FISHERY BULLETIN: VOL. 85, NO. 1 



lobsters from the water eliminates the respiratory 

 stream and the normal excretory route for am- 

 monia. This toxic product of protein catabolism can 

 then accumulate in the hemolymph. 



Binns (1969) reported 16 ;ig/mL of ammonia in 

 blood of freshly captured shore crabs, Carcinus 

 maenas. Spaargaren (1982) reported blood ammonia 

 concentrations between 4 and 9 /jg/mL for this same 

 species and also provided evidence for a close con- 

 nection between ammonia excretion and extracel- 

 lular ion regulation. Florkin (1960) reported aver- 

 age blood ammonia concentrations for 12 aquatic 

 decapods to be 13 ^g/mL, range 4-25 ;ug/mL. Nor- 

 mal hemolymph ammonia concentrations (7.22 

 /ig/mL) for spiny lobsters are toward the low end 

 of this range. After 2-h exposure, hemolymph am- 

 monia concentrations for spiny lobster increased to 

 13.77 ^g/mL. It is not known if this concentration 

 is toxic; however, hypoxia has been reported to in- 

 crease toxic effects of ammonia in minnows (Wuhr- 

 mann 1952), rainbow trout (Downing and Merkens 

 1955), and mice (Warren and Schenker 1960). 

 Exposure-induced hypoxia in the spiny lobster may 

 interact synergistically with ammonia, leading to 

 toxic effects at concentrations that would not nor- 

 mally cause problems. 



Ionized ammonia (NH4-1-) is less toxic than un- 

 ionized ammonia (NH3) because of its lower tissue 

 permeability (Warren and Nathan 1958). A decrease 

 in hemolymph pH, as occurs during exposure, would 

 shift the chemical equilibrium toward the less toxic 

 NH4-1- (Warren and Schenker 1962). Exposure- 

 induced acidosis may afford some protection against 

 ammonia toxicity by this mechanism if ammonia 

 does indeed reach concentrations toxic to spiny 

 lobsters. Ammonia, which functions as a base, may 

 also partially offset the pH decrease caused by lactic 

 acid. 



Escape Behavior and Conclusions 



All 32 spiny lobsters exposed for 2 h and then 

 reimmersed were alive after 24 h and had normal 

 hemolymph chemical values. Apparently the acute 

 effects of exposure (acidosis, ammonia, and lactic 

 acid accumulation) do not directly cause the in- 

 creased mortality reported in previous studies 

 (Lyons and Kennedy 1981; Hunt et al. 1986). Rather, 

 secondary physiological damage, persisting after 

 acute effects have vanished, may be the ultimate 

 cause of mortality. Persistant physiological damage 

 was manifested as aberrant defensive and escape 

 behavior. 



Spiny lobsters with diminished antennal defensive 



movements and tail-flip escape responses would be 

 at increased risk from predators. Brown and Caputi 

 (1983) observed that western rock lobsters, Panu- 

 lirus eygnus, exposed to air for V2-2 h were generally 

 less active, slower in seeking shelter, incapable of 

 defense, and more subject to attack by finfish and 

 octopus. 



Exposure effects severe enough to disrupt a basic 

 reflex such as the tail-flip may also affect integrated 

 nervous system functions such as feeding, locomo- 

 tion, and social and sexual behavior. Nervous tissue 

 is particularly susceptible to damage from hypoxia 

 (Prosser 1973) and from fluctuations in osmotic 

 and/or ionic concentrations of body fluids (Treherne 

 1980). Nervous system damage induced by hypox- 

 ia, acidosis, and perhaps osmotic imbalances is likely 

 the cause of behavioral aberrations in exposed spiny 

 lobsters. 



Because the transition to anaerobic metabolism 

 and resulting hemolymph changes occur so rapidly 

 after emersion, the threshold at which physiologi- 

 cal effects appear may be no more than a few 

 minutes exposure. Fishery practices which allow ex- 

 posures of 1 h or more must therefore be producing 

 large numbers of spiny lobsters that are physio- 

 logically and behaviorally impaired. 



ACKNOWLEDGMENTS 



J. H. Hunt and J. M. Marx collected lobsters and 

 reviewed the first draft. T. M. Bert, H. J. Grier, W. 

 G. Lyons, and K. A. Steidinger critically reviewed 

 the manuscript. Bill Moore provided information on 

 spiny lobster fishery practices and R. L. Squibb pro- 

 vided advice, facilities, equipment, and friendship. 

 All are gratefully acknowledged. 



LITERATURE CITED 



Albert, J. L., and W. R. Ellington. 



1985. Patterns of energy metabolism in the stone crab, 

 Menippe mercenaria during severe hypoxia and subsequent 

 recovery. J. Exp. ZooL 234:175-183. 

 Anonymous. 



1980. The fate of undersized rock lobsters returned to the 

 sea. West. Aust. Dep. Fish. Wildl., Fish. Inda. News Serv. 

 (F.I.N.S.), 13:10-12. 

 Barnes, H., D. M. Finlayson, and J. Piatigorsky. 



1963. The effect of desiccation and anaerobic conditions on 

 the behaviour, survival and general metabolism of three com- 

 mon cirripedes. J. Anim. Ecol. 32:233-252. 

 Binns, R. 



1969. The physiology of the antennal gland of Carcinus 

 maenas (L.) V. Some nitrogenous constituents in the blood 

 and urine. J. Exp. Biol. 51:41-45. 

 Bliss, D. E. 



1968. Transition from water to land in decapod crustaceans. 



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