PROGRESS IN BIOLOGICAL INQUIRIES, 1930 619 



water so that in more saline waters a greater percentage of the 

 copper is precipitated out as insohible carbonates and hydroxides. 

 Less soluble copper is available for toxic action, therefore longer 

 exposures are necessary for death in the more saline water. Higher 

 hydrogen-ion concentration tends to release the carbonates and keep 

 the copper in solution so that less exposure is necessary for death. 

 As the temperature increases the toxic action increases to such a 

 degree as to lead to the conclusion that chemical rather than physio- 

 logical factors have resulted in death to the organism. 



Consideration was given to the effect of copper sulphate on other 

 marine forms, particularly the oyster. Two parts per million of 

 copper sulphate cause the valves to close and remain so for 30 or 

 more minutes, while strong concentrations such as 1,000 parts per 

 million cause the oyster to remain closed for several hours. Young 

 oysters have a greater tendency to open in the presence of copper sul- 

 phate than the older oysters and consequently are more likely to be 

 killed. However, the danger from the poison is unimportant in 

 comparison with the total extermination of a given crop which is 

 probable when starfish are present. 



PEARL OYSTERS IN HAWAIIAN ISLANDS 



In 1928 the Territorial government of Hawaii requested that an 

 investigation be made of the pearl-oyster beds discovered in 1927 in 

 Pearl and Hermes Reef, a small lagoon located about 1,100 miles in 

 a west-northwestern direction from Honolulu. Because of a lack 

 of funds the project could not materialize until the Navy Depart- 

 ment consented to loan a vessel for the purpose, and the Territorial 

 government appropriated a small sum to cover part of the expense. 



On July 15, 1930, Dr. Paul S. Galtsoff, in charge of the expedi- 

 tion, sailed aboard the U. S. S. Whippoorwill from Pearl Harbor, 

 Hawaii, and arrived at Pearl and Hermes Reef on July 19, 1930. 

 The ship was anchored outside the lagoon about 13 miles from the 

 southeast island where headquarters were established. Pearl and 

 Herrnes Lagoon is an atoll about 18 miles long and 12 miles wide, 

 and is partially surrounded by a narrow strip of coral reefs which 

 embrace it on the east, south, and southwest, leaving the northern 

 and northwestern sides unprotected. A series of islands, most of 

 them merely sand bars, extends from the northeastern corner along 

 the eastern and southern sides of the lagoon. The lagoon itself 

 comprises a maze of small reefs and channels, with the depth of 

 water varying from a few inches to 104 feet, and the reefs growing 

 inside the lagoon are made up by a fingerlike coral " porites." The 

 flat tops of the reefs are covered with very soft sand and old broken 

 corals, while live corals grow on the very steep slopes of the reefs. 

 Pearl oysters are found almost exclusively among the corals on the 

 slopes of the reefs at a depth of from 10"to 47 feet, but below that 

 the bottom is composed of sticky coral mud unsuitable for pearl 

 oysters. 



Inasmuch as no detailed hydrographic survey of Pearl and 

 Hermes Reef has ever been made, considerable time was spent by 

 the expedition in mapping the area and in determining the exact 

 position of the islands. This part of the work has been carried out 



