The oxygen consumption of a freshwater benthic nematode, Tobrilus gracilis (Bastian)

Tobrilus gracilis (Bastian) was found to live predominantly in oxygen deficient mud layers of Neusiedlersee, Austria. The O₂-consumption of all active life stages was measured with Cartesian diver respirometers. The respiration-body weight regression (R=aW ^b; in μl O₂·10^-3/individual·h and μg wet weight) was calculated to be R=0.522 W ^0.693. This suggests that the species is not obligatory anaerobic but can use oxygen when available. Furthermore, a respiration-body weight regression was calculated for four other nematodes from a wide range of habitats using literature data. The regression coefficients ranged from 0.68-0.85 but were not significantly different (P=0.05). The intercept of the y-axis ("a" in the regression equation), which indicates the metabolic rate of a species, ranged from 1.34-2.01 μl·10^-3 O₂/individual·h at 20°C. Covariance analysis was used to test the differences in the level of metabolic activity for Tobrilus gracilis, Aphelenchus avenae and Panagrolaimus rigidus. It could be shown, that oxygen consumption of Tobrilus is significantly lower compared with the other species and it is concluded that the metabolism of this species is partially anaerobic, even when oxygen is available.