A COMPARISON OF THE PHYSIOLOGY AND ECOLOGY OF THE ESTUARINE ISOPOD CYATHURA POLITA IN MASSACHUSETTS AND GEORGIA

Abstract

ThysiologicirinT ecological aspects of 2 populations of Cyathura polita were compared and found to be similar. One of the populations was located in a beach on Sapelo Island, Georgia, the other in an estuary in Marshfield, Massachusetts. Both habitats had sandy sediments, well aerated water, and wide fluctuations of temperature and salinity. Although the Sapelo Island population was less dense and was made up of smaller animals than the Marshfield population, both had clumped distribution patterns and seasonally changing sex ratios. The fauna associated with the populations was limited, and many spp. found in the 2 areas were closely related to each other. The osmoregulatory behavior and oxygen consumption rates of animals from the 2 populations were analyzed by freezing point depression methods and bottle methods respectively, and were found to be similar. The evolutionary significance of the apparent homogeneity of the species is discussed.