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

The authors would like to thank Bill Richardson (Master), the crew of the RRS James Cook, Will Handley and the Holland-I ROV team. We also thank all the specialists in taxonomy that provided important help with identification of species: Professor Paul Tyler (ophiuroids), Dr. Tammy Horton (amphipods), Dr. Graham Oliver (bivalves), Dr. Rob van Soest (sponges), Susan Chambers, Peter Garwood, Sue Hamilton, Raimundo Blanco Pérez (polychaetes). Also we would like to thank Val Johnston (University of Aberdeen) for her contribution to cruise preparations and John Polanski (University of Aberdeen) for his help onboard the RRS James Cook. Special thanks to Dr. Alexios P. Lolas (University of Thessaly, Greece) for all the artwork. Funding for the JC073 cruise was provided by the Natural Environment Research Council (NERC) UK Ocean Acidification (UKOA) research programme’s Benthic Consortium project (NE/H017305/1 to JMR). JMR acknowledges support from Heriot-Watt University’s Environment and Climate Change theme. GK was funded by a Marine Alliance for Science and Technology for Scotland (MASTS) Ph.D. scholarship.Peer reviewedPublisher PD

Hidden structural heterogeneity enhances marine hotspots’ 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

On the effects of acid pre-treatment on the elemental and isotopic composition of lightly- and heavily-calcified marine invertebrates

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

Aim: We 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. Location: The Mingulay Reef Complex, a protected biogenic ecosystem in the northeast Atlantic (120–190 m). Methods: A 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. Results: Environmental gradients explained a significant amount of community composition (urn:x-wiley:13669516:media:ddi13363:ddi13363-math-0001 = 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 Conclusions: Our 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

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

Thanks to Bill Richardson (Master) and the crew of the Royal Research Ship “James Cook” during the JC073 “Changing Oceans” expedition, Will Handley and the Holland-I ROV team. Also thanks to Dr Christina Mueller and Dr Evina Gontikaki for their guidance on experimental set-up and sample preparation for stable isotope analysis. Funding for the JC073 cruise was provided by the Natural Environment Research Council (NERC) UK Ocean Acidification (UKOA) research programme’s Benthic Consortium project (NE/H017305/1 to J Murray Roberts). Funding for the field work and analytical costs was provided by the Marine Alliance for Science and Technology for Scotland (MASTS) (Biodiversity Grant to UW, 140 SF10003-10, Deep-Sea Forum Small Grant DSSG4 awarded to GK) and by the Netherlands Organisation for Scientific Research (awarded to DvO). GK was funded by a MASTS PhD scholarship. The ATLAS project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 678760 (ATLAS). This output reflects only the author’s views, and the European Union cannot be held responsible for any use that may be made of the information contained therein. The funding sources had no involvement in study design, the collection, analysis and interpretation of data, in the writing of the report, and in the decision to submit the article for publication. The authors would like to thank the two reviewers of the manuscript for their constructive comments.Peer reviewedPostprin

Towards a common approach to the assessment of the environmental status of deep-sea ecosystems in areas beyond national jurisdiction

Many of the marine policy frameworks developed to protect biodiversity in deep-sea areas, including areas beyond national jurisdiction (ABNJ), include indicators to assess policy objectives. These frameworks often have specific guidance on how the indicators should be applied and interpreted. Selection of indicators is an important process and those with strong scientific underpinnings are more likely to produce the expected outcomes. We reviewed three policy and assessment frameworks which include ABNJ regions or were developed specifically for ABNJ: (1) Oslo and Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) ecosystem assessments, (2) the frameworks adopted to implement the UN General Assembly (UNGA) sustainable fisheries resolutions for the management of bottom fisheries to prevent Significant Adverse Impacts on vulnerable marine ecosystems, and (3) the Aichi Biodiversity Targets adopted by Parties to the Convention on Biological Diversity (CBD). We examined whether an assessment approach based on evaluation of Good Environmental Status (GES) under the European Union's Marine Strategy Framework Directive (MSFD), could be applied to ABNJ. We examined each MSFD descriptor for its applicability to deep-sea habitats considering the work of two European projects concluding that the MSFD could be applied to ABNJ to support OSPAR, UNGA and CBD policy objectives towards a common approach to the assessment of the status of deep-sea ecosystems in ABNJ. In achieving this we also introduce readers outside of Europe to the work conducted within the MSFD

Coral cities of the deep. Species–habitat associations on the Mingulay Reef Complex

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Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic

Circulation patterns in the North Atlantic Ocean have changed and re-organized multiple times over millions of years, influencing the biodiversity, distribution, and connectivity patterns of deep-sea species and ecosystems. In this study, we review the effects of the water mass properties (temperature, salinity, food supply, carbonate chemistry, and oxygen) on deep-sea benthic megafauna (from species to community level) and discussed in future scenarios of climate change. We focus on the key oceanic controls on deep-sea megafauna biodiversity and biogeography patterns. We place particular attention on cold-water corals and sponges, as these are ecosystem-engineering organisms that constitute vulnerable marine ecosystems (VME) with high associated biodiversity. Besides documenting the current state of the knowledge on this topic, a future scenario for water mass properties in the deep North Atlantic basin was predicted. The pace and severity of climate change in the deep-sea will vary across regions. However, predicted water mass properties showed that all regions in the North Atlantic will be exposed to multiple stressors by 2100, experiencing at least one critical change in water temperature (+2 degrees C), organic carbon fluxes (reduced up to 50%), ocean acidification (pH reduced up to 0.3), aragonite saturation horizon (shoaling above 1000 m) and/or reduction in dissolved oxygen (> 5%). The northernmost regions of the North Atlantic will suffer the greatest impacts. Warmer and more acidic oceans will drastically reduce the suitable habitat for ecosystem-engineers, with severe consequences such as declines in population densities, even compromising their long-term survival, loss of biodiversity and reduced biogeographic distribution that might compromise connectivity at large scales. These effects can be aggravated by reductions in carbon fluxes, particularly in areas where food availability is already limited. Declines in benthic biomass and biodiversity will diminish ecosystem services such as habitat provision, nutrient cycling, etc. This study shows that the deep-sea VME affected by contemporary anthropogenic impacts and with the ongoing climate change impacts are unlikely to withstand additional pressures from more intrusive human activities. This study serves also as a warning to protect these ecosystems through regulations and by tempering the ongoing socio-political drivers for increasing exploitation of marine resources

The trophic structure of Spongosorites coralliophaga-coral rubble communities at two northeast Atlantic cold water coral reefs

Funding for the JC073 cruise was provided by the Natural Environment Research Council (NERC) UK Ocean Acidification (UKOA) research programme’s Benthic Consortium project (NE/H017305/1 to J Murray Roberts). Funding for analytical costs and field work was provided by the Marine Alliance for Science and Technology Scotland (MASTS) (Biodiversity Grant to Ursula FM Witte, 140 SF10003-10). Georgios Kazanidis was funded by a MASTS PhD scholarship.Peer reviewedPublisher PD