Klimagesteuerte Langzeit-Entwicklung von nordatlantischen Kaltwasserkorallen-Ökosystemen - Wachstums- und Migrationsmuster aus einer transatlantischen Perspektive
Zusammenfassung der Projektergebnisse
Within the frame of the DFG-project Palaeo-WACOM, cold-water coral sites in the NW Atlantic, namely in the Gulf of Mexico and Florida Straits, were studied with a focus on the recent coral occurrence and on the variability of mound aggradation pattern during the Late Pleistocene and Holocene. The outcomes of this project provide several new details on the depositional regime since the Late Pleistocene. These are the highlights of our results: Along the north-eastern slope of the Campeche Bank (Yucatan Peninsula), a new coral mound province with a minimum extension of 40 km2 was discovered (and described in detail), which belongs to the worldwide largest coherent coral mound areas discovered so far. The CWC community of the Campeche area is dominated by Lophelia pertusa and Enallopsammia profunda, and the associated megafauna shows a rather low abundance compared to NE Atlantic CWC sites. The recent proliferation of CWC in the Campeche CWC province is most likely controlled by high surface water production caused by a local upwelling centre and a dynamic bottom-water regime. The temporal (glacial-interglacial) development of the Campeche coral mounds resembles the pattern identified for Irish coral mounds with mound development being largely restricted to interglacial periods, although vertical mound aggradation rates seem to be significantly lower for the Campeche area with rates of 12 and 49 cm kyr^-1. Mound-like seabed structures along the West Florida slope hitherto described as coral mounds were clearly identified to be large rocky boulders (possibly related to major landslides) lying exposed on coarse sandy sediments. The rocky boulders are just sporadically colonized by living CWC and superficially covered by coral rubble and dead coral framework. Mound-like seabed structures along the western slope of the Great Bahama Bank also largely comprise rocky boulders and blocks originating from mass wasting events. In contrast to the West Florida slope, some of these blocks and boulders are covered by metre-thick accumulations of fossil CWC remnants which clearly have the attributes of typical coral mound sediments pointing to some of these structures being the initial state of coral mounds. The temporal development of the "coral mounds" along the western slope of the Great Bahama Bank seems to be far more complex than the temporal pattern identified for coral mound in the NE Atlantic. Some mounds show a continuous development since the last glacial with rather low vertical aggradation rates of ~10 cm kyr^-1, whereas the temporal development of other mounds seems to be restricted to the Holocene with very high aggradation rates of up to 190 cm kyr^-1. The number of coral ages obtained for framework-forming scleractinian CWC in the NW Atlantic could tremendously be increased by adding 68 new Lophelia ages. A compilation of Lophelia ages, thereby comparing the temporal occurrence of this species in the eastern and western Atlantic during the past 24 kyrs, revealed two deglacial refugia (off Brazil and in the Mediterranean Sea) from which coral larvae were exported towards more northern sites. Moreover, the (Atlantic part of the) global ocean conveyor belt might have acted as a key agent in controlling the spatio-temporal distribution of Lophelia (by supplying larvae) across the entire Atlantic Ocean.
Projektbezogene Publikationen (Auswahl)
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(2013). Scale worms (Polychaeta: Aphroditiformia) associated with cold-water corals in the eastern Gulf of Mexico. Journal of the Marine Biological Association of the United Kingdom 93: 2129-2143
Barnich R, Beuck L, Freiwald A
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(2014). Environmental forcing of the Campeche cold-water coral province, southern Gulf of Mexico. Biogeosciences 11(7): 1799-1815
Hebbeln D, Wienberg C, Wintersteller P, Freiwald A, Becker M, Beuck L, Dullo C, Eberli GP, Glogowski S, Matos L, Forster N, Reyes-Bonilla H, Taviani M
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(2014). Global ocean conveyor lowers extinction risk in the deep sea. Deep Sea Research Part I 88: 8-16
Henry LA, Frank N, Hebbeln D, Wienberg C, Robinson L, van de Flierdt T, Dahl M, Douarin M, Morrison CL, Correa ML, Rogers AD, Ruckelshausen M, Roberts JM
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(2015). Where did ancient carbonate mounds grow – in bathyal depths or in shallow shelf waters? Earth-Science Reviews 145: 56-65
Hebbeln D, Samankassou E
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Interglacial occurrence of cold-water corals off Cape(NW Atlantic): First evidence of the Gulf Stream influence. Deep Sea Research Part I: Oceanographic Research Papers, Volume 105, November 2015, Pages 158-170
Matos L, Mienis F, Wienberg C, Frank N, Kwiatkowski C, Groeneveld J, Thil F, Abrantes F, Cunha M, Hebbeln D
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Framework-forming scleractinian cold-water corals through space and time: A late Quaternary North Atlantic perspective. S. 1-34 in: Rossi S, Bramanti L, Gori A, Orejas Saco del Valle C. (eds), Marine Animal Forests: the ecology of benthic biodiversity hotspots. Springer, Chem, 2016. eBook Packages: Biomedical and Life Sciences. Online ISBN 978-3-319-17001-5
Wienberg C, Titschack J
