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IMPACTS OF DISSOLVED ORGANIC NITROGEN LOADING BY SUBMARINE GROUNDWATER DISCHARGE IN LITTLE LAGOON, AL JENNIFER ANDERS 1,2, BEHZAD MORTAZAVI 1,2, JUSTIN.

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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:

1 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

2 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?????

3 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

4 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

5  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???

6 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

7

8 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!!!

9 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

10 DISSOLVED ORGANIC NITROGEN CYCLING IN THE OCEAN

11 Aquifer Sediments SGD GW DON Gulf of Mexico SW DON Microbial/Phytoplankton DON utptake/remineralization Further Processing Ultimate Export

12 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

13 TESTING GROUNDWATER FOR LABILE DON

14 EXPERIMENTAL DESIGN Bioassay Experiments using LL site water: 2 Treatments: +Groundwater -Control (no addition)

15 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

16 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

17 OXYGEN CONSUMPTION

18 DON UPTAKE

19 CHLOROPHYLL CHANGES IN RESPONSE T ADDED DON

20 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

21 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?

22 ACKNOWLEDGEMENTS  Little Lagoon Preservation Society  Alice Kleinhuizen  Eric Lachenmyer  Rebecca Bernard  Laura Linn  Dr. Alice Ortmann  Dr. Jeffrey Krause  Institution Support & Funding:

23 QUESTIONS???? JENNIFER ANDERS CONTACT INFORMATION:


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