Sapelo Research Application Form
Research Application ID: GCE-41-2013 (submitted: 02/11/2013, status: approved)
Provide a brief title for web display
Nutrient Limitation of Benthic Biofilms Along the Estuarine Salinity Gradient
Investigator Information
On Island Sponsor: GCE SINERR UGAMI GADNR
| Principal Investigator: | Christopher B. Craft | ||
| Home Institution: | Indiana University at Bloomington | ||
| Award Information: | Internal Indiana University Funding, $300 | ||
| Mailing Address: | Indiana University - School of Public and Environmental Affairs | Phone Number: | (812) 856-1837 |
| Room 408. MSB II. | E-mail Address: | ccraft@indiana.edu | |
| Bloomington, Indiana 47405 | |||
| Co-investigators: | Ellen Herbert (Ducks Unlimited) | ||
Briefly describe the project goals and methodology
Two of the most pressing concerns for Georgia estuaries are eutrophication, caused by nutrient enrichment, and saltwater intrusion, resulting from reduced freshwater flows and accelerated sea-level rise (Alber and Flory 2002, Weston et al. 2006, Neubauer and Craft 2009, Weston et al. 2010, Alber and Sheldon 2011). Salinity and increased nutrient loads are predicted to act synergistically to alter ecosystem metabolism, but the overall consequences of this interaction are not well known (Tamminen and Andersen 2007). Classically, freshwater reaches are P limited due to iron complexation with orthophosphate, while saline reaches become progressively more N limited as the sulfate in seawater complexes iron, releasing bound P. Recent bioassays in rivers (Mallin 2000), coastal wetlands (Sundareshwar et al. 2003) and continental freshwaters (Johnson et al. 2009) show differential nutrient limitation (DNL) of autotrophs (N limited) and heterotrophs (P limited). Thus, understanding DNL of benthic and pelagic autotrophs and heterotrophs may be key to understanding eutrophication in the Altamaha River.
Previous research has examined nutrient limitation of coastal ecosystems in a variety of methods including large-scale and long-term nutrient additions to tidal marshes, short-term nutrient additions in laboratory bottle assays, and speculation derived from nutrient concentrations and ecological stoichiometry. In continental freshwater habitats (streams, lakes), nutrient limitation of benthic biofilms is commonly assessed using an in situ bioassay (nutrient diffusing substrata, NDS). This technique can bridge the gap between long-term and short-term nutrient limitation experiments by examining nutrient limitation over a month in situ (mid-term nutrient limitation).
To examine benthic biofilm nutrient limitation, we will deploy NDS's at multiple sites along a salinity gradient at 5 sites corresponding to tidal fresh forests, tidal fresh marsh (GCE 7), brackish marsh (GCE 8), river influenced salt marsh (GCE 9), and marine dominated salt marsh (GCE 6). NDS's will consist of a 2% agar solution amended with either no nutrient (+0), nitrate (+N), phosphate (+P), glucose (+C), or a combination of these nutrients in a fully factorial design (n=4 per treatment). NDS's will be topped with an inorganic fritted glass disc and deployed for ~1 month. At each site, one set of NDS's will be placed upright for autotrophic and heterotrophic biofilm development and one set will be place upside-down under a shade cloth to select for heterotrophic biofilm development (total n=64 per site). After retrieval, each substrate will be analyzed for gross primary production (GPP) and community respiration (CR) using a light/dark bottle oxygen assay, chlorophyll a using hot ethanol extraction, and ash-free dry mass via loss on ignition.
Where will the project be located?
GCE Sonde Pilings at : GCE 7, 8, 9, 2, 6, 10
How will you provide GPS coordinates for study sites?
GPS coordinates are already registered in the GCE-LTER database
What are the expected start and end dates of the project?
Start Date: 04/15/2012 End Date: (ongoing)
How many people will access the site and at what frequency?
Two people with boat once at the beginning and ending of a 2-week incubation period, 2 times /year (early spring and mid-summer)
Keywords that describe your project
What equipment will be deployed in the field?
At each site, a small milk crate with 50mL centrifuge tubes containing agar media for in-situ bioassay inside, will be attached to the piling for 2 weeks. The crate will be secured using large zip-ties and rope. The entire setup will be removed at the end of the 2 week incubation.
Will plants or animals be collected as part of this study?
No
What are the likely impacts of the project on the site?
None.
Will the project design include boardwalks? If not, explain why not.
No.
How long will impacts persist after the research is concluded?
None.
Research Permits:
Georgia DNR Coastal Resources Division: GCE-2-2011_Permit_Doboy_and_Altamaha_Piling_Repair_Authorization (05/18/2012-indefinite)
Georgia DNR Coastal Resources Division: GCE-2-2011_Permit_Doboy_and_Altamaha_Piling_Revocable_License (06/11/2001-indefinite)
U.S. Coast Guard: GCE-2-2011_Permit_USCG_Sonde_Deployment_Permission (12/06/2000-indefinite)
Study Area Map:
Files attached to this application
GCE-41-2013_Maps_Nutrient_Limitation_Sondes.kml (KML file, 2.91 kb, submitted 02/11/2013)
