Feeding selectivity of sesarmid crabs from northern Australian mangrove forests.

Sesarmid crabs are possibly one of the most important components of mangrove fauna because of their influence on nutrient cycling and forest structure by feeding on litterfall. Little is known about the influence of electivity on the role of crabs in mangrove forests, and how this is affected by the availability of litter items. This study investigated electivity of three northern Australian sesarmid crabs ('Perisesarma semperi';, 'Perisesarma darwinensis' and 'Neosarmatium meinerti') from leaves of various conditions and from common species, as well as the effect of the availability of propagules on feeding electivity. In almost every experiment, decayed and senescent leaves were selected over fresh leaves, and typically decayed leaves were selected over senescent. Electivity for mangrove species, however, varied among crab species and depended upon availability of litter type to select from. experiments that included propagules as well as leaves, leaves were selected over propagules. These results suggest that the sesarmid crab species included in this study may have a greater role in nutrient cycling than in forest structuring because of their selectivity of leaves over propagules.