THE RESISTANCE AND ACCLIMATIZATION OF MARINE FISHES TO TEMPERATURE CHANGES. II. EXPERIMENTS WITH FUNDULUS AND ATHERINOPS

Abstract

The resistance of F. parvipinnis and A. affinis to low and high temps. was examined in relation to acclimatization and habitat temps. The relationships between the time (duration) of exposure to test temps. and the average (median) limits of temp. tolerance were studied. They indicated the value of prolonged tests. Marked susceptibility of marine fishes to chilling, or injury at non-freezing low temps., and the influence of acclimatization upon resistance to cold and heat were confirmed. The death of Fundulus at slowly lethal low temps., but not at more extreme, rapidly lethal temps., was preceded in sea water by evident osmotic dehydration of tissues and was delayed in diluted sea water. Osmo-regulative failure thus was indicated as one of the causes of slow death of Fundulus in cold sea water.