Respiration, anaerobic survival and diel locomotory periodicity in Hirschmannia viridis Müller (Ostracoda).

The oxygen consumption rate (OCR) of the brackish water ostracod Hirschmannia viridis O. F. Muller is found to be salinity- and temperature-dependent. OCR is at its minimum at the average salinity of the area (The Sound, Oresund) (10-15%...) and an increase in the values is found both in sub- and supranormal salinities. This increase is enhanced by an increase in the temperature. The correlation between OCR and external temperature does not follow Arrhenius' law over the whole temperature range. Between 10°C and 20°C the increase in OCR is very small or absent but above and below these temperatures a clear correlation is found. There is no correlation between OCR and oxygen saturation of the surrounding water. In the range 20-80% saturation OCR is relatively constant, while a rapid decrease in OCR is found below 20% saturation (the incipient limiting point). Anaerobic conditions are survived for 13 hrs. in water of 10...%, salinity and 20°C. The time of survival is raised to 160 hrs. in water of 10% oxygen saturation and around the incipient limiting point (20% saturation) no excess mortality is found. The locomotory activity pattern of H. viridis is of the nocturnal bigeminus type. This pattern persists during dark periods of sufficient length (autumn and winter nights) but when the dark periods are shortened (spring and summer nights) only a single activity peak is found. The change between light and dark was found to be the Zeitgeber. [ABSTRACT FROM AUTHOR]