Edge, area and anthropization effects on mangrove-dwelling ant communities

In mangroves the habitat fragmentation has contributed to area reduction and increased edge extension, as well as other anthropogenic consequences that can change abiotic conditions, interfere with ecosystem functioning and lead to the loss of biodiversity. These impacts may affect terrestrial and marine invertebrates living in this coastal system. This study investigated the effects of fragment characteristics (size and matrix type) and distance to edge on ant richness, occurrence of functional groups and of the most frequent species in mangroves in North-Eastern Brazil. Our research covered ten mangrove fragments. We used sardine and honey baits in twelve randomly selected points per area. Twenty-five species of ants were recorded, with Camponotus arboreus, Crematogaster erecta, Azteca sp. and Neoponera villosa being the most frequent. Only four functional groups were found, the most representative of which were the Arboreal Omnivores with Massive Recruitment and the Generalist Predators. No relationship was found between the response variables and the environmental characteristics. Mangroves ants are mostly arboreal; thus, the pattern of competition between ant species or even tree architecture elements may have stronger effects than those related to anthropization, loss of area and fragmentation in this environment. Furthermore, the harsh physical conditions in the mangrove serve as barriers for most exotic species and to some functional groups of ants. This study highlights the natural restrictive nesting and foraging conditions in mangrove areas as the powerful forces in ant community structuring, possibly even more than anthropization itself.