Influence of salinity on prevalence of the parasite Loxothylacus panopaei in the xanthid Panopeus obesus in SW Florida.

This study was conducted to examine the potential influence of salinity, a proxy for freshwater inflow, on the prevalence of the castrator parasite Loxothylacus panopaei on saltmarsh mud crabs Panopeus obesus on SW Florida oyster reefs. Spatial and seasonal patterns of the presence of potential host crabs and the prevalence of the parasite were assessed in the Caloosahatchee, Estero, and Faka Union estuaries. Lift nets (1 m2) containing 5 1 of oyster clusters were deployed on intertidal reefs at 3 sites along the salinity gradient of each estuary.

Stimulation of defense factors for oysters deployed to contaminated sites in Pensacola Bay, Florida.

A positive association between chemical contaminants and defense factors has been established for eastern oysters (Crassostrea virginica) from Florida, but it is unknown whether such factors can be stimulated through short-term exposure to contaminants in the field. Hatchery oysters were deployed at two contaminated sites and one reference site near Pensacola, Florida, during spring and summer in 1998. Putative defense measurements, notably hemocyte count and bactericidal activity, were significantly elevated after 12-week deployment during summer at the most contaminated site.

Ovacystis-like condition in the eastern oyster Crassostrea virginica from the northeastern Gulf of Mexico.

Histological examination of the eastern oyster Crassostrea virginica from a study in Pensacola Bay, Florida, revealed 2 cases of abnormally large, basophilic ova that resembled cells characteristic of ovacystis disease previously reported in oysters from Maine and Long Island. The hypertrophied gametes measured up to 250 pm in diameter, had scant cytoplasm and contained granular nuclear-masses of Feulgen-positive material. Electron microscopy of reclaimed tissue revealed these masses to consist of virus-like particles (average 46 nm) similar to those reported in cases of ovacystis.