Brachyuran crab diversity and abundance patterns in the mangroves of Cameroon

Brachyuran crabs are the most important group of mangroves epifauna. They operate relevant ecological roles in terms of structure and function in mangrove ecosystems. The study aims to assess crab diversity and the patterns of their distribution for biodiversity documentation. The survey was carried out in mangrove forests of the Cameroon coastline. Investigations were randomly carried out on 17 degraded mangrove areas where Rhizophora stands dominated. Crabs were collected during the period of low tide, during day and night times in the 4 × 4 m2 quadrant plots delimited inside each belt zonation throughout transects. In total, 27 crab morphospecies were recorded with global sampling effort equals to 87.5%. Eleven morphospecies were recorded for the first time in Cameroon. Sesarmid crabs were most represented (10 species) with abundant taxa (72.9% of individuals). Crab community has low species richness and diversity indices (d=0.004; H′=3.3±0.1; J′=0.8). Hill evenness are close to 1, confirms that one species (Guinearma kamermani) tends to dominate the whole community. Armases elegans, Chiromantes buettikoferi, Goniopsis pelii, Metagrapsus curvatus, Guinearma alberti, G.huzardi and G. kamermani were the common species in the study areas. The Center mangrove stands appeared most diverse (E(Sn=401)=18±1.1species), followed by the South (E(Sn=401)=16±0.5species) and the North (E(Sn=401)=11±0.0species). Species abundance is typically distributed as in linear log series (Motomura model) corresponding to the disturbed environments. The lack of conservation strategies in the management of mangrove forests in Cameroon might lead to the disappearance of these ecosystem properties and its relevant components.