Do biotic interactions explain zooplankton diversity differences in the Meghna River estuary ecosystems of Bangladesh?

Differences in species diversity in ecosystems have long and often been discussed and interrogated in ecological research. A two year study on zooplankton diversity in the Meghna River and its estuary of Bangladesh found that diversity is comparatively higher in the estuary than the river. This study examines whether the biotic interactions of species can explain the diversity difference between these two aquatic habitats. The study is based on several species diversity hypotheses related to biotic interactions (i.e. low interspecific interactions, comparatively higher disturbance, higher species recruitments and higher intransitivities cause higher species diversity). A first order Markov chain model was used to estimate the biotic interactions i.e. species displacement ability, disturbance, colonization and intransitivities. Monte Carlo Markov chain (MCMC) simulations were performed to estimate species interactions from the Markov chain model. Results suggest low inter-specific interactions, comparatively higher disturbance rate, higher species recruitment and intransitivies in the Meghna estuary have caused higher zooplankton than the Meghna riverine ecosystem. In addition, it is evident that the negative association of species colonization with species displacement ability and displacement risk also led to a comparatively higher diversity in the Meghna estuary than the Meghna River. It is apparent from the zooplankton abundance data, that biotic interactions can explain the zooplankton species diversity difference in the Meghna aquatic ecosystems of Bangladesh. With these findings the current study provides valuable insights into zooplankton diversity differences in tropical ecosystems.