Claudia Wienberg

Northeastern Atlantic cold-water coral reefs and climate

U-series age patterns obtained on reef framework-forming cold-water corals collected over a nearly 6000-km-long continental margin sector, extending from off Mauritania (17 degrees N; northwest Africa) to the southwestern Barents Sea (70 degrees N; northeastern Europe), reveal strong climate influences on the geographical distribution and sustained development of these ecosystems. Over the past three glacial-interglacial cycles, framework-forming cold-water corals (Lophelia pertusa and Madrepora oculata) seem to have predominantly populated reefs, canyons, and patches in the temperate East Atlantic and the Mediterranean Sea. Above 50 degrees N corals colonize reefs in the northern East Atlantic primarily during warm climate periods with the biogeographic limit advancing from similar to 50 degrees N to similar to 70 degrees N. We propose that north-south oscillations of the biogeographic limit of reef developments are paced by ice ages and may occur synchronously with north-south displacement of cold nutrient-rich intermediate waters and surface productivity related to changes of the polar front.

Framework-Forming Scleractinian Cold-Water Corals Through Space and Time: A Late Quaternary North Atlantic Perspective

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 microto mega-scale, and some species are even exceptional in their capability to shape the seafloor by forming large C. Wienberg (*) MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany e-mail: cwberg@marum.de J. Titschack Marine Research Department, SAM – Senckenberg am Meer, Wilhelmshaven, Germany MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany e-mail: jtitschack@marum.de # Springer International Publishing Switzerland 2015 S. Rossi (ed.), Marine Animal Forests, DOI 10.1007/978-3-319-17001-5_16-1 1 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.

Mediterranean cold-water corals - an important regional carbonate factory?

This study presents aggradation rates supplemented for the first time by carbonate accumulation rates from Mediterranean cold‐water coral sites considering three different regional and geomorphological settings: (i) a cold‐water coral ridge (eastern Melilla coral province, Alboran Sea), (ii) a cold‐water coral rubble talus deposit at the base of a submarine cliff (Urania Bank, Strait of Sicily) and (iii) a cold‐water coral deposit rooted on a predefined topographic high overgrown by cold‐water corals (Santa Maria di Leuca coral province, Ionian Sea). The mean aggradation rates of the respective cold‐water coral deposits vary between 10 and 530 cm kyr−1 and the mean carbonate accumulation rates range between 8 and 396 g cm−2 kyr−1 with a maximum of 503 g cm−2 kyr−1 reached in the eastern Melilla coral province. Compared to other deep‐water depositional environments the Mediterranean cold‐water coral sites reveal significantly higher carbonate accumulation rates that were even in the range of the highest productive shallow‐water Mediterranean carbonate factories (e.g. Cladocora caespitosa coral reefs). Focusing exclusively on cold‐water coral occurrences, the carbonate accumulation rates of the Mediterranean cold‐water coral sites are in the lower range of those obtained for the prolific Norwegian coral occurrences, but exhibit much higher rates than the cold‐water coral mounds off Ireland. This study clearly indicates that cold‐water corals have the potential to act as important carbonate factories and regional carbonate sinks within the Mediterranean Sea. Moreover, the data highlight the potential of cold‐water corals to store carbonate with rates in the range of tropical shallow‐water reefs. In order to evaluate the contribution of the cold‐water coral carbonate factory to the regional or global carbonate/carbon cycle, an improved understanding of the temporal and spatial variability in aggradation and carbonate accumulation rates and areal estimates of the respective regions is needed.