Aquatic Sciences Meeting, Albuquerque 2001

PC03 Undergraduate Education

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Usher, Z, J, State University of New York at Stony Brook REU, Stony Brook, USA, usherz@wlu.edu

AN INVESTIGATION OF PHYSICAL, BIOLOGICAL AND CHEMICAL FACTORS IMPACTING MERCENARIA MERCENARIA IN THE GREAT SOUTH BAY, LONG ISLAND NY

Harvests of the clam Mercenaria mercenaria in Great South Bay have dropped precipitously since the 1970's. Proposed causes include nutrient levels, climate change, overharvesting, algal blooms, and natural ecological change such as transfer of control from benthic to planktonic communities. The marine sedimentology group analyzed three 5-m vibracores from the primary bottom types of the estuary. They indicated a thick sequence (>5 m) of estuarine fill trending toward a higher-energy regime in recent times. Lead-210 dating indicated slow sedimentation rates in the shallow (<3 m) modern basin. Other REU investigations noted an increase in brown tide blooms over the period of hard clam decline. Groundwater-associated nutrient loads have not increased in recent decades. Thus eutrophication is probably not a major contributor to recent environmental change. Wind-driven wave fields dominate local circulation and resuspension patterns, rather than tidally dominated circulation as in the past. Estuarine development and evolution may be due in large part to storm events. A definite cause for clam declines was not determined: further investigation regarding structure of the estuary is necessary before conclusions can be made.

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Aquatic Sciences Meeting, Albuquerque 2001

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