Effects of riparian forest and agricultural land use on stream fish diet and trophic position.

Autor: Effert‐Fanta, Eden L., Chow, Shaun L., Wahl, David H.
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Zdroj: Ecology of Freshwater Fish; Apr2023, Vol. 32 Issue 2, p291-304, 14p
Abstrakt: To examine agricultural impacts on stream food webs, we used gut content analysis (GCA) and stable isotope analysis (SIA) to investigate the influence of riparian forest buffers on the diet and trophic position of five stream fish species in a row‐crop agricultural watershed. Six study streams were divided into two categories (forested and agricultural) based on percentages of riparian forest and agriculture in the watershed. Results suggest alterations in riparian vegetation (forested vs. cropland) had strong impacts on instream characteristics and basal resources that affected prey abundances and fish trophic structure. Although differences varied among species, GCA revealed fish in forested streams had a more diverse diet that included greater numbers of terrestrial invertebrates and aquatic invertebrate predators, whereas fish in agricultural streams consumed more aquatic herbivores and decapods. Diet shifts of the omnivorous creek chub followed differences in basal resource biomass, with greater proportions of algae consumed in agricultural sites contrasted by greater detritus consumed in forested sites. SIA Bayesian mixing‐model results supported diet differences shown by GCA, including higher contributions of terrestrial invertebrates to fish diets in forested streams. However, the isotopic overlap of aquatic invertebrates in agricultural streams limited diet contribution comparisons. SIA indicated fish trophic position was higher in forested than agricultural streams for all species, but GCA was required to identify that greater consumption of predatory prey likely caused this widespread change in fish trophic structure. Results highlight the benefits of integrating SIA and GCA and the importance of riparian forests to stream fishes in agricultural watersheds. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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