Grantee Research Project Results
2006 Progress Report: Effect of Sea Level Rise and Climate Variability on Ecosystem Services of Tidal Marshes
EPA Grant Number: R832220Title: Effect of Sea Level Rise and Climate Variability on Ecosystem Services of Tidal Marshes
Investigators: Craft, C. B. , Ehman, Jeffrey , Park, Richard , Joye, Samantha , Pennings, Steven
Institution: Indiana University - Bloomington , Pangaea Information Technologies, Ltd. , Eco Modeling , University of Georgia , University of Houston
Current Institution: Indiana University - Bloomington , Eco Modeling , Pangaea Information Technologies, Ltd. , University of Georgia , University of Houston
EPA Project Officer: Packard, Benjamin H
Project Period: April 1, 2005 through June 30, 2009
Project Period Covered by this Report: April 1, 2006 through June 30, 2007
Project Amount: $749,974
RFA: Effects of Climate Change on Ecosystem Services Provided by Coral Reefs and Tidal Marshes (2004) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Water , Ecological Indicators/Assessment/Restoration , Climate Change , Watersheds
Objective:
Development of a conceptual model that describes how tidal marsh ecosystem services vary along the salinity gradient and a simulation model of how sea level rise and climate variability will affect the delivery of ecosystem services.
Progress Summary:
Laboratory analysis of soil cores for accretion, C sequestration, and N and P accumulation in undiked marshes is nearly complete. Field sampling of marsh-emergent vegetation and trace gas (CO2, CH4, N2O) emissions was conducted in summer (trace gases, species richness) and fall (aboveground biomass) 2006.
In summer 2006, diked marshes were identified for sampling along the Altamaha and Ogeechee Rivers. Soil cores were collected to determine rates of carbon sequestration and N and P retention, and feldspar marker layers were established to measure short-term rates of sediment deposition in diked marshes.
Simulation modeling of accelerated sea level rise (SLR) using Sea Level Affects Marshes Model (SLAMM) is progressing with: (1) development of a salinity algorithm to drive salt water intrusion and tidal marsh migration inland in river-dominated estuaries as sea level rises; and (2) simulation of accelerated SLR on tidal marsh area and delivery of ecosystem services for the southeast (GA–SC) coast.
Emergent Vegetation
We measured richness of plant species in fresh, brackish and salt tidal marshes on the Ogeechee, Altamaha, and Satilla Rivers between the 10th and 26th of July 2006. We worked at six sites on each river (two replicate sites per salinity region). At each site, we located 50 1 m2 quadrats along a transect from the creekbank to the midmarsh. The number of plant species present in each plot was recorded.
We measured end-of-season standing biomass at all 18 sites between 15 and 24 October, 2006. At each site we located 12 0.25 m2 quadrats: 3 in the creekbank zone, the next 6 along a transect running from the creekbank to the midmarsh, and the last 3 in the midmarsh. We counted the number of species present in each plot, measured vegetation height (height at each corner of the quadrat), and harvested all live and dead biomass. Harvested material was dried in the laboratory to a constant mass and weighed.
As expected, emergent species richness was highest in the tidal freshwater marshes and lowest in the salt marshes (Figure 1, top). Aboveground biomass, however, was greatest at intermediate levels of salinity, in the brackish marsh (Figure 1, bottom).
- Figure 1. Species Richness (Top) and Biomass (Bottom) in Three Salinity Zones in Georgia Tidal Marshes (Blue Lines: Mean and Standard Deviation (SD); Green Diamond: 0.95 Confidence Interval for the Mean; Box: the Middle Two Quartiles). Data were analyzed with analysis of variance (ANOVA) followed by Tukey’s Honestly Significantly Different (HSD) test means comparisons. N = 216 samples.
Biogeochemical Processes
Pore water samples were collected from replicate fresh, brackish, and salt tidal marshes on the Ogeechee, Altamaha, and Satilla rivers in August of 2006. We sampled levee and marsh soils at each of 6 sites sampled on each river, generating 12 separate subsites sampled per river and 36 sites total. Two depths, 5–10 cm and 35–40 cm, were sampled at each site, generating 72 individual samples for biogeochemical analyses.
At the same time biogeochemical samples were collected, we also collected sediment samples for rate assays to evaluate denitrification (Figure 2) and methanogenesis activity. Three replicates and a “killed” control were run for each subsite in surface and deep sediments. Rates of denitrification were determined in anaerobic incubations after amending sediments with low (100 μM) concentrations of nitrate. The acetylene block technique was used to block the conversion of nitrous oxide to dinitrogen gas; nitrous oxide production was measured using a gas chromatograph. Denitrification rates were only significant in surficial sediments. The average rates for a habitat/zone are shown in a darker color (marsh in lime green/dark green; levee in orange/dark brown). The highest denitrification rates were observed in the saltwater levee and brackish marsh sites (Figure 2). Rates at these sites were significantly higher than all other rates measured but were not different from one another. Denitrification rates observed in freshwater soils were surprisingly low, and we hypothesize that this was related to the extremely dry conditions characterizing the soils during this sampling time. We will measure denitrification in our marshes several more times in summer 2007 to obtain better estimates of ambient and potential denitrification for these wetlands.
- Figure 2. Potential Denitrification Rates in Saltwater (SALT), Brackish (BRACK), and Freshwater (FRESH) Soils. Red stars signify a significant difference between a specific data point and those across zones (saltwater, brackish, or freshwater) or between sites or subsites. Error bars represent standard deviations of the mean.
Future Activities:
We will continue active field sampling during summer and fall 2007. Soil cores will be collected from undiked tidal marshes to continue measurements of denitrification and methanogenesis. And, in situ measurements of trace gas fluxes (CO2, CH4, N2O) will be conducted in undiked marshes during the summer. We also will initiate field sampling of emergent vegetation and trace gas emissions in diked marshes along the Altamaha and Ogeechee Rivers.
With respect to modeling, we are finalizing the development of our salinity algorithm to drive saltwater intrusion into river-dominated estuaries in order to more accurately simulate tidal marsh migration upriver in response to accelerated SLR. After this is complete, we will conduct regionwide (GA–SC) simulations of the effects of accelerated SLR on tidal marsh area, habitat conversion, and delivery of ecosystem services during the next 100 years.
We anticipate that two manuscripts, one describing improvements (e.g., salinity algorithm) to SLAMM and a second one describing C sequestration and N and Pretention in tidal marsh soils along the salinity gradient, will be written up and submitted to peer-reviewed journals in the coming year.
Journal Articles:
No journal articles submitted with this report: View all 51 publications for this projectSupplemental Keywords:
estuary, ecological effects, ecosystem, scaling, regionalization, modeling, climate models, Atlantic coast, Georgia, GA, South Carolina, SC, Region 4,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, climate change, Air Pollution Effects, Chemistry, Monitoring/Modeling, Aquatic Ecosystem, Ecological Risk Assessment, Atmosphere, environmental monitoring, environmental measurement, meteorology, climatic influence, global ciruclation model, global change, climate, tidal marsh, climate models, ecosystem indicators, aquatic ecosystems, environmental stress, coastal ecosystems, global climate models, coral reef communities, sea level rise, ecological models, climate model, ecosystem stress, South Atlantic Coast, Global Climate Change, atmospheric chemistry, climate variabilityRelevant Websites:
http://www.spea.indiana.edu/wetlandsandclimatechange Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.