Efeitos da variação hidrométrica interanual sobre a assembleia de peixes em bancos de herbáceas quáticas no sistema catalão, Amazonas

Abstract

In floodplain environments there is a large number of species inhabiting banks of aquatic herbaceous plants. These species are associated with these herbaceous plants during part or throughout their entire life cycle. Specifically, fish can find shelter, feeding grounds, shelter from predators and breeding sites on aquatic herbaceous species. The flood pulse is the main agent of the structure and dynamics of aquatic communities. In this environmental cycle the dry and flooding moments are critical and extreme events have become more frequent and intense between the years in the last decades. Data from the fish assemblage that inhabited banks of aquatic herbaceous plants from 2003 to 2014 were analyzed considering the months from January to August for each year. For each year, the levels of minimum annual quotations preceding and maximum were used. Hoplias malabaricus was the most frequent species throughout the study period and Moenkhausia dichroura the most abundant species. The year with the highest number of individuals was found in 2005 (5308). The highest number of species was recorded for the year 2004 (117), the average dominance of the assembly was low, consequently the average diversity of Simpson was considered high. Wealth showed significant differences between the years considering the time intervals of 2003-2006 and 2008-2014. The dominance and Diversity showed statistically significant differences also for the time intervals in this same period. Abundance and species richness were negatively influenced by maximum river levels. The main coordinate analysis (PCoA) indicated the separation of the fish assemblage into two groups according to the composition of species, 2003-2006 and 2008-2014, these groups were validated by the analysis of similarity (ANOSIM). The change in species composition over time was correlated with the maximum river level levels without showing recovery to the initial state in the data series (2003). The analysis of anomaly and anomaly of abundance between the years, show that only the species Moenkhausia lepidura, Mylossoma duriventre and Hemigrammus levis were in fact affected by levels of maximum river quota between the years reducing in abundance in years with more intense flood .