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Fjords provide unique habitats for large cold-water coral (CWC) reefs, typically growing on sills and vertical walls. Fjord reefs are among the most thriving CWC reefs in Norway. Yet, these reefs, especially the wall reefs, are notoriously understudied. Here, we mapped the biomass, total carbon (C) stocks and C turnover (as respiration) of the reef-building coral Lophelia pertusa (syn. Desmophyllum pertusum), and dominant, large CWC reef-associated suspension feeders (the sponges Geodia barretti and Mycale lingua , the CWC Madrepora oculata and the bivalve Acesta excavata) within the Hardangerfjord, Norway. Remotely Operated Vehicle (ROV) recorded videos from wall and sill reefs were used to estimate species-specific biomass. Coupled with high resolution terrain data (2 × 2 m), predictive maps of species biomass were produced using a random forest (RF) model. The resulting biomass data were integrated with species-specific C content and C respiration rates from literature to estimate C stocks and C turnover of wall versus sill reefs. Area-specific results from the RF models reveal that wall reefs had a higher habitat suitability for all species except L. pertusa , which was more dominant on the sills. Accordingly, the wall reefs supported an up to 11 times higher biomass, C stock, and turnover for all species, except for L. pertusa , which had two-fold higher values on the sill reef. As a result, the wall reefs showed a 1.5 to 4.8 times higher total mean C turnover by dominant suspension feeders (all studied species) compared to the sill reefs. With their high C turnover and their presumably wide distribution in Norwegian fjords and globally, benthic wall reef megafauna may have a substantial, but overlooked biomass and functional role within CWC reef systems. • We provide a first insight into cold-water coral reef biomass within a fjord. • Fjordic walls may play a distinct, overlooked role as cold-water coral reef habitat. • Fjordic sill reefs have higher Lophelia pertusa biomass than the walls. • Compared to the sill, wall reefs host higher overall biomass and carbon turnover. • Some reef-associated suspension feeders may prefer walls over sill habitat. [ABSTRACT FROM AUTHOR]

Abstract Scleractinian cold-water corals (CWCs), such as Lophelia pertusa and Madrepora oculata , build complex frameworks and carbonate mound habitats in the deep-sea and are regarded as deep-sea biodiversity hotspots. However, there is a paucity of research regarding temporal change in the biological composition of these CWC habitats and analysis of this change is critical, especially considering the anthropogenic influences impacting upon these vital habitats. This study is the first to analyse temporal biological change on a CWC mound at a small temporal (4 years) and large spatial (entire mound) scale. Video datasets were collected over the Piddington Mound of the Moira Mounds, Porcupine Seabight, offshore Ireland, in 2011 and 2015. 0.25 m2 quadrats were placed on 510 screenshots from each year (1020 total). Species were identified and quantified. CTD data were also analysed to investigate potential contributory causes of change. There was a highly significant (P < 0.01) decline in average M. oculata percentage cover from 2011 (1.37 ± 3.79%) to 2015 (0.70 ± 2.76%); however, there was not a significant change (P = 0.74) in average L. pertusa percentage cover in 2011 (2.33 ± 7.52%) when comparing it with 2015 (5.28 ± 7.88%). Additionally, there was an increase in average percentage cover of two poriferan species, Aphrocallistes sp. and Hexadella sp., from 2011 (1.18 ± 2.35%; 0.21 ± 0.42%, respectively) to 2015 (2.15 ± 3.48%; 0.33 ± 0.55%, respectively) (P < 0.01 for both species). Shannon-Weiner and Pielou's Species Evenness diversity indices were generally higher in 2011 than in 2015. This overall decline in diversity and increase in poriferan abundances is attributed to the decline in M. oculata , which may have been influenced by altered environmental conditions in 2015, as indicated by the CTD data. Moreover, differing biological and ecological responses of L. pertusa and M. oculata to environmental changes were considered and discussed as possible contributors to the results observed for these two species. If M. oculata percentage cover declines linearly at the current rate (approximately 0.17% per year, if a constant decline in each of the four years), then by 2019, this species may be nearly absent from the Piddington Mound, which would have major effects on species' abundances, distributions, and biodiversity. Therefore, further research and continuous monitoring of the temporal change in biological composition within CWC reef/mound habitats are critical. Highlights • 34 species and morphospecies encompassing 7 phyla were identified on a CWC mound. • Average percentage cover of Madrepora oculata declined significantly over 4 years. • Average percentage cover of two sponge species increased significantly over 4 years. • Temporal change in water temperature and salinity was found around the CWC mound. [ABSTRACT FROM AUTHOR]

Abstract Chronostratigraphy, of a northern Gulf of Mexico Lophelia pertusa (cold-water coral) mound (Roberts Reef), indicated that mound development included periods of growth and non-growth that are closely tied to Late Pleistocene climate cycles. U/Th and 14C dating of coral fragments in two ~ 16 m cores (mound crest and mound flank) and foraminiferal biostratigraphy provided a stratigraphic framework that identified five mound-growth sequences separated by four hiatuses, a total of ~ 300 ka. Mound growth occurred during interglacials while non-growth and unconformity formation correlates to glacial periods. In each cycle, growth on the mound flank persisted after growth at the crest ceased. Results of our study suggest warming bottom-water as the most probable environmental condition for limiting L. pertusa growth and mound accretion as sea level fell toward a glacial maximum. At highstands of sea level, the mound resided in the Oxygen Minimum Layer with a present temperature range of ~ 9.0–12.8 °C. During falling-to-lowstands of sea level, isotherms of warm, Subtropical Underwater (~ 12.8–21 °C) progressively exposed the mound to water above the thermal range for L. pertusa. A comparison of non-growth periods in the mound cores indicates that coral mortality and suppression of mound growth started at the crest and moved down the flank, a trend that supports progressive immersion of the mound in warm Subtropical Underwater. Multiday episodes of vertical down-mixing may have also transported warm ocean water, above the tolerance level of Lophelia, to the mound. Present average bottom-water temperatures at the mound crest range between 9 and 10.5 °C, ideal for L. pertusa growth in the Gulf of Mexico. Experimental work indicates that relatively short periods (weeks) of L. pertusa exposure to water of ~ 12–14 °C results in mortality. At periods of lowered sea level, the mound is projected to have been immersed in ocean water of ~ 12–14 °C for millennial scale time periods. Highlights • A large (~ 40 m relief) Lophelia mound was discovered in the NE Gulf of Mexico. • U/Th dating revealed 5 mound growth periods separated by unconformities(~300 ka over 16.5m) • Mound growth correlates to interglacials and non-growth periods to glacials. • Warm water is proposed as the stressor responsible for coral mortality. • Falling sea level is the main driver to displace warm water down to the mound. [ABSTRACT FROM AUTHOR]

Large, well-developed and flourishing reefs dominated by the cold-water coral Desmophyllum pertusum have recently been discovered along the Angola margin in the southeastern Atlantic Ocean living under very low oxygen concentrations (0.6–1.5 mL L−1). This study assessed the respiration rates of this coral in a short-term (10 days) aquarium experiment under naturally low oxygen concentrations (1.4 ± 0.5 mL L−1) as well as under saturated oxygen concentrations (6.1 ± 0.6 mL L−1). We found no significant difference in respiration rates between the two oxygen concentrations. Furthermore, the respiration rates of D. pertusum were in the same order of magnitude as those of the same species living under normoxic conditions in other areas. This work expands the current knowledge on the metabolic activity of cold-water corals under hypoxic conditions, evidencing that low oxygen conditions are not a general limiting factor for the overall distribution of D. pertusum. • Desmophyllum pertusum from reefs off Angola showed the same respiration rates at hypoxic and normoxic oxygen concentration. • Respiration rates are in the same order of magnitude as those observed for the species at normoxic conditions in other areas. [ABSTRACT FROM AUTHOR]

The scleractinian cold-water corals (CWCs), including the species Madrepora oculata and especially Lophelia pertusa , have been studied extensively in an attempt to decipher environmental signals recorded during biomineralisation in order to extract environmental chronologies. However, understanding the mechanisms of carbonate precipitation is a prerequisite to interpret variations in geochemical signatures locked into the skeleton during coral growth; to date results are still inconclusive. Here a novel approach, comparing the calcification patterns within the coral microstructure of species L. pertusa and M. oculata and the geochemistry along the contact surfaces with calcified polychaete tubes is undertaken to provide additional information on the mechanisms of biomineralisation in colonial corals. The fact that no significant difference in microstructures, variations in growth rate, or geochemical composition between the corallite theca and the calcified polychaete tube was detectable leads to the conclusion that both have been deposited by the coral tissue in L. pertusa and M. oculata . Based on prior knowledge on the symbiotic relationship between CWCs and the polychaete Eunice norvegica, an involvement of mucus in the calcification of the parchment tubes had been suspected. However, we found only evidence for aragonite precipitated by coral tissue, without evidence for an involvement of mucus in the calcification. [ABSTRACT FROM AUTHOR]

Until recently, benthic habitats dominated by deep-sea corals (DSC) appeared to be less extensive on the slope of the Gulf of Mexico (GOM) than in the northeast Atlantic Ocean or off the southeastern US. There are relatively few bioherms (i.e., coral-built mounds) in the northern GOM, and most DSCs are attached to existing hard substrata (e.g., authigenically formed carbonate). The primary structure-forming, DSC in the GOM is Lophelia pertusa , but structure is also provided by other living and dead scleractinians, antipatharians (black corals), octocorals (gorgonians, soft corals), hydrocorals and sponges, as well as abundant rocky substrata. The best development of DSCs in the GOM was previously documented within Viosca Knoll oil and gas lease blocks 826 and 862/906 (north-central GOM) and on the Campeche Bank (southern GOM in Mexican waters). This paper documents extensive deep reef ecosystems composed of DSC and rocky hard-bottom recently surveyed on the West Florida Slope (WFS, eastern GOM) during six research cruises (2008–2012). Using multibeam sonar, CTD casts, and video from underwater vehicles, we describe the physical and oceanographic characteristics of these deep reefs and provide size or area estimates of deep coral and hardground habitats. The multibeam sonar analyses revealed hundreds of mounds and ridges, some of which were subsequently surveyed using underwater vehicles. Mounds and ridges in <525 m depths were usually capped with living coral colonies, dominated by L . pertusa . An extensive rocky scarp, running roughly north-south for at least 229 km, supported lower abundances of scleractinian corals than the mounds and ridges, despite an abundance of settlement substrata. Areal comparisons suggested that the WFS may exceed other parts of the GOM slope in extent of living deep coral coverage and other deep-reef habitat (dead coral and rock). The complex WFS region warrants additional studies to better understand the influences of oceanography and geology on the occurrence of DSC and associated organisms. Protection measures are being considered to ensure the long-term integrity of this diverse ecosystem. [ABSTRACT FROM AUTHOR]

The Convention on Biological Diversity mandates the establishment of Marine Protected Area (MPA) networks worldwide, with recommendations stating the importance of ‘ecological coherence,’ a responsibility to support and perpetuate the existing ecosystem, implying the need to sustain population connectivity. While recommendations exist for integrating connectivity data into MPA planning, little advice exists on how to assess the connectivity of existing networks. This study makes use of recently observed larval characteristics and freely available models to demonstrate how such an assessment could be undertaken. The cold water coral (CWC) Lophelia pertusa (Linnaeus, 1758) is used as a model species, as much of the NE Atlantic MPA network has been designated for CWC reef protection, but the ecological coherence of the network has yet to be assessed. Simulations are run for different behavioural null models allowing a comparison of ‘passive’ (current driven) and ‘active’ (currents + vertical migration) dispersal, while an average prediction is used for MPA assessment. This model suggests that the network may support widespread larval exchange and has good local retention rates but still has room for improvement. The best performing MPAs were large and central to the network facilitating transport across local dispersal barriers. On average, passive and active dispersal simulations gave statistically similar results, providing encouragement to future local dispersal assessments where active characteristics are unknown. [ABSTRACT FROM AUTHOR]

For the first time, we describe a cold-water coral reef complex in Atlantic Canada, discovered at the shelf break, in the mouth of the Laurentian Channel. The study is based on underwater video and sidescan sonar. The reef complex covered an area of approximately 490×1300 m, at 280–400 m depth. It consisted of several small mounds (< 3 m high) where the scleractinian Lophelia pertusa occurred as live colonies, dead blocks and skeletal rubble. On the mounds, a total of 67 live colonies occurred within 14 patches at 300–320 m depth. Most of these (67%) were small (< 20 cm high). Dead coral (rubble and blocks), dominated (88% of all coral observations). Extensive signs of damage by bottom-fishing gear were observed: broken and tilted coral colonies, over-turned boulders and lost fishing gear. Fisheries observer data indicated that the reef complex was subjected to heavy otter trawling annually between 1980 and 2000. In June 2004, a 15 km 2 conservation area excluding all bottom-fishing was established. Current bottom fisheries outside the closure include otter trawling for redfish and anchored longlines for halibut. Vessel monitoring system data indicate that the closure is generally respected by the fishing industry. [ABSTRACT FROM AUTHOR]

The ecological study of corals in their habitat is essential to determine the effects of global change and to develop strategies for reef conservation. Based on mark and recovery experiments, we investigated skeletal growth patterns of two reef-building cold-water coral species, Lophelia pertusa and Madrepora oculata , in the Lacaze-Duthiers canyon in the northwestern Mediterranean Sea. Coral fragments were collected, stained and deployed for short-term (2.5 months) and long-term (15 months) growth experiments at two sites located 4.5 km and 6.8 km from the canyon head. The analysis of distinct growth parameters (budding, new polyp growth and linear extension of the coral fragments) revealed that growth patterns are consistent among branches of different sizes, but discrepancies arose from the different types of staining used. Calcein appeared more suitable than alizarin red, which strongly limited growth by delaying coral recovery, for short-term experiments at least. Both species grew rapidly when redeployed in their habitat. Effects of long-term experiments could not be observed because corals were exposed to harmful environmental stress, particularly the lethal effect of sedimentation on the fragments. Despite limited in situ deployment, the growth analysis from the short-term experiment highlighted species-specific responses according to the location along a longitudinal gradient in the canyon and were likely related to the local environmental conditions. Consistent with the observed species distributions, M. oculata showed optimal growth at the site closer to the canyon head compared with L. pertusa , which had optimal growth at the deeper site. In situ experiments are difficult to conduct in deep-sea ecosystems, but with the use of remotely operated vehicles (ROVs), such a simple approach may be of interest to managers of cold-water coral ecosystems. [ABSTRACT FROM AUTHOR]

Until recently, benthic habitats dominated by deep-sea corals (DSC) appeared to be less extensive on the slope of the Gulf of Mexico (GOM) than in the northeast Atlantic Ocean or off the southeastern US. There are relatively few bioherms (i.e., coral-built mounds) in the northern GOM, and most DSCs are attached to existing hard substrata (e.g., authigenically formed carbonate). The primary structure-forming, DSC in the GOM is Lophelia pertusa , but structure is also provided by other living and dead scleractinians, antipatharians (black corals), octocorals (gorgonians, soft corals), hydrocorals and sponges, as well as abundant rocky substrata. The best development of DSCs in the GOM was previously documented within Viosca Knoll oil and gas lease blocks 826 and 862/906 (north-central GOM) and on the Campeche Bank (southern GOM in Mexican waters). This paper documents extensive deep reef ecosystems composed of DSC and rocky hard-bottom recently surveyed on the West Florida Slope (WFS, eastern GOM) during six research cruises (2008–2012). Using multibeam sonar, CTD casts, and video from underwater vehicles, we describe the physical and oceanographic characteristics of these deep reefs and provide size or area estimates of deep coral and hardground habitats. The multibeam sonar analyses revealed hundreds of mounds and ridges, some of which were subsequently surveyed using underwater vehicles. Mounds and ridges in <525 m depths were usually capped with living coral colonies, dominated by L . pertusa . An extensive rocky scarp, running roughly north-south for at least 229 km, supported lower abundances of scleractinian corals than the mounds and ridges, despite an abundance of settlement substrata. Areal comparisons suggested that the WFS may exceed other parts of the GOM slope in extent of living deep coral coverage and other deep-reef habitat (dead coral and rock). The complex WFS region warrants additional studies to better understand the influences of oceanography and geology on the occurrence of DSC and associated organisms. Protection measures are being considered to ensure the long-term integrity of this diverse ecosystem. [ABSTRACT FROM AUTHOR]

Although cold-water coral (CWC) biology, physiology, and connectivity, have been extensively studied, few studies have so far focused on their reproductive biology. The reproductive biology of colonies of the reef-building Lophelia pertusa (Linnaeus 1758), now synonymised as Desmophyllum pertusum , and Madrepora oculata (Linnaeus 1758) from the Mediterranean Sea, an area particularly exposed to the effects of anthropogenic pressures, was investigated for the first time using histological techniques. Samples were collected from the Lacaze-Duthiers canyon in the Gulf of Lion, northwestern Mediterranean Sea, where the corals are living at 13 °C, close to their upper limit of thermal tolerance. The gametogenic cycle suggests a seasonal spawning of D. pertusum in autumn to early winter, similarly to population from the Gulf of Mexico. This period corresponds to the formation of storm-induced deep-sea water plumes, likely acting as a time giver for coral spawning and facilitates larval dispersal. Madrepora oculata shows continuous reproduction as already identified in eastern and western North Atlantic, with reproductive features of a species less opportunistic than D. pertusum , consistent with its other biological characteristics. This difference between the two species is of paramount importance to define strategies of conservation. • First data on the reproduction of two cold-water corals in the Mediterranean Sea. • Potential spawning date in autumn and/or early winter for Desmophyllum pertusum. • Role of deep-sea currents in timing of spawning for this species. • Madrepora oculata harbor different strategy, with a continuous reproduction. [ABSTRACT FROM AUTHOR]

Deep-sea coral habitats, comprising mostly Lophelia pertusa (Linnaeus 1758), are well developed on the upper and middle continental slope off the southeastern United States (SEUS). These habitats support a diverse and abundant invertebrate fauna, yet ecology and biology of most of these species are poorly known. Ten cruises conducted off the SEUS (Summer–Fall; Cape Lookout, NC–Cape Canaveral, FL) from 2000 to 2005, and in 2009 provided an opportunity to investigate abundance and distribution of Eumunida picta Smith1883, a large-sized species of squat lobster commonly associated with these deep-water coral habitats. Video analysis from 70 manned-submersible dives documented occurrence, density, location on the coral colony, and behavioral observations for 5774 individuals of E. picta. Individuals collected (n = 178) from coral and adjacent habitats (e.g., rubble, soft sediments) were measured and their sex determined. Males and females were comparable in size (to 53.5 mm carapace length) and exhibited a sex ratio of approximately 1:1. Eumunida picta were most frequently observed as solitary individuals on high-profile coral matrix and were noted only infrequently on coral rubble, or rarely on soft substratum. Presence of coral habitat (i.e., live/dead L. pertusa), geographic region within the sampling area, and depth significantly influenced abundances of E. picta. Additionally, coral habitat (dead versus live coral), vertical position on the coral (upper, middle, or lower zone), as well as horizontal position in relation to the coral matrix (outer surface versus embedded in coral matrix) were significant factors influencing E. picta distributions within the coral habitat. More individuals were found on dead versus live coral, and most frequently occurred on the outer surfaces of coral branches located on the upper portion or near the tops of coral colonies. Eumunida picta were most often observed with claws extended into the water column. This unique hunting stance provides this squat lobster the opportunity to capture prey from the water column. An active predator, this species utilizes both pelagic (i.e., fishes, pyrosomes) and benthic (e.g., scavenging and grazing) food resources, and may function as an important trophic link between the water column and the benthos. Although considered a facultative reef associate in the strictest sense of the term, E. picta has a complex and intimate relationship with L. pertusa. Based on observations from dive videos, E. picta is a dominant and ecologically important member of the invertebrate assemblage associated with deep-sea coral habitats off the SEUS. As such, this species figures prominently in the structure and function of this ecosystem. • Most comprehensive dataset examining demography and behavior of Eumunida picta. • Eumunida picta has a complex and intimate relationship with Lophelia pertusa. • Eumunida picta abundance correlates primarily with abundance of L. pertusa habitat. • The claws-extended behavior is a unique hunting stance for capturing pelagic prey. • Eumunida picta is an important trophic link between the benthos and water column. [ABSTRACT FROM AUTHOR]

Cold-water corals (CWC) are main ecosystem engineers of the deep sea, and their reefs constitute hot-spots of biodiversity. However, their ecology remains poorly understood, particularly, the nature of the holobiont formed by corals with their associated bacterial communities. Here, we analyzed Madrepora oculata and Lophelia pertusa samples, collected from one location in a Mediterranean canyon in two different seasons (autumn and spring), in order to test for species specificity and temporal stability of the host-bacteria associations. The 16S rRNA sequencing revealed host-specific patterns of bacterial communities associated with L. pertusa and M. oculata, both in terms of community composition and diversity. All analyzed M. oculata polyps exhibited temporally and spatially similar bacterial communities dominated by haplotypes homologous to the known cnidarians-associated genus Endozoicomonas . In contrast, the bacterial communities associated with L. pertusa varied among polyps from the same colony, as well as among distinct colonies and between seasons. While the resilient consortium formed by M. oculata and its bacterial community fit the definition of holobiont, the versatility of the L. pertusa microbiome suggests that this association is more influenced by the environmental conditions or nutritional status. Our results thus highlight distinct host/microbes association strategies for these two closely related Scleractinians sharing the same habitat, suggesting distinct sensitivity to environmental change. [ABSTRACT FROM AUTHOR]

The Lacaze-Duthiers Canyon is located in the western Mediterranean Sea and is long known for hosting cold-water coral colonies in the canyon head region at depths ranging from 250 to 550 m. In 2019 during the CALADU cruise, three kinds of 3D-reconstructions were applied to better understand the distribution of coral colonies, their habitat and their skeleton morphologies. The canyon's flanks were mapped using a hull-mounted echosounder and an ROV multibeam echosounder. Digital terrain models were built with resolutions of 5 and 1 m and examined in three dimensions. ROV bathymetric data collected on the canyon's flanks made it possible to highlight a series of sub-parallel structures identified as lithified sedimentary strata along which coral colonies grow. Coral assemblages were explored at four locations and photographic images were assembled using structure from motion techniques to build photogrammetric models. Coral assemblages reconstructed in 3D enabled geo-localizing and recreating coral colonies on 16 models over a total area of 4370 m2. Two colonial species, Madrepora oculata and Desmophyllum pertusum were plotted and reported on bathymetric models to interpret their location at the scale of the canyon. The coordinates and depth of the colonies were used to calculate the vertical distribution (limited to our small bathymetric exploration, between 339 and 214 m depth) and density of populations (up to 4.3 colonies per m2). The spatial coverage of the 16 assemblages measured between 100 and 600 m2 each. The sizes of the colonies were measured to analyze the population structures of both species (mean sizes of 28 cm for D. pertusum and 18 cm for M. oculata , maximum sizes 1 m and 0.5 m, respectively, bushes 2.5 m long). In addition, lost fishing gears were quantified, longlines measured and their densities calculated (0.16 m/m2, up to 0.30 m/m2). An area with exuberant orange colonies of D. pertusum was discovered for the first time in the Lacaze-Duthiers Canyon. Five deep-sea scleractinian species were collected and micro-tomographic scans computed to view their intrinsic skeleton organization. Micro-CT scans of M. oculata , D. pertusum , Desmophyllum dianthus , Caryophyllia smithii , and Dendrophyllia cornigera enabled longitudinal and transversal cuts, highlighting morphological criteria for species identification and the multidirectional examination of specimens. We observed a thin canal connecting calices along the axis of D. pertusum colonies, and separate calices along the axis of M. oculata colonies. • Canyon walls were mapped with a MBES installed with a 45° angle. • A surface of 4370 m2 was reconstructed on Cold-Water Corals ecosystem. • The highest density of coral colonies among the Mediterranean canyons. • Coral colonies faced prevailing currents coming from canyon head incisions. • A thin canal connects buds of successive generation in Desmophyllum pertusum. [ABSTRACT FROM AUTHOR]

Scleractinian corals create three-dimensional reefs that provide sheltered refuges, facilitate sediment accumulation, and enhance colonization of encrusting fauna. While heterogeneous coral habitats can harbor high levels of biodiversity, their effect on the community composition within nearby sediments remains unclear, particularly in the deep sea. Sediment macrofauna from deep-sea coral habitats ( Lophelia pertusa ) and non-coral, background sediments were examined at three sites in the northern Gulf of Mexico (VK826, VK906, MC751, 350–500 m depth) to determine whether macrofaunal abundance, diversity, and community composition near corals differed from background soft-sediments. Macrofaunal densities ranged from 26 to 125 individuals 32 cm −2 and were significantly greater near coral versus background sediments only at VK826. Of the 86 benthic invertebrate taxa identified, 16 were exclusive to near-coral habitats, while 14 were found only in background sediments. Diversity (Fisher’s α ) and evenness were significantly higher within near-coral sediments only at MC751 while taxon richness was similar among all habitats. Community composition was significantly different both between near-coral and background sediments and among the three primary sites. Polychaetes numerically dominated all samples, accounting for up to 70% of the total individuals near coral, whereas peracarid crustaceans were proportionally more abundant in background sediments (18%) than in those near coral (10%). The reef effect differed among sites, with community patterns potentially influenced by the size of reef habitat. Taxon turnover occurred with distance from the reef, suggesting that reef extent may represent an important factor in structuring sediment communities near L. pertusa . Polychaete communities in both habitats differed from other Gulf of Mexico (GOM) soft sediments based on data from previous studies, and we hypothesize that local environmental conditions found near L. pertusa may influence the macrofaunal community structure beyond the edges of the reef. This study represents the first assessment of L. pertusa -associated sediment communities in the GOM and provides baseline data that can help define the role of transition zones, from deep reefs to soft sediments, in shaping macrofaunal community structure and maintaining biodiversity; this information can help guide future conservation and management activities. [ABSTRACT FROM AUTHOR]

Little is known about species distribution patterns in deep-sea environments, primarily because sampling surveys in the high seas are expensive and time consuming. The increasing need to manage and protect vulnerable marine ecosystems, such as cold-water corals, has motivated the use of predictive modelling tools, which produce continuous maps of potential species or habitat distribution from limited point observations and full coverage environmental data. Rapid advances in acoustic remote sensing, oceanographic modelling and sampling technology now provide high quality datasets, facilitating model development with high spatial detail. This paper provides a short overview of existing methodologies for predicting deep-sea benthic species distribution, and illustrates emerging issues related to spatial and thematic data resolution, and the use of transect-derived species distribution data. In order to enhance the ecological relevance and reliability of deep-sea species distribution models, novel techniques are presented based on a case study predicting the distribution of the cold-water coral Lophelia pertusa in three carbonate mound provinces in Irish waters. Specifically, the study evaluates (1) the capacity of newly developed high-resolution (250 m grid cell size) hydrodynamic variables to explain local scale cold-water coral distribution patterns, (2) the potential value of species occurrence proportion data to maintain semi-quantitative information of coral prevalence (i.e. coverage) and sampling effort per grid cell within the response variable, and (3) mixed effect modelling to deal with spatially grouped transect data. The study shows that predictive models using vertical and horizontal flow parameters perform significantly better than models based on terrain parameters only. Semi-quantitative proportion data may decrease model uncertainty and increase model reliability, and provide a fruitful avenue of research for analysing large quantities of video data in a detailed yet time-efficient manner. The study concludes with an outlook of how species distribution models could improve our understanding of vulnerable marine ecosystem functioning and processes in the deep sea. [ABSTRACT FROM AUTHOR]

Abstract: General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth׳s largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium–thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea. [Copyright &y& Elsevier]

Abstract: Using industry inspection video and ROV imaging, we examined Lophelia pertusa (Linnaeus 1758) on 10 artificial structures of known ages (9 to 100 years) in the northern Gulf of Mexico (GoM). Five different types deep-water energy installations with depths ranging from 320 to 995m, and three shipwrecks with depths ranging from approximately 530 to 615m, were examined. Density, depth ranges, and growth rates of L. pertusa colonies were calculated from video and image analysis. L. pertusa colonies were present on all structures examined. Minimum calculated growth rates for the largest colonies ranged from 0.32 to 3.23cm/yr on the different structures. The shallowest depth at which L. pertusa was observed was 201m and the deepest was 801m, considerably expanding the known depth range of this species in the northern GoM. Colony density varied with structure type, age, and depth, with the highest density between 503 and 518m on the single structure that spanned the entire depth range of occurrence of L. pertusa observed in this study. L. pertusa colonies growing on thinner and deeper installations appear to have higher colonization rates, i.e. to develop higher densities over a shorter time period, compared to those on shallower and more massive types of installations. However, on average, colonies have slower growth rates on these installations than colonies on more massive, shallower installations (compliant and solid installations). In general, the calculated minimum growth rates were higher on the installations than on the shipwrecks, which were substantially older. A continuum of colony sizes was documented on all installations, suggesting multiple settlement events. L. pertusa thickets were observed on the oldest anthropogenic structures, with most of the components of these structures covered by colonies of L. pertusa. Brown, orange, and mottled color-variants were documented for the first time in the GoM. All installations examined for this study were colonized by L. pertusa and it is likely that most artificial surfaces in appropriate depths in the GoM will be as well. [Copyright &y& Elsevier]

Abstract: In situ video observations of echinoids interacting with deep-sea coral are common in the deep-sea, but paradoxically the deep-sea literature is devoid of reports of bioerosion by extant echinoids. Here we present evidence of contemporary bioerosion of cold-water coral by four species of deep-sea echinoids, Gracilechinus elegans, Gracilechinus alexandri, Cidaris cidaris, and Araeosoma fenestratum, showing that they actively predate on the living framework of reef building corals, Lophelia pertusa and Madrepora oculata, in the NE Atlantic. Echinoid specimens were collected in six canyons located in the Bay of Biscay, France and two canyons on the north side of the Porcupine Bank and Goban Spur, Ireland. A total of 44 live specimens from the four taxa (9 of G. elegans, 4 of G. alexandri, 21 of C. cidaris and 10 of A. fenestratum) showed recent ingestion of the coral infrastructure. Upon dissection, live coral skeleton was observed encased in a thick mucus layer within the gastrointestinal tract of G. elegans and G. alexandri while both live and dead coral fragments were found in C. cidaris and A. fenestratum. Echinoid bioerosion limits the growth of shallow-water reefs. Our observations suggest that echinoids may also play an important role in the ecology of deep-water coral reefs. [Copyright &y& Elsevier]

Abstract: The cold-water coral Lophelia pertusa provides important habitat to many deep-sea fishes and invertebrates. Studies of the microbial taxa associated with L. pertusa thus far have focused on bacteria, neglecting the microeukaryotic members. This is the first study to culture fungi from living L. pertusa and to investigate carbon source utilization by the fungal associates. Twenty-seven fungal isolates from seven families, including both filamentous and yeast morphotypes, were cultured from healthy L. pertusa colonies collected from the northern Gulf of Mexico, the West Florida Slope, and the western Atlantic Ocean off the Florida coast. Isolates from different sites were phylogenetically closely related, indicating these genera are widely distributed in association with L. pertusa. Biolog™ Filamentous Fungi microtiter plates were employed to determine the functional capacity of a subset of isolates to grow on varied carbon sources. While four of the isolates exhibited no growth on any provided carbon source, the rest (n=10) grew on 8.3–66.7% of carbon sources available. Carbohydrates, carboxylic acids, and amino acids were the most commonly metabolized carbon sources, with overlap between the carbon sources used and amino acids found in L. pertusa mucus. This study represents the first attempt to characterize a microeukaryotic group associated with L. pertusa. However, the functional role of fungi within the coral holobiont remains unclear. [Copyright &y& Elsevier]

Abstract: Near-bed hydrodynamic conditions were recorded for almost one year in the Viosca Knoll area (lease block 826), one of the most well-developed cold-water coral habitats in the Gulf of Mexico. Here, a reef-like cold-water coral ecosystem, dominated by the coral Lophelia pertusa, resembles coral habitats found off the southeastern US coast and the North East Atlantic. Two landers were deployed in the vicinity and outside of the coral habitat and measured multiple near-bed parameters, including temperature, salinity, current speed and direction and optical and acoustic backscatter. Additionally, the lander deployed closest to the coral area was equipped with a sediment trap that collected settling particles over the period of deployment at 27 day intervals. Long-term monitoring showed, that in general, environmental parameters, such as temperature (6.5–11.6°C), salinity (34.95–35.4) and current speed (average 8cms−1, peak current speed up to 38cms−1) largely resembled conditions previously recorded within North East Atlantic coral habitats. Major differences between site VK 826 and coral areas in the NE Atlantic were the much higher particle load, and the origin of the particulate matter. Several significant events occurred during the deployment period beginning with an increase in current speed followed by a gradual increase in temperature and salinity, followed by a rapid decrease in temperature and salinity. Simultaneously with the decrease in temperature and salinity, the direction of the current changed from west to east and cold and less turbid water was transported upslope. The most prominent event occurred in July, when a westward flow lasted over 21 days. These events are consistent with bottom boundary layer dynamics influenced by friction (bottom Ekman layer). The Mississippi River discharges large quantities of sediment and dominates sedimentation regimes in the area. Furthermore, the Mississippi River disperses large amounts of terrestrial organic matter and nutrients, resulting in increased primary productivity, whereby marine organic matter is produced that will sink to the seafloor and can serve as food for the cold-water corals and associated species. As a result mass fluxes from the sediment trap were higher (1120–4479mgm−2 day−1) than those observed in the North East Atlantic and were highest during periods of westward-flow, which corresponded to warm turbid water. During eastward-flow, colder and less turbid water was pushed upslope, resulting in lower mass fluxes. Trap samples had a low CaCO3, high organic carbon content and high C/N ratios, suggesting a fluvial origin. The high sediment load in the water column can be a limiting factor for coral growth, especially since the corals can be smothered with sediment. However, eastward-flows provided periods of relatively clearer water that can remove sediment from the coral area and allow corals to expel sediment from their polyps. Around Viosca Knoll food supply comes from two possible sources. During April and June several fluorescence peaks were observed near the seabed, showing the arrival of phytodetritus in the area. Furthermore, a consistent diel vertical migration of zooplankton was observed that might provide an additional food source. [Copyright &y& Elsevier]

Abstract: The abundance and behaviour of fish on and around coral reefs at Twin Mounds and Giant Mounds, carbonate mounds located on the continental shelf off Ireland (600–1100m), were studied using two Remotely Operated Vehicle (ROV) dives. We recorded 30 fish taxa on the dives, together with three species of Scleractinia (Lophelia pertusa, Madrepora oculata and Desmophyllum cristagalli) and a diverse range of other corals (Antipatharia, Alcyonacea, and Stylasteridae). Stands of live coral provided the only habitat in which Guttigadus latifrons was observed whereas Neocyttus helgae was found predominantly on structural habitats provided by dead coral. Significantly more fish were found on structurally complex coral rubble habitats than on flatter areas where coral rubble was clogged with sand. The most common species recorded was Lepidion eques (2136 individuals), which always occurred a few cm above bottom and was significantly more active on the reefs than on sedimentary habitats. Synaphobranchus kaupii (1157 indiv.), N. helgae (198 indiv.) and Micromesistius poutassou (116 indiv.) were also common; S. kaupii did not exhibit habitat-related differences in behaviour, whilst N. helgae was more active over the reefs and other structured habitats whereas M. poutassou was more active with decreasing habitat complexity. Trawl damage and abandoned fishing gear was observed at both sites. We conclude that Irish coral reefs provide complex habitats that are home to a diverse assemblage of fish utilising the range of niches occurring both above and within the reef structure. [Copyright &y& Elsevier]

Abstract: The Lophelia pertusa community at Viosca Knoll (VK826) is the most extensive found to date in the Gulf of Mexico. As part of a multi-disciplinary study, the physical setting of this area was described using benthic landers, CTD transects and remotely operated vehicle observations. The site was broadly characterised into three main habitats: (1) dense coral cover that resembles biogenic reef complexes, (2) areas of sediment, and (3) authigenic carbonate blocks with sparse coral and chemosynthetic communities. The coral communities were dominated by L. pertusa but also contained numerous solitary coral species. Over areas that contained L. pertusa, the environmental conditions recorded were similar to those associated with communities in the north-eastern Atlantic, with temperature (8.5–10.6°C) and salinity (∼35) falling within the known species niche for L. pertusa. However, dissolved oxygen concentrations (2.7–2.8mll−1) and density (σΘ , 27.1–27.2kgm−3) were lower and mass fluxes from sediment trap data appeared much higher (4002–4192mgm−2 d−1). Yet, this species still appears to thrive in this region, suggesting that L. pertusa may not be as limited by lower dissolved oxygen concentrations as previously thought. The VK826 site experienced sustained eastward water flow of 10–30cms−1 over the 5-day measurement period but was also subjected to significant short-term variability in current velocity and direction. In addition, two processes were observed that caused variability in salinity and temperature; the first was consistent with internal waves that caused temperature variations of 0.8°C over 5–11h periods. The second was high-frequency variability (20–30min periods) in temperature recorded only at the ALBEX site. A further pattern observed over the coral habitat was the presence of a 24h diel vertical migration of zooplankton that may form part of a food chain that eventually reaches the corals. The majority of detailed studies concerning local environmental conditions in L. pertusa habitats have been conducted within the north-eastern Atlantic, limiting most knowledge of the niche of this species to a single part of an ocean basin. Data presented here show that the corals at VK826 are subjected to similar conditions in temperature, salinity, and flow velocity as their counterparts in the north-east Atlantic, although values for dissolved oxygen and density (sigma-theta: σΘ ) are different. Our data also highlight novel observations of short-term environmental variability in cold-water coral habitat. [Copyright &y& Elsevier]

Abstract: To investigate the importance of seep primary production to the nutrition of Lophelia pertusa and associated communities and examine local trophic interactions, we analyzed stable carbon, nitrogen, and sulfur compositions in seven quantitative L. pertusa community collections. A significant seep signature was only detected in one of the 35 species tested (Provanna sculpta, a common seep gastropod) despite the presence of seep fauna at the three sample sites. A potential predator of L. pertusa was identified (Coralliophila sp.), and a variety of other trophic interactions among the fauna occupying the coral framework were suggested by the data, including the galatheid crab Munidopsis sp. 2 feeding upon hydroids and the polychaete Eunice sp. feeding upon the sabellid polychaete Euratella sp. Stable carbon abundances were also determined for different sections of L. pertusa skeleton representing different stages in the growth and life of the aggregation. There was no temporal trend detected in the skeleton isotope values, suggesting that L. pertusa settles in these areas only after seepage has largely subsided. Isotope values of individual taxa that were collected from both L. pertusa and vestimentiferan habitats showed decreasing reliance upon seep primary production with average age of the vestimentiferan aggregation, and finally, no seep signature was detected in the coral collections. Together our data suggest that it is the presence of authigenic carbonate substrata, a product of past seep microbial activity, as well as hydrodynamic processes that drive L. pertusa occurrence at seep sites in the Gulf of Mexico, not nutritional dependence upon primary production by seep microbes. [Copyright &y& Elsevier]

Abstract: Video data and high-resolution multibeam bathymetry were acquired using a Remotely Operated Vehicle (ROV) on the flank of a carbonate mound (∼850m depth) in the Porcupine Seabight, SW Ireland. The ROV-mounted multibeam system revealed details of bathymetry that were not resolved by ship-borne multibeam survey, but appear to be important in structuring the distribution of the cold-water corals Lophelia pertusa and Madrepora oculata. Quantitative measures of slope, orientation, roughness and curvature were calculated from the ROV multibeam bathymetry data across a range of spatial scales. These parameters were analysed for their ecological relevance to the distribution of the corals and used in an Ecological Niche Factor Analysis (ENFA) to identify the most suitable areas for coral colonisation within the extent of our ROV multibeam data. The suitability map covers an area nine times the size of the area imaged directly by video. Cross-validation of the results with video data indicates that the predictions are reliable. This combined survey and modelling approach offers a comprehensive method for ground-truthing discrete seabed features such as mounds. It provides spatial context to high-resolution deep-water video observations and highlights the importance of bathymetric variables in influencing coral distribution. [Copyright &y& Elsevier]

Abstract: Ecological-niche factor analysis (ENFA) was applied to the reef framework-forming cold-water coral Lophelia pertusa. The environmental tolerances of this species were assessed using readily available oceanographic data, including physical, chemical, and biological variables. L. pertusa was found at mean depths of 468 and 480m on the regional and global scales and occupied a niche that included higher than average current speed and productivity, supporting the theory that their limited food supply is locally enhanced by currents. Most records occurred in areas with a salinity of 35, mean temperatures of 6.2–6.7 °C and dissolved oxygen levels of 6.0–6.2mll−1. The majority of records were found in areas that were saturated with aragonite but had low concentration of nutrients (silicate, phosphate, and nitrate). Suitable habitat for L. pertusa was predicted using ENFA on a global and a regional scale that incorporated the north-east Atlantic Ocean. Regional prediction was reliable due to numerous presence points throughout the area, whereas global prediction was less reliable due to the paucity of presence data outside of the north-east Atlantic. However, the species niche was supported at each spatial scale. Predicted maps at the global scale reinforced the general consensus that the North Atlantic Ocean is a key region in the worldwide distribution of L. pertusa. Predictive modelling is an approach that can be applied to cold-water coral species to locate areas of suitable habitat for further study. It may also prove a useful tool to assist spatial planning of offshore marine protected areas. However, issues with eco-geographical datasets, including their coarse resolution and limited geographical coverage, currently restrict the scope of this approach. [Copyright &y& Elsevier]

Abstract: Deep-water coral habitats off the southeastern USA (SEUS) support diverse fish and invertebrate assemblages, but are poorly explored. This study is the first to report on the hydroids collected from these habitats in this area. Thirty-five species, including two species that are likely new to science, were identified from samples collected primarily by manned submersible during 2001–2005 from deep-water coral habitats off North Carolina to east-central Florida. Eleven of the species had not been reported since the 19th to mid-20th century. Ten species, and one family, the Rosalindidae, are documented for the first time in the SEUS. Latitudinal ranges of 15 species are extended, and the deepest records in the western North Atlantic for 10 species are reported. A species accumulation curve illustrated that we continue to add to our knowledge of hydroid diversity in these habitats. Sexually mature individuals were collected for 19 species during the summer to early autumn months. Most of the observed species (89%) liberate planula larvae as part of their life cycles, suggesting that these species exhibit a reproductive strategy that reduces the risk of dispersal to sub-optimal habitats. Hydroids occurred across various substrata including coral rubble, live corals, rock and other animal hosts including hydroids themselves. All observed species were regionally widespread with typically deep-neritic to bathyal sub-tropical/tropical distributions. Hydroid assemblages from deep-water SEUS coral habitats were most similar to those from adjacent deep-water habitats off the SEUS (17 shared species), and those in the Straits of Florida/Bahamas and Caribbean/West Indian regions (14 and 8 shared species, respectively). The similarity to sub-tropical and tropical assemblages and the richness of plumularioids in the SEUS deep-water coral habitats support the idea of a Pleistocene intrusion of tropical species northwards following an intensification of the Gulf Stream from the Caribbean. [Copyright &y& Elsevier]

Abstract: Habitat formation by foundation species is a major ecological force affecting community structure in numerous systems. On the upper continental slope of the Gulf of Mexico, the cold-water scleractinian coral Lophelia pertusa creates complex habitat on cold seep-associated carbonates. In this study, the communities associated with the cold-water coral L. pertusa are described from the Gulf of Mexico for the first time. A total of 68 taxa was identified in close association with the coral framework. Three species with specific relationships to L. pertusa were identified: Eunice sp., a polychaete which may facilitate colony formation in L. pertusa; Coralliophila sp., a species of corallivorous gastropod ; and Stenopus sp., a decapod crustacean which may act in a cleaner shrimp role in these habitats. Similarity among coral-associated communities was best explained by similarity in depth of collection and the proportion of live coral in the collections. These variables were somewhat confounded with location as the sites to the east were both shallower and contained higher proportions of live coral; however, distance between collections per se was not as significant in the analyses. The coral-associated communities also showed a low degree of similarity to communities inhabiting vestimentiferan tubeworm aggregations that occur nearby at the same sites. The increased habitat heterogeneity in the coral structure, differences in the niches constructed by the two foundation species, and different direct interspecific interactions between foundation species and members of the associated community contributed to the presence of dissimilar communities in these two biogenic habitats. [Copyright &y& Elsevier]

Abstract: The cold-water scleractinian corals Lophelia pertusa and Madrepora oculata form mound structures on the continental shelf and slope in the NE Atlantic. This study is the first to compare the taxonomic biodiversity and ecological composition of the macrobenthos between on- and off-mound habitats. Seven box cores from the summits of three mounds and four cores from an adjacent off-mound area in the Belgica Mound Province in the Porcupine Seabight yielded 349 species, including 10 undescribed species. On-mound habitat was three times more speciose, and was richer with higher evenness and significantly greater Shannon''s diversity than off-mound. Species composition differed significantly between habitats and the four best discriminating species were Pliobothrus symmetricus (more frequent off-mound), Crisia nov. sp, Aphrocallistes bocagei and Lophelia pertusa (all more frequent on-mound). Filter/suspension feeders were significantly more abundant on-mound, while deposit feeders were significantly more abundant off-mound. Species composition did not significantly differ between mounds, but similarity within replicates decreased from Galway Mound

Abstract: Living deep-water coral assemblages were discovered recently inhabiting the Mediterranean Sea between the depths of 300 and 1000m off the Cape of Santa Maria di Leuca (Apulian platform, Ionian Sea). This living assemblage was dominated by two colonial scleractinian corals, Lophelia pertusa and Madrepora oculata. Two other corals, Desmophyllum crystagalli and Stenocyathus vermiformis were also recovered from this site, but were much less common. The composition of the metabolically active fraction of the microbial community associated with living specimens of L. pertusa was determined. Dead corals, proximal sediments and overlying seawater were also sampled and analyzed. Complementary 16S ribosomal DNA (crDNA) was obtained from total RNA extracted from all samples that had been subjected to reverse transcription-PCR amplification. Domain-specific 16S PCR primers were used to construct four different 16S crDNA libraries containing 45 Archaea and 201 Bacteria clones. Using Archaea-specific primers, no amplification products were obtained from any coral samples (live and dead). Living specimens of L. pertusa seem to possess a specific microbial community different from that of dead coral and sediment samples. The majority of all coral-associated riboclones was related to the Holophaga-Acidobacterium and Nitrospira divisions (80%). Moreover, more than 12% of all coral-associated riboclones formed a separate deep-branching cluster within the α-Proteobacteria with no known close relatives. The metabolically active fraction of the bacterial community colonizing the dead corals was dominated by Proteobacteria related to the gamma and epsilon subdivisions (74% and 26% of all clones, respectively). Phylogenetic analysis of the Archaea clone library retrieved from proximal sediments indicated an exclusive dominance by the members of Crenarchaea Marine Group I (MGI), a lineage of unculturable microorganisms, widely distributed in marine habitats. In contrast, bacterial diversity was considerably higher in this sample than archaeal diversity, with four abundant eubacterial phylotypes: Proteobacteria, Verrucomicrobia, Actinobacteria and Planctomycetes (95% of all clones analyzed). This is one of the first phylogenetic evaluation of the presumed metabolically active microbial community structure associated with the deep-sea scleratinian coral L. pertusa. [Copyright &y& Elsevier]

Abstract: The Darwin Mounds are a series of small (5m high, 75–100m diameter) sandy features located in the northern Rockall Trough. They provide a habitat for communities of Lophelia pertusa and associated fauna. Suspended particulate organic matter (sPOM) reaching the deep-sea floor, which could potentially fuel this deep-water coral (DWC) ecosystem, was collected during summer 2000. This was relatively “fresh” (i.e. dominated by labile lipids such as polyunsaturated fatty acids) and was derived largely from phytoplankton remains and faecal pellets, with contributions from bacteria and microzooplankton. Labile sPOM components were enriched in the benthic boundary layer (∼10m above bottom (mab)) relative to 150mab. The action of certain benthic fauna that are exclusively associated with the DWC ecosystem (e.g. echiuran worms) leads to the subduction of fresh organic material into the sediments. The mound surface sediments are enriched in organic carbon, relative to off-mound sites. There is no evidence for hydrocarbon venting at this location. [Copyright &y& Elsevier]

The Pourtalès Terrace is an exposed hard-bottom platform located south of the Florida Keys in 200–450 m depth with a diverse deep-sea coral ecosystem dominated by stylasterid hydrocorals, octocorals, and sponges that supports recreational and commercial fisheries. Portions of the Terrace have been designated as managed areas in the absence of detailed habitat maps, which hampers identifying ecological benefits derived from such management actions. Here we report analyses of historic Terrace physiographic and geologic data with more recent high-resolution bathymetric and benthic data to statistically derive a benthic community characterization across the Terrace. Multivariate analyses of faunal density from 42 standardized sites showed spatially distinct communities: East Terrace, West Terrace, Upper Terrace Edge, Sinkholes and Lophelia Coral Mound (the southernmost record of this habitat in the continental U.S.). These corresponded to physiographic divisions into an Upper Terrace comprised of Central and Karst-like regions, and Lower Terrace. A detailed description of these communities is provided. This study presents new insights into the Terrace benthic community spatial arrangement and is a necessary step towards facilitating benthic mapping. Our recommendations highlight the information needed for benthic habitat map creation and collecting data to determine if current conservation boundaries match management goals. [ABSTRACT FROM AUTHOR]

Ecological niche modelling is used in deep-sea research to investigate the environmental preferences and potential distribution of data-poor species. We present a mesoscale assessment of Mediterranean seascape suitability for the cold-water coral Lophelia pertusa (= Desmophyllum pertusum , Linnaeus, 1758). We estimated seascape suitability and uncertainty maps using an ensemble approach of three machine-learning algorithms (Generalized Boosting Model, Random Forest, Maximum Entropy) based on environmental predictors. Bathymetry, bathymetric slope and pH were the most important predictors for the models. Overall the models reached good to excellent performance, with a very reliable prediction of the most suitable areas. In the Mediterranean Sea, L. pertusa encounters environmental settings close to its physiological limits but, despite the highly variable quality of the Mediterranean seascape, we identified high suitability areas mostly along the upper slope and at submarine canyons of the Western and Central margins. The existing MPAs do not overlap with high suitability areas, and therefore L. pertusa is only protected at the deepest fringe of its potential distribution by the implementation of the bottom trawling exclusion beyond 1000 m depth. This seascape suitability assessment may assist future research, including high-resolution modelling targeting high-suitability areas, investigation on the resilience of L. pertusa populations and development of conservation actions. • We mapped the potential distribution of Lophelia pertusa in the Mediterranean Sea. • We provide uncertainty estimates for the model predictions. • Mediterranean colonies are subjected to challenging environmental conditions. • The most suitable areas occur in the continental slope of the west and central basins. • The overlap of the Mediterranean MPAs with the most suitable areas is limited. [ABSTRACT FROM AUTHOR]

Lophelia pertusa and Madrepora oculata , two cosmopolitan coral species of the deep ocean, build reef-like structures that provide ecological niches and nurseries for many species. These cold-water corals (CWCs) are thought to grow slowly making associated communities vulnerable to disturbance. However, in situ growth dynamics remains poorly known. The aim of this study was thus to quantify the growth rates of L. pertusa and M. oculata and their variability in relation to environmental conditions that are expected to influence their physiological functions. Such data can be useful to ground-truth physiological rates and improve the prediction of their sensitivity to global change. As part of a long-term monitoring programme of the Lacaze-Duthiers canyon in the Northwestern Mediterranean Sea, fragments of the two species were repeatedly sampled and redeployed at 530 m depth, from November 2010 to May 2018. Budding rates and linear extensions of L. pertusa and M. oculata were hence quantified and their inter-annual variability documented. The data were analyzed in relation to in situ monitoring of water temperature, current speed and turbidity. This study presents the longest in situ survey of the growth patterns of L. pertusa and M. oculata. The observations revealed a strong inter-annual variability in growth rates, both for L. pertusa and M. oculata , and suggest an influence of hydrological conditions on the growth dynamics. Particularly, as regard to episodic water plumes events such as NW wind-induced dense water shelf cascades and E-SE storm-induced downwellings in autumn-winter. In this study, three types of responses were observed: (i) high budding rates but low colony linear extension for strong water plume events periods (ii) high budding rates and high linear extension associated to organic matter supply during medium intensity water plume events, and (iii) low budding rates, low linear extension and high mortality due to high sedimentation rates in the absence of water plume event. Lophelia pertusa appears to be more resilient to these hydrological changes. Disturbance of the regional circulation patterns, in addition to longer-term change in water mass properties such as warming, deoxygenation and acidification, are thus important parameters to consider for CWC reef stability. This is particularly important since increased storminess, and decreased cascading/downwelling intensities, are predicted to occur within the next century. Image 1 • We conducted a temporal in situ growth study of deep corals for eight years. • Corals live in a Mediterranean canyon subject to episodic water plumes events. • Strong inter-annual variability in growth rates with the hydrological conditions. • The absence of water plumes impacts dramatically the growth of corals. [ABSTRACT FROM AUTHOR]

Seamounts represent ecologically important marine environments and undeniably play a crucial role in the functioning of the deep-sea ecosystems, thanks primarily to their contribution in supporting offshore benthic and pelagic biodiversity. In the last decades, these features have received attention in all oceans of the world, but they were relatively overlooked in the Mediterranean Sea. In particular, the Ligurian Sea hosts six major structures, whose summits, ranging from 150 to nearly 2000 m depth, are virtually unknown from the biological point of view. The summit region of the Janua Seamount, located approximately at 30 nautical miles off the harbour of Genoa at 810 m depth, was explored for the first time using Remotely Operated Vehicles. The sea bed topography is characterized by a heterogeneous hard bottom, dominated by sub-fossil thanatocoenoses of Lophelia pertusa (Linnaeus, 1758) covered in a thick Ferrous-Manganese crust, and colonized by a scattered bathyal assemblage dominated by hexactinellids and benthic cnidarians showing a distinct regionalization around the summit. Cnidarians observed in this site include a rare Atlantic bamboo coral (Isididae, Chelidonisis aurantiaca Studer, 1890), described herein for the first time for the Mediterranean Basin. These findings provide new information on the biogeographic patterns of colonization of the bathyal Mediterranean fauna but also highlight the large knowledge gap that still exists for deep-sea biodiversity of this basin. • The Janua Seamount hosts a unique bathyal benthic community. • The bamboo coral Chelidonisis aurantiaca is described for the Mediterranean Sea. • Fossil traces testify to the luxurious past of the deep coral community. • ROV footage reveals a moderate fishing impact by long lines. • Seamounts hold a paramount ecological role for deep-sea ecosystems. [ABSTRACT FROM AUTHOR]

In face of increasing anthropogenic disturbance in the deep sea, it is a priority to better understand the regional distribution of cold-water corals (CWC). These organisms create some of the most species-rich habitats in the deep sea and, for this reason, they must be properly protected and managed. In this study, we aimed to identify suitable habitat for multiple CWC taxa off the Brazilian continental margin and compare their environmental niches. Habitat suitability models were developed using the Maxent approach, which allowed for the prediction of species distribution and for the identification of potential 'hot spot' areas that may be important for biodiversity conservation. Ecological niches were determined by a PCA-env approach, and niche similarity and equivalence were evaluated based on niche overlap using the Schoener's D metric. Potentially suitable habitat for Octocorallia covered a broad latitudinal range encompassing nearly the entire Brazilian continental margin, whereas Scleractinia had greater potentially suitable habitat in the Central and Southern areas. Scleractinian species were observed to slightly differ in their environmental niche, with non-reef-forming species being more tolerant to a wider range of environmental conditions in comparison with reef-forming species, inhabiting a wider area of the South American continental margin. Due to the high potential suitability for several CWC species, the Central and Southern parts of the Brazilian continental margin should be considered as potential areas high CWC diversity. Considering the current state of the art and strategic assessment tools, these areas are important targets for conservation, management, and environmental impact assessment. Most reef-forming species had similar but not directly equivalent ecological niches, indicating that mapping efforts and management planning should consider CWCs at the species level. • Octocorallia demonstrated suitable habitat that encompassed nearly the entire Brazilian continental margin • Scleractinia suitable habitat covered principally the Central and Southern continental margin.versity. • The Central and Southern Brazilian continental margin should be considered as areas of high cold-water corals di • Reef-forming cold-water coral species had similar but not equivalent ecological niches. • The mapping efforts and management planning should consider cold-water coral at the species level. [ABSTRACT FROM AUTHOR]

Marine communities associated with oil and gas platforms beyond the continental shelf are poorly described islands of potential interaction between structure oriented and pelagic taxa. Near-bottom, biological surveys were conducted at a petroleum platform located in 305 m water depth off the coast of Louisiana between 268 m and the seabed. Surveys were performed with a remotely operated vehicle (ROV) and consisted of replicated benthic transects on all four sides of the platform extending 125 m outward from the platform. The fouling community on hard surfaces of the horizontal cross-members and verticals were surveyed using HD video and digital still images. Relative abundances of fishes were estimated using digital still images collected at regular intervals under three illumination regimes: no light, red light, and white light, while the ROV hydraulics were switched off to reduce vehicle noise. Additional surveys of fishes were conducted during day and night at the platform and at two far-field sites located 2 km and 3 km from the platform by monitoring species attracted to buckets containing an olfactory attractant. The results indicated abundant coldwater coral Lophelia pertusa present on the platform and on the surrounding rubble near the platform. The fish assemblage at the platform was dominated by American barrelfish Hyperoglyphe perciformis , greater amberjack Seriola dumerili , Darwin's slimeheads Gephyroberyx darwinii , snowy grouper Epinephelus niveatus , misty grouper Hyporthodus mystacinus , American conger Conger oceanicus and Scorpaenidae. The fish community at the farfield site was substantially different and less diverse than that observed at the platform and was dominated by king snake eels (Ophichthys rex) and Scorpaenidae. The results indicate that multiple methods and both day and night surveys are necessary to obtain a more complete picture of the biological community around platforms located on the outer continental shelf. The use of red-filtered lights and quiet surveys without hydraulic pumps on can further reduce avoidance artifacts. • ROV surveys of the base of a petroleum platform in the Gulf of Mexico indicated deepwater fishes were abundant. • Benthic transects showed megafauna near the platform structure differed from those on the surrounding soft sediments. • The use of red-filtered lights combined with a reduction in the ROV's noise reduced avoidance by fishes at the platform. • Industrial ROVs with enhanced cameras and lights provide useful data on deepwater fauna associated with complex structure. • Artificial reefs based on petroleum structures may serve as valuable habitat for coldwater corals and associated organisms. [ABSTRACT FROM AUTHOR]