Shields and Squyars: Mortality and hematology of Callinectes sapldus infected with Hematodinium perezi 



149 



where salinities are greater than W^h; i.e. much of 

 the mainstem of Chesapeake Bay. Current models 

 for blue crab populations in Chesapeake Bay are 

 based on population assessments from various sur- 

 veys (Lipcius and Van Engel, 1990; Abbe and Stagg, 

 1996; Rugolo et al., 1998). These models project crab 

 abundance for the fishery as a whole but do not sep- 

 arate the larger, low-salinity "bayside" fishery from 

 the smaller, high-salinity "seaside" fishery where 

 mortalities due to H. perezi occur. Such projections 

 include estimates of natural mortalities but do not 

 account for the potential epizootics and resulting 

 mortalities caused by H. perezi. Differential models 

 of exploitation by region may be warranted, espe- 

 cially during or immediately following epizootics. 

 Disease estimates must, however, account for the 

 variation in the prevalence of detection because the 

 prevalence in field samples may be significantly 

 underreported (see Fig. 3). 



The life cycle of H. perezi from C. sapid us has not 

 been fully documented. Several morphological and 

 life history differences, however, distinctly separate 

 Hematodinium sp. ex A'', norvegicus (Appleton and 

 Vickerman, 1998) from H. perezi ex C. sapidus. For 

 example, the syncytial and network forms of Hema- 

 todinium sp. ex N. norvegicus (Field and Appleton, 

 1995) have not been observed with H. perezi (Mes- 

 sick, 1994; present study); nor do the plasmodia (cf 

 filamentous trophonts of Appleton and Vickerman, 

 1998) of H. perezi develop as "gorgonlocks"; rather, 

 they undergo budding to produce additional Plas- 

 modia, and schizogony (cf. segmentation in malaria 

 life cycles) to produce uninucleate trophonts (senior 

 author, unpubl. data). The trophonts then undergo 

 further fission. Such differences may warrant generic 

 separation between the two parasites. 



Hematodinium perezi was successfully transmitted 

 to blue crabs by injection. Transmission experiments 



