ISSN:
1365-2427
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
〈list style="custom"〉1Crayfish in headwater streams are subjected to predation from two sources: (a) fish; and (b) terrestrial predators including wading birds and mammals. Field observations of the mortality of tethered crayfish of two size classes were used to examined how predation risks imposed by the two types of predators varied with water depth and crayfish size. We also examined the depth distribution of large and small crayfish in stream pools with and without predatory fish.2Predatory fish, mostly green sunfish, Lepomis cyctuellus, and creek chub, Semotilus atromaculatus, rapidly consumed tethered small crayfish (body length = 25–30 mm) in deep areas (0.4–0.7 m), but not in shallow areas (0.05–0.15 m) of stream pools. Tethered large crayfish (body length = 50–75 mm) suffered little mortality from fish at either depth. Terrestrial predators such as racoons, Procyou lotor, and herons, Butorides and Ardea, caused little crayfish mortality in deep areas, but rapidly consumed both small and large crayfish exposed in shallow areas.3A comparison of habitat use by crayfish in pools with and without fish suggests that small, but not large, crayfish shift their distributions to shallow water in the presence of fish. In pools without fish, the distribution of small crayfish was independent of depth, whereas large crayfish occupied deep water.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2427.2000.00524.x
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