Impacto da introdução do mexilhão dourado na alimentação do Iheringichthys labrosus no médio Rio Uruguai

Abstract

The invasion of ecosystems by exotic organisms has become frequent, and today can be considered one of the potential causes for the loss of biodiversity on planet Earth. The establishment of organisms with invasive characteristics in a new environment can cause irreversible changes in the structure of their biological communities, leading to the extinction of native species. Among the main invasive aquatic organisms are crustaceans, fish and bivalves. In turn, bivalve populations have increased dramatically worldwide, with numerous negative and positive effects on native ecosystems. The Iheringichthys labrosus is a fish that belongs to the order Siluriformes, which are known to be leather fish, with the presence of barbels as a striking feature. In this study we started from the hypothesis that I.labrosus is eating golden mussel in the middle Uruguay river, if using this bivalve as food item, we consider that its consumption could be having positive effects as well as negative for the species. The samples were collected seasonally in two moments. Previously the presence of the golden mussel, which was held in 2008 and after the registration of the golden mussel between 2015 and 2019. To evaluate the spatiotemporal variation of fish size, a one-way ANOVA was used. When the results were statistically significant, Tukey's a posteriori test was applied to identify the differences. A Dedenced Correspondence Analysis (DCA) was applied to verify the spatiotemporal variation of items consumed by Iheringichthys labrosus. The same data set was submitted to the Multiple Response Permutation Procedure (MRPP) permutation test, aiming to verify the consistency, significance and homogeneity between the groups. To verify the Condition Factor (K) of the fish used in the stomach content analysis, we used the length (Lt) - weight (Wt) ratio of all fish caught in the 6 years of study. This is the first work to evaluate the predation of golden mussel by fish in the Middle Uruguay River. This study points out positive points for I.labrosus considering the consumption of golden mussel, such as the increase in physiological quality conditioned by an increase in the condition factor (K), as well as a change in the fish eating habits after the presence of bivalve.