MARINE DIATOMS OF THE PHILIPPINE ISLANDS 3 



The richest sample among the many hundreds examined was fortu- 

 nately known to have come from the neighborhood of Jolo Jolo, Sulu 

 Island. A sort of whirlpool circling of waters coming in from differ- 

 ent directions takes place at this point, and it is doubtless in part this 

 huge movement serving to gather together and concentrate the solid 

 material from the converging currents that explains the unusual rich- 

 ness, both in species and numbers of individuals. It was also at this 

 point that many species hitherto reported from the East India islands 

 were found. 



The Philippine Islands are very advantageously located with refer- 

 ence to the great ocean currents, the chief carriers of diatoms from 

 one part of the world to another. The great northern and the south- 

 ern equatorial currents converge on the eastern and southern shores 

 of the Philippines and spread their waters about the island group. 

 Other currents skirt the islands of the East Indies, New Guinea, 

 Celebes, and Borneo on their southern sides, Java on its north- 

 ern side, Sumatra and parts of the Malay Peninsula on their east- 

 ern sides; they then stream northward and northeastward to come 

 to rest along the western coasts of the Philippines. The Sulu Sea 

 is especially a focal center for many such currents, and represents 

 one of the most complexly connected oceanographic localities known. 

 On the other hand, the cold current from Bering Sea and the Arctic 

 which flows southwest along the coasts of Kamchatka, Manchuria, 

 and the eastern side of Korea is here pushed back by a warm current 

 moving up between Korea and Japan and fails to reach the Philip- 

 pines. It is quite evident that this great convergence of powerful 

 ocean currents is largely responsible for the rich flora and fauna of 

 the Philippine waters. 



Another thing helping to bring about this richness of marine life at 

 the Philippines is the great range of depth of its waters. The east- 

 ern shores lie adjacent to some of the most profound depths in the 

 Pacific Ocean, one point just east of the northern end of Mindanao 

 being the deepest sea abyss yet discovered, 5,350 fathoms, or 32,100 

 feet, or over 6 miles. On the other hand, the western side is shallow 

 and many of the channels between the islands .are extremely so. 

 Thus Manila Bay has an average depth of only 3 to 4 fathoms. This 

 wide diversity of depth, with its attendant range in temperature, 

 salinity, and light, must be responsible to no small degree for the 

 diversity of life, including diatom life at the Philippines. 



There is in preparation a report on the diatoms of the Hawaiian 

 Islands, studies for which, though incomplete, reveal the fact that 

 outside of strictly cosmopolitan species, hardly any of the Hawaiian 

 diatoms are represented in the Philippine flora. This probably is 

 accounted for not so much by the distance between them as by the 

 fact that the powerful northern equatorial current flowing westward 



