PATTEN: SHORT-TERM THERMAL RESISTANCE OF CRAB ZOEAE 



TABLE 2. — Percentage survival of first stage zoeae 48 h after testing of 10 species of crabs subjected to a range of temperatures at four 

 durations (percentages are from combined data of two or more tests). Increases to and decreases from a test temperature were rapid for 

 the 20-min test (heat exchanger test) and gradual for the longer durations of exposure (thermal plume test). 



'Italic denotes the TL50. 



holding boxes containing zoeae were replaced in 

 aquaria with running seawater. 



The numbers of replicate tests made at a 

 temperature for a test varied because of numbers 

 of ovigerous crabs available and numbers of zoeae 

 resulting from a hatching. The offspring from at 

 least two parent crabs of a species were used 

 (Table 2). Some species were tested at intervals 

 over a 2- to 3-mo period to indicate seasonal 

 acclimation effects. One test for C. magister was 

 made in 1972; all other species were tested in 

 1971. Percentage survival of a species of crab for a 

 given duration and temperature is the combined 

 survival of two to five tests made for a species 

 (Table 2). 



Observations were made on the levels of 



activity, point of torpor, and the TL 50 (maximum 

 temperature-time combination survived by 507c 

 or more of subjects 48 h after testing) to evaluate 

 the effects of experimental conditions. A 48-h 

 posttest observation duration was deemed appro- 

 priate for these tests as the zoeae were not fed and 

 could have been affected by starvation although 

 they readily survived to 72 h. 



TEMPERATURE EFFECTS 



Temperature-time combinations for a type of 

 test that was critical to the survival of the zoeae of 

 a species were indicated by survival of the controls 

 and by experimental conditions affecting activity 

 and survival of the test subjects. 



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