The cornucopia of chilly winters: Ocean quahog (Arctica islandica L., Mollusca) master chronology reveals bottom water nutrient enrichment during colder winters (North Sea)

Abstract

The cornucopia of chilly winters: Ocean quahog (Arctica islandica L., Mollusca) master chronology reveals bottom water nutrient enrichment during colder winters (North Sea). -Senckenbergiana marit., 32 (1/2): 165-175, 6 figs., 1 tab.; Frankfurt a.M.]We studied variations in annual shell growth rates of ten live-collected Arctica islandica specimens from three localities at the Dogger Bank in the central North Sea. Synchronous growth curves from contemporaneous specimens enabled the construction of a 65-year multi-locality master chronology.Stepwise multiple linear correlation analysis indicated a highly significant (p < 0.01) negative relationship between annual shell growth and winter sea surface temperatures (SST) during the period of 1953 to 1995. Up to 27.5% of the variation in the annual shell growth is explained by winter temperature. We explain the higher growth levels in colder winters by higher food supply. During warmer winters both the stratification and bottom water currents in the study area seem to be stronger and prevent downwardmixing of nutrients as well as settlement of food on the sea floor. During colder winters, however, the stratification weakens and phytoplankton produced in the cold surface layer reaches the sea floor. Longterm changes in shell growth rates are thus directly connected to hydrographic changes in the North Sea, which in turn are related to fluctuations of the North Atlantic Oscillation (NAO).Our study demonstrates the usefulness of Arctica islandica for long-term, high-resolution environmental reconstructions and contributes to further understanding natural and anthropogenic variability in the environmental history of the North Sea.

Growth trends in three bivalve species indicate climate forcing on the benthic ecosystem in the southeastern North Sea

“…Furthermore, hypoxic conditions associated with high summer temperatures in the Oyster Grounds (de Wilde et al 1984) could lead to a reduction of shell growth rates, because the animals become dormant (Abele 2002). The weak positive relation between growth and temperature in spring and summer, and the stronger negative relation with autumn and winter temperatures, are consistent with the results of Schöne et al (2003Schöne et al ( , 2004, who found a significant negative correlation between winter air temperature and shell growth in A. islandica from the Dogger Bank (central North Sea). Schöne et al (2004) showed that increment width in A. islandica shells from the Amrum Bank did not correlate with stable isotope derived temperatures in the main growing season (February to September).…”

Compound response of marine and terrestrial ecosystems to varying climate: Pre-anthropogenic perspective from bivalve shell growth increments and tree-rings

“…Climate affects the marine ecosystems indirectly by changing the ecosystem properties that are of importance to the growth of organisms (Ottersen et al, 2001(Ottersen et al, , 2004; significant aquatic properties for the growth of marine organisms include temperature, salinity, food supply, water column stratification and sedimentation (Schö ne et al, 2003a;Witbaard et al, 2003). Growth may be influenced contemporaneously or with lagged responses (Witbaard et al, 2003;Ottersen et al, 2001Ottersen et al, , 2004.…”

Environmental influence on the bottom and near-bottom megafauna communities of the Dogger Bank: a long-term survey

“…Another example is the bivalve Arctica islandica. The growth rings of its shell are a good index for climatic events, impressively demonstrated by Schöne et al (2003Schöne et al ( , 2005. Additionally, the shell of A. islandica together with the shells of Mya truncata and Chamelea striatula can be used to show sediment re-suspension strength due to storms, as shown by Witbaard et al (2005).…”