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The Mingulay reef complex in the Sea of the Hebrides west of Scotland was first mapped in 2003 with a further survey in 2006 revealing previously unknown live coral reef areas at 120 to 190 m depth. Habitat mapping confirmed that distinctive mounded bathymetry was formed by reefs of Lophelia pertusa with surficial coral debris dating to almost 4000 yr. Benthic lander and mooring deployments revealed 2 dominant food supply mechanisms to the reefs: a regular rapid downwelling of surface water delivering pulses of warm fluorescent water, and periodic advection of high turbidity bottom waters. Closed chamber respirometry studies suggest that L. pertusa responds to seawater warming, such as that seen during the rapid downwelling events, with increases in metabolic rate. Lipid biomarker analysis implies that corals at Mingulay feed predominantly on herbivorous calanoid copepods. Integrating geophysical and hydrographical survey data allowed us to quantify the roles of these environmental factors in controlling biodiversity of attached epifaunal species across the reefs. Longitudinal structuring of these communities is striking: species richness (α) and turnover (β) change significantly west to east, with variation in community composition largely explained by bathymetric variables that are spatially structured on the reef complex. Vibro-cores through the reef mounds show abundant coral debris with significant hiatuses. High resolution side-scan sonar revealed trawl marks in areas south of the coral reefs where vessel monitoring system data showed the highest density of local fishing activity. The interdisciplinary approach in this study allowed us to record the food supply and hydrographic environment experienced by L. pertusa and determine how it may be ecophysiologically adapted to these conditions. Improved basic understanding of cold-water coral biology and biodiversity alongside efforts to map and date these long-lived habitats are vital to development of future conservation policies. KEY WORDS: Ecological engineer · Lophelia pertusa · Seamounts · Internal waves Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Conservation and management of deep-sea corals and coral reefs'

Despite its importance as an ecological engineer, little is known about the feeding ecology of the widespread reef framework-forming cold-water coral Lophelia pertusa. This is the first study to compare lipid signatures of L. pertusa from different areas in the North Atlantic using samples from 2 sites in the eastern Atlantic and 2 seamounts in the western Atlantic. Lipid samples were collected in February, May, July and November from the Mingulay reef complex off western Scotland, but no clear seasonal pattern was observed. High lipid content and large wax ester fractions were recorded from all sites, with the highest values recorded at the shallowest site (Mingulay). Here the prevalence of copepod lipid biomarkers-monounsaturated fatty acids 20:1(n-9) and 22:1(n-11) and their fatty alcohols-indicates L. pertusa feeds predominantly on calanoid copepods. At deeper offshore sites, the abundance of the fatty acid 18:1(n-9) and fatty alcohol 16:0 suggest a significant dietary input from non-calanoid copepods. Our results imply that the shallow Mingulay site is likely to receive a greater input of fresh surficial material and a higher abundance of herbivorous calanoid copepods, while at the deeper sites, carnivorous or omnivorous non-calanoid copepods are likely to be more abundant. L. pertusa therefore appears to be an opportunistic feeder capable of taking a variety of zooplankton prey. Further investigation is required to assess site-specific dependence on prey sources.

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