larval activity was sluggish, frequently ending in 

 death. 



Aliquots from individual daily crab samples ( 1 

 or 2 ml; count ^ 200) were sorted under a dissect- 

 ing microscope and classified. Normal first-stage 

 larvae ( Hyman 1925; Porter 1960) were denoted as 

 viable; whole eggs, partially hatched eggs, prezoea 

 (Hyman 1925; no rostral or lateral extension), and 

 deformed first-stage larvae were denoted as invi- 

 able. Stein's two-stage sample test i Steel and Tor- 

 rie 1960) indicated that six replicate aliquots from 

 each sample provided reliable counts (within 

 95% confidence limits) of total numbers of viable 

 and inviable eggs and larvae present each day. 

 Because results of aliquot counts were inconsis- 

 tent when samples contained clumps of eggs, 1-8 

 ml of chlorine bleach (5.25% sodium hypochlorite) 

 were added to dissolve stalks and dissociate eggs 

 uniformly before aliquots were taken. 



Number of eggs carried by individual crabs at 

 time of capture was estimated by combining daily 

 totals of viable and inviable eggs and larvae. Total 

 hatching success was expressed as percent of orig- 

 inal egg mass that hatched viably. Total egg mass 

 mortality was expressed as the percent not hatch- 

 ing or hatching inviably. Average daily mortality 

 (per group) was calculated by dividing total mor- 

 tality per day by the number of crabs yielding 

 inviable eggs and larvae that day. Crabs not 

 yielding any larvae were eliminated from 

 analysis; two crabs in Group I and one crab each m 

 Groups III, IV, and VI were so eliminated. 



Comparison among groups was made by pre- 

 senting prehatch, posthatch, and total egg mass 

 mortality for each group. I chose this method be- 

 cause inviable eggs and larvae were evident in 

 some form in all daily samples, but viable larvae 

 were present for only 24-48 h. 



Results and Discussion 



Experiment 1 



Initial egg loss from crabs in Group I (Figure 2) 

 was probably caused by handling at capture and 

 stress from transport to laboratory. With acclima- 

 tion to holding tanks, average daily mortality de- 

 creased until major hatch, when highest egg and 

 larval mortality coincided with maximum first- 

 stage larval survival. 



Crabs desiccated for 2 h (Group II) showed im- 

 mediate preening activity upon return to water 

 and daily prehatch mortality peaked at 3.6%, 3 



Posthotch 

 Days after MH 



FK^IUI^E 2. — Average daily percent egg mortality in ovigerous 

 stone crabs as related to desiccation. Group I crabs untreated 

 I control ), Group II crabs exposed to 2-h desiccation and Group III 

 crabs exposed to 5-h desiccation. DD - day of desiccation: MH - 

 day when major hatching occurred; Prehatch - days following 

 DD; Posthatch  days following MH. Starred points represent 

 percent mortality excluding one of three crabs which accounted 

 for 96% total mortality on posthatch days 4 and 5. 



days after desiccation (Figure 2). Thereafter, daily 

 percent mortality decreased until major hatch. 

 Posthatch mortality was similar to, but slightly 

 higher than that of Group I. Total prehatch mor- 

 tality ( 12.1% ) was four times greater than that of 

 Group I (Table 1) and posthatch mortality (9.3%) 

 was nearly twice that of Group I. Total mortality 

 for Group IK 2 1.4% ) was 13.0% higher than control 

 (Group I). 



Desiccation for 5 h (Group III) caused temporary 

 lethargy in crab mobility; sponge care and initial 

 mortality were below those of Group I (Figure 2). 

 Crabs recovered slowly during prehatch, resulting 

 in 5 days of generally increasing daily egg mortal- 

 ity. Maximum daily egg and larval mortality usu- 

 ally occurred on the day of major hatch, but was 

 delayed 2 days for most Group III crabs. Improper 

 maternal care of eggs during prehatch and 

 through posthatch may have prolonged oxygen 



697 



