Indicator+Species

Indicator Species & the Chesapeake Bay
Indicator species are used to determine the health of an environment. The Virginia Institute of Marine Science completed a study which tracked the amount of Submerged Aquatic Vegetation (SAV) each year in the Chesapeake Bay. SAV was chosen as the indicator species because it creates food and oxygen through photosynthesis and supplies this to waterfowl, fish, shellfish and invertebrates. Thus, the amount of SAV is directly related to the survival rate of the other aquatic species. Other ways that SAV supports the health of the bay is by absorbing nutrients that stimulate the growth of harmful planktonic algae, lessening shore erosion by preventing waves, and collecting sediment to protect benthic organisms from being buried. The loss of major amounts of SAV was first documented in the 1960s and aerial photographs show almost half the amount of SAV present that was there in the 1930s. Causing this problem is mainly eutrophication and the resulting lack of sunlight. Sediment and excess plant growth due to excess nutrients block sunlight from reaching the SAV and reduce SAV growth. The chart below demonstrates the fluctuation of SAV presence, an ongoing problem. As seen, recent SAV levels are steadily increasing again ("Submerged," 2007).



The above picture was an attempt to generate more SAV in the Chesapeake Bay. The Maryland Department of Natural Resources threw the grass seeds into the water with the hope of restoring SAV and regaining biological diversity (Ruark, 2004).

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