Structure of the ichthyoplankton community in a Neotropical floodplain lake affected by environmental degradation.

Many Amazonian fish' reproduction is associated to seasonality and to the conditions of habitat integrity. In a Neotropical floodplain lake of the Amazon region, the temporal structure of ichthyoplankton was investigated and the hypothesis that the density of fish eggs and larvae and the diversity of species vary between two areas with different levels of environmental changes occurred was tested. The sampling occurred monthly between September 2017 and August 2018. Six sampling stations were used, distributed in locations close to and far from the altered area. 195 eggs and 1,785 larvae from nine orders and 27 species were captured. The eggs were from non-migratory fish species and occurred during two moments. The larvae presented different abundance peaks during the sample months and all the initial stages of development occurred. Clupeiformes was the most abundant and Characiformes the species richest. The density of the ichthyoplankton and the diversity of species presented temporal variation. However, only the larval density varied between the areas of the lake. The Lake Juá is a spawning area for resident fish and is a nursery and growth area for larvae of species with different ecological categories and socioeconomic importance during different periods of the year.