Species of the Hoplias aff malabaricus complex (Characiformes: Erythrinidae): An investigation of coexistence in a Neotropical floodplain

Abstract

This study assessed the coexistence of three species of thraira present in the Upper Paraná River floodplain, using population structure as an investigation tool. The species were designated as: Hoplias sp. 1, introduced after the construction of the Itaipu reservoir, and Hoplias sp. 2 and Hoplias sp. 3, native species that have been identified as Hoplias aff. malabaricus. We tested the hypothesis that those species in fact differ from each other in respect of population abundance, sex ratio, relative frequency of adults and juveniles, length structure and weight-length relationship. Additionally, possible effects of the flood pulse on the first four of these parameters were investigated. Samples were collected quarterly from March 2006 to December 2007 from nine collection sites on the floodplain. Hoplias sp. 1 presented a greater balance of sex ratio and length structures over the seasons, as well as a higher allometric coefficient. The population attributes of Hoplias sp. 2 and Hoplias sp. 3 showed a high responsiveness to hydrological seasonality, indicating that these species exploit available resources in a conspicuous flood period with greater efficiency. These differences, beyond reflecting possible mechanisms that allow closely related species to coexist, indicate the importance of understanding the life strategies adopted by each species which, as part of a complex system, are considered key elements of the aquatic community structure in the region, providing important information for habitat management and biodiversity conservation

Is coexistence between non-native and native Erythrinidae species mediated by niche differentiation or environmental filtering? A case study in the upper Paraná River floodplain

“…in the H. mbigua diet may be related to this high degree of territorialism; this species presented a large overlap with the native species, and the consumption of congeneric species is noted as a possible mechanism that could facilitate its establishment in the floodplain (Strictar-Pereira et al, 2015). In addition to the tendency for competition, due to their morphological similarities, the two species possess similar abundances in the floodplain, with the presence of the non-native species not eliminating or even reducing the abundance of the native species (Hauser, Benedito, 2012).…”

Stable isotopes reveal niche segregation between native and non‐native Hoplias in a Neotropical floodplain

“…littoral areas). During low-water periods, prey items concentrate in small areas, increasing the possibility for both species to rely on many different food sources more efficiently (Hauser & Benedito, 2012;Luz-Agostinho et al, 2008). Even though both Hoplias species showed similar trophic diversity, we observed a higher isotopic niche width for the native species.…”

“…Even though both Hoplias species showed similar trophic diversity, we observed a higher isotopic niche width for the native species. The diet analysis performed by Strictar-Pereira et al 2017 restrictions such as environmental filtering (Mouillot et al, 2007;Southwood, 1977) do not seem to be operating among Hoplias populations, enabling them to maintain viable populations in the floodplain (Hauser & Benedito, 2012). Because we found complementary results for the feeding dynamics of Hoplias species in the Upper Paraná River floodplain, we advocate for new studies on trophic interactions using integrative methods, as well as studies regarding population dynamics between native and non-native fish species so we may improve our understanding of the mechanisms underlying coexistence patterns in freshwater ecosystems.…”

“…B (Bifi, 2013;Pazza & Júlio, 2003). Unlike the piranha, however, the non-native Hoplias maintains a lower abundance than its congeneric (Hauser & Benedito, 2012). As such, new insights are needed to understand how these species interact and coexist since the H. mbigua introduction.…”

Estructura de tallas de captura y relación longitud-peso de peces nativos en el humedal Abras de Mantequilla, Ecuador

“…La especie H. microlepis, presentó un crecimiento isométrico (b=3.011; p=0.05), de la misma manera que Hauser & Benedito (2012) reportaron un crecimiento isométrico para Hoplias aff. malabaricus en el río Paraná, Brasil.…”