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70 Wetland Science & Practice September 2016
INTRODUCTION
Coastal wetlands, including tidal marshes and forests,
provide a number of key ecosystem services, includ-
ing habitat for recreationally and commercially important
nsh and shellsh, protection from wind, waves, storms
and oods, and removal of excess nutrients, namely nitro-
gen (N) and phosphorus (P), from agricultural and urban
runoff (e.g., Tiner 2013). Along the coast, climate change
will be manifested as rising sea level with attendant coastal
ooding and saltwater intrusion. A more immediate impact
which has already been experienced is drought, particularly
in late summer and fall. These processes will lead to migra-
tion of tidal wetlands inland, where possible, and changes
in habitat as freshwater wetlands convert to brackish marsh
or open water (Figure 1).
As part of the National Science Foundation’s Georgia
Coastal Ecosystems Long Term Ecological Research (GCE
LTER) project, scientists from seven institutions of higher
learning, including the University of Georgia, Indiana Uni-
WETLAND RESEARCH
versity, Virginia Institute of Marine Sciences, University of
Houston, University of Florida, Georgia Southern Universi-
ty, College of Coastal Georgia, and the U.S. Environmental
Protection Agency, initiated a eld experiment - Seawater
Addition Long Term Experiment or SALTEx - to investigate
how saltwater intrusion and increased ooding will alter
the direction and pace of change of microbial, plant, and
animal communities and key biogeochemical processes
in a tidal freshwater marsh. SALTEx consists of an array
of eld plots that are used to answer three main questions
regarding sea level rise and saltwater intrusion:
1. How does long-term, chronic (“press”) addition of
diluted seawater affect tidal freshwater marsh structure
and function?
2. What are the effects of periodic pulsing of diluted seawa-
ter to simulate low river ow or
drought conditions?
3. What are the effects of freshwater additions?
STUDY AREA
The SALTEx site is located on the Alta-
maha River near Sapelo Island, Georgia
(Figure 2). The Altamaha River is the third
largest river on the U.S. East Coast. It is
not dammed along the 200-mile (330 km)
stretch from the conuence of the Oc-
mulgee and Oconee Rivers to the Atlantic
Ocean, making it one of the most ecologi-
cally intact river systems in the East. The
river and estuary contain large areas of tid-
al marsh and forest and extensive alluvial
bottomland hardwood forest upstream.
The tidal freshwater marsh plant com-
munity consists of four dominant species
that are common in freshwater marshes of
the southeastern U.S.: creeping primrose-
willow (Ludwigia repens), smartweed
(Polygonum hydropiper), pickerelweed
(Pontederia cordata), and giant cutgrass
(Zizaniopsis miliacea).
Climate Change and the Fate of Coastal Wetlands
Christopher Craft1, Indiana University, Ellen Herbert, Virginia Institute of Marine Sciences, Fan Li, University
of Houston, Dontrece Smith, University of Georgia, Joe Schubauer-Berigan, U.S. Environmental Protection
Agency, Sarah Widney, Indiana University, Christine Angelini, University of Florida, Steve Pennings, Univer-
sity of Houston, Patricia Medeiros, University of Georgia, Jeb Byers, University of Georgia, and Merryl Alber,
University of Georgia
1 Corresponding author: ccraft@indiana.edu
FIGURE 1. Aerial view of deteriorating tidal marsh in southeastern Georgia.
Wetland Science & Practice September 2016 71
FIGURE 2. Site map of the GCE LTER (inset). SALTEx’s location is indicated with the
black star.
FIGURE 2. (a) Delivery of seawater-river water mixture to a plot. (b) Press plot
(replicate 3) in July 2015, 15 months after treatments were initiated. Note the loss of
vegetation in the plot as only some giant cutgrass remains, and all other plant species
have disappeared. The four porewater wells are visible in each quarter of the plot.
a)
b)
METHODS
The SALTEx experiment was initiated in 2012
and consists of 30 eld plots, each 2.5 m on a
side. There are three treatments (Press, Pulse,
and Fresh) and two types of controls (with and
without sides), each consisting of six replicates.
The Press treatment plots receive regular (4 times
each week) additions of a mixture of seawater
and fresh river water (Figure 3a). Pulse plots
receive the same mixture of seawater and river
water during September and October, which is
typically a time of low ow in the river when
saltwater intrusion naturally occurs. The Fresh
treatment plots receive regular additions of fresh
river water. Treatment water is added during low
tide to facilitate its inltration into the soil, and
all plots are inundated by astronomical tides at
high tide.
Response measurements include (1) soil
porewater chemistry and nutrient cycling, (2)
plant community, (3) terrestrial and aquatic
invertebrates, (4) microbial activity, and (5) soil
properties and soil elevation change (Table 1).
Baseline (pre-treatment) data were collected in
2013 and early 2014 and treatments were initi-
ated in April 2014.
RESEARCH FINDINGS TO DATE
Changes in porewater chemistry and microbial
activity were evident almost immediately follow-
ing treatment additions. Porewater chloride and
sulfate (both present in seawater) and salinity
increased within the rst month following Press
additions (Figure 4a). Hydrogen sulde produced
by sulfate-reducing bacteria also increased (Fig-
ure 4b), while the emission of methane (CH4),
a potent greenhouse gas, declined in the Press
plots within six months of the start of treat-
ments. The plant community also was affected
during the rst year of treatments. Creeping
primrose-willow, a succulent groundcover spe-
cies, disappeared from the Press plots during the
rst summer and never recovered. Smartweed
and pickerelweed also declined later during the
rst year. By the second year of treatments, even
the hardy giant cutgrass was in decline in the
Press plots. The reduction of plant biomass led
to reduced carbon uptake by emergent vegeta-
tion, which may lead to long-term declines in soil
carbon sequestration. After 18 months of Press
additions, vegetation in Press plots was nearly
extirpated (Figure 3b) and some Press plots had
lost nearly 2 cm of soil elevation, which we attri-
bute to a loss of roots and rhizomes accompany-
ing the loss of aboveground biomass.
72 Wetland Science & Practice September 2016
Pulse additions of diluted seawater
led to transient increases in porewater
salinity and sulfate that disappeared
once treatments were halted (Figure 4a).
Creeping primrose-willow nearly disap-
peared from Pulse plots after the rst
year, recovering only slightly in year 2.
Other plant species were not affected by
the Pulse addition, nor were greenhouse
gas emissions affected.
WHAT IT MEANS
Our preliminary ndings suggest that
climate change-driven chronic saltwater
intrusion will lead to rapid changes in mi-
crobial and plant communities with atten-
dant changes in ecosystem services such
as productivity, carbon sequestration, and
greenhouse gas emissions. Of concern is
the loss of vegetation and soil elevation
within the rst two years of Press addi-
tion of diluted seawater. We will continue
treatments for several more years to better
understand the effects of transient low
ow or drought conditions and freshwater
additions on tidal freshwater marshes. In
addition, we plan to follow recovery of
the plots when we discontinue the treat-
ments to see if recovery follows the same
trajectories in the different treatments and
to see how quickly the system recovers, if
at all. SALTEx is complemented by other
work in the GCE LTER that examines
ecosystems at the landscape scale, such
as tracking vegetation productivity and
community changes along the Altamaha
River annually and relating these changes
to salinity and other factors. We also have
a long-term monitoring site at a healthy
tidal freshwater forest to detect any possi-
ble saltwater intrusion in its early stages.
We hope that understanding the response
Porewater: Salinity, chloride, sulfate, sulde, dissolved organic C, inorganic and organic forms of N and P
Plant community: Aboveground biomass, photosynthesis, leaf N and P, benthic microalgae
Animal community: Grasshoppers, insects, crabs, snails
Microbial community: Extracellular enzyme activity, diversity
Ecosystem: Net ecosystem exchange, ecosystem respiration, greenhouse gases (CO2, CH4, N2O)
Soils: Bulk density, C, N, and P content, organic matter quality and composition,
soil elevation, temperature
TABLE 1. Measurements to assess the effects of SALTEx treatments on tidal freshwater marsh structure and function.
FIGURE 3. Concentrations of salinity (a) and sulde (b) in SALTEx treatment plots pre-
(January and March 2014) and post-treatment. Means with an asterisk (*) are signicantly
different from other treatments within the same month.
a)
b)
Wetland Science & Practice September 2016 73
of marshes and forests to salinization will
inform adaptive management strategies of
coastal communities. Stay tuned.
ABOUT THE GCE LTER
The Georgia Coastal Ecosystems Long
Term Ecological Research site was estab-
lished in 2000 by the National Science
Foundation. It encompasses three adjacent
sounds, the Altamaha, Doboy, and Sapelo,
that vary in freshwater input, and includes
upland, intertidal, and subtidal habitat. The
overarching goal of the GCE LTER is to
understand how variation in source and
amount of freshwater and seawater struc-
ture estuarine habitats and processes and
to identify and predict changes that occur
in response to natural and anthropogenic
perturbations. More than 60 participants
representing 14 academic institutions
and agencies are involved in GCE LTER
research and education programs. The eld
site is based at the University of Georgia
Marine Institute on Sapelo Island and is ad-
ministered by the University of Georgia De-
partment of Marine Sciences. Christopher
Craft is a founding member of the GCE
LTER and serves on its executive commit-
tee (http://gce-lter.marsci.uga.edu/). n
ABOUT THE INDIANA UNIVERSITY WETLANDS
LABORATORY
The Wetlands Lab investigates the effects of human
activities such as eutrophication, urbanization, and
climate change on freshwater and estuarine wetlands
and the ecosystem services they support, as well as
how restoration can be employed to re-establish these
services. The Lab actively supports graduate and
undergraduate research, education, and service (http://
www.indiana.edu/~craftlab/home.php).
REFERENCES
Tiner, R.W. 2013. Tidal Wetlands Primer: An Intro-
duction to their Ecology, Natural History, Status, and
Conservation. University of Massachusetts Press,
Amherst, MA.
WETLAND PRACTICE
The need for effective and inuential communication about science
never been more important than it is today. Politicians and political
interests are redening and reinterpreting science—with great persis-
tence and impact. While the majority of the public still respect scien-
tists and value science, they often nd it challenging to discern who
and what is legitimate. The American Institute of Biological Sciences
(AIBS) is responding to this need by offering scientists a new profes-
sional development opportunity. The AIBS Communications Training
Boot Camp for Scientists expands on our highly successful media and
science policy training workshops. The program meets the needs of
everyone from graduate students to senior researchers and program
administrators.
AIBS is the scientic organization that promotes the use of sci-
ence to inform decision-making that advances biology for the benet
of science and society. The organization has a long and successful track
record of engaging, informing, and inuencing the public and science
policy decision-makers. Our audiences include members of Congress,
federal agency heads and program managers, state ofcials, and univer-
sity administrators. In addition to working directly with these groups,
we routinely engage the public through traditional and new media.
Our staff members have used their decades of science policy and
communications experience to develop training materials and resources
that provide scientists with the skills needed to successfully communi-
cate about their research with decision-makers and reporters. To date,
AIBS has trained more than 1,000 scientists.
AIBS is sponsoring a Communications Boot Camp, an intensive,
two-day, hands-on training program in Washington, DC (December
7–8, 2016). Participants will learn:
• How to translate scientic ndings for non-technical audiences
• How to tell a resonant story that informs decision-makers
• How to prepare for and participate in a news interview, includ-
ing broadcast interviews
• How to prepare for and engage in a meeting with a decision-
maker
• How to protect your scientic reputation
• How to identify and dene the audience you need to reach
• What policymakers want and need to know from a scientist
• What reporters are looking for in an interview
• How the nation’s science policy is developed and implemented
Participants will have the opportunity for formal and informal
discussions with science policy and communications experts work-
ing in Washington, DC. Go online for more information about
the Boot Camp including costs and a course outline: https://www.
aibs.org/public-policy/communications_boot_camp.html?utm_
source=AIBS+Master+List&utm_campaign=69e633d3fa-Bootcamp_
Campaign8_4_2016&utm_medium=email&utm_term=0_def270e561-
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AIBS to Hold Communications Boot Camp
REGULATION, POLICY AND MANAGEMENT
