Redundância funcional em recifes impactados pelo turismo em Porto de Galinhas, Nordeste do Brasil

Abstract

Coral reefs are one of the most diverse and impacted ecosystems. Loss of diversity is related to changes in ecosystem stability and can affect functional groups, also influencing reef resilience. Tourism is an activity that is known to reduce species richness but it is not yet known how this affects ecosystem functionality. The fact that there are several species performing the same function (functional redundancy) increases the community's capacity for response and / or adaptation to disturbances. The present study aimed to evaluate how tourism affects functional redundancy in coral reefs. Two areas were selected on the reef of Porto de Galinhas, an area open to visitors and another area closed to visitation. A survey of the macrobenthic species present in the areas was carried out and data available in the literature were used. Eight important functions were selected to maintain the functioning of coral reefs and all species were classified into functional groups. Functional redundancy was quantified through the size of the functional group, so the degree of redundancy varied as a function of the number of species within the group. These data were classified and compared between the open and closed areas of tourism. Functional diversity (calculated using the Shannon-Wiener Index) was also compared. The community was represented by the typical biota of reefs such as algae, sponges, cnidarians, annelids, mollusks and crustaceans. Twenty - four species were identified in the open area and 43 species in the closed area, with significant differences between the areas. Although there was a reduction in the size of several functional groups in the open area, there was no significant difference in the functional diversity of the communities, with low values in the two areas. Some important groups such as Heterotrophic-Onivorous and Pastadores / Scrapers did not present redundancy, with only one species in each group in the open area. The correlation analysis of the redundancy values in each functional group between the two areas showed that the loss of the species proportionally affected all the functional groups. However, some groups were out of the confidence interval (99%) as Suspensivore / Filtrator, Non-bioerosives, Massif / Non-branched, with different responses to species loss due to tourism. These results show that, although there is still no reduction in functional redundancy in the area open to tourism in Porto de Galinhas, the loss of species already affected affects some specific functional groups, highlighting the need for more comprehensive studies on the subject in the reefs Brazilians.