Recap of Day 1 and Linking Biogeochemical Trends Across Spatio-Temporal Scales in Estuarine Environments

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Phoebe Allison
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1 Recap of Day 1 and Linking Biogeochemical Trends Across Spatio-Temporal Scales in Estuarine Environments Jeremy Testa Walter Boynton Lora Harris Casey Hodgkins Ben Henry

2 Key Questions/Objectives Does management focused on triblets provide new opportunities to meet CBP goals? Do Triblets have an outsized influence on CB? Do triblets behave like larger regions of CB and do they have unique problems?

3 Why We Emphasize Triblets? (from yesterday) This is the scale at which BMPs implemented, i.e., triblet knowledge will guide BMP planning Assess water quality where people live (and in the waters they adore) Understand reactor function of triblets are they Reactors or Pipes?

4 We are Here (I think) Because We Think They are Reactors

5 Non-conservative material Pipe Reactors Net consumption (reactor) Net production (reactor) Salinity is a conservative tracer of mixing Fit line between source concentration and saline endmember Non-conservative materials deviate from conservative line Salinity

Total nitrogen inputs, transport, stocks and losses in the Patuxent estuary NEW INPUTS 3456 NEW INPUTS WC Biota Sed 1933 Mid Patuxent 89 50 460 DENITRIFICATION MARSH 850 SUBTIDAL 285

6 Total nitrogen inputs, transport, stocks and losses in the Patuxent estuary NEW INPUTS 3456 NEW INPUTS WC Biota Sed 1933 Mid Patuxent DENITRIFICATION MARSH 850 SUBTIDAL 285 MARSH 789 SUBTIDAL 582 Mid Patuxent Inputs Denitrification Burial Export Net 46 TRANSPORT Downstream 2929 BURIAL Flows kg N day -1 Stocks kg x10 3 N Boynton et al. 2008

7 Corsica River: an example reactor

8 Residence Time is a Key Determinant of Reactor Role 100 Norsminde Fjord Boston Harbor Estuaries listed in Nixon et al Chesapeake Bay estuaries 80 Ochlockonee Bay Guadalupe, wet % Total N Exported Narragansett Bay Maryland Chesapeake N. Adriatic Scheldt Estuary Delaware Bay Potomac Chesapeake Bay System Guadalupe, dry 20 Is Corsica Patuxent particularly Choptank Effective at Could residence Baltic Sea retention? time be this long? Residence Time, months Nixon et al., 1996

9 Residence Time is a Key Determinant of Reactor Role Testa et al. 2012

10 BUT If these ecosystems are very retentive, they are ALSO:.probably (1) Highly sensitive to eutrophication/degradation Recall from yesterday: - hypoxia in Severn, Church creek, Corsica, Rock Creek - bacterial pollution - degradation with land-use change (2) Likely to store nutrients in sediments = legacy?

11 Limited Sediment Legacy in Mesohaline Sediments ~12 days Despite hypoxia, PO4 fluxes decline after 5 days By late summer, NH4 flux declines Boynton 2000

12 Modeling Sediment Legacy Testa, unpublished

13 Modeling Sediment Legacy Testa, unpublished

14 In Shallow Water Systems (triblets), Light is Key Mediator of Nutrient Transformation

15 Sediment O 2 flux (mmol O 2 m -2 d -1 ) Microphytobenthos produce O 2 and counteract hypoxia Dark Cores Light Cores Day Field data from Choptank River, courtesy of Cornwell and Owens

16 Sediment O 2 flux (mmol O 2 m -2 d -1 ) Microphytobenthos produce O 2 and counteract hypoxia Day Dark Cores Light Cores Dark Model Light Model Field data from Choptank River, courtesy of Cornwell and Owens

17 Sediment O 2 flux (mmol m -2 d -1 ) Sediment NH 4 flux (mmol m -2 d -1 ) Sediment O 2 and NH 4 Flux in Corsica River Dark Cores Light Cores Dark Model Light Model Dark Cores Light cores Dark model Light model Day Day

18 Sediment O 2 flux (mmol m -2 d -1 ) Sediment NH 4 flux (mmol m -2 d -1 ) Illumination Alters O 2 and NH 4 Flux in Spring/Fall O 2 NH 4 4 0% Light 3 50% Light 100% Light 2 200% Light Day % Light 50% Light 100% Light 200% Light Day

19 Potential Light Effects on System Scale N Budget Small increase in Secchi (0.5 m 1.0 m) yields large increase in photic bottom (1% surface light) from 28 85% Need to better understand these non-linear dynamics

20 Shallow Triblets Abound Living resources: SAV Nursery Benthos

Predominance of load and concentration declines

and TP, respectively) Not all improvements

concentration increases (8% and 4% for TN and TP)

21 Load Declines Generally Correspond to Concentration Declines Across all Bay Segments Predominance of load and concentration declines for TN and TP (79% and 62% of all sites for TN and TP, respectively) Not all improvements significant Some sites exhibited load and concentration increases (8% and 4% for TN and TP) 13% (TN) and 34% (TP) of sites showed unexpected patterns Testa et al., unpublished

22 Triblets Respond To Load Reductions, Some more than others Corsica River, Limited Change Mattawoman Creek Large Load Reduction Cover Crops 60% Sycamore Point Jun-Aug Mean 70 50% 60 Boynton et al DO criteria failure 40% 30% 20% Chlorophyll, gl -1 10% DO Criteria Failure 0% Time Testa et al

23 Some Useful Activities? (1) Quantitative Framework to Analyze Triblets/subestuaries (2) Identify potential new research avenues (3) Identify what we do and don t know about triblets -What characteristics of subestuaries are most important? -We need data to assess biophysical setting -New tools are available (e.g., models), plenty of data to synthesize

Modeling Chester River Water Quality...

Modeling Chester River Water Quality... Jeremy Testa Damian Brady Kelly Cole Ming Li University of Maryland Center for Environmental Science University of Maine Outline (1) Quick update on ROMS (2) Comparison