VERMEER: EFFECTS OF EXPOSURE ON SPINY LOBSTER 



Sigma kit hydrazine buffer, recommended by 

 Graham et al. (1983) for cases of end point in- 

 stabihty, was not used because stable end points 

 were obtained after 90 min. 



One group of spiny lobsters was exposed for 2 h 

 and then returned to the acclimation tank for 24 h 

 before sampling to observe whether the blood chem- 

 istry changes which I observed immediately after 

 exposure persisted after reimmersion. 



Escape Behavior 



Controls were individually netted, marked, and 

 returned to the tank in less than 1 min. Exposed 

 spiny lobsters were netted, marked, and placed in 

 a shaded fish box for 2 h before being returned to 

 the tank. Twenty-four h later, spiny lobsters were 

 netted from the tank again and escape responses 

 were recorded. A delayed or absent tail-flip after 

 an antenna touch or tug was considered an impaired 

 escape response; an immediate tail-flip was con- 

 sidered normal. 



Student's f-test was used to analyze all desicca- 

 tion and hemolymph chemical data. Values of P < 

 0.05 were considered significant. All data are ex- 

 pressed as means ±1 SE. Since the control hemo- 

 lymph chemical values from each exposure interval 

 and from the reimmersed exposed spiny lobster ex- 

 periment were not significantly different, they were 

 pooled. 



RESULTS 



Desiccation Rate 



Control spiny lobsters, which remained sub- 

 merged except during weighings, maintained con- 

 stant weights (Table 1). Percentage of initial weight 

 remaining at the end of 2-h air exposure was 95.30% 

 for shorts and 96.37% for legals, or an average 

 weight loss of 2.35%/hour and 1.82%/hour respec- 

 tively. 



Hemolymph Chemistry 



During a 2-h exposure, hemolymph lactic acid 

 levels increased more than 11 times (from 4.4 

 mg/100 mL to 49.5 mg/100 mL), pH decreased more 

 than one-half unit (from 7.91 to 7.40), and ammonia 

 concentration nearly doubled (from 7.22 /ug/mL to 

 13.77 tig/mL) (Fig. 1). Exposure-induced changes in 

 hemolymph parameters occurred very rapidly then 

 leveled off. Lactic acid and pH changed more in the 

 first 30 min of exposure than in the subsequent 90 

 min. Ammonia accumulation was also at its max- 

 imum rate during the first 30 min. 



All spiny lobsters exposed for 2 h, then returned 

 to the acclimation tank for 24 h before sampling, 

 survived and had normal hemolymph parameters 

 (Fig. 1). Evidently, acute hemolymph effects of ex- 

 posure (i.e., elevated lactic acid and ammonia, 

 depressed pH) do not persist beyond 24 h. 



Escape Behavior 



Nonexposed spiny lobsters defended their posi- 

 tions in the concrete block holes with vigorous anten- 

 nal movements directed toward an approaching 

 hand until contact was made. Then a tap or, more 

 frequently, a light tug on the tip of one antenna 

 elicited an immediate tail-flip, propelling the lobster 

 backward into the net. This method of removing 

 lobsters from the acclimation tank was 100% effec- 

 tive on nonexposed lobsters. 



Although hemolymph parameters of exposed 

 spiny lobsters returned to normal within 24 h after 

 reimmersion, it was evident that defensive and 

 escape behavior of these lobsters was abnormal. In 

 lobsters exposed for 2 h and then reimmersed for 

 24 h, defensive antennal movements were feeble or 

 absent, and an antennal tap or tug usually failed to 

 elicit an immediate escape response. When it did oc- 

 cur, the tail-flip response required several strong 

 antennal tugs over a 3-4 s period. In some cases, 

 a tail-flip could not be induced by any form of anten- 



Table 1 . — Percentage of initial spiny lobster weight remaining after various exposure 

 times. Data are means + 1 SE; N is in parentheses. Differences between shorts and 

 legals are significant at 2 h but not 1 h. 



Exposure time (hours) 



47 



