Does fecundity of Macrobrachium amazonicum (Heller, 1862) change between upstream and downstream a dam? A case study in Água Vermelha Reservoir, Brazil

Abstract

We investigated the fecundity of Macrobrachium amazonicum upstream and downstream of the reservoir Água Vermelha in the border between the State of Minas Gerais and the State of São Paulo, Brazil. We collected no more than 30 females in each area in monthly samples from October 2017 to October 2018 using sieves and traps. The CL was compared between sites by the Mann-Whitney U test. CL and egg number association was tested by linear regression. Monthly abundance of females was compared using Generalized Linear Model (GLM). We collected 572 females (258 upstream and 314 downstream). Upstream fecundity was higher. Despite the precarious abiotic conditions from upstream, food availability probably enabled higher fecundity. Lower fecundity downstream was probably due to egg loss induced by friction against the substrate through the water current.