Ecología trófica del pez exótico Guatapote del Lerma <i>Poeciliopsis infans</i> (Cyprinodontiformes: Poeciliidae) en el Lago de Pátzcuaro, Región Central de México

Abstract

Ecología trófica del pez exótico Guatapote del Lerma Poeciliopsis infans (Cyprinodontiformes: Poeciliidae) en el Lago de Pátzcuaro, Región Central de México. Exotic fish species has caused several impacts on aquatic biodiversity. The Lago de Pátzcuaro has some well-studied exotic species, except the Lerma livebearer Poeciliopsis infans. This fish species was introduced into the Lago de Pátzcuaro before 1997 and the aspects of its biology are still unknown. In this study we assessed aspects of the trophic ecology of this exotic fish, P. infans, using gut content and stable isotope analysis to understand its capacity to tolerate anthropogenic environmental degradation in the Lago de Pátzcuaro. We also determined its trophic guild position (TP) using the TrophLab Program and stable isotope. Niche breadth was calculated by standardized Levins' Index (Bi). Fish was captured with a seine during wet and dry seasons at six environmentally different sites and gut contents were obtained. We analyzed a total of 239 gut contents of P. infans. The contribution of each food item in the diet was quantified using frequency of occurrence and area percentage. The importance of each prey item was determined according to the index of relative importance (IRI), and the omnivory index (OI) was used to assess the feeding behavior. Fish were categorized by size and the diet was compared between fish sizes and sites. Dorsal muscle tissue and water hyacinth tissue was obtained for nitrogen isotope signature (δ 15 N) analysis. Additionally, we measured water and habitat quality to evaluate environmental conditions at each site. We concluded that P. infans is an omnivore (OI=0.28) that consumes mainly detritus (44%), epiphytic diatoms (37%), and secondary on terrestrial insects (6%) and zooplankton (10%). The fish can behave as a specialist (Bi=0.39) or generalist (Bi=0.68) and as a primary consumer (TROPH=2.2; TP=2.3) with a feeding strategy that was the same at different sizes, seasons and sites. None of the evaluated sites showed good environmental quality. We argue that P. infans can tolerate changes in water quality and feeding items availability, because it can exploit resources in multiple trophic webs. However, this species could be dependent on habitat complexity, especially in the aquatic vegetation cover.

Trophic interrelations between introduced common carp, Cyprinus carpio (Actinopterygii: Cypriniformes: Cyprinidae), and fish community in a eutrophic shallow lake

“…The same occurs for Poeciliopsis infans (see Ramírez-Herrejón et al 2013). Common carp fed mainly on the bottom (except for juvenile individuals < 100 mm SL), whereas G. atripinnis and Oreochromis spp.…”

“…The average depth is 4.9 m, and watershed covers of 9340 km 2 (Bravo-Espinosa et al 2006). During September and November 2009 (wet season) and February and June 2010 (dry season), we sampled six sites the water properties (total dissolved solids, transparency, and turbidity) and habitat characteristics (depth, floating vegetation cover, and bottom type) as described by Ramírez-Herrejón et al (2013) (Fig. 1).…”

“…We only found remains of insects and it was not possible the identification of insects at a lower taxonomical level. A modified version of the index of relative importance (IRI) of Pinkas et al (1971) proposed by Yáñez-Arancibia et al (1976) was used: IRI = FA · 100 -1 where: F is the frequency of occurrence, and A is the area, following Ramírez-Herrejón et al (2013). This method is used when the gut content is constituted by small feeding components (diatoms, copepods, ostracods, rotifers, cladocerans) or when its quantification is not possible (detritus, plant debris) (Vega Cendejas 1990, Canto-Maza andVega-Cendejas 2008).…”

“…We used 3.4‰ as trophic level enrichment (∆ TP ), as reported by Vander Zanden et al (2003). The information of Poeciliopsis infans about trophic guild, niche breadth, trophic position and stable isotope analysis were taken from Ramírez-Herrejón et al (2013). Data analysis.…”

“…The physical and chemical water properties of this lake are well described (Alcocer and Bernal-Brooks 2002) and their habitat too (Ramírez-Herrejón et al 2013). For these reasons, we postulated that Lago de Pátzcuaro probably would be a good model for assessing trophic interrelations between common carp and the lake fish fauna as well as the associations of habitat characteristics with trophic interrelations.…”