Conservações e áreas afins - Comunicações orais

The size at sexual maturity of brachyuran crabs plays a crucial role in understanding their biology and has been investigated in fiddler crabs (Gelasiminae) to facilitate conservation efforts. This study focused on Minuca vocator, conducted in a mangrove along the Itanhaém River, south coast of São Paulo state. Crabs were collected, sexed, and subjected to measurements of carapace width (CW), and propodus length of the major chela (PL) for males, and abdominal width (5^th somite) (AW) for females. Regression analyses were applied to the PLxCW and AWxCW relationships and fitted using a power function to determine the breaking point between juveniles and adults (using “segmented” function in R-environment) or the proportion of overlap (using a logistic equation). The growth rate (constant 'b') varied with ontogeny in both sexes. Male analysis included 208 individuals (2.5 to 22.1mm CW) and revealed a breaking point at 8.5mm CW, indicating a positive allometric growth smaller for juveniles (b=1.24) than adults (b=1.82). Female analysis involved 130 specimens (4.3mm to 21.9mm CW) and indicated a maturity size 28.4% larger than males (10.8mm CW), with higher positive allometric growth in juveniles (b=1.55) than in adults (b=1.17). The growth pattern observed in these morphometric relationships was similar to those reported in previous studies of Brazilian Gelasiminae (differential allometric growth throughout ontogeny, regardless of sex). In the north coast mangroves (Ubatuba, SP), a more pristine region, the maturity size recorded for M. vocator was 30% larger than that found in Itanhaém (SP) mangrove, which experiences high urbanization pressure and shows greater effects of contaminants (e.g., metals, PAHs, etc.) documented in previous studies. Despite the latitudinal proximity, the difference between areas is likely due to contrasting food quality, such as organic matter, as more pristine mangroves promote a better energy budget, which can directly influence the size at maturity.