Convergent responses of fish belonging to different feeding guilds to sewage pollution

Abstract

This study aimed to evaluate if the presence of pollutants promotes changes in feeding habits of fish species from different trophic guilds: the detritivorous species, Hypostomus francisci, and the piscivorous, Hoplias intermedius. Both species were sampled at 12 sites (with different degrees of pollution) in the Rio das Velhas basin, which is heavily polluted by domestic and industrial sewage from the Metropolitan Region of Belo Horizonte (MRBH). Stable isotope analyses of carbon (δ13C) and nitrogen (δ15N) of fish tissue and the main food resources were performed. Fishes from both trophic guilds altered their diets in degraded environments, but the detritivorous species showed greater trophic plasticity. The isotopic niche of both trophic guilds was broadest in unpolluted sites and more δ15N enriched in polluted regions. The detritivorous species presented high niche-breadth in unpolluted sites, probably due to the greater variety of resources consumed. In addition, the δ15N of the detritivorous was more enriched than the piscivorous species in polluted sites. In conclusion, fishes from both trophic guilds presented similar isotopic responses to environmental pollution. However, the detritivorous species was more sensitive to these alterations and therefore, is likely a better indicator of environmental condition than the piscivorous.

SIA‐BRA: A database of animal stable carbon and nitrogen isotope ratios of Brazil

“…Complementary, stable N isotope ratios are widely used in diet‐tracing studies, providing information on trophic levels within food chains (Hobson & Clark, 1992; Layman et al., 2012; McCann, 2007; Newsome et al., 2010; Vogel, 1978). Also, stable N isotope ratios indicate changes in environmental factors that influence the whole food web, such as pollution by nitrate and ammonium, allowing the evaluation of animal ecology (Prado et al., 2020).…”

Ecofisiologia e relações tróficas de elasmobrânquios: biomarcadores como ferramentas para conservação

“…The enriched δ 15 N values found in urban sharks could be associated with the contribution of anthropogenic nutrient enrichment caused by both domestic and industrial wastewater (e.g., Mancinelli and Vizzini, 2014;Prado et al, 2020). As a consequence, it is plausible that the nutrient enrichment is being transferred up the food web, from autotrophic organisms to consumers (e.g., Prado et al, 2020). Corroborating the possible influence of domestic and industrial wastewater on nutrients, higher percentages of SFA (C16:0 and C18:0) were found in sharks sampled in high urbanized area.…”

“…We therefore predicted that blacktip sharks exposed to greater market gravity would exhibit an enriched δ 15 N and lower overall proportion of n3 PUFAs and of both diatoms and dinoflagellates fatty acid markers due to the increased contribution of anthropogenic nutrient enrichment (e.g. nitrogen and phosphorus) Mancinelli and Vizzini, 2014;Prado et al, 2020). We also expected to find that blacktip sharks sampled in high urbanized areas would exhibit higher proportions of saturated and bacterial fatty acids, which are markers for domestic sewage effluent (e.g.…”