General empirical models for predicting the release of nutrients by fish, with a comparison between detritivores and non-detritivores

摘要

1. We derived models of nutrient release [nitrogen (N) and phosphorus (P)] by fish based on studies that directly measured the release rates from 56 species across a broad range of fish mass, feeding histories and temperature. 2. We developed four separate models of nutrient release from multiple regression analysis: detritivore release rates of N and P, and non-detritivore release rates of N and P. 3. Fish mass explained most of the variance (78-92%) in release rates. 4. Our predicted rates of release of P by fish (g hap# dayp#) were similar to observed rates in the literature from other lakes. 5. The influence of a shift in diet (planktivory to detritivory) by a single species (gizzard shad, Dorosoma cepedianum, a facultative detritivore) on nutrient release rates was estimated. During periods of detritivory, gizzard shad accounted for on average 39% (<1-96%) of all nutrients released by the fish assemblage, and increased total fish assemblage release rates on average by 59% (<1-331%) compared to when gizzard shad were modelled as planktivores. 6. These models provide a rapid means for predicting the release of nutrients by fish assemblages and may facilitate more comprehensive comparisons of nutrient cycling by fish with other internal pathways.