. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 338 SANDRA E. SHUMWAY TABLE IV Values of KI and K2 in the expression QO2 = PO2/K, + K2 PO2for seven specimens of A. crenata of various sizes, subjected to declining oxygen tensions. QO2, ml Q2/(h-g dry wt); PO2, mm Hg. Animal Number K, K2 K,/K2 i 196 : >.14 2 206 .60 3 237 .45 4 177 .72 5 191 .27 6 124 .54 7 113 .30 Small individuals with high metabolic rates are, therefore, less independent of the ambient oxygen tension than are larger individuals with low metabolic rates. Ef
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 338 SANDRA E. SHUMWAY TABLE IV Values of KI and K2 in the expression QO2 = PO2/K, + K2 PO2for seven specimens of A. crenata of various sizes, subjected to declining oxygen tensions. QO2, ml Q2/(h-g dry wt); PO2, mm Hg. Animal Number K, K2 K,/K2 i 196 : >.14 2 206 .60 3 237 .45 4 177 .72 5 191 .27 6 124 .54 7 113 .30 Small individuals with high metabolic rates are, therefore, less independent of the ambient oxygen tension than are larger individuals with low metabolic rates. Effect of time spent in the laboratory on the ability to regulate QO2 Bayne (1971) showed that the length of time the mussel, Mytilus edulis, was maintained in the laboratory could affect the animals' capacity to regulate oxygen uptake in declining oxygen tensions. This possibility was therefore investigated in A. crenata. Animals of similar size were kept in the laboratory for periods of 1, 2, 3, 5, 7, 9, and 12 weeks, after which their response to declining oxygen tension was mea- sured. Table V shows the change in the ratio K,/K2 for 70 experiments. It can be seen from these values that, like Mytilus, A. crenata loses at least part of its ability to regulate its rate of oxygen consumption in declining oxygen tensions if kept in the laboratory for extended periods. Combined effects of salinity, declining oxygen tension, and anoxia on oxygen consumption The effect of salinity on oxygen dependence is shown in Table VI where the oxygen dependence index, K,/K2, is given for snails from six different salinities. 200 100 50 10. = QO I I I I I I I I I QO, FIGURE 2. The "oxygen dependence index" K,/K2, plotted against weight-specific oxygen con- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the
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