Survival strategies on a semi-arid island: submersion and desiccation tolerances of fiddler crabs from the Galapagos Archipelago

During tidal cycles, fiddler crabs undergo alternating periods of submersion and desiccation. We compare physiological biochemical adjustments to desiccation challenge in two gelasminids from the Galapagos archipelago: indigenous Leptuca helleri, Minuca galapagensis. examine population distributions habitat characteristics; survival hemolymph osmolality after 6 h at several salinities, or 12 desiccation; oxidative stress responses hepatopancreas gills, accompanying glutathione enzyme antioxidant activities, lipid peroxidation. provide an integrated biomarker response index based on each tissue, condition species. helleri occupies a restricted intertidal niche while M. galapagensis is supralittoral. Burrow density declined with increasing salinity decreasing substrate moisture; L. burrow showed no correlation. After submersion, survived only 21‰S 0 42 ‰S. desiccation, decreased markedly but increased Antioxidant activities peroxidation gills tissue- species-specific challenge. The indexes for were highest control crabs, driven by stress. In galapagensis, was determining factor both tissues. generalist species more habitat. species’ respective limitations flexibilities insights into how might respond environmental change semi-arid islands.