Presentation on theme: "IMPACTS OF DISSOLVED ORGANIC NITROGEN LOADING BY SUBMARINE GROUNDWATER DISCHARGE IN LITTLE LAGOON, AL JENNIFER ANDERS 1,2, BEHZAD MORTAZAVI 1,2, JUSTIN."— Presentation transcript:
IMPACTS OF DISSOLVED ORGANIC NITROGEN LOADING BY SUBMARINE GROUNDWATER DISCHARGE IN LITTLE LAGOON, AL JENNIFER ANDERS 1,2, BEHZAD MORTAZAVI 1,2, JUSTIN LIEFER 1,2, WILLIAM BURNETT 3, HUGH MACINTYRE 4 1 DEPARTMENT OF BIOLOGICAL SCIENCES, UNIVERSITY OF ALABAMA, TUSCALOOSA, AL 35487, U.S.A. 2 DAUPHIN ISLAND SEA LAB, 102 B BIENVILLE BLVD, DAUPHIN ISLAND, AL 36528, U.S.A. 3 DEPARTMENT OF EARTH, OCEAN AND ATMOSPHERIC SCIENCES, FLORIDA STATE UNIVERSITY, TALLAHASSEE, FL 32306, U.S.A. 4 DEPARTMENT OF OCEANOGRAPHY, DALHOUSIE UNIVERSITY, HALIFAX, NS, B3H 4J1, CANADA
LITTLE LAGOON, GULF SHORES, AL Exchanges with northern Gulf of Mexico Freshwater inputs from submarine groundwater discharge (SGD) Hot spot for toxic diatom blooms Blooms are correlated with groundwater discharge WHY?????
WHY IS SUBMARINE GROUNDWATER DISCHARGE (SGD) IMPORTANT? Small freshwater input but still substantial nitrogen contribution Transport of land-derived nutrients via SGD rival river runoff Excess nutrients can affect phytoplankton community composition
GROUNDWATER MONITORING IN GULF SHORES, AL Initial wells were set-up in 2010 Biweekly sampling from of groundwater environmental conditions and nutrients Florida State University used tracers to as a proxy for groundwater discharge in Little Lagoon
Distribution of 222 Rn concentrations (dpm L –1 ) throughout Little Lagoon on May 27, 2010 (Su et al. 2012) Groundwater discharge correlates to diatom blooms What is driving this???
NITROGEN INPUTS FROM SGD Site DON μ mol/L DIN μ mol/L TDN μ mol/L TN Μ mol/L Well Well Site Site Site Site
WHAT IS DISSOLVED ORGANIC NITROGEN (DON)? Specific components of DON are largely unknown Urea and amino acids (rapidly utilized) DON frequently exceeds that of dissolved inorganic nitrogen in aquatic systems Components of the DON have been shown to play a role in nitrogen nutrition to phytoplankton and bacteria BLACK BOX!!!
WHAT IS DISSOLVED ORGANIC NITROGEN (DON)? Specific components of DON are largely unknown Urea and amino acids (rapidly utilized) DON frequently exceeds that of dissolved inorganic nitrogen in aquatic systems Components of the DON have been shown to play a role in nitrogen nutrition to phytoplankton and bacteria
DISSOLVED ORGANIC NITROGEN CYCLING IN THE OCEAN
Aquifer Sediments SGD GW DON Gulf of Mexico SW DON Microbial/Phytoplankton DON utptake/remineralization Further Processing Ultimate Export
IS GROUNDWATER DERIVED DON BIOLOGICALLY AVAILABLE? Is groundwater DON causing shift in the microbial community composition? Hypothesis: Certain micrbiota species from Little Lagoon dominate when inputs of groundwater DON are high Hypothesis: A fraction of the DON inputs from SGD is readily remineralized and/or directly assimilated by the microbial communities. AND/OR
TESTING GROUNDWATER FOR LABILE DON
EXPERIMENTAL DESIGN Bioassay Experiments using LL site water: 2 Treatments: +Groundwater -Control (no addition)
AT EACH TIME POINT….. Samples are taken to measure nutrient uptake/production: Dissolved Inorganic Nitrogen (ammonia, nitrate, and nitrite) Total Dissolved Nitrogen DON =TDN-DIN Dissolved Organic Carbon Oxygen consumption Samples are collected to measure biomass and to look at community structure HPLC (pigment analysis) Chl-a Flow Cytometry
3 EXPERIMENTS IN 2014: FEBRURARY (EXP. 1), JUNE (EXP. 2), AND JULY (EXP. 3) February (Exp. 1): high salinity (~30 ppt) low temperatures low rain fall June (Exp. 2): low salinity (~5 ppt) high temperatures high rainfall July (Exp. 3): high salinity (~20 ppt) High temperatures high rainfall
CHLOROPHYLL CHANGES IN RESPONSE T ADDED DON
CONCLUSIONS Groundwater inputs of high DON concentrations to surface water from Little Lagoon can influence both phytoplankton groups and the bacterial community. As demonstrated by: Increased chlorophyll concentrations High rates of bacterial oxygen consumption These results could indicate a response in microbiota groups that are able to utilize some portion of the groundwater DON under high input conditions Environmental conditions such as SALINITY may play a role in DON bioavailability DON production in the incubations could balance out DON consumption to result in not net change of DON concentrations
THOUGHTS FOR THE FUTURE Characterize the DON Fluorescent indicators What is the quality of the DON and what are it’s sources? How does the quality of the DON vary seasonally?
ACKNOWLEDGEMENTS Little Lagoon Preservation Society Alice Kleinhuizen Eric Lachenmyer Rebecca Bernard Laura Linn Dr. Alice Ortmann Dr. Jeffrey Krause Institution Support & Funding:
QUESTIONS???? JENNIFER ANDERS CONTACT INFORMATION: