Relação da diversidade taxonômica e funcional com a produção secundária de Polychaeta em estuários tropicais

Abstract

In the evaluation of ecosystem productivity, the secondary production is considered as a key process, since it can be a direct measure of the provisioning and availability of energy in the system. Therefore, the objective of this work is to evaluate the relationship of taxonomic and functional diversity with the secondary production of polychaetes from tropical estuaries. As hypotheses we have that (i) functional diversity is the component of diversity that has a positive relation with secondary production, ie, the greater the functional diversity, the greater the secondary production of ecosystems; and (ii) secondary production is positively related mainly to the functional characteristics of the species with higher biomass in the community, as suggested by the mass ratio hypothesis. To test the hypotheses, the samples were collected in two estuaries located in the state of Paraíba / Brazil, (Paraíba estuary and Mamanguape estuary), and in an estuary located in the state of Pernambuco / Brazil (Passos estuary) in the period of November 2016, and in each estuary were defined four sample zones according to the salt gradient, and in each zone sampled three points, and each point with three replicates. Five functional characteristics were selected for polychaetes: maximum body size, feeding strategy, shelf life, larval development and fecundity. In order to measure functional diversity, the quadratic Entropy of RAO, Functional Wealth and CWM was calculated, and Shannon-Wiener Diversity and Taxonomic Wealth were used as a measure of taxonomic diversity. To measure the secondary production, the biomass of the polychaetes was determined by the ash-free dry weight and then the Brey (2001) method was used. The Spearman correlation test was performed between the taxonomic and functional diversity indexes with the secondary production, and for those that presented a significant correlation with the secondary production, linear regression models were generated. As the taxonomic diversity in Passos and Paraíba estuaries increases, there is a concomitant increase in secondary production. Functional diversity was related to secondary production only in Paraíba estuary. In Mamanguape the secondary production was not related to the taxonomic and functional diversity of the polychaetes. The response of taxonomic and functional diversity to secondary production may vary depending on the composition and structure of the polychaete community according to each estuary. Regarding the functional characteristics, it is necessary to investigate how the function of each functional attribute in a community can influence the levels of secondary production.