Water mass dynamics around cold-water coral reefs in the North Atlantic

Cold-water coral reefs are distributed all over the world’s oceans and form a high variety of ecosystems depending on their specific environmental factors. The surrounding parameter of cold-water coral reef growth is characterised by hydrophysical signals such as temperature and salinity, both yielded in potential density as a function of temperature, salinity and pressure. Within the past years a serious increase in knowledge on these cold-water coral occurrences and their hydrographic boundary conditions yielded worldwide, especially in the north-east Atlantic. This study investigates in the assessment of the environmental conditions of cold-water coral (CWC) growth in response to geochemical, hydrographic and oceanographic boundary processes. This study aims to unravel the environmental signals that influence CWC growth in different latitudes, which are of great importance for growth and occurrences. For this purpose, cold-water coral reefs in the north Atlantic margin, in the Gulf of Mexico, off Bahamas, in the Bay of Biscay, and off Morocco as well as Mauretania were selected. The comparison of data sets collected with identical tools yielded detailed information on the environmental conditions needed for healthy cold-water-reef growth

Environmental forcing of the Campeche cold-water coral province, southern Gulf of Mexico

With an extension of >40 km2 the recently discovered Campeche cold-water coral province located at the northeastern rim of the Campeche Bank in the southern Gulf of Mexico belongs to the largest coherent cold-water coral areas discovered so far. The Campeche province consists of numerous 20 to 40 m high coral ridges that are developed in intermediate water depths of 500 to 600 m. The ridges are colonized by a vivid cold-water coral ecosystem that covers the upper flanks and summits. The rich coral community is dominated by the framework-building scleractinia Enallopsammia profunda and Lophelia pertusa while the associated benthic megafauna shows a rather scarce occurrence. The recent environmental setting is characterized by a high surface water production caused by a local upwelling center and a dynamic bottom water regime comprising vigorous bottom currents, internal waves and strong density contrasts, which all together provide optimal conditions for the growth of cold-water corals. The strong hydrodynamics – potentially supported by the diel vertical migration of zooplankton in the Campeche area – drive the delivering of food particles to the corals. The Campeche cold-water coral province is, thus, an excellent example highlighting the importance of the hydrographic setting in securing the food supply for the development of large and vivid cold-water coral ecosystems

Morphology, processes and geohazards of giant landslides in and around Agadir Canyon, northwest Africa - Cruise MSM32 - September 25 - October 30, 2013 - Bremen (Germany) - Cádiz (Spain)

Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. CTD casts were collected at nine stations including one 13 hour Yo-yo CTD. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. Living deep-water corals were recovered from a large mound field north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz

Wassermassendynamik in der Umgebung der Kaltwasser-Korallen im Nordatlantik

Cold-water coral reefs are distributed all over the world’s oceans and form a high variety of ecosystems depending on their specific environmental factors. The surrounding parameter of cold-water coral reef growth is characterised by hydrophysical signals such as temperature and salinity, both yielded in potential density as a function of temperature, salinity and pressure. Within the past years a serious increase in knowledge on these cold-water coral occurrences and their hydrographic boundary conditions yielded worldwide, especially in the north-east Atlantic. This study investigates in the assessment of the environmental conditions of cold-water coral (CWC) growth in response to geochemical, hydrographic and oceanographic boundary processes. This study aims to unravel the environmental signals that influence CWC growth in different latitudes, which are of great importance for growth and occurrences. For this purpose, cold-water coral reefs in the north Atlantic margin, in the Gulf of Mexico, off Bahamas, in the Bay of Biscay, and off Morocco as well as Mauretania were selected. The comparison of data sets collected with identical tools yielded detailed information on the environmental conditions needed for healthy cold-water-reef growth.Kaltwasser-Korallenriffe sind weltweit in den Ozeanen verbreitet und bilden eine große Variabilität in ihrem Ökosystem und ihren damit einhergehenden, spezifischen ökologischen Faktoren. Die umgebenden hydrophysikalischen Parameter, die das Wachstum der Kaltwasser-Korallenriffe kennzeichnen, sind u.a. Temperatur und Salzgehalt, welche die potenzielle Dichte als eine Funktion aus Temperatur, Salzgehalt und Umgebungsdruck ergeben. Innerhalb der vergangenen Jahre haben sich die Erkenntnisse der weltweiten, hydrografischen Randbedingungen zu diesen existierenden Kaltwasser-Korallenriffen erheblich verstärkt, insbesondere im Nordost-Atlantik. Diese Studie untersucht und beurteilt die vorhandenen Wachstums- und Umweltbedingungen der Kaltwasser-Korallenriffe in Abhängigkeit zu den geochemisch, hydrographisch und ozeanographisch abgrenzenden Prozessen. Ein Ziel dieser Studie ist die Entwirrung der bestehenden Signale, welche das Wachstum der Kaltwasser-Korallenriffe in unterschiedlichen Breitengraden beeinflussen und von großer Bedeutung für deren Wachstum und Vorkommen sind. Zu diesem Zweck werden die Kaltwasser-Korallenriffe im Nord-Atlantik, im Golf von Mexiko, vor den Bahamas, im Golf von Biskaya, und vor Marokko und Mauretanien herangezogen. Für diesen Datenvergleich wurden identische Bedingungen, Instrumente und Methoden zur Datengewinnung verwendet, mit dem Ziel, detaillierte Informationen zu den umgebenden Bedingungen zu erzielen, die als Voraussetzung für ein gesundes Wachstum und zur Verbreitung der Kaltwasser-Korallenriffe benötigt werden. Kaltwasser-Korallenriffe sind weltweit in den Ozeanen verteilt und bilden eine große ökologische Bandbreite für das jeweilige Ökosystem, das von den dort vorherrschenden spezifischen Faktoren abhängig ist