Fish larvae diversity in a conservation area of a neotropical floodplain: influence of temporal and spatial scales

The diversity of fish larvae in floodplain environments exhibits spatial and temporal variations since fish have different ontogenetic requirements, and is influenced by their reproductive period. In order to evaluate how the diversity of fish larvae is structured in different temporal and spatial scales in the sub-basin of the Ivinhema River, Upper Parana River floodplain (MS, Brazil), we performed monthly samplings in two reproductive periods (2010/2011 and 2011/2012). Variation in alpha (alpha) diversity was evaluated through a nested ANOVA, while beta (beta) diversity was evaluated with distance-based tests for the homogeneity of multivariate dispersions (PERMDISP). Additive partitioning of diversity was used to verify the relative contribution of each scale to gamma (gamma) diversity. The first reproductive period showed higher intensity and duration of flooding, which favored a higher gamma diversity. Alpha and beta diversities also varied among the different habitats, each one being occupied by species with distinct reproductive strategies. Components beta(1) (variation among months) and beta(3) (variation among habitats) significantly explained gamma diversity in both reproductive periods, indicating that more intense floods favor reproduction and increase diversity of fish larvae. This study reinforces the importance of temporal and spatial scales in the maintenance of fish larvae diversity in floodplains.