56 U, S. BUUEAU OF FISH KK IKS 



ECOLOGICAL AND OCEANOGRAPHIC STUDIES 

 CONTUOL OF ^lOSQlITOE.S IJY ^MIOAXS OF FlSlf 



Invest i<;ations relative to the use of fish for mosquito control were 

 continiiecl at Auji'iista. Ga., by Samuel F. Hildebi-and, assisted by 

 Irvino; L. Towers, until October 5. The season was unfavorable 

 because of periods of heavy rainfall, causin*^ flood conditions to 

 prevail. Some interesting data, nevertheless, were obtained. The 

 results of these and similar investigations of three previous summers 

 have been studied and a rather comprehensive report is being i)re- 

 pared for publication. 



Mr. Hildebrand also prepared and read before the annual ccjnfer- 

 ence of field workers in malaria, held in Xew Orleans from Novem- 

 ber 28 to 25, a paper dealing with the propagation of the top min- 

 now, Gambusia, for mosquito control on large tracts of land which 

 are to be flooded as in damming rivers for hydroelectric purposes. 

 This paper w^ill be published by the United States Public Health 

 Service. 



OCEAN(JGRAFIIY 



A study of the hydrogen-ion concentration of sea water in Long 

 Island Sound was made by Dr. P. S. Galtsoff. It is known that the 

 colorimetric determination of the pH value in sea water can not be 

 accurate because of the so-called salt error. The latter varies with 

 the concentration of salts and with the indicator used. So far the 

 salt error has been determined for phenolphtalein and alpha-naph- 

 tolphtalein. It has been noticed that previous colorimetric deter- 

 minations made in Long Island Sound give too high values. In 

 order to check up these observations a series of experiments was 

 made at the Woods Hole laboratory to determine the salt error of 

 ciesol red. A set of phosphate mixtures with cresol red was made 

 up, poured into non sol glass tubes, and sealed. The pH values of 

 the bufi'er mixtures were checked up by the electric method. The 

 determination of the salt error was made in a buffered artificial sea 

 Avater at pH values ranging from 6.9 to 8.G and at the concentrations 

 of salts from 10 to H2 per thousand. 



In October a special cruise was made on the Fish Hawk in Long 

 Island Sound. The hydrogen-ion concentration was determined by 

 comparison with buffer solutions wnth cresol red as indicator and by 

 using the Palitsch borax-boric acid mixtures with alpha-naph- 

 tolphtalein. The latter were checked up by the electric method 

 before and after the cruise. Both methods gave identical results, 

 indicating a considerable increase in hydrogen-ion concentration in 

 the Housatonic Eiver and in Bridgeport and New Haven Harbors. 



The report on the ])lankton of the Gulf of Maine, a ])art of a com- 

 IH-ehensive study of this body of water which is being conducted by 

 Dr. H. B. Biffelow. of Harvard University, has been completed and 

 is in press. The report on the fishes of the Gulf of Maine .Avas com- 

 pleted some time ago and the re])ort on the physical oceanography 

 is nearly finished. 



During the latter part of the summer a series of drift bottles was 

 set out on three lines across the Vineyard Sound-Nantucket Sound 



