TOXIC EFFECTS DUE TO HIGH TEMPERATURE. 



BY ALFRED GOLDSBOBOTJGH MAYER. 



The experiments cited below appear to indicate that death from high 

 temperature may be due to the accumulation of acid in the tissues. 



Reef corals from Tortugas, Florida, were kept at a constant tem- 

 perature in warm ocean-water for 60 minutes in a thermostat, in the 

 dark the temperature remaining constant within about 0.1 C. through- 

 out the hour. In this manner the temperature was found that is just 

 sufficient to kill the coral. The results are as follows: 



c. c. 



Acropora muricata 34 . 7 Maeandra areolata 36 . 8 



Orbicella annularis 35.6 Porites furcata 36.85 



Porites astrseoides 35 . 8 Favia fragum 37 . 05 



Porites clavaria 36 . 4 Siderastrea radians 38 . 2 



It is apparent that those corals which live in cool, relatively agitated 

 water, free from silt, are those that can not withstand high tem- 

 peratures, whereas those which live in the hot, silt-laden shallows near 

 shore are, generally speaking, forms which can resist high temperature. 

 Favia fragum is, however, an exception, for it lives not only in the shal- 

 lows close to shore, but also in the pure water of the seaward reefs. 



If sea-water be charged to saturation with carbon-dioxide gas from a 

 soda-water siphon, the corals show nearly the same relative resistance 

 to the toxic effect of carbonic acid as they do to high temperature. 

 Thus these corals from least to most resistant are Acropora muricata, 

 Orbicella annularis, Porites astrceoides, P. clavaria, P. furcata, Mceandra 

 areolata, Favia fragum, Siderastrea radians. A. muricata die in less 

 than an hour and S. radians survive for more than 4 hours. In my 

 experiments, however, M. areolata appeared to be slightly more resist- 

 ant to CO 2 than does Porites furcata, whereas the reverse is the case 

 with high temperature ; but the two forms are so nearly alike in their 

 reaction that the discrepancy may be due to errors in experimentation 

 or to individual differences of constitution in the specimens, for there is 

 considerable range in this respect. The toxic effect of CO 2 may, how- 

 ever, be independent of asphyxiation, and this supposition is strength- 

 ened by the fact that with the exception of Acropora muricata, all 

 of these corals can survive in the dark for more than 1 1 hours in sea- 

 water deprived of oxygen under an air-pump; and even Acropora 

 muricata can withstand 6 hours of this treatment. 



It will be recalled that Henze (1910) found that sea-anemones con- 

 sume less oxygen as the oxygen in the surrounding sea- water is reduced ; 

 and in 1917 McClendon discovered that the medusa Cassiopea can live 



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