Growth of north-east Atlantic cold-water coral reefs and mounds during the Holocene: A high resolution U-series and 14C chronology

Abstract

We investigate the Holocene growth history of the Mingulay Reef Complex, a seascape of inshore cold-water coral reefs off western Scotland, using U-series dating of 34 downcore and radiocarbon dating of 21 superficial corals. Both chronologies reveal that the reef framework-forming scleractinian coral Lophelia pertusa shows episodic occurrence during the late Holocene. Downcore U-series dating revealed unprecedented reef growth rates of up to 12 mm a -1 with a mean rate of 3 -4 mm a -1 .Our study highlighted a persistent hiatus in coral occurrence from 1.4 ka to modern times despite present day conditions being conducive for coral growth. The growth history of the complex was punctuated at least twice by periods of reduced growth rates: 1.75 -2.8 ka, 3.2 -3.6 ka and to a lesser extent at 3.8 -4 ka and 4.2 ka. Timing of coral hiatuses and reduced reef growth rates at Mingulay were synchronous with those occurring across northern Europe. Our study suggests that large-scale shifts in 1 palaeoenvironmental regimes associated with changes to the North Atlantic subpolar gyre may control these ecosystems. IntroductionOne of the most widespread cold-water corals is the reef framework-forming scleractinian Lophelia pertusa, which to date is known from all oceans except the Southern Ocean ). In the NE Atlantic, Lophelia occurs preferentially along the European continental margin (De Mol et al., 2002;Kenyon et al., 2003;Wheeler et al., 2007) where it is often associated with areas of positive topographic relief such as banks, seamounts and ridges likely due to favourable environmental conditions (e.g. hydrology, food supply, current strength; Davies et al., 2008). Local hydrodynamics are crucial for coral dispersal and recruitment, preventing corals from being smothered by sediments, and as a food supply mechanism for sessile suspension feeders such as corals (Genin et al., 1986;Frederiksen et al., 1992;White et al., 2005;Mienis et al., 2007;White, 2007;Davies et al., 2009;Mienis et al., 2009).Some of the best-studied Lophelia reefs are those found on coral carbonate mounds that can grow hundreds of metres high and few kilometres long (Wheeler et al., 2007). Several models of coral carbonate mound ontogeny have been proposed to explain the initiation and development of such structures, which generally converge on the importance of a complex interaction between sediment accumulation and coldwater coral colonisation and growth under favourable environmental regimes (Henriet et al., 2001;De Mol et al., 2002;Dorschel, 2003;Roberts et al., 2006;Eisele et al., 2008; de Haas et al., 2008). The last 11 ka, as well as previous warm interglacial periods such as marine isotope stages (MIS) 5, 7 and 9, have been favourable for coral growth and thus coral carbonate mound development in the NE Atlantic between 50°N and 70°N (Frank et al., 2009;Douville et al., 2010;. To date no Lophelia from glacial periods have been found at these latitudes in the NE Atlantic (Dorschel, 2003;Kenyon et al., 2003;Schröder-Ritzrau et al., 2003;Fra...

Ecohydrodynamics of Cold-Water Coral Reefs: A Case Study of the Mingulay Reef Complex (Western Scotland)

“…The Mingulay reefs have developed intermittently during the Holocene with the oldest coral material so far dated from 7.7 ka [38]. A number of cases of apparently recent established coral colonies have been noted suggesting recruitment is still occurring [24].…”

Aggradation and carbonate accumulation of Holocene Norwegian cold‐water coral reefs

“…S1) highlight the importance of the baffling capacity of the CWC framework for CWC reef aggradation. The maximal reef aggradation rates of 10 to 15 mm yr −1 (Tables and S2; Douarin et al ., ; López Correa et al ., ) are on a similar order of magnitude as growth rate estimates of the predominant Norwegian framework‐builder Lophelia pertusa that range between 5·5 mm and 25 mm yr −1 (e.g. Mikkelsen et al ., ; Freiwald et al ., ; Mortensen, ; Orejas et al ., ; Sabatier et al ., ).…”

Eastern Mediterranean hydroclimate over the late glacial and Holocene, reconstructed from the sediments of Nar lake, central Turkey, using stable isotopes and carbonate mineralogy

“…Samples were processed using a total dissolution approach following Bischoff and Fitzpatrick (1991) and Luo and Ku (1991). Our analytical protocol was based on Edwards et al (1987) with modifications as described in Douarin et al (2013). This protocol was further augmented here to ensure complete silicate component dissolution.…”