influence of dissolved oxygen concentrations on three species of water mites (Hydracarina)

The influence of various concentrations of dissolved oxygen on the metabolic rate, survival, accumulation of lactic acid and rate of movement of Hydryphantes tenuabilis from a pond and Lebertia quinquemaculosa and Limnesia undulata from a constant-temperature spring run was investigated. H. tenuabilis proved to be an oxygen regulator which reached a maximum oxygen consumption of 483 mm3/g wet wt/hr at about 30% oxygen saturation. L. quinquemaculosa and L. undulata had maximum oxygen consumptions of 568 and 732 mm3/g wet wt/hr, respectively, at the highest oxygen concentration tested, 5.8 mg/l, and appear to be oxygen conformers. H. tenuabilis showed a more variable and higher rate of survival at dissolved oxygen concentrations less than 0.1 mg/l than did either L. quinquemaculosa or L. undulata. None of the three species showed significant accumulation of lactic acid in reduced oxygen concentrations. The rate of movement of L. quinquemaculosa was greatly influenced by the dissolved oxygen concentration, with activity being reduced at low oxygen levels; L. undulata was influenced to a lesser degree; and H. tenuabilis was virtually unaffected. The difference in responses of H. tenuabilis to various dissolved oxygen concentrations as compared to L. undulata and L. quinquemaculosa may result from its evolution in ponds which experience radical changes in oxygen concentrations as opposed to the more uniform conditions of streams inhabited by the other two species.