On exposure to the atmosphere at low tide, bivalve molluscs avoid desiccation by shell closure, which can result in hypoxic conditions within the mantle cavity. Thus, these animals may exhibit an anaerobic pattern of metabolism during tidal exposure. However, during exposure to the atmosphere, the four species of bivalve molluscs (Mytilus edulis, Cardium edule, Scrobicularla plane and Macoma balthica) investigated were found to be able to incorporate atmospheric 14C02 into their tissues. It is suggested that the accessibility of atmospheric 14CO2 into the interior of these animals during exposure argues that atmospheric oxygen is also accessible to the interior and that these animals are not normally completely anaerobic during exposure to the atmosphere. Significant seasonal changes in the metabolism of 14C02 by tissues of M. edulis were observed. It is argued that these changes are due to seasonally-dependent changes in the energy reserve and not to differences in temperature. However, experimentally induced changes in temperature were found to reinforce the succinate pathway. Experiments designed to measure the metabolism of 14C02 by M. edulis, C. edule and S. plane e- under various environmental conditions (aerobic, anaerobic exposed and buried) indicate clear species differences. The results are discussed in relation to the ecological distribution of each species. C. edule was observed to be independent of the succinate pathway during exposure. This independence was not seasonally linked. However, S. plane utilised the succinate pathway during exposure to the atmosphere and the extent-62f such utilisation is subjected to significant seasonal changes. A comparative study on the metabolism of 14C02 by the four species of bivalve molluscs suggests that the pattern of incorporation is dominated by species differences. Significant tissue differences were also observed. The effect of temperature on the kinetics of the enzyme pyruvate kinase from the adductor muscle of M. edulis was examined. It is suggested that the succinate pathway operates not only during hypoxia, but also in response to stressful situations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635851 |
| Date | January 1979 |
| Creators | Ahmad, T. A. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0016 seconds