Efeito da interconexão de uma lagoa costeira neotropical com mar/estuário na diversidade de crustáceos Decapoda

Abstract

Coastal lagoons are aquatic environments located at the coast-ocean interface. Ecologically important, they harbor a high abundance of macroinvertebrates, especially Decapoda crustaceans. Despite recent advances, knowledge about the dynamics and diversity in these habitats is still scarce. Therefore, the present study evaluated the influence of physical factors on the diversity of decapod crustaceans in a coastal lagoon and elaborated a list of species, with emphasis on new occurrences for this habitat. The study was conducted from January/2013 to January/2014 in the Lagoa de Barra do Rio/RN, which is seasonally connected to the sea, by means of sandbanks and rocky shore, and to the mangrove. Ecological indices were estimated to understand biotic diversity, and in addition, correlations and type II regression were performed in bivariate combinations to assess the degree of interaction between biotic vs. abiotic variables. Finally, a partial least squares regression was performed to evaluate such a relationship in the multivariate setting. Field observations showed a period of lagoon opening in March and total isolation in October. The most abundant taxa were Penaeus, Callinectes sp., C. danae, Pagurus criniticornis and Clibanarius sclopetarius. November was the month with the highest diversity, dominance and equitability, while September had the highest abundance. The investigation showed an association between minimum monthly Astronomical Tide and equitability, and the only variables that showed relevant contribution to the model were maximum wind gust, hourly wind speed and minimum monthly Astronomical Tide. These results showed that wind and tide can act as a proxy for morphodynamic analysis, by promoting seasonal events of opening and isolation of connectivity, assisting in the transport of individuals by water mass carriage. Furthermore, the coastal lagoon was presented as a place of shelter and foraging for biota, especially for the genera Penaeus and Callinectes, which use the lagoons to complete their life cycle in the sea-estuary transition. Therefore, this study contributed to the knowledge of biotic and abiotic dynamics of Neotropical lagoons, which can help management actions for the conservation of these areas and species.