little lagoon, gulf shores, al
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
IMPACTS OF DISSOLVED ORGANIC NITROGEN LOADING BY SUBMARINE
GROUNDWATER DISCHARGE IN LITTLE LAGOON, AL
JENNIFER ANDERS1,2, BEHZAD MORTAZAVI1,2, JUSTIN LIEFER1,2, WILLIAM BURNETT3, HUGH MACINTYRE4
1DEPARTMENT OF BIOLOGICAL SCIENCES, UNIVERSITY OF ALABAMA, TUSCALOOSA, AL 35487, U.S.A.
2DAUPHIN ISLAND SEA LAB, 102 B BIENVILLE BLVD, DAUPHIN ISLAND, AL 36528, U.S.A.
3DEPARTMENT OF EARTH, OCEAN AND ATMOSPHERIC SCIENCES, FLORIDA STATE UNIVERSITY, TALLAHASSEE, FL 32306, U.S.A.
4DEPARTMENT 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 2010-2012 of groundwater environmental conditions and nutrients
Florida State University used tracers to as a proxy for groundwater discharge in Little Lagoon
Distribution of 222Rn 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 μmol/L
DIN μmol/L
TDN μmol/L
TN Μmol/L
Well 1 151.8 105.7 257.6 302.4
Well 2 231.2 35.6 266.8 337.2
Site 1 42.3 6.8 47.8 67.3
Site 2 23.5 1.9 29.5 51.2
Site 3 24.4 2.1 25.9 44.2
Site 4 28.5 2.7 31.2 55.5
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
OXYGEN CONSUMPTION
12 24 48 72
-30
-20
-10
0
10
20
30
40
50
Exp. 2
Control
Hours
Change in O
2 (
µm
ol/L)
from
in
itia
l
24 48 72 120-20
0
20
40
60
80
100
120
Exp. 1
ControlGroundwater
HoursChange in O
2 (
µm
ol/L)
from
in
itia
l
24 48 72 960
10
20
30
40
50
60
70
Exp. 3
ControlGroundwater
Hours
Change in O
2 (
µm
ol/L)
from
in
itia
l
DON UPTAKE
0 12 24 36 48 60 720.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00 Bacteria Exp. 2
DON Control
DON groundwater
Hours
DO
N (
uM
)
0 48 960.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00 Phytoplankton Exp. 2
DON control
DON groundwater
Hours
DO
N (
uM
)
0 24 48 96 1440.00
10.00
20.00
30.00
40.00
Phytoplankton Exp. 1
Control
Hours
DO
N (
uM
)
0 24 48 72 1200.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
Bacteria Exp. 1
ControlGroundwa-ter
Hours
DO
N (
uM
)
CHLOROPHYLL CHANGES IN RESPONSE T ADDED DON
0 20 40 60 80 100 120 1400
10
20
30
40
50
60
f(x) = 0.192505630630631 x + 33.1477027027027R² = 0.954414172790132
f(x) = 0.074183558558559 x + 35.2097747747747R² = 0.421476117621023
Exp. 1
Control
Linear (Control)
Groundwater
Hours
Chl a (
µg/L
)
0 24 48 72 960
20
40
60
80
100
120
f(x) = 0.267208333333333 x + 65.488R² = 0.942453455231399f(x) = 0.0923472222222224 x + 80.0666666666667R² = 0.0594123520590233
Exp. 2
Hours
Chl-a (
ug/L
)
0 24 48 72 960
20
40
60
80
100
120
140
160
f(x) = − 0.294888888888892 x + 136.664R² = 0.39904768138953f(x) = 0.146444444444446 x + 117.156666666667R² = 0.216405622011694
Exp. 3
Hours
Chl-a (
ug/L
)
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:
