Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than previously recognised.
Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question-where is all the plastic?
Supplementary Materials for Ashford et al. 'Phylogenetic and functional evidence that deep-ocean ecosystems are highly sensitive to environmental change and direct human disturbance' Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2018.0923
One of the key messages to come from the OceanObs'09 Conference was that the 1990's revolution in technology for observing ocean physics (e.g.Argo (Array for Realtime Geostrophic Oceanography) and remote sensing) provided the scope for a truly operational Global Ocean Observing System (GOOS) for key ocean physics variables during the first decade of the 21st century.Over the same period however, there had been limited progress in development of biological components within GOOS, the expansion of the Continuous Plankton Recorder network and the development of an Ocean Tracking network being promising exceptions.
Abstract The tall sea pen Funiculina quadrangularis has a patchy distribution around the UK , being found in sheltered waters below 20 m depth on the northwest coast of Scotland and Ireland. The limited distribution and sensitivity to bottom fishing activities make F. quadrangularis vulnerable to reduction in population numbers that may lead to genetic isolation and reduced diversity. Because of this vulnerability and low resilience to physical disturbance, the tall sea pen is recognised as a Species of Principle Importance under the Natural Environment and Rural Communities Act, 2006, UK. ( http://www.legislation.gov.uk/ukpga/2006/16/contents ) and is also on the Biodiversity Action Plan list of Priority Species for the UK . In the Mediterranean it is recognised as a sensitive and essential fish habitat because it forms habitat for several commercially important crustaceans. The aim of this study was to understand the current state of the genetic structure and gene flow of F. quadrangularis in areas of NW Scotland. We developed 10 microsatellite markers and used them to genotype 176 samples from four populations. Overall, our results suggest that there is high genetic diversity and high gene flow between colonies of F. quadrangularis in and among locations in Loch Linnhe and Loch Duich. As a result of the high rates of gene flow, genetic differentiation between sites was low. This may provide resilience to human impacts if distant populations have a high connectivity. However, care must be taken, as small but significant isolation by distance was found between the most geographically distant sites and only a small part of the species range was examined in this study. The genetic tools developed here will provide a foundation for wider studies of this vulnerable species.
Vulnerable marine ecosystems (VMEs) are considered hotspots of biodiversity and ecosystem functioning in the deep sea, but are also characterised by a high vulnerability to disturbance and a low recovery potential. Since 2006, a series of United Nations General Assembly resolutions have been developed, attempting to ensure the protection of VMEs in international waters. In the Northwest Atlantic Fisheries Organisation (NAFO) Regulatory Area, large areas of seabed have been closed to bottom-contact fishing to protect VMEs. However, knowledge of the influence of VME-indicator taxa on macrofaunal assemblages, and the appropriateness of current fishery closures for protecting macrofaunal biodiversity in this area is limited. Here we investigate relationships between the prevalence of VME-indicator taxa (poriferans [sponges], gorgonian corals and pennatulaceans [sea pens]) and an extensive suite of peracarid crustacean biodiversity metrics in the NAFO Regulatory Area. We also examine whether the current NAFO VME closures protect areas of significantly elevated peracarid diversity. Of the VME-indicator taxa analysed, poriferans were found to have by far the greatest influence over peracarid assemblages. Assemblage structure was altered, and peracarid abundance, biomass, richness, diversity, and variability were enhanced in areas of elevated poriferan biomass, whilst assemblage evenness was slightly depressed in these areas. These findings reaffirm the perception of poriferans as crucial components of VMEs. In contrast, gorgonian coral density had little influence over the faunal assemblages investigated, perhaps reflecting their relatively low prevalence in the study area. Similarly, pennatulaceans were found to influence peracarid assemblages only weakly. This too may reflect a moderately low density of Pennatulacea in the study area. Our results highlight that the application of taxon distribution model outputs to ecological investigations and management decisions in data-limited environments should be treated with caution. Finally, our results indicate that the current system of fishery closures in the NAFO Regulatory Area may not be optimal in terms of providing adequate protection to VMEs against the impacts of bottom trawling.
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