Meeting Abstract
P2.26 Saturday, Jan. 5 Environmentally-driven changes to metabolic scaling relationships in grazing mollusks CAREY, N; SIGWART, JD*; Queen’s Univerity Belfast; Queen’s Univerity Belfast j.sigwart@qub.ac.uk
Scaling of metabolic rate with organismal body mass shows significant natural variation within certain boundaries associated with ecology and activity patterns, not following traditional 2/3 or 3/4 scaling. Chitons (polyplacophoran mollusks) exhibit natural variation in both basal metabolic rates and scaling relationships, with differences linked to lifestyle and natural history. The magnitude of the scaling exponent can describe relationships between organisms of different sizes, so this has broad scale implications for the dynamics and composition of natural communities. If metabolic scaling exponents are plastic to extrinsic factors, they may be altered under conditions of environmental change, such as future warming and ocean acidification. To test this, we acclimated three species of chiton from the north-eastern Pacific (Katharina tunicata, Tonicella lineata, Mopalia muscosa) to conditions from future climate change scenarios. Three temperatures and two pH conditions were examined in a factorial design, to determine the synergistic and antagonistic effects of these factors on both basal metabolism and the scaling of metabolism. Thirty specimens of each species, representing full ontogenetic series were acclimated to treatment for one week (i.e. 540 specimens in total), and then examined for changes to basal metabolic rate (respiration). Acclimation to higher temperature, as expected, caused metabolic rate to increase; however, the effect of increased pCO₂ was less pronounced. The combined effects of increased temperature and pCO₂ were erratic, and not simply additive. These data suggest species’ physiology will show complex, unpredictable reactions to multiple stressors under future climate change scenarios, and this may have similarly unpredictable and complex effects on community composition.
