Feeding ecology of mangrove crabs in Cameroon

Abstract

The feeding ecology of several species of mangrove crabs was studied in Cameroon mangrove forest through tethering experiments and gut analyses from September 2010 to March 2011. Field observations were two-fold: to investigate mangrove propagules predation and feeding preferences of mangrove leaves. Feeding preference was determined on fresh and senescent leaves of Laguncularia racemosa, Avicennia germinans and Rhizophora species. Propagule predation was investigated on Rhizophora mangle, Rhizophora harrisonii and Rhizophora racemosa. In the laboratory, gut content analysis was done on Metagrapsus curvatus, Sesarma huzardi, Sesarma elegans, Sesarma alberti, Goniopsis pelii and Grapsus grapsus to assess their natural diets. The field observations suggest that 65.9% of the propagules studied was predated, 71.3% of the leaves was damaged. Mangrove material was the main component of crabs diet, it constituted 45.4% of Metagrapsus curvatus diet, 55% Sesarma elegans diet, 62.5% Sesarma alberti, 65.9% Goniopsis pelii diet, 47.8% Sesarma huzardi diet and 37.3% Grapsus grapsus diet. Damage on young mangrove trees was highly correlated to the number of crabs on trees (r2 = 0.75). The high damage rate of mangrove materials indicate that crabs play a significant ecological role in the functioning of the mangrove ecosystem, by affecting mangrove recruitment and biogeochemical functioning. © 2014, ALÖKI Kft., Budapest, Hungary.