Mapping the critical habitats for migratory species of the upper Grande river region, Minas Gerais state, Brazil

Abstract

Spawning sites, floodplain lakes and the vegetation integrity were mapped and quantified in the upper Grande River basin, to aid the conservation of local migratory fish fauna, including the management of the existing fish pass. The distribution of critical habitats for the life cycle of migratory species, such as spawning sites and nursery areas, is essential because some significant impacts, such as "source-sink" dynamics and ecological traps may take place depending on their distribution. We assessed seven lotic stretches throughout the upper Grande River basin, including the Aiuruoca, Capivari, Mortes, and Cervo tributaries and three regions in main stem. Floodplain lakes were present and well distributed in all of the tributaries and stretches of the Grande River, although all of them had less than half of the original vegetation. Due to their high density of eggs and larvae, the Mortes and Aiuruoca tributaries stood out as essential for fish recruitment in the basin. It was possible to figure out the current situation of the upper Grande River basin in terms of the remaining vegetation surrounding the lotic stretches, the presence of nurseries (floodplain lakes), and spawning sites (egg and larvae drift), and to propose management strategies for the entire basin.