Effects of Flow Regime and Cyprinid Predation on a Headwater Stream

作者：Isaac J. Schlosser, Kenneth K. Ebel · 发表于：Ecological Monographs · 年份：1989 · DOI：10.2307/2937291 · 被引用次数：124 · 研究领域：Fish Ecology and Management Studies、Freshwater macroinvertebrate diversity and ecology、Aquatic Invertebrate Ecology and Behavior

We used descriptive and experimental approaches on Gould Creek, a first—order tributary of the Mississippi River near Lake Itasca, Minnesota to assess the influence of (1) flow regime on the colonization dynamics and abundance of invertebrates and cyprinids, and (2) cyprinid predation on invertebrates and fishes. Stream flow varied annually during the 3—yr (1984—1986) period. One dry year (1984), with few periods of elevated flow, was followed by two wet years (1985—1986), with prolonged elevated (nonscouring) discharge. The density of benthic and drifting invertebrates increased dramatically with elevated flow. Benthic riffle invertebrates in particular increased, from a maximum of 9000 individuals/m2 in 1984 to 91 000 individuals/m2 in 1985 and 51 000 individuals/m2 in 1986. Larval Hydropsychidae and Simuliidae were the primary groups increasing in abundance during elevated flow. To assess directly the influence of flow regime on benthic insect densities, flow was manipulated in six subsections of a riffle and colonization of natural rock substrates monitored. Total insect abundance was higher under elevated (nonscouring) vs. low flow within 6—8 d; after 24 d insect abundance was three times as high under elevated flow. Insect families responded differently to elevated flow, with the largest increase resulting from a pulse of colonization by larval Hydropsychidae in 6—8 d. Cyprinid density in Gould Creek also increased with elevated flow from 0.1—0.3 cyprinids/m2 in 1984 to...