60 



E 

 o 

 o 



i.0 



< 



.y 20- 



-ih 



19 



X 



a 



7.6 



f 



73- 



I r R 



Time h 



FISHERY BULLETIN: VOL. 85, NO. 1 



1'^ 



3. 



.5 '0 



c 

 o 



E 



I 5 



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V/^ 



Figure 1.— Hemolymph lactic acid, pH and ammonia concentrations of spiny lobsters 

 after air exposures of (controls, pooled values), V2, 1, and 2 h. R = chemical values 

 after 2-h exposure followed by 24-h reimmersion. A^ = 45, 20, 17, 16, and 20 for 0, V2, 

 1, 2, and R, respectively. 



nal manipulation. The degree of antennal defensive 

 movements was difficult to quantify, so the obser- 

 vation of feeble or absent movements is given here 

 as anecdotal information. None of the immersed 

 (control) lobsters showed an impaired tail-flip, 

 whereas 75% of previously exposed lobsters showed 

 some tail-flip impairment, i.e., tail-flip delayed or 

 absent (Table 2). Controls tested again after 24 h 

 still showed no tail-flip impairment, indicating that 

 observed behavioral aberrations were not caused by 

 netting and were not learned net-avoidance 

 behavior. 



Table 2. — Escape response (E.R.) impairment 24 h after 2-h ex- 

 posure. Lobsters with delayed or absent tail-flip response to an 

 antenna tug were considered impaired. 



DISCUSSION 



Aquatic organisms suffer water loss and other 

 stresses during air exposure. Inability to ventilate 

 gills may lead to hypoxia, anaerobic metabolism, and 

 accumulation of toxic metabolites. Intertidal crusta- 

 ceans, which are periodically exposed to air, have 

 behavioral, anatomical, and physiological adapta- 

 tions that moderate deleterious effects of exposure. 

 The barnacle, Pollicipes polymerus, easily recovers 



after a 40-50% water loss (Fyhn et al. 1972). Bar- 

 nacles can reduce their metabolic rate during emer- 

 sion and tolerate extended periods of anaerobiosis 

 (Barnes et al. 1963). The stone crab, Menippe 

 mercenaria, can survive severe hypoxia for at least 

 12 h at 28° -30° C and can tolerate high levels of 

 hemolymph lactate (Albert and Ellington 1985). 

 Crustaceans that have made a permanent transition 

 from water to land have even more elaborate adap- 

 tations to the special rigors of the terrestrial en- 

 vironment (Bliss 1968). Terrestrial decapods (e.g., 

 Cardisoma and Gecarcinus) exhibit extensive ana- 

 tomical modifications of the gills and branchial 

 chambers, including a reduction in gill number, 

 volume, and area, which presumably minimize 

 desiccation effects, and strongly sclerotized and 

 ridged gills which do not collapse in air (Pearse 1950; 

 Gray 1957; Edney 1960). Enhanced exoskeletal 

 resistance to water loss is also a common adapta- 

 tion of semiterrestrial and terrestrial crustacean 

 species. Aquatic decapods in air lose 3-5 times as 

 much water as do terrestrial decapods (Herreid 

 1969). 



The spiny lobster lives subtidally throughout its 

 life cycle and is only exposed to air as a byproduct 

 of present fishery practices. Because there has been 

 no selective pressure to evolve behavioral, anatomi- 

 cal, or physiological adaptations to aerial exposure, 

 tolerance by spiny lobster should be low. Present 

 results support that contention. Exposing spiny 

 lobsters for even relatively short periods results 

 in metabolic acidosis, accumulation of the toxic 

 excretory product, ammonia, and impairment 

 of defensive and escape behavior after reimmer- 

 sion. 



48 



