ABSTRACT

Six carbon-dated late Holocene Queen Scallop (Aequipecten opercularis) shells from the southern North Sea, ranging in age from 2,535 to 965 years BP, were serially sampled and analysed for oxygen and carbon stable isotopic composition. Oxygen isotope profiles show substantial cyclical variation and reflect seawater temperature fluctuation, whose full seasonal range was recorded. Considered in relation to the dates of the shells, the temperature information does not support previous notions of late Holocene climatic change in the European area. Specifically, shells from allegedly warm periods provide evidence of relatively cool conditions; those from allegedly cool periods indicate relatively warm conditions. The data must, however, be treated with great circumspection because of the small number of shells analysed. Carbon isotope profiles exhibit relatively little variation, no consistent pattern, and are difficult to interpret in terms of environmental variables. There is, however, a statistically significant difference between the means of late Holocene and modern carbon isotopic compositions; this probably reflects changes in the anthropogenic supply of CO₂ to the atmosphere. Late Holocene A. opercularis rarely exhibit the winter growth interruptions observed in modern shells from the North Sea, and are more abundant. This may reflect the absence of pollution.

Jon A. Hickson and Andrew L.A. Johnson. Division of Earth Sciences, School of Environmental and Applied Sciences, University of Derby, Derby DE22 1GB, UK.
Tim H.E. Heaton. Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham NG12 5GG, UK.
Peter S. Balson. Coastal Geology and Engineering Group, British Geological Survey, Keyworth, Nottingham NG12 5GG, UK.

KEY WORDS: Queen Scallop, stable isotopes, seasonal temperature, Holocene