Hematodinium perezi infections in adult arid juvenile blue crabs Callinectes sapidus from coastal bays of Maryland and Virginia, USA

In coastal bays of Maryland and Virginia, USA, adult and juvenile blue crabs Callinectes sapidus were severely infected with the parasitic dinoflagellate I-lematodinium perezi. Dinoflagellates were observed in the hemo- coel of all infected crabs; associated histopathological changes were evident in some tissues. Dinoflagellates could be observed with an inverted microscope through the 5th pleopod of heavily infected juvenile crabs (5 to 29 mm) without invasion. This note documents a high prevalence of H. perezj infections in juvenile blue crabs from coastal bays in Maryland and Virginia. The seasonal infection prevalence cycle reported by previous authors is consistent with observations made during this study.