Feeding rate inhibition in crowded Daphnia pulex |
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Authors: | Judith C Helgen |
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Institution: | (1) Department of Biology, Saint Olaf College, 55057 Northfield, MN, USA |
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Abstract: | Feeding rates of Daphnia pulex fed a range of levels of the alga Chlamydomonas reinhardi of 15 °C are strongly density-dependent. At lower densities, Daphnia (30 1–1) fed at higher rates than crowded (270 1–1) Daphnia which manifest a relatively depressed saturation feeding response. At 30 individuals/liter, Daphnia consumed 8.5 – 15.7 × 104 cells d–1h–1 (on a volume basis, 12.1 – 22.2 × 106 m3), at 270 L–1 3.7 – 3.9 × 104 (5.2 – 5.5 = 106 m3 cells d–1h–1 when feeding on algae at 80 000 cells ml–1 (11.3 × 106 m3 ml–1). The feeding rate data best fit an Ivlev feeding function. An autoallelopath might be causing the repression. Water preconditioned with crowded Daphnia completely repressed feeding in uncrowded Daphnia after six hours. |
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Keywords: | cladocerans Daphnia density-dependent feeding crowding inhibition |
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