Logo Universitat Bremen
 

books

.
 
.
..

Wienberg C, Freiwald A, Frank N, Mienis F, Titschack J, Orejas C, Hebbeln D (2023). Chapter 8: Cold-wa­ter coral reefs in the oxy­gen min­imum zones off West Africa. In: Cordes E, Mienis F, Cold-Wa­ter Coral Reefs of the World, Sprin­ger se­ries: Co­ral Reefs of the World. Springer International Publishing, Cham, pp. 199-235.

Abstract - The discoveries of large reefs within cold-water coral mound provinces revealed that the West African margin is a coral hotspot area in the Atlantic Ocean. The most striking observation is that cold-water corals thrive in extensive oxygen minimum zones under extreme conditions. This points to a wide tolerance of cold-water corals in these regions to low oxygen concentrations. The coral mound provinces off Mauritania, Angola, and Namibia, which are located in the centre of the local oxygen minimum zones, were selected as key study areas, and their regional oceanographic, bio-ecological, and geo-morphological settings are described in detail. Even though all three provinces are characterised by highly productive, oxygen-depleted, and relatively warm environmental conditions, they differ considerably with respect to the present-day reef status and the timing of mound formation during the last glacial-interglacial cycle. Today's bottom-trawl fishing and oil and gas exploration pose severe threats to the coral communities, and together with predicted ocean warming and deoxygenation, these areas may not continue to support living coral reefs. To fully understand the ecology of the West African cold-water corals and the regional environmental control mechanisms, research strategies following a multidisciplinary and integrated approach are needed.

cover
(c) Springer

Gori A, Wienberg C, Grinyo J, Tavi­ani M, Hebbeln D, Lo Iac­ono C, Freiwald A, Orejas C (2023). Chapter 7: Life and death of cold-wa­ter cor­als across the Medi­ter­ranean Sea. In: Cordes E, Mienis F, Cold-Wa­ter Coral Reefs of the World, Sprin­ger se­ries: Co­ral Reefs of the World. Springer International Publishing, Cham, pp. 171-197.

Abstract - The development of underwater technology and the increased use of remotely operated vehicles (ROVs) and manned submersibles for the exploration of the deep sea has resulted in a recent change of paradigm about Mediterranean cold-water coral abundance and distribution. Whereas initially thought to have been almost eradicated by oceanographic changes during the last deglaciation, expeditions run in the last two decades have found evidence of abundant living cold-water coral communities in the Mediterranean, especially in its western and central basins. As a result, we now know that the Mediterranean Sea offers appropriate conditions for cold-water corals in many areas, where scleractinians, gorgonians and black corals grow on both hard and soft substrata constituting emblematic ecosystems, whereas other areas only show fossil evidence of their past prosperity. Here, we update the current knowledge on the present and past occurrence of cold-water corals in the Mediterranean Sea, highlighting specificities, and discussing threats they are exposed to in this semienclosed basin under high human-induced pressure.

cover
(c) Springer

Cordes EE, Mienis F, Gasbarro R, Davies A, Baco AR, Bernardino AF, Clark MR, Freiwald A, Hennige SJ, Huvenne VAI, Buhl-Mortensen P, Orejas C, Quattrini AM, Tracey DM, Wheeler AJ, Wienberg C (2023) A Global View of the Cold-Water Coral Reefs of the World. In: Cordes E, Mienis F (eds) Cold-Water Coral Reefs of the World. Springer International Publishing, Cham, pp. 1-30.

Abstract - Cold-water corals (CWC) form reef structures in continental margin and seamount settings at tropical, temperate, and even some polar latitudes. This global distribution makes them more widespread than shallow-water reefs, while their role in these regions is no less important than the influence that shallow-water coral reefs have on shallow, tropical systems. They create habitat structure, host endemic species, enhance elemental cycling, alter current flow, sequester carbon, and provide many other ecosystem services that we are just beginning to understand. This introductory chapter to The Cold-Water Coral Reefs of the World reviews historical and recent information, reveals new findings from reefs that have been discovered only recently, and presents key avenues for future research. Global distribution and environmental data are synthesized into an ensemble model that described the niche of key species of framework-forming corals. Using an algorithm to distinguish coral colony occurrence from coral reef and mound occurrence, we further describe the subset of conditions under which CWC form reefs. This effort reveals new areas that are highly likely to host undiscovered CWC reef habitats and provides a framework for future ocean exploration. We are on the cusp of understanding the critical role that CWC reefs play in the world ocean, and this chapter and this book helps to set the stage for future efforts to determine their global impact and potential threats to the ecosystem services they provide.

cover
(c) Springer

Wienberg C (2019). A de­gla­cial cold-wa­ter coral boom in the Al­boran Sea: from coral mounds and spe­cies dom­in­ance. In: Orejas C, Jiménez C, Medi­ter­ranean Cold-Wa­ter Cor­als: Past, Present and Fu­ture, Springer series: Coral Reefs of the World. Springer, pp. 57-60.

Abstract - The two scleractinian cold-water corals Lophelia pertusa and Madrepora oculata are widely distributed in the Alborán Sea. They have been found (alive and fossil) on seamounts, volcanic ridges and mud volcanoes, and they formed coral mounds in the geological past. While the cold-water corals show a reduced occurrence during the last glacial period, they experienced a boom since the last deglaciation until the Early Holocene. The proliferation of cold-water corals during this time is expressed in very high vertical mound aggradation rates of >400 cm kyr−1. Since the mid-Holocene coral mound aggradation significantly slowed-down, which is ascribed to the reduced occurrence of cold-water corals likely supplemented by a reduced sediment supply. During the Holocene, a shift in coral species dominance towards a M. oculata-dominated cold-water coral community becomes apparent. It is speculated that in comparison to L. pertusa, M. oculata has a higher tolerance against the increasing Holocene bottom water temperatures, but is not efficient in building-up mounds likely attributed to its thinly branching framework.

cover
(c) Springer

2017

Wienberg C, Titschack J (2017). Framework-forming scleractinian cold-water corals through space and time: A late Quaternary North Atlantic perspective. In: Rossi S, Bramanti L, Gori A, Orejas C, Mar­ine An­imal Forests: the Eco­logy of Benthic Biod­iversity Hot­spots. Springer, pp. 699-732.

Abstract: Framework-forming scleractinian cold-water corals, with Lophelia pertusa and Madrepora oculata being the most common species, show an outstanding concentration in the North Atlantic Ocean. They are unique in their ability to provide habitats for other organisms ranging from micro- to mega-scale, and some species are even exceptional in their capability to shape the seafloor by forming large three-dimensional structures called coral mounds. Our understanding about the spatial and temporal distribution of cold-water corals and coral mounds and the environmental factors that control coral occurrence and influence mound development increased tremendously during the past 15 years. This synthesis highlights that: (i) species-specific environmental preferences and tolerances need to be considered when describing any coral distribution pattern; (ii) corals and coral mounds are linked to a complex set of multiple environmental variables that must work in concert as each variable might present a stimulator as well as a suppressor for coral occurrence and mound formation; (iii) environmental conditions for mound aggradation are more restrictive than those for coral occurrence; and (iv) the majority of environmental variables influencing the occurrence of corals and mound development are linked to distinct water masses whose characteristics vary with climatic fluctuations. Hence, regional coral distribution pattern and mound aggradation periods are in phase with these fluctuations, even though the specific environmental controls might vary from region to region. Nevertheless, certain data limitations and resulting constraints to generate generalized pattern regarding the climate-related spatiotemporal distribution of cold-water corals and coral mounds still exist and ask for more sophisticated future research strategies.

cover
(c) Springer