Distribuição espacial e biologia populacional de leptuca leptodactyla (rathbun, 1898) (decapoda: ocypodidae: gelasiminae) em um manguezal do Nordeste Semiárido brasileiro

Abstract

The environmental factors that regulates the spatial distribution of Leptuca leptodactyla at Baixa Grande mangrove in Areia Branca, RN (4º55’90”S, 37º04”51”W) were studied in the period of November 2015 until October 2016. The specie’s populational biology was analyzed in terms of age structure, reproductive biology, density and sexual ratio. Three transects have been established in a mangrove area next to the river mouth, which were visited monthly. In each transect, 10 squares of 50 × 50 (0.25 cm²) were demarcated, where all specimens of L. leptodactyla were collected, which, in laboratory, were determined the genders, measured the sizes and quantified. Sedimentological analysis (granulometry, organic matter content and humidity) were made in three squares of each transect, comprising the mangroves border, the intermediate region and the riverside, in which interstitial temperature and salinity were also measured. The results showed that L. leptodactyla occurred in every sampled area, however, showed higher affinity for fine sediments. The specie presented a negative correlation for all measured abiotic parameters, except for humidity. However, a strong and significant relationship was only observed for salinity. In terms of populational biology, a density of 36.46 ind./m² was found and sexual ratio corresponded to the expected of 1: 1. The population presented a unimodal frequency distribution, suggesting a continuous reproduction. Meanwhile, the occurrence of ovigerous females and juvenile individuals showed a strong relation with rainfall, thus indicating that the reproductive period occurs in synchrony with the rainy period of the region.