Abstract The Atlantic marsh fiddler crab, Minuca pugnax (Smith, 1870), spans a broad latitudinal range from Maine to Florida, USA, experiencing chronic thermal variation that may drive physiological adaptation. We investigated how acclimatization with latitude alters acute thermal effects on oxygen consumption rate and visual speed in populations from Rhode Island, Delaware, and South Carolina. Whole-animal oxygen consumption rate and retinal critical flicker fusion frequency (CFF; visual speed) were measured at acute temperatures of 15°C, 20°C, and 25°C within each population during summer. Oxygen consumption rate varied with acute temperature and latitude, with crabs from the Rhode Island population showing the highest rates and lowest thermal sensitivity (Q10= 0.86), consistent with metabolic cold adaptation. Crabs from the South Carolina and Delaware populations exhibited lower oxygen consumption rates but higher thermal sensitivity (Q10= 1.63 and 1.85 respectively). CFF did not differ significantly (P = 0.1207) among locations or temperatures, suggesting visual speed is more thermally stable than oxygen consumption. While metabolism in fiddler crabs varies with latitude-dependent physiological compensation, visual performance appears more rigid, highlighting differential thermal sensitivity across physiological systems in response to environmental variability.
LeBlanc et al. (Wed,) studied this question.