EDGE EFFECTS ON THE ABUNDANCE OF THE CRAB Ucides cordatus (DECAPODA: OCYPODIDAE) IN A NEOTROPICAL MANGROVE

Mangroves are among the most productive and biologically important ecosystems in the world and are currently undergoing extensive habitat loss and fragmentation. Such habitat loss and fragmentation result in the creation of edges, which can cause edge effects on the remaining habitat, resulting in changes in abiotic conditions, alterations in ecosystem functioning, and loss of biodiversity. The crab Ucides cordatus (Linnaeus, 1763), locally known as “caranguejo-uçá,” is a species of great economic and ecological importance in these environments. This species is also considered an important indicator of environmental quality, being sensitive to various pollutants. Therefore, we evaluated how anthropogenic edges affect the U. cordatus population in a mangrove area and compared these patterns to those observed at natural edges. We found a positive effect of edge creation on crab abundance for the total number of burrows and the number of open burrows, but no effect on the number of closed burrows. Conversely, we detected a negative effect of natural edges on the quantity of closed burrows. Our findings suggest that anthropogenic edges may alter crab abundances, becoming the preferred habitat for young crabs. However, we emphasize that the interior of the mangrove is also crucial for species maintenance, especially for adult crabs and juveniles during molting.