Effect of diet on oxygen uptake rate in the talitrid amphipod <i>Platorchestia platensis</i>

The primary ecotope for <i>Platorchestia platensis</i> is supralittoral wrack, but occasionally this species may be found living in, and feeding on, rotting driftwood as a secondary ecotope. Lower oxygen uptake rates were measured for driftwood-fed compared with wrack-fed <i>P. platensis</i>. The null hypothesis that the metabolic rate in <i>P. platensis</i> would remain unchanged after reversing the diet from driftwood to wrack was rejected. Diet reversal experiments demonstrated that the oxygen consumption rates of <i>P. platensis</i> were reversible and gradually attained. This is consistent with the change of diet from wrack to driftwood, or vice versa, causing physiological changes involving oxygen consumption in <i>P. platensis</i>, which are described as acclimation rather than adaptation.