost, familiarity to the public and large developer community. We
currently provide access to several GCE spatial datasets through this application, including study
sites and sampling locations, land use/land cover, and a digital elevation model (Figure 18).
24
GCE-LTER NSF Progress Report
Year 9 (2009)
Figure 18. Interactive GIS map of the GCE domain.
In addition to these spatial datasets, we also include links to relevant GCE tabular data and study
site information in the informational balloons for each spatial feature, allowing users to discover
related GCE research products using this map interface.
After prototyping these map applications, Carpenter presented the results to a working group of
LTER GIS specialists. The group chose to adopt this approach to develop an Internet map to
provide standardized geographic information for all 26 LTER sites and Carpenter led this effort
(demo available at http://gce-lter.marsci.uga.edu/public/gis/LTERmaps.html),.
We continue to maintain a comprehensive collection of reference GIS data (e.g. aerial and
satellite imagery, elevation, land use/land cover) and GCE spatial data in two ArcSDE
geodatabases. A 1 m2 elevation dataset of the Duplin River is now available in .grid and .img
formats for compatibility with several common GIS software packages. Examples of reference
data stored in two primary geodatabases include Georgia Land Use Trends, aerial and satellite
imagery, elevation, and topographic images.
A third production geodatabase was established in 2009 for managing GPS data collected for
GCE research projects. Metadata for all GIS datasets is created regularly and updated when new
information becomes available. General GIS files are distributed in various formats through the
GCE file archive (http://gce-lter.marsci.uga.edu/public/app/resource_search.asp); research GIS
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GCE-LTER NSF Progress Report
Year 9 (2009)
data from the Hammock study is currently being processed for inclusion in the GCE Data
Catalog.
Website Development
A major redesign of the GCE web site was completed in 2008, so with the exception of the
interactive map described above only minor refinements were made this year to support new
initiatives. For example, additional metadata search options were added to the GCE Data Catalog
(http://gce-lter.marsci.uga.edu/public/app/data_catalog.asp), such as study theme, location name,
and author name, to support data search links in Google Earth KML files and broader text-based
searches. New guidelines on data search interfaces were established by the LTER network in
2008 to address disparities in data search and access across the network, and work is currently
underway at GCE to implement search and browse interfaces (based on controlled keyword
vocabularies) that are more similar to the LTER Network data catalog (e.g.
http://metacat.lternet.edu:8080/knb/style/skins/lter/index_advancedsearch.jsp). These
modifications to the GCE data catalog will allow us to support more generic search interfaces,
while still retaining our existing interface for refining and ordering search results.
We also developed a series of REST and SOAP web services this year for accessing information
in GCE databases to support various applications. For example, web services are available for
retrieving tide predictions across the GCE domain (as XML), geographic information for GCE
study sites and point locations (as KML), personnel directory information (as EML) and data sets
(as XML). These web services are used to provide daily tide information on the GCE web site
home page and to provide dynamic mapping links on data set detail pages, study site pages, and
location search result pages. The interactive Google Maps on study site pages (e.g. http://gcelter.marsci.uga.edu/public/app/sitedetails.asp?site=GCE10, Figure 19) also use REST web
services to retrieve polygon coordinates and generate Google Earth files dynamically for each
study site.
We are currently designing comprehensive new web pages to describe the GCE research
program, including detailed descriptions of each overarching research question and our
approach, with links to information about each component project and associated products (data,
publications and reports). Sheldon, working in collaboration with other LTER information
managers, recently developed an XML schema and web-based application for managing research
project information. He also developed a relational database, database interface forms, and web
services to generate the XML documents for GCE projects, and we are currently populating the
database. In addition to providing more detailed information about GCE research, this addition to
our web site will provide a powerful new way to discover and access data and information
resulting from our work, and will support cross-site searches for related LTER research.
Software Development
We have continued to enhance the GCE Data Toolbox for MATLAB software and offer a
compiled version of this toolbox for public download on our web site (http://gcelter.marsci.uga.edu/public/im/tools/data_toolbox.htm) and on the LTER Information
Management web site (http://intranet.lternet.edu/im/project/gce_toolbox). We also provide
source code on request to LTER affiliates for examination and customization. This software can
be used to search and download data from the GCE Data Catalog and GCE Data Portal as well as
import data from various sources, and then perform metadata-based analysis, transformation,
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GCE-LTER NSF Progress Report
Year 9 (2009)
Figure 19. Google map display of GCE study site details.
integration and visualization. Users can also retrieve data from any USGS, ClimDB/HydroDB or
NOAA Hydro-meteorological Automated Data System station directly over the Internet, using
either command-line functions or graphical dialogs, and then integrate these data with GCE data
sets or their own data on demand. Nearly 3000 web visitors have downloaded the toolbox
package since the initial release in July 2002.
Support for EML Metadata
We continue to support the XML-based EML metadata standard adopted by LTER in all GCE
databases, allowing us to dynamically generate EML for all data sets in our catalog as well as
species lists, personnel entries and bibliographic citations. Our EML implementation is among
the most comprehensive in LTER, supporting metadata-mediated data access and integration
(Level 5 in the EML Best Practices guidelines, a document created by a 2004 working group
chaired by Sheldon). In 2009 we updated our EML implementation to support version 2.1.0 of
the standard to improve compatibility with modern XML editors and code libraries.
We also collaborated with LTER Network Information System developers at LNO to develop
and test a network-wide Data Access Server (DAS), to provide centralized, audited access to
LTER data in accordance with the LTER data access policy. We now provide proxy data URLs
in EML stored in Metacat to enable EML-based data access to be logged at LNO (after user
registration) as well as in the GCE database to support data use reporting. However, data access
through Metacat dropped sharply after implementing this change (possibly due to the new login
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GCE-LTER NSF Progress Report
Year 9 (2009)
requirement or unresolved usability issues with the current DAS architecture), so we are
currently reviewing suitability of this service for disseminating GCE data going forward.
Web Site and Data Access Statistics
Public downloads of GCE data sets from Fall 2001 to Fall 2009 are listed in Table 2, broken
down by data set theme and user affiliation. Downloads by GCE participants are not currently
tracked, due to open data access policies within the project. As mentioned above, we observed a
major drop in data requests through external metadata catalogs, such as the LNO Metacat server,
in 2008-2009. This may be due to the Data Access Server issues already mentioned, or due to the
ending of the SEEK project and reduction in use of GCE and other EML-described data to
develop, test and demonstrate the Kepler workflow software. We also saw a drop in data access
by educational users, although downloads by these groups typically wane in summer and resume
in late fall, when over half of all data downloads typically occur.
Table 2. Public downloads of GCE data sets, 2001-2009, by theme and affiliation.
Theme
Various (custom file)
Terrestrial Insect Ecology
Real-time Climate
Pore-water Chemistry
Plant Ecology
Phytoplankton Productivity
Physical Oceanography
Organic Matter
Meteorology
Hydrography
Geology
General Nutrient Chemistry
Fungal Productivity
Chemistry
Bacterial Productivity
Aquatic Invertebrate Ecology
Algal Productivity
All Themes
Affiliation
Other/Unspecified
Other LTER Site
LTER Network Office
International LTER Site
Government Agency
Advocacy Group
Educational (College)
Educational (K-12)
Academic Research
All Affiliations
Annual Data Downloads by Theme
2001 2002 2003 2004 2005 2006
0
0
0
0
1
5
4
7
3
12
15
27
0
0
0
4
78
29
0
0
0
2
8
4
0
13
9
19
97
28
0
0
1
17
42
20
0
2
2
54
312
128
0
5
1
13
17
12
12
27
8
20
22
13
0
0
0
0
4
6
0
0
0
0
0
2
0
7
5
8
31
11
0
2
1
1
13
1
0
0
0
0
6
2
0
0
4
15
36
16
0
0
12
137
110
94
0
0
0
0
1
13
16
63
46
302
793
411
Annual Data Downloads by Affiliation
2001 2002 2003 2004 2005 2006
0
4
10
28
69
33
1
12
16
10
29
29
0
0
2
148
166
131
0
0
0
2
1
1
6
1
0
19
210
26
0
1
0
0
0
3
4
12
1
50
129
65
0
7
2
0
36
5
5
26
15
45
153
118
16
63
46
302
793
411
2007
12
29
54
5
29
5
83
27
31
5
18
8
3
8
39
101
9
466
2008
7
40
55
3
65
57
244
66
47
11
6
20
4
5
115
122
13
880
2009
2
16
31
2
44
2
62
16
33
1
5
8
3
2
10
18
1
256
All
27
153
251
24
304
144
887
157
213
27
31
98
28
23
235
594
37
3233
2007
28
5
115
4
10
1
114
3
186
466
2008
156
41
421
0
3
0
66
15
178
880
2009
18
8
76
0
64
1
9
9
71
256
All
346
151
1059
8
339
6
450
77
797
3233
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GCE-LTER NSF Progress Report
Year 9 (2009)
Web site activity was very consistent with 2008 levels. Over 5000 visitors viewed 20,000-35,000
web pages each month (excluding malicious requests and hits from web indexing spiders). Since
January 2001, over 1.5 million GCE web pages have been viewed by more than 400,000 visitors
from 207 distinct countries and territories (based on web log analysis and DNS resolution).
Following the home page, the file archive, bibliography, EML metadata and personnel directory
pages were the most popular pages requested in 2008-2009, respectively.
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GCE-LTER NSF Progress Report
Year 9 (2009)
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GCE-LTER NSF Progress Report
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Publications and Presentations (2007-2009)
Journal Articles
Alber, M., Swenson, E.M., Adamowicz, S.C. and Mendelssohn, I.A. 2008. Salt marsh dieback:
An overview of recent events in the US. Estuarine, Coastal and Shelf Science. 80:1-11. (DOI:
10.1016/j.ecss.2008.08.009)
Bertness, M.D. and Silliman, B.R. 2008. Consumer Control of Salt Marshes Driven by Human
Disturbance. Conservation Biology. 22(3):618-623. (DOI: 10.1111/j.15231739.2008.00962.x)
Biers, E.J., Zepp, R.G. and Moran, M.A. 2007. The role of nitrogen in chromophoric and
fluorescent dissolved organic matter formation. Marine Chemistry. 103:46–60. (DOI:
10.1016/j.marchem.2006.06.003)
Bromberg-Gedan, K. and Silliman, B.R. 2009. Using Facilitation Theory to Enhance Mangrove
Restoration. Ambio. 38(2):109.
Bromberg-Gedan, K., Silliman, B.R. and Bertness, M.D. 2009. Centuries of human-driven
change in salt marsh ecosystems. Annual Review of Marine Science. 1:117-141. (DOI:
10.1146/annurev.marine.010908.163930)
Caffrey, J.M., Bano, N., Kalanetra, K. and Hollibaugh, J.T. 2007. Ammonia oxidation and
ammonia-oxidizing Bacteria and Archaea populations from estuaries with differing histories
of hypoxia. ISME Journal. 1:660-662. (DOI: http://dx.doi.org/10.1038/ismej.2007.79)
Caffrey, J.M., Hollibaugh, J.T., Bano, N. and Haskins, J. (in review). Effects of upwelling on
short term variability in microbial processes in estuarine sediments. Aquatic Microbial
Ecology.
Cai, W.-J., Dai, M. and Wang, Y. 2006. Air-sea exchange of carbon dioxide in ocean margins: A
province-based synthesis. Geophysical Research Letters. 33:L12603. (DOI:
10.1029/2006GL026219)
Clark, C.M., Cleland, E.E., Collins, S.L., Fargione, J.E., Gough L., Gross, K.L., Pennings, S.C.,
Suding, K.N., Grace, J.B. 2007. Environmental and plant community determinants of species
loss following nitrogen enrichment. Ecology Letters, 10:596-607
Cleland, E.E., Clark, C.M., Collins, S.L., Fargione, J.E., Gough, L., Gross, K.L., Milchunas,
D.G., Pennings, S.C., Bowman, W.D., Burke, I.C., Lauenroth, G.P., Robertson, J.C.,
Simpson, J.C., Tilman, D. and Suding, K.N. 2008. Species responses to nitrogen fertilization
in herbaceous plant communities, and associated species traits. Ecology. 89:1175.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Collins, S.L., Suding, K.N., Cleland, E.E., Batty, M., Pennings, S.C., Gross, K.L., Grace, J.B.,
Gough, L., Fargione, J.E. and Clark, C.M. 2008. Rank clocks and plant community
dynamics. Ecology. 89(12):3534-3541. (DOI: 10.1890/07-1646.1)
Craft, C.B. 2007. Freshwater input structures soil properties, vertical accretion, and nutrient
accumulation of Georgia and U.S. tidal marshes. Limnology & Oceanography. 52(3):12201230.
Craft, C.B., Clough, J., Ehman, J., Joye, S.B., Park, R., Pennings, S.C., Guo, H. and Machmuller,
M. 2009. Forecasting the effects of accelerated sea level rise on tidal marsh ecosystem
services. Frontiers in Ecology and the Environment. 7(2):73-78. (DOI: 10.1890/070219)
Daleo, P., Silliman, B.R., Alberti, J., Canepuccia, A., Escapa, M., Canepuccia, A., Pena, N. and
Iribarne, O. 2009. Top-down control of salt marsh plant production by crab facilitation of
fungal infection. Journal of Plant Ecology. 97:781-787.
Di Iorio, D. and Kang, K. 2007. Variations of turbulent flow with river discharge in the
Altamaha River Estuary, Georgia. Journal of Geophysical Research - Oceans. 112:C05016.
(DOI: 10.1029/2006JC003763)
Diaz-Ferguson, E., Robinson, J.D., Silliman, B.R. and Wares, J.P. 2009. Comparative
Phylogeography of East Coast American Salt Marsh Communities. Estuaries and Coasts. (in
press)
Dong, Y., Guerrero, S. and Moran, M.A. 2008. Exploring marine bacterial diversity in coastal
Georgia salt marshes using DNA technology. The American Biology Teacher. 70:279-283.
Edmonds, J.W., Weston, N.B., Joye, S.B. and Moran, M.A. 2008. Variation in Prokaryotic
Community Composition as a Function of Resource Availability in Tidal Creek Sediments.
Applied and Environmental Microbiology. 74(6):1836-1844. (DOI: 10.1128/AEM.00854-07)
Edmonds, J.W., Weston, N.B., Joye, S.B., Mou, X. and Moran, M.A. 2009. Microbial
Community Response to Seawater Amendment in Low-Salinity Tidal Sediments. Microbial
Ecology. 58(3):558-568. (DOI: 10.1007/s00248-009-9556-2)
Ewers, C., Beiersdorf, A., Wieski, K., Pennings, S.C. and Zimmer, M. (in review). Intra-guild
predator/prey-interactions promote decomposition of low-quality detritus in a saltmarsh
system.
Farina, J., Silliman, B.R. and Bertness, M.D. 2009. Can conservation biologists rely on
established community structure rules to manage novel systems? . . Not in salt marshes.
Ecological Applications. 19(2):413–422. (DOI: 10.1890/07-1000.1)
First, M.R. and Hollibaugh, J.T. (in press). The model high molecular weight DOC compound,
dextran, is ingested by the benthic ciliate, Uronema marinum, but does not supplement ciliate
growth. Aquatic Microbial Ecology. 57:79-87. (DOI: 10.3354/ame01338)
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GCE-LTER NSF Progress Report
Year 9 (2009)
First, M.R. and Hollibaugh, J.T. (in review). Ciliate ingestion and digestion: Flow cytometric
measurements and recovery of a digestion-resistant Campylobacter jejuni. Applied and
Environmental Microbiology.
First, M.R. and Hollibaugh, J.T. (in review). Environmental Factors Shaping Microbial
Community Structure in Salt Marsh Sediments. Marine Ecology Progress Series.
First, M.R. and Hollibaugh, J.T. 2008. Protistan bacterivory and benthic microbial biomass in an
intertidal creek mudflat. Marine Ecology Progress Series. 361:59-68. (DOI:
10.3354/meps07422)
First, M.R., Miller, H.L. III, Lavrentyev, P.J., Pinckney, J.L. and Burd, A.B. 2009.
Microzooplankton growth and trophic interactions and their effects on herbivory in coastal
and offshore environments. Aquatic Microbial Ecology 54: 255-267. Aquatic Microbial
Ecology. 54:255-267. (DOI: 10.3354/ame01271)
Frost, J.W., Schleicher, T. and Craft, C.B. 2009. Effects of nitrogen and phosphorus additions on
primary production and invertebrate densities in a Georgia (USA) tidal freshwater marsh.
Wetlands. 29(1):196-203. (DOI: 10.1672/07-79.1)
Gustafson, D.J., Kilheffer, J. and Silliman, B.R. 2006. Relative impacts of Littoraria irrorata and
Prokelisia marginata on Spartina alterniflora. Estuaries. 26:639-644.
Ho, C.-K. and Pennings, S.C. 2008. Consequences of omnivory for trophic interactions on a saltmarsh shrub. Ecology. 89(6):1714-1722. (DOI: 10.1890/07-1069.1)
Hopkinson, C., Lugo, A., Alber, M., Covich, A. and Van Bloem, S.J. 2008. Understanding and
forecasting the effects of sea level rise and intense windstorms on coastal and upland
ecosystems: the need for a continental-scale network of observatories. Frontiers in Ecology.
6(5):255-263. (DOI: 10.1890/070153)
Hübner, L., Pennings, S.C. and Zimmer, M. (in preparation). A re-assessment of the ecology of
the so-called saltmarsh crab Armases cinereum.
Jiang, L., Cai, W.-J. and Wang, Y. 2008. A comparative study of carbon dioxide degassing in
river- and marine-dominated estuaries. Limnology and Oceanography. 53(6):2603-2615.
Jiang, L., Cai, W.-J., Wang, Y., Diaz, J., Yager, P. and Hu, X. 2009. Pelagic community
respiration on the continental shelf off Georgia, USA. Biogeochemistry. (in press)
Jiang, L., Cai, W.-J., Wang, Y., Wanninkhof, R. and Luger, H. 2008. Air-sea CO2 fluxes on the
US South Atlantic Bight: Spatial and temporal variability. Journal of Geophysical ResearchOcean. 113:C07019. (DOI: 10.1029/2007JC004366)
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GCE-LTER NSF Progress Report
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Kang, K. and Di Iorio, D. 2008. A study of estuarine flow using the roving adcp data. Ocean
Science Journal. 43(2):81-90. (DOI: 10.1007/BF03020584)
Koch, E.W., Barbier, E.B., Silliman, B.R., Reed, D.J., Perillo, M.E., Hacker, S.D., Granek, E.F.,
Primavera, J.H., Muthiga, N., Polasky, S., Halpern, B.S., Kennedy, C.J., Kappel, C.V. and
Wolanski, E. 2009. Non-linearity in ecosystem services: temporal and spatial variability in
coastal protection. Frontiers in Ecology and the Environment. 7(1):29-37. (DOI:
10.1890/080126)
Krull, K. and Craft, C.B. 2009. Ecosystem development of a sandbar emergent tidal marsh,
Altamaha River estuary, Georgia USA. Wetlands. 29(1):314-322. (DOI: 10.1672/06-178.1)
Kunza, A.E. and Pennings, S.C. 2008. Patterns of plant diversity in Georgia and Texas salt
marshes. Estuaries and Coasts. 31:673-681.
Lasher, C., Dyszynski, G., Everett, K., Ye, W., Sheldon, W.M. Jr., Joye, S.B., Moran, M.A. and
Whitman, W.B. 2009. The diverse bacterial community in intertidal, anaerobic sediments at
Sapelo Island, Georgia. Microbial Ecology. 58(2):244-261. (DOI: 10.1007/s00248-008-94819)
Loomis, M.J. and Craft, C.B. (in revision). Carbon sequestration and nutrient (N, P)
accumulation in river-dominated tidal marshes, Georgia, USA. Soil Science Society of
America Journal.
Lyons, J.I., Alber, M. and Hollibaugh, J.T. 2009. Ascomycete fungal communities associated
with early decay leaf blades of three Spartina species and a Spartina hybrid in the San
Francisco Bay. Oecologia. (DOI: 10.1007/s00442-009-1460-4) (in press)
McFarlin, C.R., Brewer, J.S., Buck, T.L. and Pennings, S.C. 2008. Impact of fertilization on a
salt marsh food web in Georgia. Estuaries and Coasts. 31:313-325.
McKay, P. and Di Iorio, D. 2008. Heat budget for a shallow, sinuous salt marsh estuary.
Continental Shelf Research. 28:1740–1753. (DOI: 10.1016/j.csr.2008.04.008)
McKay, P. and Di Iorio, D. 2009. The Cycle of Vertical and Horizontal Mixing in a Tidal Creek.
Journal of Geophysical Research. (in press)
Meile, C., Porubsky, W.P., Walter, R. and Payne, K. (in revision). Natural attenuation of
nitrogen loading from septic effluents: Spatial and environmental controls. Water Research.
Mews, M., Pennings, S.C. and Zimmer, M. (in preparation). Interspecific interactions in the
decomposition of common saltmarsh detritus.
Moore, W.S., Blanton, J.O. and Joye, S.B. 2006. Estimates of flushing times, submarine
groundwater discharge, and nutrient fluxes to Okatee Estuary, South Carolina. Journal of
Geophysical Research. 111:C09006. (DOI: 10.1029/2005JC003041)
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GCE-LTER NSF Progress Report
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Mou, X., Hodson, R.E. and Moran, M.A. 2007. Bacterioplankton assemblages transforming
dissolved organic compounds in coastal seawater. Environmental Microbiology. 9:2025–
2037. (DOI: 10.1111/j.1462-2920.2007.01318)
Mou, X., Moran, M.A., Stepansuskas, R., González, J.M. and Hodson, R.E. 2005. Cultureindependent identification of bacterioplankton involved in DMSP transformations by flow
cytometric cell sorting and subsequent molecular analyses. Applied and Environmental
Microbiology. 71:1405-1416. (DOI: 10.1128/AEM.71.3.1405–1416.2005)
Pennings, S.C. and Simpson, J.C. 2008. Like herbivores, parasitic plants are limited by host
nitrogen content. Plant Ecology. 196:245-250. (DOI: 10.1007/s11258-007-9348-z)
Pennings, S.C., Ho, C.-K., Salgado, C.S., Wieski, K., Davé, N.B., Kunza, A.E. and Wason, E.L.
2009. Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes. Ecology.
90(1):183-195. (DOI: 10.1890/08-0222.1)
Pennings, S.C., Zimmer, M., Dias, N., Sprung, M., Davé, N., Ho, C.-K., Kunza, A., McFarlin,
C., Mews, M., Pfauder, A. and Salgado, C. 2007. Latitudinal variation in plant-herbivore
interactions in European salt marshes. Oikos. 116:543-549.
Poretsky, R.S., Bano, N., Buchan, A., LeCleir, G., Kleikemper, J., Pickering, M., Pate, W.M.,
Moran, M.A. and Hollibaugh, J.T. 2005. Analysis of microbial gene transcripts in
environmental samples. Applied and Environmental Microbiology. 71: 4121-4126.
Porubsky, W.P., Joye, S.B., Moore, W.S., Tuncay, K. and Meile, C. (in review). Hammock
groundwater biogeochemistry and flow: Field measurements and modeling.
Biogeochemistry.
Porubsky, W.P., Velasquez, L.E. and Joye, S.B. 2008. Nutrient replete benthic microalgae as a
source of labile dissolved organic carbon to coastal waters. Estuaries and Coasts. 31(5):860876. (DOI: 10.1007/s12237-008-9077-0)
Porubsky, W.P., Weston, N.B. and Joye, S.B. 2009. Benthic metabolism and the fate of
dissolved inorganic nitrogen in intertidal sediments. Estuarine Coastal and Shelf Science.
83(4):392-402. (DOI: 10.1016/j.ecss.2009.04.012)
Richards, C.L., White, S.N., McGuire, M.A., Franks, S.J., Donovan, L.A. and Mauricio, R. 2009.
Plasticity, Not Adaptation to Salt Level, Explains Variation Along a Salinity Gradient in a
Salt Marsh Perennial. Estuaries and Coasts. (DOI: 10.1007/s12237-009-9186-4) (in press)
Robinson, J.D., Diaz-Ferguson, E., Poelchau, M., Pennings, S.C., Bishop, T.D. and Wares, J.P.
2009. Multiscale Diversity in the Marshes of the Georgia Coastal Ecosystems LTER.
Estuaries and Coasts. (DOI: 10.1007/s12237-009-9188-2) (in press)
35
GCE-LTER NSF Progress Report
Year 9 (2009)
Sala, N., Bertness, M.D. and Silliman, B.R. 2008. The Dynamics of Top-down and Bottom-up
control in New England salt marshes. Oikos. 117(7):1050-1056. (DOI: 10.1111/j.00301299.2008.16296.x)
Schaefer, S.C. and Alber, M.A. 2007. Temperature controls a latitudinal gradient in the
proportion of waterhsed nitrogren exported to coastal ecosystems. Biogeochemistry. 85:333346.
Schaefer, S.C. and Alber, M.A. 2007. Temporal and spatial trends in nitrogen and phosphorus
inputs to the watershed of the Altamaha River, Georgia, USA. Biogeochemistry. 86(3):231249. (DOI: 10.1007/s10533-007-9155-6)
Schaefer, S.C., Hollibaugh, J.T. and Alber, M. 2009. Watershed nitrogen input and riverine
export on the west coast of the U.S. Biogeochemistry. 93(3):219-233. (DOI: 10.1007/s10533009-9299-7)
Seay, J.E., Bishop, T.D., Miller, H.L. III and Tilburg, C.E. (in review). Spatial and Temporal
Distribution of Green Porcelain Crab Larvae in a South Atlantic Bight Estuary. Estuaries and
Coasts.
Seer, F., Putze, G., Pennings, S.C. and Zimmer, M. (in preparation). Habitat-specific
decomposition of saltmarsh detritus along a marine-terrestrial gradient.
Seim, H.E., Blanton, J.O. and Elston, S.A. 2008. The effect of secondary circulation on the salt
distribution in a sinuous coastal plain estuary: Satilla River, GA, USA. Continental Shelf
Research. 29(1):15-28. (DOI: 10.1016/j.csr.2008.03.018)
Tackett, N. and Craft, C.B. (in press). Ecosystem development on a coastal barrier island dune
chronosequence. Journal of Coastal Research.
Thompson, V.D. and Turck, J.A. 2009. Adaptive Cycles of Coastal Hunter-Gatherers. American
Antiquity. 74(2):255-278.
Thomsen, M.S., McGlathery, K.J., Schwarzschild, A. and Silliman, B.R. 2009. Distribution and
ecological role of the non-native macroalga Gracilaria vermiculophylla in Virginia salt
marshes. Biological Invasions. (DOI: 10.1007/s10530-008-9417-9) (in press)
Thomsen, M.S., Wernberg, T., Tuya, F. and Silliman, B.R. 2009. Evidence for impacts of nonindigenous macroalgae: a meta-analysis of experimental field studies. Journal of Phycology.
45(4):812-819. (DOI: 10.1111/j.1529-8817.2009.00709.x)
Tilburg, C.E., Seay, J.E., Bishop, T.D., Miller, H.L. and Meile, C. (in review). Distribution and
retention of Petrolisthes armatus in a coastal plain estuary: the role of vertical movement in
larval transport. Estuarine Coastal and Shelf Science.
36
GCE-LTER NSF Progress Report
Year 9 (2009)
Verity, P.G., Alber, M. and Bricker, S.B. 2006. Development of Hypoxia in Well-mixed
Subtropical Estuaries in the Southeastern USA. Estuaries and Coasts, 29(4):665–673.
Wason, E.L. and Pennings, S.C. 2008. Grasshopper (Orthoptera: Tettigoniidae) species
composition and size across latitude in Atlantic Coast salt marshes. Estuaries and Coasts.
31:335-343.
Weston, N.B., Dixon, R.E. and Joye, S.B. 2006. Microbial and geochemical ramifications of
salinity intrusion into tidal freshwater sediments. Journal of Geophysical Research.
111:G01009. (DOI: 10.1029/2005JG000071)
Weston, N.B., Hollibaugh, J.T. and Joye, S.B. 2009. Population growth away from the coastal
zone: Thirty years of land use change and nutrient export from the Altamaha River, GA.
Science of the Total Environment. 407:3347-3356.
Weston, N.B., Porubsky, W.P., Samarkin, V., MacAvoy, S., Erickson, M. and Joye, S.B. 2006.
Pore water stoichiometry of terminal metabolic products, sulfate, and dissolved organic
carbon and nitrogen in intertidal creek-bank sediments. Biogeochemistry. 77:375-408.
White, S.N. and Alber, M. 2009. Drought-associated shifts in Spartina alterniflora and S.
cynosuroides in the Altamaha River estuary. Wetlands. 29(1):215-224. (DOI: 10.1672/0839.1)
Wieski, K., Guo, H., Craft, C.B. and Pennings, S.C. (in revision). Ecosystem functions of tidal
fresh, brackish and salt marshes on the Georgia coast. Estuaries and Coasts.
Wrona, A.M., Batzer, D., Alber, M. and Sharitz, R.R. 2007. Savannah River, Georgia: Science to
support adaptive implementation of environmental flows to a large coastal river, floodplain,
and estuary. Water Resources Impact. 9(4):21-24.
Books and Book Sections
Bertness, M.D., Silliman, B.R. and Holdredge, C. 2009. Shoreline development and the future of
New England salt marsh landscapes. Pages 137-148 in: Silliman, B.R., Grosholtz, T. and
Bertness, M.D. (editors). Human Impacts on Salt Marshes: A Global Perspective. University
of California Press.
Bromberg, K. and Silliman, B.R. 2009. Patterns of salt marsh loss within coastal regions of
North America: pre-settlement to present. Pages 253-266 in: Silliman, B.R., Grosholtz, T.
and Bertness, M.D. (editors). Human Impacts on Salt Marshes: A Global Perspective.
University of California Press.
Broome, S.W. and Craft, C.B. 2009. Tidal marsh creation. Pages 715-786 in: Perillo, G.M.E.,
Wolanski, E., Cahoon, D. and Brinson, M.M. (editors). Coastal Wetlands. Elsevier,
Amsterdam, The Netherlands.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Craft, C.B., Bertram, J. and Broome, S.W. 2008. Restoration of coastal zones. Pages 637-644 in:
Jorgensen, S.E. and Fath, B. (editors). Ecologicial Engineering. Elsevier B.V., Oxford.
Joye, S.B. and Anderson, I. 2008. Nitrogen Cycling in Estuarine and Nearshore Sediments.
Pages 867-915 in: Capone, D.G., Bronk, D.A., Mulholland, M.A. and Carpenter, E.J.
(editors). Nitrogen in the Marine Environment, Second Edition. Elsevier Inc. (DOI:
10.1016/B978-0-12-372522-6.00019-0)
Joye, S.B., Cook, P. and de Beer, D. 2009. Biogeochemical dynamics of coastal tidal flats. Pages
345-374 in: Perillo, G., Cahoon, D. and Brinson, M. (editors). Coastal Wetlands: An
Integrated Ecosystem Approach. Elsevier, Amsterdam, The Netherlands.
Neubauer, S. and Craft, C.B. 2009. Global change and tidal freshwater wetlands: Scenarios and
impacts. Pages 253-310 in: Barendregt, A., Whigham, D. and Baldwin, A. (editors). Tidal
Freshwater Wetlands. Backhuys Publishers, Leiden, The Netherlands.
Newell, S.Y., Lyons, J.I. and Moran, M.A. 2007. A saltmarsh decomposition system and its
ascomycetous laccase genes. Pages 357-370 in: Gadd, G., Dyer, P. and Watkinson, S.
(editors). Fungi in the Environment. Cambridge University Press, Cambridge, UK.
Osgood, D. and Silliman, B.R. 2009. From climate change to snails: potential causes of salt
marsh die-back along the U.S. Eastern Seaboard and Gulf Coasts. Pages 231-252 in:
Silliman, B.R., Grosholtz, T. and Bertness, M.D. (editors). Human Impacts on Salt Marshes:
A Global Perspective. University of California Press.
Schultz, G.M., Ruppel, C.D. and Fulton, P. 2007. Integrating hydrologic and geophysical data to
constrain coastal surficial aquifer processes at multiple spatial and temporal scales. Pages
161-182 in: Hyndman, D.W., Day-Lewis, E.D. and Singha, K. (editors). Subsurface
Hydrology: Data Integration for Properties and Processes. American Geophysical Union
Geophysical Monograph, Series Volume 171. (DOI: 10.1029/171GM13)
Sharitz, R.R. and Pennings, S.C. 2006. Development of wetland plant communities. Pages 177241 in: Batzer, D.P. and Sharitz, R.R. (editors). Ecology of freshwater and estuarine
wetlands. University of California Press, Berkeley.
Silliman, B.R., Bertness, M.D. and Thomsen, M.S. 2009. Top-down control and human
intensification of consumer pressure in southern U.S. salt marshes. Pages 103-114 in:
Silliman, B.R., Grosholtz, T. and Bertness, M.D. (editors). Human Impacts in Salt Marshes:
A Global Perspective. University of California Press, Berkeley, California.
Silliman, B.R., Grosholtz, T. and Bertness, M.D. 2009. Salt marshes under global siege. Pages
391-398 in: Silliman, B.R., Grosholtz, T. and Bertness, M.D. (editors). Human Impacts on
Salt Marshes: A Global Perspective. University of California Press.
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Thomsen, M.S., Adams, P. and Silliman, B.R. 2009. Anthropogenic threats to Australasian
coastal salt marshes. Pages 361-390 in: Silliman, B.R., Grosholtz, T. and Bertness, M.D.
(editors). Human Impacts on Salt Marshes: A Global Perspective. University of California
Press.
Conference Proceedings (Published Papers and Abstracts)
Henshaw, D.L., Sheldon, W.M., Remillard, S.M. and Kotwica, K. 2006. ClimDB/HydroDB: A
web harvester and data warehouse approach to building a cross-site climate and hydrology
database. Proceedings of the 7th International Conference on Hydroscience and Engineering
(ICHE 2006). Michael Piasecki and College of Engineering, Drexel University, Philadelphia,
USA.
McFarlin, C.R. and Alber, M. 2007. Coastal Watershed Condition Assessment of Fort Pulaski
National Monument. In: Georgia Water Resources Conference. Proceedings of the 2007
Georgia Water Resources Conference.
Porubsky, W.P. and Meile, C. 2009. Controls on groundwater nutrient mitigation: Natural
attenuation of nitrogen loading from septic effluents. In: Hatcher, K.J. (editor). Proceedings
of the Georgia Water Resources Conference. Athens, Georgia.
Sheldon, W.M. Jr. 2008. Dynamic, Rule-based Quality Control Framework for Real-time Sensor
Data. Pages 145-150 in: Gries, C. and Jones, M.B. (editors). Proceedings of the
Environmental Information Management Conference 2008 (EIM 2008): Sensor Networks.
Albuquerque, New Mexico.
Thompson, V.D., Turck, J.A. and DePratter, C. 2009. The Historical Ecology of Islands Large
and Small along the Georgia Coast. In: Thompson, V.D. and Waggoner, J. (editors). The
Historical Ecology of Hunter-Gatherers. 74th Society for American Archaeology
Conference, Atlanta, Georgia.
Turck, J.A. and Thompson, V.D. 2008. Geoarchaeological Analysis of Two Back-Barrier Islands
on the Coast of Georgia, U.S.A. In: Reitz, E.J. and Thomas, D.H. (editors). Environmental
Archaeology in the Georgia Bight. 65th Southeastern Archaeology Conference, Charlotte,
North Carolina.
Theses and Dissertations
First, M.R. 2008. Benthic Microbial Food Webs: Spatial and Temporal Variations and the Role
of Heterotrophic Protists in Salt Marsh Sediments. Ph.D. Dissertation. University of Georgia,
Athens, Georgia.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Hartmann, J. 2007. Determination of gas exchange velocities based on measurements of air-sea
CO2 partial pressure gradients and direct chamber fluxes in the Duplin River, Sapelo Island,
GA. M.S. Thesis. University of Georgia, Athens, Georgia. 84 pages.
Ho, C.-K. 2008. Plant-herbivore interactions in U.S. Atlantic Coast salt marshes: the effect of
omnivory and geographic location. Ph.D. Dissertation. University of Houston, Houston, TX.
116 pages.
Kunza, A.E. 2006. Patterns of plant diversity in two salt marsh regions. M.S. Thesis. University
of Houston, Houston, Texas. 70 pages.
Lee, R.Y. 2006. Primary production, nitrogen cycling and the ecosystem role of mangrove
microbial mats on Twin Cays, Belize. Ph.D. Dissertation. University of Georgia, Athens,
Georgia. 157 pages.
Lyons, J.I. 2007. Molecular description of ascomycete fungal communities on Spartina spp. in
the U.S. Ph.D. Dissertation. University of Georgia, Athens, Georgia.
McKay, P. 2008. Temporal and Spatial Variability of Transport and Mixing Mechanisms: Using
Heat and Salt in the Duplin River, Georgia. Ph.D. Dissertation. University of Georgia,
Athens GA. 217 pages.
Mou, X. 2006. Culture-independent Characterization Of DOC-Transforming Bacterioplankton in
Coastal Seawater. Ph.D. Dissertation. University of Georgia, Athens, Georgia. 182 pages.
Porubsky, W.P. 2008. Biogeochemical dynamics in coastal sediments and shallow aquifers.
Ph.D. Dissertation. University of Georgia, Athens, Georgia. 222 pages.
Schaefer, S.C. 2006 Nutrient budgets for watersheds on the southeastern Atlantic coast of the
United States: temporal and spatial variation. M.S. Thesis, University of Georgia, Athens,
Georgia, 105 pp.
Conference Posters and Presentations
Alber, M. 2006. Presentation: CSI Ecology: Salt marsh dieback in Georgia. University of
Georgia Department of Geology, Athens, Georgia.
Alber, M. 2006. Presentation: Losses of foundation species and the consequences for ecosystem
structure and function. Working group at the LTER All Scientists Meeting, September 20-24,
2006. Estes Park, Colorado.
Alber, M. 2006. Presentation: Salt marsh dieback in Georgia. Sudden wetland dieback meeting,
May 24, 2006, Wellfleet, Massachussetts.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Alber, M. 2006. Presentation: The Georgia Coastal Research Council - Project overview. Coastal
Incentive Grant Colloquium, October 2006, Savannah, Georgia.
Alber, M. 2007. Presentation: The Earth has one big ocean with many features. Georgia
Association of Marine Educators, 10/07, Tybee Island, GA.
Alber, M. 2008. Presentation: How scientists can become involved in education and public
outreach. American Society of Limnology and Oceanography, 3/08, Orlando, FL.
Alber, M. 2008. Presentation: The Earth has one big ocean with many features. National Marine
Educators Association, 7/08, Savannah, GA.
Alber, M. and Sheldon, J.E. 2006. Calculating estuary turnover times during non-steady-state
conditions using freshwater fraction techniques. Southeastern Estuarine Research Society
meeting, Ponte Vedra Beach, Florida.
Alber, M. and Sheldon, J.E. 2006. Presentation: Simple tools for assessing coastal systems: can
we get there from here? Coastal Observing Systems Workshop, LTER All Scientists
Meeting, September 20-24, 2006, Estes Park Colorado.
Alber, M., Mackinnon, J., Hurley, D. and Curran, M.C. 2007. Presentation: Salt Marsh Dieback
in Georgia. Estuarine Research Federations 2007 Annual Meeting, 4-8 November 2007,
Providence, Rhode Island.
Alber, M., Schaefer, S.C., Pomeroy, L.R., Sheldon, J.E. and Joye, S.B. 2008. Presentation:
Nitrogen inputs to the Altamaha River estuary (Georgia, USA): a historic analysis. American
Society of Limnology and Oceanography, 3/08, Orlando, FL.
Alexander, C.R. Jr. 2008. Presentation: Stratigraphic Development of Holocene and Pleistocene
Marsh Islands. Tidalites 2008 - Seventh International Conference on Tidal Environments,
25th-27th September, 2008, Qingdao, China.
Booth, M.G. and Muscarella, M. (accepted). Presentation: Factors influencing bacteriophage
activities in estuaries near Sapelo Island, GA. SCI-015 Microbes: A Synthesis of Diversity,
Gene Expression and Ecological Function. 2009 Coastal and Estuarine Research Federation
Annual Meeting, November 2009, Portland, Oregon.
Booth, M.G. and Poole, A. 2008. Poster: Utilizing nasA and 15N-NO3- Uptake to Characterize
and Quantify Nitrate Assimilation in Estuarine Heterotrophic Bacterioplankton. N-029. 2009
American Society of Microbiology Annual Meeting, June 2008, Boston, Massachusetts.
Collins, S.L., Suding, K.N., Cleland, E.E., Batty, M., Pennings, S.C., Gross, K.L., Grace, J.S.,
Gough, L., Fargione, J.E., Clark, C.M. Presentation: Rank clocks and plant community
dynamics. Joint Ecological Society of America / Society for Ecological Restoration 2007
Meeting, August 5-10, 2007, San Jose, CA.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Craft, C., Clough, J., Ehman, J. and Park, R. 2007. Presentation: Effects of accelerated sea level
rise on biogeochemical cycles of tidal marshes of the southeast U.S. coast: a landscape
simulation. 10th International Symposium on Wetland Biogeochemistry, April 1-4 2007,
Annapolis, Maryland.
Craft, C., Clough, J., Ehman, J. and Park, R. 2007. Presentation: Effects of accelerated sea level
rise on C, N and P retention by tidal marshes: a landscape simulation. 2nd International
Symposium on Wetland Pollution Dynamics and Control (WETPOL), September 16-20
2007, University of Tartu, Tartu, Estonia.
Craft, C.B. 2007. Keynote presentation: Tidal marshes and climate change. 2nd International
Symposium on Wetland Pollution Dynamics and Control (WETPOL), September 16-20
2007, University of Tartu, Tartu, Estonia.
Craft, C.B. and Krull, K. 2006. Presentation: Ecosystem development of a newly emerged tidal
marsh. 6th International Workshop on Nutrient Cycling and retention in Natural and
Constructed Wetlands, May 31-June 4, 2006, Trebon, Czech Republic.
Craft, C.B. and Krull, K. 2007. Presentation: Ecosystem development of a newly emerged tidal
marsh: a model for evaluating "success" of created and restored marshes. Society of Wetland
Scientists 27th International Conference, July 9-14, 2006, Cairnes, Australia.
Di Iorio, D., Ait Amrouche, M., Blanton, J.O. and Amft, J. 2009. Poster: Observations of the
dynamical response of heat and salt to buoyancy, oceanic, and wind forcing, and atmospheric
fluxes in the GCE domain. LTER All Scientist Meeting, Sept 13-16, 2009, Estes Park, CO.
Doherty, M., Poretsky, R.S., Muscarella, M., Moran, M.A. and Booth, M.G. 2009. Presentation:
Tracking Metabolism of an Important Terrestrial Carbon Source by Marine
Bacterioplankton. 2009 Coastal and Estuarine Research Federation Annual Meeting,
November 2009, Portland, Oregon.
First, M. 2005. Georgia Coastal Ecosystems Long-Term Ecological Research (GCE-LTER) Site
Review. LTER Graduate Student Collaborative Research Symposium. Andrews
Experimental Research Forest, April 2005, Blue River, Oregon.
First, M. and Hollibaugh, J.T. 2006. Presentation: Temporal and spatial patterns of benthic
microbial communities in a subtropical salt marsh (Sapelo Island, GA). Long Term
Ecological Research Network All-Scientists Meeting, September 20-24, 2006, Estes Park,
Colorado.
First, M.R. 2006. Presentation: Benthic microbial food webs: daily and yearly variations and
short cuts in the microbial loop. University of Georgia Marine Science Graduate Student
Seminar Series, August, 2006, University of Georgia, Athens, Georgia.
First, M.R. and Hollibaugh, J.T. (accepted). Presentation: Environmental controls on benthic
microbial food webs. Microbial Ecology. LTER ASM 2009, 13 Sept, 2009, Estes Park CO.
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GCE-LTER NSF Progress Report
Year 9 (2009)
First, M.R. and Hollibaugh, J.T. 2006. Diel monitoring of sediment bacteria and protists in a
subtropical tidal creek, Sapelo Island, Georgia. ASLO Summer Meeting, June 2006, Victoria,
British Colombia.
First, M.R. and Hollibaugh, J.T. 2007. Presentation: Direct uptake of high molecular weight
dissolved organic carbon by benthic ciliates. ASLO Aquatic Sciences Meeting, February
2007, Santa Fe, New Mexico.
Guo, H., Pennings, S.C. and Wieski, K. 2008. Poster: Physical stress, plant productivity,
competition, and diversity in Georgia tidal marshes. Coastal Habitats. 93rd Annual Meeting
of the Ecological Society of America, August 3-8, 2008, Milwaukee, Wisconsin.
Hester, M.W., Mendelssohn, I.A., Alber, M. and Joye, S.B. 2007. Presentation: Climate-Linked
Alteration of Ecosystem Services in Tidal Salt Marshes of Georgia and Louisiana:
Preliminary Findings. Estuarine Research Federations 2007 Annual Meeting, 4-8 November
2007, Providence, Rhode Island.
Ho, C.-K. and Pennings, S. C. Presentation: Preference and performance in plant-herbivore
interactions across latitude. 91st Annual Meeting of the Ecological Society of America.
August 6-11, 2006, Memphis, Tennessee, USA.
Ho, C.-K. and Pennings, S.C. 2007. Presentation: Bergmann¡'s Rule and latitudinal variation in
herbivore body size. Joint Ecological Society of America / Society for Ecological Restoration
2007 Meeting, August 5-10, 2007, San Jose, California, USA.
Hollibaugh, J.T. and Alber, M. 2006. Presentation: Georgia's Coast - Past, present, and future.
Georgia Certified Court Reporters Class, September 2006, St. Simons, Georgia.
Hollibaugh, J.T. and Ransom, B. 2007. Poster: Comparison of fish species reveals major
differences in the composition of gut microflora. ERF 2007, 4-8 November 2007,
Providence, Rhode Island.
Johnson, H.E. 2007. Poster: Screening of Fosmid Library of Environmental Genomic DNA from
Sapelo Island. Center for Undergraduate Research Opportunities Symposium, April 9, 2007,
University of Georgia, Athens, Georgia.
Joye, S.B., Hunter, K.S., Bernier, M., Craft, C. 2007. Presentation: Salinity-driven patterns in
sediment biogeochemistry and microbial activity in Georgia coastal estuaries. 10th
International Symposium on the Biogeochemistry of Wetlands, 1-4 April 2007, Annapolis,
Maryland.
Joye, S.B., Hyacinthe, C., Samarkin, V., Baas, P. and Hester, M.W. 2009. Presentation:
Biogeochemical signatures and microbial activity in sediments recovering from salt marsh
dieback. Coastal and Estuarine Research Federation Conference, November 2009, Portland,
Oregon.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Kenemer, B., McFarlin, C. and Alber, M. 2006. Poster: Fiddler Crabs Dig It: A Study of Burrow
Dynamics in a Salt Marsh. Fall 2006 Meeting of the Southeastern Estuarine Research
Society, October 19-21, 2006, Savannah, Georgia.
Kunza, A.E. and Pennings, S.C. 2006. Poster: Patterns of plant diversity in two salt marsh
regions. Long Term Ecological Research Network All-Scientists Meeting, September 20-24,
2006, Estes Park, Colorado.
Lyons, J., Alber, M. and Hollibaugh, J.T. 2006. Poster: Molecular comparison of ascomycete
fungal communities on Spartina species found along the east, west, and Gulf coasts of the
U.S. LTER All Scientists Meeting, September 20-24, 2006, Estes Park, Colorado.
Lyons, J.I., Alber, M. and Hollibaugh, J.T. 2006. Poster: Molecular comparison of ascomycete
fungal communities on Spartina species found along the east, west, and Gulf coasts of the
U.S. Southeastern Estuarine Research Society. March 30-April 1, 2006, St. Augustine,
Florida.
McFarlin, C.R., Kenemer, B., Alber, M., Hester, M.W. and Bishop, T.D. 2007. Poster: A
Comparison of Dieback Effects on Salt Marsh Invertebrates in Georgia and Louisiana.
Estuarine Research Federations 2007 Annual Meeting, 4-8 November 2007, Providence,
Rhode Island.
McFarlin, C.R., Ogburn, M.B. and Alber, M. 2006. Poster: The recent status and trends of two
Georgia marsh dieback sites. Spring 2006 Meeting of the Southeastern Estuarine Research
Society, March 30-April 1, 2006, St. Augustine, Florida.
McKay, P. and Di Iorio, D. 2006. Presentation: Salt and heat fluxes in a sinuous, macrotidal salt
channel in the south Atlantic Bight. AGU Ocean Sciences Meeting, February 2006,
Honolulu, Hawaii.
McKay, P. and Di Iorio, D. 2009. Poster: Tidal correlations, groundwater and the reversing
salinity gradient in a tidal creek. 2009 Gordon Research Conference on Coastal Circulation,
Jun 10, 2009, Colby Sawyer College, New London, NH.
Palomo, L., Hyacinthe, C. and Joye, S.B. 2009. Presentation: Drought impacts on
biogeochemistry and microbial processes in salt marsh sediments. Coastal and Estuarine
Research Federation Conference, November 2009, Portland, Oregon.
Pennings, S.C. 2006. Presentation: Plant community response to nitrogen enrichment: results
from a cross-site synthesis. Long Term Ecological Research Network All-Scientists Meeting,
September 20-24, 2006, Estes Park, Colorado.
Pennings, S.C. 2006. Presentation: Sea-level rise and ecosystem services of tidal marshes. Sealevel rise, hurricanes, and the future of our coasts. Sigma Xi Meeting,Texas A&M
University, March 30, 2006.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Pennings, S.C., Buck, T.L., Lynes, A.R. and Grace, J.B. 2009. Poster: Centrifugal organization
of vegetation in salt marsh plant communities. 2009 LTER All Scientists Meeting, September
14-16, 2009, Estes Park, Colorado.
Pennings, S.C., Ho, C.-K., Salgado, C., Wieski, K., Dave, N., Kunza, A.E., Wason, E.L. 2007.
Presentation: Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes. Joint
Ecological Society of America / Society for Ecological Restoration 2007 Meeting, August 510, 2007, San Jose, CA.
Porubsky, W.P., Meile, C. and Joye, S.B. 2006. Poster: Nutrient dynamics in the hammock
subsurface: The impact of flow and reactions on coastal groundwater biogeochemistry.
Academy of the Environment Meeting, October 2006, Athens, Georgia.
Porubsky, W.P., Meile, C. and Joye, S.B. 2007. Poster: Variations in groundwater
biogeochemistry and flow on Moses Hammock (Sapelo Island, GA): Field measurements,
laboratory assays, and modeling. American Society of Limnology and Oceanography 2007
Aquatic Sciences Meeting, 4-9 February 2007, Santa Fe, New Mexico.
Porubsky, W.P., Meile, C. and Joye, S.B. 2007. Presentation: Using field measurements,
laboratory assays and modeling to examine flow conditions and variations in groundwater
biogeochemistry. Estuarine Research Federation 2007 Annual Meeting, 4-8 November 2007,
Providence, Rhode Island.
Robinson, J.D., Cozad, M. and Wares, J.P. 2007. Presentation: Population structure of salt
marsh invertebrates from the GCE-LTER. Benthic Ecology Meeting, March 21-25 2007,
Atlanta, Georgia, USA.
Schaefer, S.C. and Alber, M. 2006. Nutrient inputs to the Altamaha River Watershed, 19542002. Southeastern Estuarine Research Society, Savannah, Georgia.
Schaefer, S.C. and Alber, M. 2006. Poster: Temperature response of denitrification drives a
latitudinal gradient in coastal export. LTER All Scientists Meeting, September 20-24, 2006,
Estes Park, Colorado.
Schaefer, S.C. and Alber, M. 2006. Presentation: A latitudinal gradient in the percentage of net
anthropogenic nitrogen input exported to Atlantic coast rivers. Estuaries session. Semiannual meeting of the Southeastern Estuarine Research Societ, March 31-April 1, 2006, St.
Augustine, Florida.
Schaefer, S.C. and Alber, M. 2007. Presentation: Temperature as a Control on Proportional
Nitrogen Export to Coastal Ecosystems: An application of the SCOPE nitrogen budgeting
method. Estuarine Research Federations 2007 Annual Meeting, 4-8 November 2007,
Providence, Rhode Island.
45
GCE-LTER NSF Progress Report
Year 9 (2009)
Schalles, J., Hladik, C., Whitehurst, L. and Merani, P. 2006. Poster: Hyperspectral imaging of
wetlands and estuarine waters of National Estuarine Research Reserves in the Southeastern
and Mid-Atlantic Regions of the United States. Shallow Water Optics. Ocean Optics XVIII,
The Oceanographic Society, October 9-13, 2006, Montreal, Quebec, Canada.
Schalles, J.F., Hladik, C.M., Volkmer, M. and Saucedo, D.F. 2007. Presentation: Geospatial
Mapping of Species and Biomass in Georgia Salt Marshes using AISA Airborne
Hyperspectral Imagery. Estuarine Research Federation 2007 Annual Meeting, 4-8 November
2007, Providence, Rhode Island.
Schutte, C., Moore, W.S., Wilson, A.M. and Joye, S.B. 2009. Poster: Mechanisms for variability
in groundwater nutrient flux to estuaries and the coastal ocean. LTER All Scientists Meeting,
September 13-17, 2009, Estes Park, Colorado.
Seay, J.E., Bishop, T.D. and Tilburg, C.E. 2006. Poster: Spatial and temporal variations of
fiddler crab (Uca spp.) larval abundance in a Georgia estuary. Southeastern Estuarine
Research Society Spring 2007 Meeting, 30 March - 1 April 2006, St. Augustine, Florida.
Seay, J.E., Bishop, T.D. and Tilburg, C.E. 2006. Poster: Spatial and temporal variations of
Porcelain Crab larval abundance in a Georgia Estuary. Southeastern Estuarine Research
Society Fall 2006 Meeting, 19 October - 21 October 2006, Savannah, Georgia.
Segarra, K., Samarkin, V. and Joye, S.B. 2007. Presentation: Temperature driven variations in
terminal metabolism in methanogenic freshwater sedments. Estuarine Research Federation
2007 Annual Meeting, 4-8 November 2007, Providence, Rhode Island.
Segarra, K., Samarkin, V. and Joye, S.B. 2008. Presentation: Competition between methanogens
and iron reducing bacteria in freshwater sediments. Gordon Research Conference on
Microbial Metabolism of C1 Compounds, Lewiston Maine.
Sheldon, J.E. and Burd, A.B. 2007. Poster: Detecting climate signals in river discharge and
precipitation data for the central Georgia coast. 2007 AERS/SEERS Meeting, March 15-17,
2007, Pine Knoll Shores, NC.
Sheldon, J.E. and Burd, A.B. 2007. Presentation: Seasonal Effects of the Southern Oscillation
and Bermuda High on Freshwater Delivery to Coastal Georgia, U.S.A. Estuarine Research
Federation 2007 Annual Meeting, 4-8 November 2007, Providence, Rhode Island.
Sheldon, J.E. and Burd, A.B. 2008. Poster: Seasonal effects of the Southern Oscillation and
Bermuda High on freshwater delivery to the central Georgia coast. GCE-LTER 2008 Annual
Meeting, March 14-15, 2008, Athens, Georgia.
Sheldon, J.E. and Burd, A.B. 2009. Poster: The Effects of Climate Signals on Freshwater
Delivery to Coastal Georgia, U.S.A. 2009 LTER All Scientists Meeting, Sept. 14-16, 2009,
Estes Park, CO.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Sheldon, J.E. and Burd, A.B. 2009. Presentation: An In-depth Look at Alternating Effects of
Climate Signals on Freshwater Delivery to Coastal Georgia, U.S.A. Hydrologic Prediction in
Estuaries and Coastal Ecosystems. CERF 2009: Estuaries and Coasts in a Changing World,
November 1-5, 2009, Portland, OR.
Sheldon, W.M. 2007. Presentation: Synthesis of incomplete and qualified data using the GCE
Data Toolbox. Workshop to define quality management standards for data completeness in
derived data products, January 31-February 1, 2007, Jornada Experimental Range, Las
Cruces, New Mexico.
Sheldon, W.M. and Remillard, S. 2006. Poster: Software tools for automated synthesis of LTER,
USGS and NOAA climate and hydrologic data. Long Term Ecological Research Network
All-Scientists Meeting, September 20-24, 2006, Estes Park, Colorado.
Sheldon, W.M. Jr. 2008. Presentation: Dynamic, Rule-based Quality Control Framework for
Real-time Sensor Data. Quality Assurance Systems. Environmental Information Management
2008, September 10-11, 2008, University of New Mexico, Albuquerque, New Mexico.
Sheldon, W.M. Jr. 2009. Poster: Dynamic, Rule-based Quality Control Framework
for Real-time Sensor Data. 2009 LTER All Scientists Meeting, September 13-17, 2009, Estes
Park, Colorado.
Sheldon, W.M. Jr. 2009. Poster: GCE Software Tools for Data Mining, Analysis and Synthesis.
2009 Annual Meeting of the Georgia Coastal Ecosystems LTER Project, January 6-7, 2009,
Athens, Georgia.
Sheldon, W.M. Jr. 2009. Presentation: GCE-LTER Taxonomic Database. 2009 LTER All
Scientists Meeting, September 13-17, 2009, Estes Park, Colorado.
Turck, J.A. and Thompson, V.D. 2009. Poster: Natural and Human Impacts on Back-Barrier
Islands. Georgia Coastal Ecosystems Long Term Ecological Research Meeting, Athens,
Georgia.
Wason, E.L. and Pennings, S.C. 2007. Poster: Gradients of grasshopper species composition and
size in Atlantic Coast salt marshes. Joint Ecological Society of America / Society for
Ecological Restoration 2007 Meeting, August 5-10, 2007, San Jose, CA.
Weston, N.B., Vile, M.A., Velinksy, D.J., Joye, S.B. and Neubauer, S.C. 2007. Presentation:
Shifting pathways and magnitude of organic matter mineralization in tidal freshwater
marshes following sea-level rise. Estuarine Research Federation 2007 Annual Meeting, 4-8
November 2007, Providence, Rhode Island.
Whigham, D.F., Barendregt, A., Craft, C. and Neubauer, S. 2007. Climate change consequences
for tidal freshwater wetlands at the east and west coast of the Atlantic. International
Association of Landscape Ecology, July 8-12 2007, World Congress, Wageningen, The
Netherlands.
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GCE-LTER NSF Progress Report
Year 9 (2009)
Wieski, K., Guo, H. and Pennings, S.C. 2008. Poster: Ecosystem functions of tidal fresh,
brackish, and salt marshes. Estuarine, Coastal and Intertidal Systems. 93rd Annual Meeting
of the Ecological Society of America, August 3-8, 2008, Milwaukee, Wisconsin.
Wilson, A.M., Anderson, J., Moore, W.S., Schutte, C. and Joye, S.B. 2009. Presentation: Stormdriven groundwater flow and nutrient transport in a barrier island. American Geophysical
Union, Fall Meeting, December 2009, San Francisco, California.
Newsletter and Newspaper Articles
Alber, M. 2009. Connecting Academic Scientists and Coastal Managers in Georgia. Pages 66-68
in: Limnology and Oceanography Bulletin.
Georgia Coastal Research Council. 2007. Research Summary: On the shoulders of giant plants.
Georgia Sound Newsletter. 13(3):1.
Sheldon, W.M. 2006. Mining and Integrating Data from ClimDB and USGS using the GCE Data
Toolbox. DataBits: An electronic newsletter for Information Managers, Spring 2006 issue.
Long Term Ecological Research Network, Albuquerque, NM.
Sheldon, W.M. 2008. Developing a Searchable Document and Imagery Archive for the GCELTER Web Site. DataBits: An electronic newsletter for Information Managers. Long Term
Ecological Research Network, Albuquerque, NM. Spring 2008 Issue, p. 5-8.
Sheldon, W.M. Jr. 2007. Practical Distributed Computing Approach for Web Enabling
Processor-intensive Programs. DataBits: An electronic newsletter for Information Managers,
Spring 2007 issue. Long Term Ecological Research Network, Albuquerque, NM.
Sheldon, W.M. Jr. 2009. Getting started with eXist and XQuery. In: LTER Databits Information Management Newsletter for the Long Term Ecological Research Network:
Spring 2009. Long Term Ecological Research Network.
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