Mingulay Reef Complex Research Articles

Hidden structural heterogeneity enhances marine hotspots\u2019 biodiversity

Studies in terrestrial and shallow-water ecosystems have unravelled the key role of interspecific interactions in enhancing biodiversity, but important knowledge gaps persist for the deep sea. Cold-water coral reefs are hotspots of biodiversity, but the role of interspecific interactions and “habitat cascades” (i.e. positive effects on focal organisms mediated by biogenic habitat formation) in shaping their biodiversity is unknown. Associations between macrofaunal hosts and epifauna were examined in 47 stations at the Mingulay Reef Complex (northeast Atlantic). In total, 101 (group level) and 340 (species level) unique types of facultative associations formed by 43 hosts and 39 epifaunal species were found. Molluscs and empty polychaete tubes had higher values for the type and number of host-epifaunal associations, the Shannon–Wiener (H) and Margalef (d) indices of the epifauna than the rest of the taxonomic groups (p < 0.05). Hosts’ body size, orientation, surface smoothness, and growth form explained a significant amount of variability (32.96%) in epifauna community composition. Epifaunal species richness (S), H and d were 27.4 (± 2.2%), 56.2 (± 2.8%) and 39.9 (± 2.3%) of the respective values for the total sessile communities living on coral framework. This is intriguing as coral framework is orders of magnitude larger than the size of macrofaunal hosts. It is suggested that bivalves, tunicates and empty polychaete tubes increase habitat heterogeneity and enhance biodiversity through “habitat cascades”, in a similar way that epiphytes do in tropical rainforests. Most macrofaunal habitat suppliers in the studied cold-water coral reef are calcified species and likely susceptible to ocean acidification. This indicates that the impacts of climate change on the total biodiversity, structure and health of cold-water coral reefs may potentially be more severe than previously thought.

Sensitivity of a cold‐water coral reef to interannual variability in regional oceanography

AbstractAimWe assessed the effects of regional oceanographic shifts on the macrofaunal biodiversity and biogeography of cold‐water coral reefs (CWCRs). CWCRs are often hotspots of biodiversity and ecosystem services and are in the frontline of exposure to multiple human pressures and climate change. Almost nothing is known about how large‐scale atmospheric variability affects the structure of CWCRs’ communities over ecological timescales, and this hinders their efficient conservation. This knowledge gap is especially evident for species‐rich macrofauna, a key component for ecosystem functioning.LocationThe Mingulay Reef Complex, a protected biogenic ecosystem in the northeast Atlantic (120–190 m).MethodsA unique time series (2003–2011) at 79 stations was used to make the first assessment of interannual changes in CWCRs’ macrofaunal biodiversity, biogeography and functional traits. We quantified the impacts of interannual changes in North Atlantic Oscillation Index (NAOI)—the major mode of atmospheric variability in the North Atlantic, bottom temperature and salinity alongside static variables of seafloor terrain and hydrography.ResultsEnvironmental gradients explained a significant amount of community composition ( = 26.7%, p &lt; .01) with interannual changes in bottom temperature, salinity and NAOI explaining nearly twice as much variability than changes in terrain or hydrography. We observed significant differences in community composition, diversity and functional traits but not in species richness across interannual variability in bottom temperature. In warmer years, the biogeographic composition shifted more towards a temperate and subtropical affinity.Main ConclusionsOur findings highlight the necessity for thorough investigations of faunal communities in CWCRs as they may be sensitive to interannual changes in regional oceanography. Considering the scientific consensus on the substantial warming of North Atlantic by 2100, we recommend the establishment of programmes for the monitoring of CWCRs. This will support an advanced understanding of CWCRs’ environmental status over time and will serve their conservation for the future.

Mapping cold-water coral biomass: an approach to derive ecosystem functions

This study presents a novel approach resulting in the first cold-water coral reef biomass maps, used to assess associated ecosystem functions, such as carbon (C) stock and turnover. We focussed on two dominant ecosystem engineers at the Mingulay Reef Complex, the coral Lophelia pertusa (rubble, live and dead framework) and the sponge Spongosorites coralliophaga. Firstly, from combining biological (high-definition video, collected specimens), environmental (extracted from multibeam bathymetry) and ecosystem function (oxygen consumption rate values) data, we calculated biomass, C stock and turnover which can feed into assessments of C budgets. Secondly, using those values, we employed random forest modelling to predictively map whole-reef live coral and sponge biomass. The whole-reef mean biomass of S. coralliophaga was estimated to be 304 T (range 168–440 T biomass), containing 10 T C (range 5–18 T C) stock. The mean skeletal mass of the coral colonies (live and dead framework) was estimated to be 3874 T (range 507–9352 T skeletal mass), containing a mean of 209 T of biomass (range 26–515 T biomass) and a mean of 465 T C (range 60–1122 T C) stock. These estimates were used to calculate the C turnover rates, using respiration data available in the literature. These calculations revealed that the epi- and microbial fauna associated with coral rubble were the largest contributor towards C turnover in the area with a mean of 163 T C year−1 (range 149–176 T C year−1). The live and dead framework of L. pertusa were estimated to overturn a mean of 32 T C year−1 (range 4–93 T C year−1) and 44 T C year−1 (range 6–139 T C year−1), respectively. Our calculations showed that the Mingulay Reef overturned three to seven (with a mean of four) times more C than a soft-sediment area at a similar depth. As proof of concept, the supply of C needed from surface water primary productivity to the reef was inferred. Since 65–124 T C year−1 is supplied by natural deposition and our study suggested that a mean of 241 T C year−1 (range 160–400 T C year−1), was turned over by the reef, a mean of 117–176 T C year−1 (range 36–335 T C year−1) of the reef would therefore be supplied by tidal downwelling and/or deep-water advection. Our results indicate that monitoring and/or managing surface primary productivity would be a key consideration for any efforts towards the conservation of cold-water coral reef ecosystems.

Public Perceptions of Deep-Sea Environment: Evidence From Scotland and Norway

Knowledge of people’s understanding of environmental problems is vital for the effective implementation of the ecosystem approach to marine management. This is especially relevant when conservation goals are aimed at ecosystems in the deep-sea that are remote to the consciousness of most people. This study explores public perceptions of the deep-sea environment among the Scottish and Norwegian public. It further analyses the relationships between respondents’ pro-environmental concerns towards the marine environment and personal characteristics using a multiple indicators multiple causes model. The results show that public knowledge of the deep-sea environment is low for Scottish and moderate for Norwegians. Awareness of cold-water corals was high for the Lofoten case study area amongst the Norwegian public and low for the Mingulay reef complex in the Scottish case. These differences might arise because Norway is known to host the world’s largest cold-water corals in the Lofoten area; a fact that has been well publicised. We find that most people think changes in the deep-sea have at least some effect on them. On average, the public perceive the deep-sea condition to be at most ‘fairly good’ but are dissatisfied with the management of it with approximately only one third or less thinking it is well-managed. Generally, the public perception from both countries show ecocentric attitudes towards the marine environment implying that they recognize the value of ecosystem services, the current ecological crisis and the need for sustainable management.

Holocene shifts in sub-surface water circulation of the North-East Atlantic inferred from Nd isotopic composition in cold-water corals

Variations of the Sub-Polar Gyre (SPG) and the Sub-Tropical Gyre (STG) circulation during the Holocene are believed to be related to regional and global climate over this time period. To improve our understanding of these phenomena we provide new constraints on variations in surface circulation patterns using neodymium isotopes (εNd) on precisely U-Th dated coral fragments of L. pertusa. The fragments were retrieved from two sediment cores taken from cold-water coral (CWC) mounds at ~ 127–134 m water depth in the Mingulay Reef Complex located on the Western British continental shelf. The results have been combined with εNd analyzed on seawater samples from two stations located on the continental shelf and margin in order to establish whether εNd is a reliable proxy of the ocean circulation variations and notably of the relative contribution of water originating from the SPG and STG. εNd values in CWCs from the Mingulay Reef Complex range from −14.5 ± 0.4 to −11.8 ± 0.3, highlighting two major variations. Unradiogenic εNd values (−14.5 ± 0.4) indicate a higher contribution of water from the SPG around 2.8 ka. Conversely, more radiogenic values at 3.4 ka (−11.8 ± 0.3) point to a declining SPG strength, accompanied by stronger northward penetration of STG water along the western European margin transported by the Shelf Edge Current (SEC) and/or cooler and fresher waters from the interior Seas. The eastward extension of the SPG at 2.8 ka is associated with lower 14C reservoir age (200 yrs) compared to periods associated with a higher contribution of STG waters. This indicates that 14C reservoir ages are mainly a function of vertical mixing of the sub-surface of the ocean. As stronger vertical ventilation is not associated with a higher proportion of local radiogenic surface water, we hypothesize it could represent vertical ventilation in the North-Eastern Atlantic. Active SPG is associated with a better ventilation of the water masses within the SPG and warmer climatic conditions in Northern Europe and in the Eastern Norwegian Sea linked to an intensification of the surface limb of the AMOC.

Unravelling the versatile feeding and metabolic strategies of the cold-water ecosystem engineer Spongosorites coralliophaga (Stephens, 1915)

Sponges are often major players in the functioning of shallow-water ecosystems through their high biomass and high capacity in filter feeding. In comparison, little is known about the feeding and metabolic strategies of deep-sea sponges, although they can also form dense aggregations with high biomass. This situation hinders our understanding about how some sponge species thrive under the often food-limited conditions of the deep sea. In the present study we examined the feeding and metabolic strategies of 1) the massive demosponge Spongosorites coralliophaga, which was recently described as an important ecosystem engineer in cold-water coral reefs (CWCRs) and 2) the anthozoan Parazoanthus anguicomus and the ophiuroid Ophiura ophiura, i.e. two dominant epibionts on S. coralliophaga. All three benthic species have high density at CWCRs of the North-East Atlantic and knowing their feeding strategies facilitates future studies on carbon (C) and nitrogen (N) cycling at CWCRs. The on-board feeding experiments examined the processing of four isotopically-labelled food sources, namely 15N-ammonium chloride, 13C-glucose, 13C/15N-labelled microalgae, 13C/15N-labelled bacteria by S. coralliophaga and its symbiotic bacteria and the epibionts P. anguicomus and O. ophiura from the Mingulay reef complex and the Logachev mound (North-East Atlantic). There were no significant differences among the three species in terms of biomass-specific C and N assimilation rates; however, there were differences among S. coralliophaga, P. anguicomus and O. ophiura in how they processed the food sources and this maybe is linked to interspecific variability in metabolic needs. S. coralliophaga preferentially assimilated particulate organic N (PON) over particulate organic C (POC) while this was not the case for P. anguicomus and O. ophiura. We did not detect the 15N tracer in the bacterial biomarker D-Alanine suggesting that the preferential assimilation of N over C in S. coralliophaga was mediated by sponge cells instead of the bacterial symbionts. S. coralliophaga assimilated C and N from all four food sources and this versatile feeding strategy was accompanied by an ability for de novo synthesis of essential and non-essential hydrolysable amino acids (HAAs). We suggest that the recorded feeding and metabolic flexibility of S. coralliophaga plays an important role in the survival of this massive sponge under food-limited conditions in the deep sea.

Assessing the living and dead proportions of cold-water coral colonies: implications for deep-water Marine Protected Area monitoring in a changing ocean.

Coral growth patterns result from an interplay of coral biology and environmental conditions. In this study colony size and proportion of live and dead skeletons in the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were measured using video footage from Remotely Operated Vehicle (ROV) transects conducted at the inshore Mingulay Reef Complex (MRC) and at the offshore PISCES site (Rockall Bank) in the NE Atlantic. The main goal of this paper was to explore the development of a simple method to quantify coral growth and its potential application as an assessment tool of the health of these remote habitats. Eighteen colonies were selected and whole colony and dead/living layer size were measured. Live to dead layer ratios for each colony were then determined and analysed. The age of each colony was estimated using previously published data. Our paper shows that: (1) two distinct morphotypes can be described: at the MRC, colonies displayed a ‘cauliflower-shaped’ morphotype whereas at the PISCES site, colonies presented a more flattened ‘bush-shaped’ morphotype; (2) living layer size was positively correlated with whole colony size; (3) live to dead layer ratio was negatively correlated to whole colony size; (4) live to dead layer ratio never exceeded 0.27. These results suggest that as a colony develops and its growth rate slows down, the proportion of living polyps in the colony decreases. Furthermore, at least 73% of L. pertusa colonies are composed of exposed dead coral skeleton, vulnerable to ocean acidification and the associated shallowing of the aragonite saturation horizon, with significant implications for future deep-sea reef framework integrity. The clear visual contrast between white/pale living and grey/dark dead portions of the colonies also gives a new way by which they can be visually monitored over time. The increased use of marine autonomous survey vehicles offers an important new platform from which such a surveying technique could be applied to monitor deep-water marine protected areas in the future.

Biodiversity of Spongosorites coralliophaga (Stephens, 1915) on coral rubble at two contrasting cold-water coral reef settings

Cold-water coral reefs (CWRs) in the northeast Atlantic harbor diverse sponge communities. Knowledge of deep-sea sponge ecology is limited and this leaves us with a fragmented understanding of the ecological roles that sponges play in CWR ecosystems. We present the first study of faunal biodiversity associated with the massive demosponge Spongosorites coralliophaga (Stephens, 1915) that typically colonizes coral debris fields of CWRs. Our study focused on the sessile fauna inhabiting sponges mixed with coral rubble at two contrasting settings in the northeast Atlantic: the shallow inshore (120–190 m water depth) Mingulay Reef Complex (MRC) and the deep offshore (500–1200 m) Logachev Mound (LM) coral province. MRC is dominated by the scleractinian Lophelia pertusa, while LM is dominated by L. pertusa and Madrepora oculata. Nine sponge–coral rubble associations were collected from MRC and four from LM. Measurements of abundance, species richness, diversity, evenness, dry biomass, and composition of sessile fauna on sponge and coral rubble microhabitats were undertaken. Differences in community composition between the two regions were mainly a response to changes in fauna with depth. Fauna composition was also different between sponge and coral rubble within each region. Infauna constituted a minor component of the sponge-associated fauna in MRC but had a higher contribution in LM. Sponge and coral rubble sessile fauna in both regions was mainly composed of cnidarians and molluscs, similarly to some previous studies. Sponges’ outer surfaces at MRC were colonized by a species-rich community with high abundance and biomass suggesting that S. coralliophaga at MRC acts as a settlement surface for various organisms but such a role is not the case at LM. This difference in the role of S. coralliophaga as a biological structure is probably related to differences in fauna composition with depth, bottom current speed, and the quantity/quality of food supplied to the benthos.

Benthic O2 uptake of two cold-water coral communities estimated with the non-invasive eddy correlation technique

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 525:97-104 (2015) - DOI: https://doi.org/10.3354/meps11211 Benthic O2 uptake of two cold-water coral communities estimated with the non-invasive eddy correlation technique Lorenzo Rovelli1,*, Karl M. Attard2,3, Lee D. Bryant4,8, Sascha Flögel4, Henrik Stahl1,9, J. Murray Roberts1,5,6, Peter Linke4, Ronnie N. Glud1,2,3,7 1Scottish Association for Marine Sciences, Scottish Marine Institute, Oban PA37 1QA, UK 2Nordic Centre for Earth Evolution (NordCEE), University of Southern Denmark, 5230 Odense M, Denmark 3Greenland Climate Research Centre, Greenland Institute of Natural Resources, 3900 Nuuk, Greenland 4GEOMAR, Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany 5Centre for Marine Biodiversity and Biotechnology, School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK 6Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC 28409, USA 7Arctic Research Centre, University of Århus, 8000 Århus C, Denmark 8Present address: Department of Architecture and Civil Engineering, University of Bath, Bath BA2 7AY, UK 9Present address: Zayed University, Dubai Academic City, Dubai, United Arab Emirates *Corresponding author: lorenzo.rovelli@sams.ac.uk ABSTRACT: The community respiration of 2 tidally dominated cold-water coral (CWC) sites was estimated using the non-invasive eddy correlation (EC) technique. The first site, Mingulay Reef Complex, was a rock ridge located in the Sea of Hebrides off Scotland at a depth of 128 m and the second site, Stjernsund, was a channel-like sound in Northern Norway at a depth of 220 m. Both sites were characterized by the presence of live mounds of the reef framework-forming scleractinian Lophelia pertusa and reef-associated fauna such as sponges, crustaceans and other corals. The measured O2 uptake at the 2 sites varied between 5 and 46 mmol m–2 d–1, mainly depending on the ambient flow characteristics. The average uptake rate estimated from the ~24 h long deployments amounted to 27.8 ± 2.3 mmol m–2 d–1 at Mingulay and 24.8 ± 2.6 mmol m–2 d–1 at Stjernsund (mean ± SE). These rates are 4 to 5 times higher than the global mean for soft sediment communities at comparable depths. The measurements document the importance of CWC communities for local and regional carbon cycling and demonstrate that the EC technique is a valuable tool for assessing rates of benthic O2 uptake in such complex and dynamic settings. KEY WORDS: Eddy correlation · Cold-water coral · Community oxygen exchange · Mingulay Reef Complex · Stjernsund Full text in pdf format PreviousNextCite this article as: Rovelli L, Attard KM, Bryant LD, Flögel S and others (2015) Benthic O2 uptake of two cold-water coral communities estimated with the non-invasive eddy correlation technique. Mar Ecol Prog Ser 525:97-104. https://doi.org/10.3354/meps11211 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 525. Online publication date: April 09, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

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

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

Ecohydrodynamics of cold-water coral reefs: a case study of the Mingulay Reef Complex (western Scotland).

Ecohydrodynamics investigates the hydrodynamic constraints on ecosystems across different temporal and spatial scales. Ecohydrodynamics play a pivotal role in the structure and functioning of marine ecosystems, however the lack of integrated complex flow models for deep-water ecosystems beyond the coastal zone prevents further synthesis in these settings. We present a hydrodynamic model for one of Earth's most biologically diverse deep-water ecosystems, cold-water coral reefs. The Mingulay Reef Complex (western Scotland) is an inshore seascape of cold-water coral reefs formed by the scleractinian coral Lophelia pertusa. We applied single-image edge detection and composite front maps using satellite remote sensing, to detect oceanographic fronts and peaks of chlorophyll a values that likely affect food supply to corals and other suspension-feeding fauna. We also present a high resolution 3D ocean model to incorporate salient aspects of the regional and local oceanography. Model validation using in situ current speed, direction and sea elevation data confirmed the model's realistic representation of spatial and temporal aspects of circulation at the reef complex including a tidally driven current regime, eddies, and downwelling phenomena. This novel combination of 3D hydrodynamic modelling and remote sensing in deep-water ecosystems improves our understanding of the temporal and spatial scales of ecological processes occurring in marine systems. The modelled information has been integrated into a 3D GIS, providing a user interface for visualization and interrogation of results that allows wider ecological application of the model and that can provide valuable input for marine biodiversity and conservation applications.

Effects of high temperature and CO2 on intracellular DMSP in the cold-water coral Lophelia pertusa

Significant warming and acidification of the oceans is projected to occur by the end of the century. CO2 vents, areas of upwelling and downwelling, and potential leaks from carbon capture and storage facilities may also cause localised environmental changes, enhancing or depressing the effect of global climate change. Cold-water coral ecosystems are threatened by future changes in carbonate chemistry, yet our knowledge of the response of these corals to high temperature and high CO2 conditions is limited. Dimethylsulphoniopropionate (DMSP), and its breakdown product dimethylsulphide (DMS), are putative antioxidants that may be accumulated by invertebrates via their food or symbionts, although recent research suggests that some invertebrates may also be able to synthesise DMSP. This study provides the first information on the impact of high temperature (12 °C) and high CO2 (817 ppm) on intracellular DMSP in the cold-water coral Lophelia pertusa from the Mingulay Reef Complex, Scotland (56°49′N, 07°23′W), where in situ environmental conditions are meditated by tidally induced downwellings. An increase in intracellular DMSP under high CO2 conditions was observed, whilst water column particulate DMS + DMSP was reduced. In both high temperature treatments, intracellular DMSP was similar to the control treatment, whilst dissolved DMSP + DMS was not significantly different between any of the treatments. These results suggest that L. pertusa accumulates DMSP from the surrounding water column; uptake may be up-regulated under high CO2 conditions, but mediated by high temperature. These results provide new insight into the biotic control of deep-sea biogeochemistry and may impact our understanding of the global sulphur cycle, and the survival of cold-water corals under projected global change.

Changes in fossil assemblage in sediment cores from Mingulay Reef Complex (NE Atlantic): Implications for coral reef build-up

CT scanning and descriptions of sedimentary sequences have been conducted to describe the internal structure and define the evolutionary sequence of events leading to the build-up of cold-water coral reef constructed by the azooxanthellate scleractinian Lophelia pertusa. Two vibrocores containing coral clasts and associated fauna embedded in a matrix of marine sediment were taken at the Mingulay Reef Complex, an inshore (~120–190m water depth) L. pertusa reef off western Scotland. The cores were scanned using computed x-ray tomography (CT scan) with the aim of (1) reconstructing and quantifying the relative abundance and preservation of coral fragments in the cores, (2) identifying distinct reef facies, and hence (3) providing data that could lead to a conceptual model of reef growth. U-series dates were obtained on L. pertusa clasts from the two sediment cores to provide a temporal framework of the reef build-up. After exploring a range of methods for processing CT scans, three simple parameters were used to classify different strata within the cores: the overall density of the cores, the number of fossil clasts, and the sum of the area of clasts detected by the CT scan. These parameters were validated by comparing with density measurements from a multi-sensor core logger (MSCL) and physical dissection and analysis of fossils in the cores. From the CT scan analyses, three distinct reef facies were evident: Coral-Rich, Sediment-Rich and Shelly-Coral Hash Layers. The succession and rapid cycle of reef framework-forming L. pertusa development, disturbance and recovery allow us to provide a model of cold-water coral reef build-up including shifts in biodiversity, physical/chemical/biological processes and the sedimentary regime.

Short-term metabolic and growth responses of the cold-water coral Lophelia pertusa to ocean acidification

Cold-water corals are associated with high local biodiversity, but despite their importance as ecosystem engineers, little is known about how these organisms will respond to projected ocean acidification. Since preindustrial times, average ocean pH has decreased from 8.2 to ~8.1, and predicted CO2 emissions will decrease by up to another 0.3 pH units by the end of the century. This decrease in pH may have a wide range of impacts upon marine life, and in particular upon calcifiers such as cold-water corals. Lophelia pertusa is the most widespread cold-water coral (CWC) species, frequently found in the North Atlantic. Here, we present the first short-term (21 days) data on the effects of increased CO2 (750ppm) upon the metabolism of freshly collected L. pertusa from Mingulay Reef Complex, Scotland, for comparison with net calcification. Over 21 days, corals exposed to increased CO2 conditions had significantly lower respiration rates (11.4±1.39 SE, µmolO2g−1tissuedryweighth−1) than corals in control conditions (28.6±7.30 SE µmolO2g−1tissuedryweighth−1). There was no corresponding change in calcification rates between treatments, measured using the alkalinity anomaly technique and 14C uptake. The decrease in respiration rate and maintenance of calcification rate indicates an energetic imbalance, likely facilitated by utilisation of lipid reserves. These data from freshly collected L. pertusa from the Mingulay Reef Complex will help define the impact of ocean acidification upon the growth, physiology and structural integrity of this key reef framework forming species.

Tidal downwelling and implications for the carbon biogeochemistry of cold‐water corals in relation to future ocean acidification and warming

Cold-water coral (CWC) reefs are recognized as ecologically and biologically significant areas that generate habitats and diversity. The interaction between hydrodynamics and CWCs has been well studied at the Mingulay Reef Complex, a relatively shallow area of reefs found on the continental shelf off Scotland, UK. Within 'Mingulay Area 01' a rapid tidal downwelling of surface waters, brought about as an internal wave, is known to supply warmer, phytoplankton-rich waters to corals growing on the northern flank of an east-west trending seabed ridge. This study shows that this tidal downwelling also causes short-term perturbations in the inorganic carbon (CT ) and nutrient dynamics through the water column and immediately above the reef. Over a 14h period, corresponding to one semi-diurnal tidal cycle, seawater pH overlying the reef varied by ca. 0.1 pH unit, while pCO2 shifted by >60μatm, a shift equivalent to a ca. 25year jump into the future, with respect to atmospheric pCO2 . During the summer stratified period, these downwelling events result in the reef being washed over with surface water that has higher pH, is warmer, nutrient depleted, but rich in phytoplankton-derived particles compared to the deeper waters in which the corals sit. Empirical observations, together with outputs from the European Regional Shelf Sea Ecosystem Model, demonstrate that the variability that the CWC reefs experience changes through the seasons and into the future. Hence, as ocean acidification and warming increase into the future, the downwelling event specific to this site could provide short-term amelioration of corrosive conditions at certain times of the year; however, it could additionally result in enhanced detrimental impacts of warming on CWCs. Natural variability in the CT and nutrient conditions, as well as local hydrodynamic regimes, must be accounted for in any future predictions concerning the responses of marine ecosystems to climate change.

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

We investigated the Holocene growth history of the Mingulay Reef Complex, a seascape of inshore cold-water coral reefs off western Scotland, using U-series and radiocarbon dating methods. Both chronologies revealed episodic occurrences of the reef framework-forming scleractinian coral Lophelia pertusa during the late Holocene. Downcore U-series dating revealed unprecedented reef growth rates of up to 12mma−1 with a mean rate of 3–4mma−1. Our study highlighted a persistent hiatus in coral occurrence from 1.4ka 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: 1.75–2.8ka, 3.2–3.6ka and to a lesser extent at 3.8–4ka and at 4.2ka. Timing of coral hiatuses and reduced reef growth rates at Mingulay were synchronous with those occurring across the wider northern European region, which suggests a close relationship between these ecosystems and large-scale shifts in palaeoenvironmental regimes associated with changes to the North Atlantic subpolar gyre.

Cold-water coral reef habitats benefit recreationally valuable sharks

We provide a case study to demonstrate how a key ecosystem function of coral reefs (habitat provision) co-benefits both sharks and humans. Spawning grounds of the blackmouth catshark Galeus melastomus were discovered using seabed and video surveys on the Mingulay Reef Complex, a seascape of cold-water coral reefs off western Scotland. Spawning habitats were environmentally similar across years. Shark abundance of G. melastomus, a species valued by the recreational sea angling industry, was significantly higher nearer reef habitats. Our case study demonstrates how a local coral vulnerable marine ecosystem (VME) helps maintain key life stages of shark populations and provides socioeconomic benefits. Evidence for co-benefits between corals, sharks and humans provides a compelling case for identifying and protecting coral VMEs.

Spatial and tidal variation in food supply to shallow cold-water coral reefs of the Mingulay Reef complex (Outer Hebrides, Scotland)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 444:97-115 (2012) - DOI: https://doi.org/10.3354/meps09430 Spatial and tidal variation in food supply to shallow cold-water coral reefs of the Mingulay Reef complex (Outer Hebrides, Scotland) Gerard C.A. Duineveld1,*, Rachel M. Jeffreys1,2, Marc S.S. Lavaleye1, Andrew J. Davies3, Magda J.N. Bergman1, Thalia Watmough1, Rob Witbaard1 1Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands 2School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, Liverpool, L69 3GP, UK 3School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK *Email: gerard.duineveld@nioz.nl ABSTRACT: The finding of a previously undescribed cold-water coral reef (Banana Reef) in the Scottish Mingulay reef complex, with denser coverage of living Lophelia pertusa than the principal Mingulay 1 Reef, was the incentive for a comparative study of the food supply to the 2 reefs. Suspended particulate matter (SPM) samples from the surface and bottom water covering a tidal cycle were compared with respect to lipids, pigments, and δ13C and δ15N. Lipid profiles and stable isotope signatures of SPM were compared with those of coral tissue samples. Concurrently, hydrographic measurements were conducted to track the movement of the water masses across both reefs. Between-reef differences in SPM lipid concentrations were small compared to those in coral tissue. Corals at Banana Reef had lower lipid concentrations, pointing to less favourable food conditions than at Mingulay 1. Stable isotopes signatures and lipid profiles showed that corals on both reefs feed primarily on surface algal matter, within the timeframe of our study. At Mingulay 1, fresh microalgae are supplied to the coral reef by local downwelling. This downwelling pulse is tidally advected to Banana Reef. Food conditions observed during this study at both reefs do not explain the between-reef difference in coral coverage. A speculative explanation for the denser coral coverage at the deeper Banana Reef encompasses the slightly lower temperature that exhibits lower metabolic stress on corals, in combination with a higher current speed and particle encounter rate. KEY WORDS: Lophelia pertusa · Cold-water corals · Suspended particulate organic matter · Food supply · Internal wave · Downwelling Full text in pdf format PreviousNextCite this article as: Duineveld GCA, Jeffreys RM, Lavaleye MSS, Davies AJ, Bergman MJN, Watmough T, Witbaard R (2012) Spatial and tidal variation in food supply to shallow cold-water coral reefs of the Mingulay Reef complex (Outer Hebrides, Scotland). Mar Ecol Prog Ser 444:97-115. https://doi.org/10.3354/meps09430 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 444. Online publication date: January 10, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Hymedesmia(Porifera: Demospongiae: Poecilosclerida) from Irish and Scottish cold-water coral reefs, with a description of five new species

This study describes species of the genusHymedesmiafrom three areas of cold-water coral reef: Mingulay Reef Complex (Scotland, UK) and Rockall and Porcupine Banks (off UK and Irish coasts). Five new species are described:Hymedesmia (Hymedesmia) gibbosa, H. stoneae, H. tendali, H. xavieraeandH. valentinae. Records are provided of other poorly knownHymedesmiaspecies:H. bocki, H. cohesibacilla, H. curvichela, H. ebria, H. gustafsoni, H. simillima, H. irregularis, H. proxima, H. hibernicaandH. primitiva. Information on distribution of otherHymedesmiaspecies occurring in Britain and Ireland is presented. The sites studied represent a variety of depth-ranges and the data collected suggest that someHymedesmiaspecies may be restricted to particular bathymetric zones.

Beta diversity of cold-water coral reef communities off western Scotland

Spatial heterogeneity in coral reef communities is well documented. This “species turnover” (beta diversity) on shallow warm-water reefs strongly conforms to spatial gradients in the environment as well as spatially autocorrelated biotic processes such as dispersal and competition. But the extent to which the environment and spatial autocorrelation create beta diversity on deep cold-water coral reefs such as those formed by Lophelia pertusa (Scleractinia) is unknown. The effects of remotely sensed and ground-truthed data were tested on the community composition of sessile suspension-feeding communities from the Mingulay Reef Complex, a landscape of inshore Lophelia reefs off the Scottish west coast. Canonical correspondence analysis determined that a statistically significant proportion (68%) of the variance in community composition could be explained by remotely sensed environmental variables (northerly and easterly aspect, seabed rugosity, depth), ground-truthed environmental variables (species richness and reef macrohabitat) and geospatial location. This variation was further partitioned into fractions explained by pure effects of the environment (51%), spatially structured environmental variables (12%) and spatial autocorrelation (5%). Beta diversity in these communities reflected the effects of both measured and unmeasured and spatially dependent environmental variables that vary across the reef complex, i.e., hydrography. Future work will quantify the significance and relative contributions of these variables in creating beta diversity in these rich communities.