[ 1^2 ] 



The Action of some Denitrifying Bacteria in Tropical 



and Temperate Seas, and the Bacterial Precipitation of 



Calcium Carbonate in the Sea. 



By 

 G. Harold Drew. 



TABLE OF CONTENTS. 



Introduction ....... 



Methods ....... 



The investigation of samples of water taken off Port Royal, Jamaica 



The investigation of samples of water taken round the Dry Tortugas and in the 



Straits of Florida ...... 



The investigation of sami)les from a point 70 miles west of Ushant 



Investigation of samples of water from the Marquesas Keys, and the experimental 



precipitation of calcium carbonate hy bacterial agency 

 Discussion of results ...... 



PAGE 

 142 



143 



146 



147 

 150 



151 

 154 



INTEODUCTIOK 



It is generally conceded that the plankton of tropical and snb-tropical 

 seas is far less in quantity than that found in colder waters. 



The zoo-plankton depends ultimately for its food on the phyto- 

 plankton ; hence any factor limiting the growth of the phyto-plankton, 

 which is capable of functioning in tropical and not in temperate or 

 Arctic waters, might offer an explanation of this phenomenon. It has 

 been shown by various investigators that this factor is not tempera- 

 ture, light, or salinity, and it has been suggested that the explanation 

 may lie in the relative deficiency in tropical seas of the nitrates or 

 nitrogenous compounds which are so essential for all plant life, 

 A matter of common observation in support of this view is the 

 remarkable scarcity of algal growth in the shallow waters of tropical 

 shores as compared with that in similar situations in temperate 

 regions, and the fact that in the tropics, wherever sewage or other 

 nitrogenous waste is poured into the sea, a free growth of algae is 

 found. 



At present no reliable and accurate chemical method of estimating 

 the combined nitrogen in sea-water exists, hence this theory cannot be 



