Local Perception of Climate Change and Adaptation in Mangrove Areas of the Cameroon Coast

Mangroves supply essential ecosystem services to tropical informal economies. In the Cameroon coastal region, the impacts of various projections on change in temperatures and precipitations sound low compared to the pressure of human activities. This survey evaluated the sensitivity of local population on the impact of climate change and the vulnerability of coastal ecosystems. An investigation carried out on 425 individuals was based on the major income and development activities, the knowledge of the subject, the information sources, the origin of changes, perceptible effects, risks and consequences. More than 90% of interviewees have heard about climate change essentially from radio (20%). Industries (47.53%) are perceived to have major responsibility for temperature (78%) and precipitation (67%) changes and increased inundation (39.07%) was perceived as the highest risk. Compared with Cartesian predictions in the area, the results have shown the sensitivity of population to local variation of climate factors. No efficient endogenous measure has been recorded. Forest and specially mangroves are the most affected ecosystems by local activities. Expected extension of the dry season could affect the natural regeneration and the structure of mangrove forests. Considering the importance of woody species in the local economies, the lack of appropriate actions and adaptation measures will lead to the total degradation of mangroves.

Biology and Distribution of Mangrove Crabs in the Wouri River Estuary, Douala, Cameroon

Crabs appear as the most important group of mangrove epifauna. Their distribution seems influenced by some biotic and abiotic parameters. To verify the interactions between crab populations and relevant environmental components, six mangrove sites around the city of Douala (3°40' - 4°11'N and 9°16' - 9°52'E) were selected. During six months, four 25-min independent time-biased samples methods were conducted in the plot of 4 × 4 m2 delimited inside each zonation throughout transect. The distance from plot to water and its groundwater salinity, temperature, conductivity and pH were measured. The individual sex, fresh weight and carapace size were determined. 3016 individuals were harvested (57% of females). Perisesarma kamermani was the most abundant (29%) while Chiromates angolense was the most frequent (13.47%). Cardisoma armatum was only found in Pandanus zone. Crab species number was positively correlated with tree, suggesting that the mangrove vegetation is important to the crab fauna as a habitat and food supply. Sex ratio showed a significant difference for Chiromates buetikoferi 1:2.34 (χ2 = 33.21) and for Perisesarma huzardi 1.36:1 (χ2 = 39.98). Portunus validus live closer to water between 5 - 20 m while Cardisoma armatum was found 70 m away from water. Portunus validus was present exclusively in high salinity zones whereas Perisesarma kamermani dominate in low salinity zone. This baseline ecological study of crab mangroves is important for monitoring, management and conservation of mangrove ecosystems.