Dullo, Wolf-Christian

Flögel, Sascha

Rüggeberg, Andres

English

OceanRep

Geophysical Research Abstracts,Vol. 11, EGU2009-5029, 2009EGU General Assembly 2009© Author(s) 2009Physical controls on cold-water coral growthS. Floegel, A. Rueggeberg, and C. DulloIFM-GEOMAR, Paleoceanography, Kiel, Germany (sfloegel@ifm-geomar.de)Along the Atlantic European continental margin, living cold-water coral reefs occur over a wide bathymetric andhydrographical range. Focussing on two regions, the Celtic and the Norwegian shelves we found that they arebound to different intermediate water masses. Measurements of the physical and geological properties indicatethat parameters such as temperature, salinity, dissolved oxygen content, current intensities, and different substratesdo vary in a wide range without impacting the distribution of living cold-water coral reefs to a first degree.Our study shows that cold-water corals in the North Atlantic tolerate a wide range of environmental conditions.The habitat of living reefs comprises a temperature-salinity field with its lower boundary being equivalent to theIntermediate Salinity Maximum (ISM). The ISM on the Celtic margin is represented by Mediterranean OutflowWater, while it is replaced by Atlantic Water on the Norwegian margin. The upper limit corresponds to water massboundaries of Eastern North Atlantic Water / Mediterranean Outflow Water on the Celtic margin and NorwegianCoastal Water / Atlantic Water on the Norwegian margin.The density of seawater is a frequently used parameter by oceanographers to describe and understand ocean-mixing processes, as it is easier to mix water along a surface of constant density (an ísopycnal)´ rather than acrossit. The potential density anomaly sigma-theta is a function of salinity, potential temperature, and pressure at the seasurface. This parameter indicates values of sigma-theta = 27.35 - 27.65 kg m-3 for all living cold-water coral reefsof the Porcupine Seabight, the Rockall Bank, and the Norwegian margin highlighting the importance of physicalboundary conditions on cold-water coral growth and distribution. Additional information from literature showsthat this value is also valid for reef sites along the Western Atlantic (Nova Scotia, Florida Strait, Brazilian margin)suggesting that this observation is an Atlantic-wide phenomenon. In areas where coral growth is restricted to somesmall patches and reefs, or recent mound growth is limited, like in the Gulf of Cadiz or off Mauritania, recentsigma theta values lay outside the envelope of 27.5 ± 0.15 kg m-3. However, it has to be mentioned that corals donot occur everywhere along the European continental margins where sigma theta values are around 27.5 kg m-3.In this case, second order parameters like sedimentation rates, currents, the lack or presence of good settlementsubstrates, nutrient concentrations, etc. are controlling the coral growth and settlement.LiteratureDullo, W.-Chr., Flögel, S., Rüggeberg, A. (in press) Cold-water coral growth in relation to the hydrography of theCeltic and Nordic European Continental Margin. Marine Ecology Progress Series.

Physical controls on cold-water coral growth

Abstract

Similar works

Full text

Available Versions

OceanRep