Population structure and reproductive biology of the fiddler crab Leptuca leptodactyla (Rathbun in Rankin, 1898) (Brachyura: Ocypodidae) in two estuaries from Sergipe state

Leptuca leptodactyla is a broad-fronted species with a wide distribution and complex reproductive behavior. To evaluate possible local variations, the present study aimed to analyze the population structure of L. leptodactyla in two tropical estuaries located at the same latitude. Additionally, the effect of seasonality of environmental factors on reproductive activity in the species was evaluated. Individuals were sampled by randomly throwing a 30×30 cm square into each estuary 20 times. The number of hoods in the internal area of the square was recorded, and subsequently, the entire internal area was excavated to approximately 20 cm. All individuals were placed in plastic bags and taken to the UFS Carcinology Laboratory. In addition to abundance, each individual had the carapace width measured, in males, the size of the largest cheliped was also measured, and in females the abdomen width was measured. These measurements were used to compare the size of individuals between estuaries and to estimate morphological sexual maturity. Among the abiotic factors, differences were found in the organic matter and grain size of the substrate. The Vaza-Barris estuary had a greater abundance of females, embryonated females, hoods, and larger individuals than the Sergipe estuary. The difference in population structure may be related to the difference in food availability and the different levels of anthropogenic impact between estuaries.