A Preliminary Study of the Distribution, Food and Reproductive Capacity of Some Fresh-Water Amphipods (Classic Reprint) - Softcover

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Excerpt from A Preliminary Study of the Distribution, Food and Reproductive Capacity of Some Fresh-Water Amphipods

During the progress of this study a few supposedly new facts came to light which had no apparent relation with the original problem. It is believed however that these are of sufficient importance to other lines of investigation to justify their inclusion here.

I desire to express my gratitude to Dr. J. G. Needham of Cornell University, under whose helpful guidance this investigation was carried on. His constant sympathy with the work and his generous and kindly criticism contributed largely to its successful completion.

II. Relative sizes of the forms studied.

The maximum sizes attained by adults of the four species in the water examined are contrasted on plates I and II, and likewise in table I). It will be noticed that G. limnaeus is larger than the other three; G. fasciatus ranking second; E. gracilis, third and Hyalella being the smallest.

Miss Weckel states (1907 p. 33) that adults of E. gracilis vary in length from 7 to 18 mm. At Ashland, Va., the writer found them as long as 13 mm, and at Irvington, Ind., in pools not inhabited by fish individuals as long as 15 mm were common. The writer is unable to account for the small size attained by those in waters at Ithaca, unless it be from the fact (Table XI, p. 23) that these amphipods grow much less rapidly than the other three forms and also that fishes and other enemies are abundant enough to devour them before the maximum size is reached.

III. Distribution about Ithaca, New York.

G. fasciatus so far as known is confined to Cayuga Lake and its immediate tributaries.

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