Use of time, space and food resources in the mangrove climbing crab Selatium elongatum (Grapsidae : Sesarminae)

The activity patterns and use of space of the mangrove dweller Selatium elo ngatum were studied in the field, in combination with gut content analyses for evaluation of the crab's natural diet. This sesarmine crab proves to be one of the most adapted to climbing and living on mangroves. Moreover, S. elongatum showed a strong preference for being active at high tide, both du ring the day and night, always along the trunks a few centimetres above the water level, feeding on floating algae and mangrove leaves. Larger males w ere always recorded within activity areas into which they allow females and smaller males but exclude males of the same size, which probably compete f or females. These results confirm that, in spite of the homogeneous herbivo rous diet, little niche overlap exists among the several sesarmine crabs in habiting the East African mangroves, all being leaf consumers segregated on the basis of their horizontal and vertical zonation, and/or of their activ ity rhythm.