Use of food resources by Plagioscion squamosissimus - a non-native piscivore in Sobradinho reservoir-BA, Brazil

Abstract

The species Plagioscion squamosissimus (Heckel, 1940), popularly known as pescada, is endemic to the Amazon basin and found in all rivers and lakes of this region. It is considered one of the main introduced species, with successful colonization in several basins in Brazil. This study aimed to evaluate the pattern of use of food resources by P. squamosissimus in a Northeastern reservoir, with emphasis on spatial and temporal scales. Bimonthly sampling was undertaken between November 2006 and September 2009, along different stretches of the reservoir (lotic, transition and lentic) and periods (dry and flooding). A total of 44 food items were consumed, which were grouped into six categories. Diet was assessed through a combination of spatial and temporal factors using a Non Metric Multidimensional Scaling (NMDS, PERMANOVA). The ontogenetic change of diet was tested by means of a Multi-Response Permutation Procedure (MRPP). The results of the ordination showed that Fish was the category that mostly influenced the diet. Significant alterations were recorded during the ontogeny of P. squamosissimus. It could be concluded that the pescada behaves as piscivore in the Sobradinho reservoir, thus maximizing its diet, regardless of the extent of temporal and spatial variation in the reservoir.