Changes in trophic characteristics of two fish species of Astyanax (Teleostei: Characidae) in response to aquatic pollution

Abstract

The trophic plasticity of most fish species of Astyanax Baird & Girard, 1854 in response to environmental changes and resource availability is high. This work evaluates the differences in the trophic characteristics of two congeneric species, Astyanaxtaeniatus (Jenyns, 1842) and Astyanaxlacustris (Lütken, 1875), in Rio das Velhas Basin, which is highly impacted by the discharge of sewage from the Metropolitan Region of Belo Horizonte (MRBH). Eight sites were sampled and grouped into three regions: upper course (two sites upstream of the MRBH); middle course (three sites located in the middle portion of the Rio das Velhas, region with greater influence of the MRBH), and lower course (three sites downstream of the MRBH). Samples of fish and food resources were collected from all sites to obtain the isotopic composition of nitrogen (δ15N) and carbon (δ13C), and the stomach contents of the two species was analized. The most common items in the stomach of A.lacustris and A.taeniatus, respectively, were from plants and insects, followed by algae/periphyton (especially at the low course of Rio das Velhas). In contrast, stable isotope analyses indicated that algae (in polluted sites) and periphyton (in least-disturbed sites) were best assimilated both species. Both analyses indicated that the trophic niches of the two species overlap more in more polluted sites relative to less polluted sites. Astyanaxtaeniatus and A.lacustris only presented different isotopic composition of carbon and nitrogen in the upper course of the Rio das Velhas, probably in response to the greater diversity of food items consumed by each species. In the other regions, the species presented similar isotopic signatures, with δ15N and δ13C notably enriched in the most polluted regions (middle and low course). Our results suggest that pollution acts by increasing trophic niche overlap of these species, altering the type of resources most assimilated, and promoting a greater enrichment of δ15N in fish and resources.

Nutrients Affecting the Characteristics of Food-Web Structure in Aquatic Ecosystem of Pearl River

“…In river ecosystems, periphyton is the main carbon source for consumers, [26], there were studies showing that the δ 13 C values of periphyton are relatively low, ranging from −37.34‰ to −19.19‰ [27][28][29], and have noted that these values can be affected by other primary producers in the water along the rock belt [30][31][32]. The δ 13 C value of periphyton is significantly related to their growth environment.…”

Use of stable isotopes for assessing urbanization impacts on freshwater fishes

“…For instance, changes in riparian habitat associated with urbanization can reduce the proportion of high quality terrestrial prey consumed by freshwater fishes and impact prey production sources, with potential implications for growth, survival, and overall ecosystem function (Francis and Schindler, 2009;Burbank et al, 2022). Additionally, channelization and addition of contaminants can impact the prey species available to fishes resulting in altered diets (Northington and Hershey, 2006;de Carvalho et al, 2019). Stable isotope analyses provide insights into the trophic level, food chain length, the type of habitat prey are sourced from, the relative contribution of prey to the diet of fishes (i.e., diet reconstruction), and the resulting dietary niche breadth of freshwater fishes, all of which help understand shifts in the feeding ecology associated with urbanization.…”

“…Shifts in the trophic position of urban-affected freshwater fishes have been estimated and quantified in several freshwater ecosystems such as the urbanized streams of Piedmont, United States (Helms et al, 2018), the Hawaiian islands (Lisi et al, 2018), the Kansas River (Eitzmann and Paukert, 2010) and constructed wetlands in Melbourne, Australia (Mackintosh et al, 2017). Additionally, there have been several studies that have examined trophic shifts experienced by freshwater fishes and invertebrates in response to wastewater impacts (Di Lascio et al, 2013;Loomer et al, 2014;de Carvalho et al, 2019). Such studies typically quantify the trophic shifts associated with the stressor.…”

“…Bayesian stable isotope mixing model packages have been employed extensively by freshwater fish ecologists to reconstruct the diet of numerous fishes including Lake Trout (Salvelinus namaycush) in Lake Ontario (Colborne et al, 2016), Lake Sturgeon (Acipenser fulvescens) in Rainy River, Ontario Canada (Smith et al, 2016), and Eastern Sand Darter (Ammocrypta pellucida) in the Thames River, Ontario, Canada (Burbank et al, 2019), and would be equally useful to reconstruct diet of fishes occupying urbanized environments. In this respect, there have been few applications MixSIAR models to reconstruct the diet of urban affected freshwater fishes (but see Alonso et al, 2019;de Carvalho et al, 2019;Woodland et al, 2022). de Carvalho et al (2019) found exotic species of guppies were consuming and assimilating notable amounts of sewage in wastewater impacted systems.…”

Ajustes fisiológicos de Astyanax altiparanae (Teleostei: Characiformes: Characidae) expostos a fármacos de preocupação emergente

“…Esta espécie foi selecionada devido à sua abundância e ampla distribuição nos locais de estudo. É uma espécie que habita locais com diferentes níveis tróficos (Alonso et al, 2019), apresenta importância econômica, sendo utilizada na pesca esportiva para consumo humano , e tem importância ecológica por ser parte da cadeia alimentar (Marceniuk e Hilsdorf, 2010).…”