Abstract
ABSTRACT Pseudoxiphophorus bimaculatus is an invasive species widely spread throughout freshwater ecosystems in central Mexico, for that reason we described its trophic strategy into a gradient of environmental quality. We sampled individuals of P. bimaculatus at eight sites located in the Lerma-Chapala and Pánuco River Basins during dry season. These basins have been impacted by industrialization and urbanization processes, but are considered as water reserves in México. To evaluate the environmental quality of the river, we applied the Visual-based Habitat Assessment, the Index of Biological Integrity and the Family-level Biotic Index. We assessed the trophic guild, the diet width, the omnivory level, and the diet selectivity. We also explored the relation of trophic strategies with the habitat condition. We captured a total of 202 individuals of P. bimaculatus from 10 to 67 mm of SL, finding a total of 24 food items. The diet of P. bimaculatus was composed of terrestrial, aquatic insects and bony fish. Pseudoxiphophorus bimaculatus in some sites can feed on different trophic levels, in other it is a specialist and secondary consumer. We found that P. bimaculatus changes its diet according the alterations in the habitat structure, water quality, and biotic integrity. Moreover, this invasive species can endure changes in the trophic web and food availability.
Highlights
The introduction of exotic fish species represents a threat for the persistence of native fish in global scale (Bruton, 1995; Vitule et al, 2019), and the benefits that they provide fail to compensate the damage caused on ecosystems biodiversity (Moyle, 1997; Vitule et al, 2019)
The Paso de Vaqueros (PVA) site showed the lowest values of temperature (13oC) and the highest value was in XOT and Charco del Ingenio (CHI) sites (28 oC), the average value was 22.6 ± 5.31 °C
We classified the study sites XOT, GAL and Presa del Carmen (PRC) as the most modified according to VHBA, Integrity Based on Aquatic Macroinvertebrates Assemblages (IIBAMA) and Family-level Biotic Index (FBI) scores
Summary
The introduction of exotic fish species represents a threat for the persistence of native fish in global scale (Bruton, 1995; Vitule et al, 2019), and the benefits that they provide fail to compensate the damage caused on ecosystems biodiversity (Moyle, 1997; Vitule et al, 2019). The introduction and the population establishment of exotic fish species represent a biological pollution and it can have similar effect to the physical and chemical alteration on freshwater ecosystems (Lachner et al, 1970; Capps, Flecker, 2013) This phenomenon is widely documented with exotic and invasive species of commercial importance, such as the Common carp (Cyprinus carpio Linnaeus, 1758), the Nile tilapia (Oreochromis niloticus (Linnaeus, 1758)), the Largemouth black bass (Micropterus salmoides (Lacepède, 1802)) or the Amazon sailfin catfish (Pterygoplichthys sp.) (Contreras-MacBeath et al, 2014). Their invasion negative effect is commonly related to the exclusion of native fish population by predation, aggressiveness and territorial behavior, or indirect effects such as sediment re-suspension and habitat destruction (Zambrano, Hinojosa, 1999; Canonico et al, 2005; Cortés, 2016)
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