Masters Thesis

The influence of season upon the oxygen consumption of two populations of the freshwater amphipod Hyalella azteca.

This study was undertaken to investigate seasonal acclimatization in two populations of Hyalella azteca as measured by their oxygen consumption. One population was taken from a high Mg habitat and one from a low Mg environment. No significant seasonal differences between the two populations appeared to exist except during fall when the high Mg population showed lowered rates while the low Mg population increased its oxygen uptake. Similarity between summer and winter rates for both populations indicates that the seasonal patterns of oxygen consumption are probably due to some factor(s) other than temperature. Differing water types also apparently have little effect on m oxygen consumption with only slightly lowered oxygen consumption seen in water from the opposite source which may indicate a shock reaction as no time for acclimation to a new aquatic medium was given. Analysis of variance tests yielded F values which indicated that oxygen uptake patterns for the two populations studied were significantly influenced by an interaction of the factors studied in this project and most likely other factors not investigate