Monday, August 6, 2007

PS 16-165: Evaluation of conceptual models of fish reproduction in floodplain rivers: A life history-based approach

Steven C. Zeug and Kirk O. Winemiller. Texas A&M University

Reproductive activity of seven species representing three divergent life history strategies was monitored monthly for two years in channel and floodplain habitats of the Brazos River, Texas, to evaluate predictions of conceptual models of fish reproduction in floodplain rivers (flood pulse concept and low flow recruitment hypothesis).  An information-theoretic approach was used to select best approximating models for each species and model averaged estimates of regression coefficients were calculated.  Model selection indicted that support for conceptual models was strongly associated with species life history strategies.  Species with delayed maturation, large adult size, and high fecundity, supported predictions of the flood pulse concept and were abundant in habitats where flood probability was high.  Nest building species with parental care supported the low flow recruitment hypothesis and were abundant in off-channel habitats where floods were less common.  Small species with extended breeding seasons tended to be abundant throughout the year within their preferred habitats.  The flood-pulse model is consistent with reproductive patterns of periodic species and opportunistic species in off-channel habitats, and the low-flow recruitment model describes reproductive patterns of equilibrium species and opportunistic species common in channel habitats.  Instream flow management would benefit from consideration of flow and habitat requirements needed to support the diverse life history strategies displayed by fishes in river-floodplain systems.

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