Shields and Squyars Mortality and hematology of Callinectes sapidus Infected with Hematodlnium perezi 



147 



"Immune" crabs exhibited a fluctuation in cell types 

 with significantly higher proportions of granulocytes 

 to semigranulocytes during the first five weeks after 

 inoculation (F=4.35, df =5, 18, P<0.01). By day 40, 

 the hemograms of "immune" hosts were virtually 

 identical to those of the uninfected controls (Table 7, 

 Fig. 5, C and D). 



In the early infection experiment, hemocyte popu- 

 lations shifted within the first three days of infec- 

 tion (Tables 5 and 6; ANOVA, log hemocytes, F=9.16; 

 df =3, 31, P<0.01); the proportion of granulocytes in 

 infected crabs increased significantly compared with 

 the proportion of semigranulocytes (ANOVA, 7^=4.39, 

 P<0.05). Uninfected crabs exhibited minor fluctua- 

 tions in the proportion of granulocytes to that of hya- 

 linocytes but the proportions were similar to those 

 observed in the mortality-I and mortality-II experi- 

 ments (Tables 6 and 7). 



Discussion 



In laboratory experiments, Hematodinium perezi 

 caused significant mortality to infected mature, 



nonovigerous blue crabs. Infections were not always 

 fatal (four crabs survived inoculation without devel- 

 oping infections), but the overall mortality to labo- 

 oratory-inoculated crabs was high at 86% over 40 

 days. The proportional hazards model indicated that 

 infected crabs were seven to eight times more likely to 

 die than uninfected crabs. Infections in Tanner crab, 

 Chionoecetes bairdi, and Norway lobster, Nephrops 

 norvegiciis, are frequently fatal to the host (Meyers 

 et al., 1987; Field et al., 1992). The mortality of natu- 

 urally infected Tanner crabs held in aquaria for 97 

 days was 67% (;? = 11) and hosts survived from 20 to 

 158 days in the laboratory. Uninfected Tanner crabs 

 experienced no mortality during the course of the 

 experiment (Meyers et al., 1987). Naturally infected 

 Norway lobsters suffered mortality rates of 86% to 

 100% over 27 d and 75 d, respectively, and had mor- 

 tality rates 2-4 times higher than uninfected lob- 

 sters, and most of the deaths occurred early in the 

 course of the experiment (Field et al., 1992). 



During epizootics, juvenile blue crabs have a 

 higher prevalence of//, perezi than do mature hosts 

 (Messick, 1994). Male blue crabs have a prevalence 

 of infection similar to that for females along the 



Total hemocyte density 



S 7 5 

 o. 



g ■^ 



= 55 



5 







10 15 20 25 30 35 



|o 



Immune" hosts 

 6 



•S 4 



c 

 o 



I 0.2 

 o 



u. 



a. 



40 



granule 



semigranulo 



hyalino 



5 10 15 20 25 30 35 40 



Infected hosts 



O-0.6 



04 



|02 







 ^ / 



granulo 



semigranulo 



hyalino 







10 15 20 25 30 35 40 



Uninfected hosts 

 g.06 



04 



o 



|02 

 p 



granulo 



semigranulo 



hyalino 



5 10 15 20 25 30 35 40 



Days after inoculation Days after moculation 



Figure S 



Total hemocyte densities and proportions of host cell types in uninfected, infected and "immune" crabs. Data combined from mor- 

 tality-I and mortality-II e.xperiments. Bars = SE. Standard errors (not shown) for proportion of host cell types were low (0.02-0.05). 

 "Immune" crabs were survivors from mortality-II e.\periment that never developed infections. Sample sizes given in Table 3. 



