The Productivity of Fish Food in Oneida Lake 41 



plant seeds, crustacean skeletons, fragments of shells, caddis- 

 fly cases, the hard coverings of insects, and a large amount of 

 fine, almost dust-fine, material. This bottom debris corre- 

 sponds to Petersen's " dust-fine detritus," first noted on the 

 sea bottom in Danish waters (Petersen, '11, p. 6; Baker, '16, 

 pp. 120-152). In some places this material is of a flocculent 

 character representing probably the decomposing soft parts of 

 some of the animals of the lake. All of this bottom material 

 is probably of great value as a source of food supply, not only 

 for the bottom mud eating fish, but for many animals which 

 are the food of fish. This matter is discussed in a later chap- 

 ter. In Lower South Bay and Short Point Bay the bottom is 

 almost completely covered with filamentous, as well as unicel- 

 lular, algse which forms a dense blanket in many places. This 

 will be more fully noted in the chapter on vegetation and in 

 the discussions of the bottom inhabiting animals. 



The clearness of the water was noted at different dredging 

 stations. The instrument used for measuring the density of 

 clams and also of the vegetation was a square frame of bright 

 tin. This was clearly seen at a depth of seven feet in Lower 

 South Bay. Owing to the thickness of the vegetation in most 

 places it was impossible to see the bottom or even the instru- 

 ment when lowered in water deeper than six feet. The white 

 disc generally used in such measurements was not available 

 for study at this time.* Temperatures were planned for but 

 the deep sea thermometers were found to be broken when we 

 reached the lake, and there was not time to procure new ones. 



The variety of material forming the bottom of the bay and 

 the adjacent part of the lake makes possible an abundant 

 development of plant life, providing almost every kind of 

 environment, from a quiet, pond-like habitat with mud bottom, 



* While conducting field work in September, 1917, opportunity was 

 given for observing the transparency of the water of the west end of 

 Oneida Lake. In the channel opposite Nicholson Bay a white tile six 

 inches square disappeared at a depth of 9 feet 8 inches. In the middle 

 of the lake between Walnut Point and Shaw Point opposite Frenchman 

 Island, the white tile disappeared at a depth of 10 feet. Both experi- 

 ments were made in the middle of the afternoon when the sun was 

 shining brightly. The water was clouded with plankton. 



