Ahermatypic Coral Banks off Mid-Norway: Evidence for a Link with Seepage of Light Hydrocarbons

Hovland, Martin; Buhl‐Mortensen, Lene; Brattegard, Torleiv; Strass, Per; Rokengen, Kare

doi:10.2307/3515489

Cited by 109 publications

(73 citation statements)

References 31 publications

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“…Low methane concentrations (<1 µM) at all investigated sediment depths in both coral reefs (data not shown) do not provide evidence for a coupling of cold-water coral reef distribution and the appearance of hydrocarbon seepage at the Mid-Norwegian cold-water coral reefs as previously suggested (Henriet et al, 1998;Hovland et al, 1998;Hovland and Risk, 2003;Hovland and Thomsen, 1997). The reefs are also underlain by very compact glacial clays, which inhibit the flux of deeper seated hydrocarbons into the post-glacial deposits.…”

Section: Microbial-mediated Organic Carbon Mineralizationmentioning

confidence: 56%

“…Previous studies have suggested an internal control linking micro-seepage of deep thermogenic hydrocarbons to coral reef occurrence on continental shelves (Hovland et al, 1998;Hovland and Risk, 2003;Hovland and Thomsen, 1997). The authors propose a model in which the migration of hydrocarbons into the water column locally "fertilizes" the ambient seawater with organic and inorganic compounds fueling thriving microbial and coral communities.…”

Section: Introductionmentioning

confidence: 99%

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Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

et al. 2009

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Abstract. Cold-water coral ecosystems are considered hotspots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the MidNorwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmol S cm −3 d −1 , suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH 2 O groups and 43% carbon in -CH 2 -groups. Methane concentrations were below 1 µM, and failed to support the hypothesis of a linkage between the distribution of coldwater coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron

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Section: Microbial-mediated Organic Carbon Mineralizationmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

et al. 2009

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“…Two theories have been forwarded to explain the initiation and growth of these impressive structures: (1) oceanographic and paleoenvironmental conditions control mound initiation and growth (external control), and (2) hydrocarbon seepage initiates microbial-induced carbonate formation and indirectly fuels coral growth (internal control) (Hovland et al, 1998;Henriet et al, 2001). The oceanographic or environmental hypothesis states that the two most important conditions for stimulating mound development are (1) strong, nutrient-rich currents that provide suspended food to the fi lter-feeding corals, sweep the polyps clean of detritus and inhibit sediment burial, and (2) a stable substrate for settlement of coral larvae (Frederiksen et al, 1992).…”

Section: External Vs Internal Control On Mound Developmentmentioning

confidence: 99%

IODP Expedition 307 Drills Cold-Water Coral Mound Along the Irish Continental Margin

Ferdelman

Kano

Williams

2006

Scientific Drilling

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Introduction Over the past decade, oceanographic and geophysical surveys along the slope of the Porcupine Seabight off the southwestern continental margin of Ireland have identified upwards of a thousand enigmatic mound-like structures (Figs. 1 and 2). The mounds of the Porcupine Seabight rise from the seafl oor in water depths of 600–900 m and formimpressive conical bodies several kilometers wide and up to 200 m high. Although a few mounds such as Thérèse Mound and Galway Mound are covered by a thriving thicket of coldwater corals, most mound tops and fl anks are covered by dead coral rubble or are entirely buried by sediment (De Mol et al., 2002; Fig. 2, Beyer et al., 2003). Lophelia pertusa (Fig.3) and Madrepora oculata are the most prominent cold-water corals growing without photosynthetic symbionts. The widespread discovery of large and numerous coral-bearing banks and the association of these corals with the mounds have generated signifi cant interest as to the composition, origin and development of these mound structures.Challenger Mound, in the Belgica mound province, has an elongated shape oriented along a north-northeast to south-southwest axis and ispartially buried under Pleistocene drift sediments. In high-resolution seismic profiles the mounds appear to root on an erosion surface (van Rooij et al., 2003). During IODP Expedition307 the Challenger Mound in the Porcupine Seabight was drilled with the goal of unveiling the origin and depositional processes withinthese intriguing sedimentary structures. Challenger Mound, unlike its near neighbors the Thérèse and Galway mounds, has little to no livecoral coverage and, therefore, was chosen as the main target for drilling activities, so that no living ecosystem would be disturbed

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“…Since about a decade these deep-water coral reefs are subject to extensive European research efforts to better constrain ecosystem functioning and coral reef development (Henriet et al, 1998;Hovland et al, 1998;de Mol et al, 2002;Dorschel et al, 2005;Freiwald and Roberts, 2005;White et al, 2005;Roberts et al, 2006;van Rooij et al, 2006;Dorschel et al, 2007;Mienis et al, 2007;Wheeler et al, 2007). These mounds can achieve a height of several hundred meters and measure several square kilometres at the base (Hovland et al, 1994;de Mol et al, 2002;Huvenne et al, 2003;Kenyon et al, 2003;van Weering et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

The Holocene occurrence of cold water corals in the NE Atlantic: Implications for coral carbonate mound evolution

et al. 2009

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U-series dating of constructional cold-water corals is a powerful tool to reconstruct the evolution of corals on carbonate mounds. Here we have investigated the time framework of corals such as Lophelia pertusa and Madrepora oculata on five different mound settings of the eastern North Atlantic (on Rockall Bank and in Porcupine Seabight), sampled at variable depth and location (610-880 m water depth). We have found that the past 11 ka reflect a period generally favourable for coral development. We further determined local mound growth rates and identified mound surface erosion (framework collapse) during times of active coral framework construction. "Local" vertical mound growth rates vary between less than 5 cm ka − 1 and up to 220 cm ka − 1 . We interpret rates exceeding 15 cm ka − 1 as representative of densely populated coral reefs. During times of reduced or absent coral development, mound evolution rates are by far smaller (0 to < 5 cm ka − 1 ). The time resolution achieved here furthermore provides first evidence for reduced coral (ecosystem) activity at 1.8-2.0 ka, 4.2-4.8 ka and between 6 and 8.2 ka within the Holocene that may be related to climate driven changes of the coral growth environments. During Glacial periods coral growth in those areas seems apparently extremely reduced or is even absent on mounds.

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Ahermatypic Coral Banks off Mid-Norway: Evidence for a Link with Seepage of Light Hydrocarbons

Cited by 109 publications

References 31 publications

Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

IODP Expedition 307 Drills Cold-Water Coral Mound Along the Irish Continental Margin

The Holocene occurrence of cold water corals in the NE Atlantic: Implications for coral carbonate mound evolution

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