Title slideDeveloping a Nutrient Framework
for Managing and Restoring the Biological Integrity Of Southwest Florida Tidal Creeks
Jay Leverone, Ph.D.Sarasota Bay Estuary Program
Restore America’s Estuaries8th National Summit
Our Coasts, Our Future, Our Choice
December 13, 2016
BACKGROUNDRecommendations from our NNC Reports for
SW Florida Estuaries
• The three NEPs worked together to develop estuarine NNC for their respective estuaries
• We suggested that EPA and FDEP consider tidal creeks as unique waterbodies; that separate NNC should be developed for these waterbodies. (EPA SAB concurred).
• Inadequate/insufficient data from regional tidal creeks compelled us to do this study
EPA Region IVWetland Development Grant
Acknowledgements
Tidal creeks are expected to possess water quality characteristics that differ from freshwater systems and the open
estuary. Why?
Direct connection and proximity to watershed sources of nutrients AND smaller volume relative to open estuary EQUAL relatively high nutrient and chlorophyll (and low dissolved oxygen) compared to downstream waterbodies
Florida Nutrient Criteria Development
Pro
ject
Go
al
Classification and Selection(306 creeks: 16 creeks sampled)
Long creeks;High nutrientloadings
High LDI;Unique
soils
Low LDI;Unique
soils
Low soil P;close to passes
Estuary
Fresh Study Area
Fish sample <1.5m depthand composite benthicchla sample <1.0m depth
WQ Sample
Creek Study Sampling Design
S1
S2
S3
Current Narrative Nutrient Model
Dissolved Oxygen and Chlorophyll a
Nutrients Chl a DOFish/
Benthos
Stressor Response Endpoints Adverse Effects
Surrogate Endpoints
N=18
Highest Snook Biomass
Most Snook
= Class C : mostundeveloped creeks
Estuarine DO Evaluation
Estuarine Chl aEvaluation
Narrative Standards
Analytical Lines of Evidence
1. Nutrients -> Chla -> DO %saturationa) Nutrients-> Chla
b) Nutrients->DO
2. Salinity Mediated Influences
3. Nutrients as a Conservative Substance
4. WQ Response Grouping
5. Fish Response Indicators
6. Reference Condition Approaches
Line 1- Nutrients, Chlorophyll, and Dissolved Oxygen
Nutrients and Chlorophyll a
• Significant relationship between TN chlorophyll a (same with TP)
• Considerable variation was unexplained
• Temperature was a significant covariant
Chlorophyll a and Dissolved Oxygen
Nutrients Chla DOFish/
Benthos
General NutrientManagement Model
Stressor Response Endpoints Adverse Effects
Line 3- Nutrients as Conservative Substances
Mixing Curves/Nutrient Dynamics
Some creeks contribute nutrients!
Nutrients Chla DOFish/
Benthos
General NutrientManagement Model
Stressor Response Endpoints Adverse Effects
?
Response Endpoints Are Biologically Based
• “Healthy, Well Balanced Population of Fish and Wildlife”
• “Fishable / Swimable”
• “Full Aquatic Life Support”
Nutrients Chl a DOFish/
Benthos
Line 5 – Fish Response Indicators
Scientific Name Common name TotalAnchoa mitchilli Bay anchovy 15,099Eucinostomus spp. 11,242Palaemonetes pugio Grass shrimp 2,837Menidia spp. 2,555Lucania parva Rainwater killifish 2,086Eucinostomus harengulus Tidewater mojarra 1,921Gambusia holbrooki Eastern mosquito fish 1,125Diapterus auratus Irish pompano 982Centropomus undecimalis Common snook 775Eugerres plumieri Striped mojarra 593Trinectes maculatus Hogchoker 561Poecilia latipinna Sailfin molly 454Lagodon rhomboides Pinfish 412Microgobius gulosus Clown goby 287Sciaenops ocellatus Red drum 271Leiostomus xanthurus Spot 262Brevoortia spp. 243Clupeidae spp. 204Callinectes sapidus Blue crab 191Oreochromis/Sarotherodon spp. Tilapias 174Gobiosoma spp. 147Gobiosoma bosc Naked goby 141Fundulus grandis Gulf killifish 101
Most Abundant Fish Taxa
Nutrients and FishDiversity Indices
TP (mg/l) TN (mg/l)
D
J’
H’
#
S
The Reference–Based Approach
Setting Nutrient Targets and Thresholds in the Absence of any Observed Adverse Effects
Standard1.65
Computer Simulation
Target
Caution
Level
Management
Action Plan
Regulatory
Threshold
Stewardship Goals Management Thresholds
Stewardship Management
Example Application ofManagement Strategy
Tampa Bay
Charlotte Harbor
• Tidal creeks provide critical habitat for estuarine dependent fish.
• Tidal creek water quality was characteristic of wetland environments.
• Existing DO and chlorophyll criteria are unreliable indicators of nutrient impairment in southwest Florida tidal creeks.
• Tidal portion can contribute nutrients to the system.
• Unclear if addition nutrients are natural or anthropogenic.
• Emergent vegetation seems important in nutrient dynamics and biological response.
• Observed nutrient levels have not yet resulted in highly eutrophic or dystrophic conditions in sampled creeks.
Principle Findings
Future Efforts
• Look at nutrient speciation within the tidal portions of the sample creeks
• Investigate nutrient inputs from adjacent wetlands (mangroves)
• Conduct sediment flux studies to look at sediment-nutrient contributions
• Fine tune the nutrient management framework
• Broaden the inference to remaining creeks within southwest Florida
Thank You
