Along the Atlantic European continental margin, living cold-water coral reefs occur over a wide bathymetric and hydrographical range. Focusing on 2 regions, the Celtic and the Norwegian shelves, we found that cold-water coral reefs are limited to different intermediate water masses. Measurements of the physical and geological properties showed that parameters such as temperature, salinity, dissolved oxygen content, current intensities, and different substrates vary widely without specifically impacting the distribution of living cold-water coral reefs. The habitat of living reefs within the NE Atlantic comprises a temperature-salinity field, with its lower boundary equivalent to the Intermediate Salinity Maximum (ISM). The ISM on the Celtic margin is represented by Mediterranean Outflow Water (MOW), but is replaced by Atlantic Water (AW) on the Norwegian margin. The upper limit corresponds to water mass boundaries of Eastern North Atlantic Water / MOW on the Celtic margin and Norwegian Coastal Water / AW on the Norwegian margin. Our study shows that cold-water corals in the North Atlantic tolerate a wide range of environmental conditions. However, our data indicate that living cold-water coral reefs occur within the density envelope of sigma-theta (σ Θ ) = 27.35 to 27.65 kg m -3 , thus highlighting the importance of physical boundary conditions for cold-water coral growth and distribution.

Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CREA-IT),

No abstract

[1] An 8 million year record of subtropical and midlatitude shelf-sea temperatures, derived from oxygen isotopes of well-preserved brachiopods from a variety of European sections, demonstrates a long-term Cenomanian temperature rise (16-20°C, midlatitudes) that reached its maximum early in the late Turonian (23°C, midlatitudes). Superimposed on the long-term trend, shelf-sea temperatures vary at shorter timescales in relation to global carbon cycle perturbations. In the mid-Cenomanian and the late Turonian, two minor shelf-sea cooling events (2-3°C) coincide with carbon cycle perturbations and times of high-amplitude sea level falls. Although this evidence supports the hypothesis of potential glacioeustatic effects on Cretaceous sea level, the occurrence of minimum shelf-sea temperatures within transgressive beds argues for regional changes in shelf-sea circulation as the most plausible mechanism. The major carbon cycle event in the latest Cenomanian (oceanic anoxic event 2) is accompanied by a substantial increase in shelf-sea temperatures (4-5°C) that occurred $150 kyr after the commencement of the d 13 C excursion and is related to the spread of oceanic conditions in western European shelf-sea basins. Our oxygen isotope record and published d 18 O data of pristinely preserved foraminifera allow the consideration of North Atlantic surface water properties in the Cenomanian along a transect from the tropics to the midlatitudes. On the basis of fossil-derived d 18 O, estimated dw ranges, and modeled salinities, temperature-salinity-density ranges were estimated for tropical, subtropical, and midlatitude surface waters. Accordingly, the Cenomanian temperate shelf-seas waters have potentially the highest surface water density and could have contributed to North Atlantic intermediate to deep waters in the preopening stage of the equatorial Atlantic gateway.

Auslöser für größtes Massenaussterben der Erdgeschichte identifiziert Neue Studie liefert umfassende Rekonstruktion der Perm-Trias-Grenze 19.10.2020/Kiel. Vor 252 Millionen Jahren starben am Übergang vom Erdzeitalter des Perm zu dem der Trias die meisten damals auf der Erde existierenden Lebensformen aus. Mit Hilfe neuester Analysemethoden und detaillierter Modellrechnungen ist es Wissenschaftlerinnen und Wissenschaftlern des GEOMAR Helmholtz-Zentrums für Ozeanforschung Kiel in Kooperation mit dem Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum und internationalen Partnern jetzt erstmals gelungen, die geochemischen Abläufe, die zu diesem Massenaussterben geführt haben, schlüssig nachzuvollziehen. Die Studie ist heute in der Fachzeitschrift Nature Geoscience erschienen.