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Oysters, Seagrasses and Estuarine Water Quality
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Project Title: Modeling the Effects of Changes in Turbidity on Light Available for Submerged Aquatic Vegetation
Research Locations: Chesapeake Bay - MD
Last Update: 8-30-02
The loss of bottom habitats in the Chesapeake Bay in the last four decades is well documented. Once filled with seagrasses and oyster beds, these species have all decreased dramatically along with a corresponding decrease in water clarity. Management strategies often focus on decreasing nutrient inputs, but this does not directly impact inorganic suspended solids. This project is studying the interrelationships between bivalves (oysters and clams), which filter the suspended solids from the water column, and seagrasses, which also promote water clarity. The end result of this project will be a user-friendly model that will allow managers to explore how this relationship can be used to improve restoration planning and water quality.
Project Approach
Data from field and laboratory experiments are used to create a
model that accurately reflects:
- the impacts of oyster and clam filtration on the distribution and density of seagrasses
- the aspects of a seagrass bed (density, etc.) that affect its ability to trap sediment
Results
The data show that bivalves filter suspended matter and increase
light penetration, which promotes seagrass health. Since seagrasses
also promote water quality, these results suggest that multispecies
restoration efforts may be an effective method for improving
degraded ecosystems.
- In model simulations, as seen in the graph below, oysters significantly increased the growth of seagrass plants. Hard clams, because of their lower filtration rates, did not benefit seagrasses to the same extent as oysters.
- Field studies at clam aquaculture farms do show increased light penetration as result of filtration by dense clam populations.
Supporting the Chesapeake Bay 2000 Agreement
The Chesapeake Bay 2000 Agreement, signed by the governors
of Maryland, Virginia, the District of Columbia and
Pennsylvania, set a goal of increasing by tenfold the number of
native oysters in the Bay by the year 2010. The model developed
for this project demonstrates that the benefits of oyster
restoration go beyond the context of the oyster fishery.
Making a Complex Model Accessible and User Friendly
Useful models are simple to use yet detailed enough to be representative
of natural processes. For this project, researchers
are using specialized software to boost the ability of STELLA, a
modeling software renowned for being user friendly (from High
Performance Systems, Inc.), so that it can handle the many
factors related to seagrass, bivalves and water clarity. When
completed, the model will be made available via the CICEET and
Horn Point Laboratory, MD web sites.
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Project Coordinator
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Roger Newell Univ. of Maryland Center for Environmental Science Horn Point Laboratory (410) 221-8410 newell@hpl.umces.edu |
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Start -End Date:
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09/01/1999 - 09/01/2001
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NERR Reserve(s):
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Chesapeake Bay - MD
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| For more information: |
Dolores Jalbert Leonard Phone: (603) 862-3685 Email: dolores.leonard@unh.edu |