Impacts of Altered Hydrology on the Sources of Particulate Organic Carbon on the Diet ofCrassostrea virginicain the Northern Everglades, Florida, USA

Abstract

ABSTRACT Stable isotope composition of the eastern oyster Crassostrea virginica was characterized from three estuaries in the Ten Thousand Islands (Florida). Freshwater in flow from watershed management is affecting this region and has deeply modified the salinity gradient. Stable carbon and nitrogen isotopes were used to trace specific sources of organic matter and the influence of these sources of carbon on the diet of the eastern oyster in the Greater Everglades. Oysters, as well as particulate organic matter (POM) and benthicmicroalgae (BMA) were sampled in three bays at three different stations from upstream to downstream during both wet and dry seasons. Significant salinity differences were observed in all estuaries between summer (wet) and winter (dry) seasons and were linked to freshwater inputs into the bays. Temperature followed a typical seasonal trend. Oysters were enriched in δ15N compared with POM and BMA, and similarly or slightly enriched in δ13C for both seasons. Lighter δ13C values in th...