Stability and persistence of a fish community in a neotropical coastal lagoon

Abstract

Studies approaching the temporal variation of fish community structure on coastal lagoons give us the opportunity to access its stability and persistence, besides of being important tools to monitor the quality of environment. However, few researches use a temporal approach to evaluate this kind of ecosystems. The present study aimed to compare the fish community structure of Caconde lagoon, north coast of RS, at two time periods (1992-1994 and 2009-2011). A Student’s t-test was used to compare the proportion of abundance and of biomass of each species between the two time periods. Additionally, we performed an ordination with the fish species compositions of the two periods. Five new species occurrences were registered for Caconde lagoon at the recent sample, three of which are allochthonous. Eight species found at the original sample were not found at the recent one. Results of t-test revealed significant differences on the abundances of four species as well as a temporal partition between the two temporal samples. Besides the presence of allochthonous species, we found differences in the stability of the community characterized by decreasing relative abundances of original dominant species. Notwithstanding the inability to clearly explain the causes of the observed changes, we infer they can be partly explained by the presence of allochthonous species as well as by land-use changes at lagoon surroundings.