Counting marmots…
We studied the feeding and positioning periodicity on natural substrates of the overwintering and fast-growing summer generations of a grazing mayfly, Baetis bicaudatus, in a third-order trout stream and a fishless, first-order tributary in western Colorado. At 4-h intervals over 24-h, we recorded the number of Baetis on stone tops in flow-through enclosures in situ and in streamside circular flow-through chambers. We determined the feeding periodicity of Baetis using abundance of plant pigments as an index of gut fullness. Baetis were nocturnal in the trout stream; more animals were found on stone tops and guts were fuller at night, suggesting that individuals came to stone tops to feed during darkness. However, Baetis from the fishless stream were either aperiodic or weakly nocturnal. We tested the hypothesis that nocturnal feeding by Baetis is a response to the presence of visually feeding trout by conducting transplant experiments in the circular streams. After 24 h, Baetis transferred from the trout stream to fishless water remained strongly nocturnal, while Baetis transferred from the fishless stream to trout water became significantly more nocturnal, suggesting that the risk of fish predation outweighs the benefits of relaxing nocturnal periodicity to feed continuously.
Knowledge graph centered on Diel feeding and positioning periodicity of a graz with 13 nodes and 48 connections. Top connected: Sublethal consequences of stream-dwelling predator, Life histories and the strengths of species intera, Determinants of diet of brook trout (<i>Salvelinus, B. L. Peckarsky, The influence of predatory fish on mayfly drift: e.
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