Temperature and basal metabolism in two Antarctic marine herbivores
V̇o2 was measured for specimens of the Antarctic brachiopod Liothyrella uva and limpet Nacella concinna, using couloximetric techniques. Time-course studies revealed different responses to starvation by each species. N. concinna initially responded with a rise in V̇o2 (68%) which lasted for ≈ 14 days, followed by a decline to a steady (basal) level which was reached 30–50 days after the start. The fed V̇o2 was 1.29 times the basal rate. L. uva did not show the initial rise in V̇o2 but exhibited a steady decline, resulting i basal rates after 25–30 days. Both species did, however, show a similar response in basal V̇o2 to 1.5 °C increments in temperature. This was a rise in V̇o2 to a peak which was reached between 2 and 7 days after the rise in temperature, followed by a decline to another steady level. In both species, acclimated and acute V̇o2 showed larger responses to 1.5 °C increments at lower temperatures than at higher ones. Acclimated V̇o2 essentially rose with each temperature increment to a plateau in both species and remained at those levels until the upper lethal temperature was reached. The brachiopods survived from an initial starting temperature of − 1.5 to 4.5 °C while the limpets had a much larger temperature range, from − 1.5 to 9.0 °C. Q10 coefficients reflected these patterns, declining with temperature. The highest figures for L. uva were obtained at the − 1.5 to 0.0 °C step and were 1.97 for acclimated rates and 9.73 for acute responses. The overall Q10 values ( − 1.5 to 3.0 °C) were 1.46 and 3.09, respectively. For N. concinna, the − 1.5 to 0.0 °C values were 3.17 (acclimated) and 34.19 (acute) and the overall figures (− 1.5 to 9.0 °C) were 2.41 and 15.62, respectively. This suggests that low Q10 values (≤2.5) are appropriate for use with cold-water species.