TITLE:
Biology and Distribution of Mangrove Crabs in the Wouri River Estuary, Douala, Cameroon
AUTHORS:
Vanessa Maxemilie Ngo-Massou, Guillaume Léopold Essomè-Koum, Ernest Kottè-Mapoko, Ndongo Din
KEYWORDS:
Abundance; Diversity; Frequency; Sesarmidae; Sex Ratio
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.4,
March
25,
2014
ABSTRACT: 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.