Date of Award


Document Type


Degree Name

Master of Science




Serum calcium levels were determined colorimetrically in Pomoxis nigromaculatus, the black crappie, subjected to rapid changes in temperature. Two experiments were conducted; in the first, fish were exposed to stress for 30 minutes before measuring serum calcium, and in the second, fish were exposed to stress for 5 minutes and returned to normal conditions for 25 minutes before measuring serum calcium. Condit ion (K-value) and sexual development were noted for the fish. Serum calcium increased in all stressed fish, regardless of sex, but higher serum calcium values were observed in stressed mature females than in stressed males or stressed immature females-no difference was observed for unstressed control fish. The initial temperature change appears to be the stimulus for the rapid rise in serum calcium as neither the direction of the temperature change nor the duration of the str-ess affected the results. It is suggested the source of the calcium observed in the present study is internal and probably mobilized from scales.

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