A Note On Tidal Asymmetry In The Severn Estuary

A one-dimensional, non-linear numerical model is used to investigate the tidally averaged frictional stress and set-up of water level due to tidal asymmetry in the Severn Estuary; these quantities depend on the overtides in the region. A linearized model of the overtides is applied to calculations of the M4 currents in order to delineate the mechanisms responsible for their generation. The relative importance of individual non-linear mechanisms to the tidally averaged stress and set-up is determined; these mechanisms are interactions between tidal flow and changes in depth or breadth over a cross-section, frictional interaction between the tidal flow and Stokes drift, interaction between the tidal fluctuations in water depth and frictional retardation and non-linear advection.

Responses Of Mytilus-Edulis L To Low Oxygen-Tension - Acclimation Of Rate Of Oxygen-Consumption

1. Mytilus edulis acclimated its rates of oxygen consumption when maintained at reduced oxygen tensions for periods in excess of five days. 2. Acclimation was complete down to approximately 55 mm Hg PO2 at slightly lower oxygen tensions (51, 49 and 43 mm Hg) acclimation was complete in one experiment and partial in two others. 3. The capacity to acclimate oxygen consumption was not affected by a reduction in ration nor by an increase in temperature (10 to 22 °C). 4. Mussels that were acclimated to reduced oxygen tension (40–80 mm Hg), and then exposed to P O 2 of less than 20 mm Hg for two or five hours, had depressed rates of oxygen uptake when subsequently “recovered” to 40–80 mm Hg. 5. These results are discussed in the context of biochemical studies of anaerobic metabolism in mussels from the same experiments.