Spider diversity in mangrove and terra firme forest ecosystems in the Reserva Extrativista Marinha de Soure, Marajó Island, Pará, Brazil

Abstract

The aim of this research is to characterize the spider fauna of the mangrove and terra firme ecosystems of the Reserva Extrativista Marinha de Soure, located in Soure, Marajó Island, Pará, Brazil. This is the first inventory for the region, in which three sampling methods were used in ten areas. In total, 2,629 individuals were collected, including 2,075 juveniles and 554 adults belonging to 121 species and 30 spider families. Of adults collected, 296 (53.4%) came from mangroves and 258 (46.6%) from terra firme areas. The most abundant families were Araneidae (26.7%), Theridiidae (16.4%), and Trechaleidae (11.9%); the families with the highest species richness were Araneidae (31 spp.), Salticidae (25 spp.), and Theridiidae (14 spp.). The observed richness was 69 species for the mangrove areas and 74 for the terra firme areas, from which 47 and 52 species, respectively, were exclusive to each environment. Ten guilds were recorded, eight from the mangrove and ten from the terra firme. Inventories with greater sampling effort should be made to increase the representativity of species from the reserve. The large number of exclusive species indicates high complementarity between ecosystems, suggesting a high conservation value of the habitat fragments throughout the region.