Meeting Abstract

48.5  Thursday, Jan. 5  Metabolic rates of an aquatic tardigrade, Dactylobiotus nuovo species. MEADE, Mark/E*; ROMANO, Frank; SEWELL, Susan; Jacksonville State University mmeade@jsu.edu

We report here the use of a fiber optic, micro-respirometry system to monitor oxygen consumption rates in aquatic tardigrades. The system is highly sensitive (accuracy ±0.15% at 1% air saturation with a limit of detection of 15 ppb dissolved oxygen) and is not prone to drift as polarographic sensors are. Oxygen consumption of individual adults, eggs, and cysts of Dactylobiotus nuovo sp. were measured at 17C, 22C, and 27C. Individual adults acclimated to 17C averaged 238.1 + 7.2 mgO2/kg/hr and increased oxygen consumption rates to 601.33 + 9.8 mgO2/kg/hr when acclimated to 22C. Adults acclimated to 27C had significantly decreased oxygen consumption rates averaging 0.325 + 0.2 mgO2/kg/hr. Individual eggs at 17C averaged 545.1 + 14.1 mgO2/kg/hr and increased oxygen consumption rates to 1478.5 + 23.6 mgO2/kg/hr at 22C. Cysts acclimated at 17C averaged 104.1 + 8.1 mgO2/kg/hr and more than quadrupled oxygen consumption rates to 446.2 + 13.1 mgO2/kg/hr at 22C. Eggs and cysts were not produced from animals held at higher temperatures, thus no data is presented for individuals at 27C. These results indicate that oxygen consumption rates in this Tardigrade species follows previous trends demonstrated by other invertebrate species where environmental temperatures greatly influence oxygen consumption and, hence, overall metabolism. As indicated by significantly reduced oxygen consumption rates at 27C, this temperature may be beyond limits of tolerance for Dactylobiotus nuovo sp. Higher oxygen consumption rates in eggs may be reflective of higher energetic demands associated with developmental processes. Lower oxygen consumption rates for cysts indicate a reduction in metabolism as previously hypothesized.