Evaluating the Influence that Anthropogenic Inputs have on Carbon and Nitrogen Cycling and on the Biological Assemblages

1. Evaluating the Influence that Anthropogenic Inputs have on Carbon and Nitrogen Cycling and on the Biological Assemblages in Tampa Bay, FL David Hollander, Elon Malkin, Ed Van Vleet College of Marine Science, St. Petersburg, FL 33701 in collaboration with T. Edgar, T Cronin, P. Swarzenski, K. Yates, USGS Program Leaders Project Objectives: Determine how historical human influences have: • Altered the geochemical cycling of carbon and nitrogen (today’s presentation) • Modified ecosystem structure as recorded in the inputs of sedimentary organic matter.

2. Research Strategy Field studies: •Sediment coring throughout Tampa Bay Analytical approach: •Organic carbon and nitrogen concentrations • reflects increasing input & production of organic matter • C:N Ratios determine algal vs terrestrial inputs •Stable Isotopes of organic carbon and nitrogen • reflects specific nutrient inputs and assimilation • trophic relationships •Molecular organic geochemical analysis • reflects organic inputs (algal, bacterial, terrestrial and pollution) Historical Land-use characterization: •USGS mapping group •Southwest Water management District

3. Linking the Sedimentary Geochemical Record in Tampa Bay to Historical Changes in Land Use Development and Nutrient Inputs Watershed’s land use Urban / Industrial, Agricultural, Natural • Changing nutrient inputs: • Sources-15N specific • concentrations • bioavailability Recorded in Tampa Bay’s Sediments: TOC, TON, C/N, d15N, Molecular Biomarkers

4. Tampa Bay •6 Watersheds •Variable land-use Safety Harbor/ Feather Sound Study Sites: Hillsborough Bay/ Alafia River •Sediment Cores•Geochemical Studies •Area of land-use characterization Terra Ceia/ Aquatic Preseerve

5. Historical Land-Use Changes • Alafia: increasing urbanization/industrialization • Terra Ceia: increasing agriculture, recent urban • Feather Sound: increasing residential urbanization

6. Nitrogen Isotope Fingerprinting of Nutrient Inputs Urban-Sewage Industrial Safety Harbor- Residential Soil d15N, o/oo Air Hillsborough- Urban Fertilizer Land Plants Terra Ceia- Agriculture Specific Nutrient Input

7. Linking Sedimentary & Land-Use Records: 1952 1995 Hillsborough Bay/Alafia River Urbanization/Industrialization TOC, Wt% d15N, ‰ Air C/N, Atomic Ratio Redeposited layer Human Impact Depth (cm) Fertilizer/ Algal Terr Plants Soil Urban Ter Plant TON, Wt% • TON/TOC- 4x increase due to nutrient input and increased production • Transition from vascular plant to algal/bacterial inputs (C:N, biomarkers) • Enriched 15N > 10 ‰, coprastanol reflect wastewater-industrial inputs

8. Linking Sedimentary and Land-Use Records Terra Ceia/Aquatic Preserve Agricultural Recent urbanization 1952 1995 TOC, Wt% C/N, Atomic Ratio d15N, ‰ Air Alafia Human Impact Depth (cm) Agricult/ TerPlant Fertilizer/ Terr Plants Algal Terr Plants Soil Urban TON, Wt% Urban • Increasing nutrient inputs leading to production (TOC/TON) • Transition from vascular plant to algal/bacterial inputs (C:N, biomarkers) • 15N- Agricultural nutrient mimic vascular plant inputs, recent urban

9. Linking Sedimentary and Land-Use Records Safety Harbor/Feather Sound: Residential Urbanization 1995 1952 C/N, Atomic Ratio TOC, Wt% d15N, ‰ Air Redeposited layer Terra Ceia Human Impact Alafia Depth (cm) Fertilizer/ Terr Plants Soil Urban Algal Terr Plants TON, Wt% • Delayed geochemical response reflects later land use development • Abrupt transition to algal/ bacterial inputs • 15N reflects increasing residential inputs • (commercial fertilizer, septic-wastewater)

10. Geochemical Implications for Ecosystem Modes • Enables “hind-forecasting” of regional Bay productivity • Linking biological responses recorded in sediments to historical land use and nutrient inputs • Allows model refinement of nutrient forcing functions • Distinguishing nutrient abundance from bioavailability • Allows for predictive food-web behavior • Defines relationships among nutrient inputs, primary productivity, and the abundance of economically important upper trophic level consumers