224 



CARNEGIE INSTITUTION OF WASHINGTON. 



experiments on the exclusion of light from shoal-water corals; and (7) to ascer- 

 tain the length of the free-sv^imming larval stage of several other species. 

 The need of more information on decrease in temperature with increasing 

 depth of water and on the range of variation in the salinity of the water along 

 the Florida reef tract was mentioned. Attempts were made to provide for 

 the indicated deficiencies in information. 



The Bureau of Fisheries, in cooperation with the Coast and Geodetic Survey, 

 has recently been conducting investigations between the east coast of the 

 United States and Bermuda, Bahamas, and Cuba, and has promised a copy 

 of the temperature records for use in my proposed account of the ecology of the 

 Florida and Bahama corals as soon as they are available; and Dr. Mayer has 

 consented to make a series of experiments on the upper and lower temperature 

 limits at which corals will take food. With these two supplements to data 

 already accumulated a satisfactory treatment of this aspect of the ecology of 

 the corals in this area should be possible, 



Mr. R. B. Dole, of the U. S. Geological Survey, kindly consented to titrate 

 and report on a series of daily water samples from some place along the 

 fine of the Florida reef. Through an arrangement between the Bureau of 

 Fisheries, the Lighthouse Bureau, and the Geological Survey, samples are being 

 collected daily at Fowey Rock, off Miami. Mr. Dole will also make quantita- 

 tive determinations of calcium in Florida sea-water. 



During the past season at Tortugas I conducted experiments on the amount 

 of dilution of sea-water the common reef species would endure, wath the fol- 

 lowing results : 



Effect of diluted sea-water on Florida reef corals. 



Species. 



Effect of searwater of salinity 18.28.^ 



6 hours. 



12 hours 



DichocoDnia stokesi 1 None. ' 



Eusmilia aspera '.j Pale, damaged. .1 Damaged, partly 



1 macerated. 

 Oculina diffifsa ! None do 



Orbicella annularis Pale Pale 



Orbicella cavernosa J None. . .do. 



Fa via fragum I ... do i ..... j ... do . 



Mseandra areolata 1. . .do •...'..! None. 



Ma^andra strigosa I. . .do 



Mseandra clivosa . . . .• .do 



Manicina gyrosa [. . .do 



Siderastrea radians .do 



Siderastrea eiderea 



Agaricia purpurea 



Acropora muricata (cervi- 



cornis). 

 Porites clavaria (Auct.) . . . . 



Pale . . 



None. 



..do.. 



..do.. 



..do.. 



Damaged Killed. 



None do. . 



.do. 



.do None . 



Porites furcata (Auct.) . . . .j. . .do. 

 Porites astreoides . .do. 



.do. 

 .do. 



24 hours. 



Killed. 



About half 

 macerated. 



Killed 



Pale 



Slightly pale . 



None 



Pale 



..do 



..do 



None 



Slightly pale. 



Killed 



..do 



Scarcely 

 damaged. 



..do 



None 



Effect of 

 eea-water 

 of salinity 



27.87, 

 48 hours. 



None. 



Do. 



Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 



Do. 



Do. 

 Do. 



'Salinity determination, by R. B. Dole. 



The experiments show that for most species of Florida reef corals 24 hours 

 in about 50 per cent sea-water is either beyond or near their limit of endurance; 

 while thev wnW endure a little less than 80 per cent for a long period, and 



