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Seamounts and oceanic islands rise from the seafloor and provide suitable habitat for a diverse range of biological assemblages including Vulnerable Marine Ecosystems (VMEs). Whilst they have been the focus of some work globally, there has been little description of the biological and physical environments of seamounts in the South Atlantic Ocean. In this study, we characterized benthic assemblage composition from 13 seamounts and oceanic islands spanning 8–40°S within the exclusive economic zones (EEZs) of Ascension Island, Saint Helena and Tristan da Cunha. Drop camera imagery was collected between 170 and 1000 m. All fauna present in images were identified and quantified, and multivariate statistics were used to describe biological assemblages and identify their environmental drivers. Benthic communities of temperate regions (Tristan da Cunha archipelago) were shown to be distinct from those found in the tropics, with latitude and depth identified as key environmental drivers of assemblage composition. Our results are consistent with the current understanding of the biogeography of the South Atlantic, both in terms of the distinction between tropical and temperate regions, and the influence of depth and water mass structure on assemblage distribution. Faunal assemblages are similar to those observed in the North Atlantic in terms of functional groups. VMEs are present within the EEZs of all three territories and are potentially protected from some threats by large marine protected areas (MPAs). Our imagery, data and analyses provide a baseline for south Atlantic seamounts so that future monitoring can establish whether existing protected status is sufficient to conserve both unique biodiversity and considerable potential for vital ecosystem services.

The South Sandwich Islands (SSI) are a chain of volcanic islands located to the east of the Scotia Sea, approximately 700 km south-east of South Georgia. To date, knowledge of the SSI benthic environment remains limited. In this context, the Blue Belt Programme conducted a scientific survey in the SSI Marine Protected Area (MPA) during February/March 2019 to examine the biodiversity and distribution of benthic communities and their potential vulnerability to licensed longline research fisheries. Here we report results from analysis of multibeam echosounder (MBES) data and drop camera imagery data collected in selected locations around the SSI. A total of eight vulnerable marine ecosystem (VME) indicator morphotaxa were mapped along the slopes of the SSI, showing a substantial variation in taxon composition and frequency of occurrence, both along bathymetric and latitudinal gradients. Our results suggest that VME indicator taxa are mostly restricted to waters shallower than 700 m. As such, based on our present understanding of the region’s benthic environment the MPA, as currently established, offers effective protection for the majority of the VME indicator taxa.

The concept of “vulnerable marine ecosystem” (VME) was included in United Nations (UN) General Assembly Resolution 61/105 as part of an international effort to minimize the effects of seafloor fisheries on the high seas. However, defining a VME was left to be developed by technical guidance to the UN Food and Agricultural Organization. In that venue certain categories of organisms were deemed to be indicator species, suggesting that areas with those species would be considered VMEs with subsequent management measures implemented to conserve those ecosystem attributes. We note that on seamounts VME indicator species can be distributed widely, in dense clusters or sparsely. A dense cluster, for example, of scleractinian corals or sponges, is most often referred to as a VME, but we argue that any such dense cluster is not an ecosystem, rather it is a community, likely one of many that make up the ecosystem. Other communities on the seamount that are not part of that dense cluster could include many small species (some yet to be discovered) who are also part of the ecosystem because they are part of the web of interactions and flow of materials/energy on the seamount. We also suggest that a seamount ecosystem might extend over several or many seamounts in a biogeographic area. We conclude that the term “ecosystem” in the VME concept outlined by the United Nations needs to be re-evaluated from a classical ecological perspective leading to spatial management approaches that better address ecologically relevant space and time scales.

Protection of vulnerable marine ecosystems (VME) is a critical goal for marine conservation. Yet, in many deep-sea settings, where quantitative data are typically sparse, it is challenging to correctly identify the location and size of VMEs. Here we assess the sensitivity of a method to identify coral reef VMEs based on bottom cover and abundance of the stony coral Solenosmilia variabilis on deep seamounts, using image data from a 2018 large survey off Tasmania, Australia. Whilst there was some detectable influence of varying coral cover and the abundance of live coral heads, the distribution of coral reef VMEs was not substantially shifted by changing these criteria or altering the attributes of a moving window used to spatially aggregate coral patches. Whilst applying stricter criteria for classifying VMEs predictably produced smaller areas of coral reef VME, these differences are not sizeable and were often negligible. A model prediction of the area of suitable habitat for coral reef in the Tasmanian area was much greater than that estimated in this study. Coral reef VMEs formed large contiguous ‘blankets’, mainly on the peaks and flanks of seamounts, but were absent from the continental slope where S. variabilis occurred at low abundance (cover) and/or had no living colonies. The true size of the Tasmanian coral reef VMEs ranged from 0.02 to 1.16 km2; this was relatively large compared to reefs of S. variabilis mapped on New Zealand seamounts, but is small compared to the scales used for regional model predictions of suitable habitat (typically 1 km2 grid cell), much smaller than the smallest units of management interest (100s – 1000s km²). That the method is not overly sensitive to the choice of criteria is highly encouraging in the context of designing spatial conservation measures that are robust, although its broader application, including to other VME indicator taxa, needs to be substantiated by scenario testing in different environments. Importantly, it should encourage uptake by the broader community (e.g. fishing and mining sectors) and forms the basis for better predictive VME models at larger spatial scales and beyond single taxa.

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.

The United Nations General Assembly has called for the adoption of conservation management measures to protect vulnerable marine ecosystems (VMEs) from significant adverse impacts outside of areas of national jurisdiction. In response, many regional fisheries management organisations (RFMOs) have implemented move-on rules triggered by encounter threshold levels for the biomass of VME indicator taxa retained as bycatch. However, due to uncertainty of the relationships between catch, catch efficiency and the in-situ biomass of VME indicator taxa, move-on rules alone may not be enough to prevent significant adverse impacts on VMEs. Although spatial management measures present one possible solution to these concerns, a lack of empirical data on the distribution of VMEs within the high seas means spatial management is often informed by model predictions of the spatial distribution of VME indicator taxa. Given the uncertainty associated with predicted distributions, move-on rules can provide immediate responses when spatial management measures may not be providing the expected conservation benefits. Using bycatch data from 9,771 New Zealand bottom trawls within the South Pacific RFMO Convention Area, we illustrate a data-informed approach for selecting high move-on encounter thresholds that may suggest the predicted distributions of VME taxa used to underpin spatial management are highly inaccurate. The reasoning that high thresholds act as a safeguard against uncertainty in the performance of spatial management measures requires untested assumptions regarding the level of permissible bycatch before further management action is required, with the acceptance of those assumptions a management decision balancing the sensitivity of the move-on rule with uncertainty regarding the effectives of the spatial management measures. Additional work is required to support these management decisions, including the determination of taxa-specific catchability estimates, and the seafloor density/biomass of VME indicator taxa that represents a VME. Obtaining this information will allow for the identification of encounter thresholds that are more ecologically meaningful. In the interim, the choice of thresholds should be re-evaluated as more experience with their application is gathered.

Biogenic reefs are known worldwide to play a key role in benthic ecosystems, enhancing biodiversity and ecosystem functioning at every level, from shallow to deeper waters. Unfortunately, several stressors threaten these vulnerable systems. The widespread presence of marine litter represents one of these. The harmful effects of marine litter on several organisms are known so far. However, only in the last decade, there was increasingly scientific and public attention on the impacts on reef organisms and habitats caused by litter accumulating on the seafloor. This review aims to synthesize literature and discuss the state of current knowledge on the interactions between marine litter and reef organisms in a strongly polluted basin, the Mediterranean Sea. The multiple impacts (e.g., entanglement, ghost-fishing, coverage, etc.) of litter on reef systems, the list of species impacted, and the main litter categories were identified, and a map of the knowledge available so far on this topic was provided. Seventy-eight taxa resulted impacted by marine litter on Mediterranean reefs, and the majority belonged to the phylum Cnidaria (41%), including endangered species like the red coral (Corallium rubrum) and the madrepora coral (Madrepora oculata). Entanglement, caused mainly by abandoned, lost or otherwise discarded fishing gear (ALDFG), was the most frequent impact, playing a detrimental effect mainly on coralligenous arborescent species and cold-water corals (CWCs). The information was spatially heterogeneous, with some areas almost uncovered by scientific studies (e.g., the Aegean-Levantine Sea and the Southern Mediterranean Sea). Although many legal and policy frameworks have been established to tackle this issue (e.g., Marine Strategy Framework Directive and the Barcelona Convention), several gaps still exist concerning the assessment of the impact of marine litter on marine organisms, and in particular on reefs. There is a need for harmonized and standardized monitoring protocols for the collection of quantitative data to assess the impact of litter on reefs and animal forests. At the same time, urgent management measures limiting, for instance, the impact of ALDFG and other marine litter are needed to preserve these valuable and vulnerable marine ecosystems.

Rising demand for minerals and metals, including for use in the technology sector, has led to a resurgence of interest in exploration of mineral resources located on the seabed. Such resources, whether seafloor massive (polymetallic) sulfides around hydrothermal vents, cobalt-rich crusts on the flanks of seamounts or fields of manganese (polymetallic) nodules on the abyssal plains, cannot be considered in isolation of the distinctive, in some cases unique, assemblages of marine species associated with the same habitats and structures. In addition to mineral deposits, there is interest in extracting methane from gas hydrates on continental slopes and rises. Many of the regions identified for future seabed mining are already recognised as vulnerable marine ecosystems. Since its inception in 1982, the International Seabed Authority (ISA), charged with regulating human activities on the deep-sea floor beyond the continental shelf, has issued 27 contracts for mineral exploration, encompassing a combined area of more than 1.4 million km2, and continues to develop rules for commercial mining. At the same time, some seabed mining operations are already taking place within continental shelf areas of nation states, generally at relatively shallow depths, and with others at advanced stages of planning. The first commercial enterprise, expected to target mineral-rich sulfides in deeper waters, at depths between 1,500 and 2,000 metres on the continental shelf of Papua New Guinea, is scheduled to begin early in 2019. In this review, we explore three broad aspects relating to the exploration and exploitation of seabed mineral resources: (1) the current state of development of such activities in areas both within and beyond national jurisdictions, (2) possible environmental impacts both close to and more distant from mining activities and (3) the uncertainties and gaps in scientific knowledge and understanding which render baseline and impact assessments particularly difficult for the deep sea. We also consider whether there are alternative approaches to the management of existing mineral reserves and resources, which may reduce incentives for seabed mining.

Aim Seamounts are conspicuous geological features with an important ecological role and can be considered vulnerable marine ecosystems (VMEs). Since many deep‐sea regions remain largely unexplored, investigating the occurrence of VME taxa on seamounts is challenging. Our study aimed to predict the distribution of four cold‐water coral (CWC) taxa, indicators for VMEs, in a region where occurrence data are scarce. Location Seamounts around the Cabo Verde archipelago (NW Africa). Methods We used species presence–absence data obtained from remotely operated vehicle (ROV) footage collected during two research expeditions. Terrain variables calculated using a multiscale approach from a 100‐m‐resolution bathymetry grid, as well as physical oceanographical data from the VIKING20X model, at a native resolution of 1/20°, were used as environmental predictors. Two modelling techniques (generalized additive model and random forest) were employed and single‐model predictions were combined into a final weighted‐average ensemble model. Model performance was validated using different metrics through cross‐validation. Results Terrain orientation, at broad scale, presented one of the highest relative variable contributions to the distribution models of all CWC taxa, suggesting that hydrodynamic–topographic interactions on the seamounts could benefit CWCs by maximizing food supply. However, changes at finer scales in terrain morphology and bottom salinity were important for driving differences in the distribution of specific CWCs. The ensemble model predicted the presence of VME taxa on all seamounts and consistently achieved the highest performance metrics, outperforming individual models. Nonetheless, model extrapolation and uncertainty, measured as the coefficient of variation, were high, particularly, in least surveyed areas across seamounts, highlighting the need to collect more data in future surveys. Main Conclusions Our study shows how data‐poor areas may be assessed for the likelihood of VMEs and provides important information to guide future research in Cabo Verde, which is fundamental to advise ongoing conservation planning. Resumo Objetivo Montes submarinos são importantes formações geológicas com um notável papel ecológico e podem ser considerados Ecossistemas Marinhos Vulneráveis (VMEs). Dado que muitas regiões do mar profundo permanecem inexploradas, investigar a ocorrência de espécies indicadoras de VMEs é um desafio. O nosso estudo teve como objetivo prever a distribuição de quatro taxa de corais de água fria (CWC), indicadores de VMEs, numa região onde dados de ocorrência são escassos. Localização Montes submarinos no Arquipélago de Cabo Verde (NO África). Métodos Utilizamos dados de presença‐ausência de CWC obtidos a partir de imagens de um Veículo de Operação Remota (ROV) durante duas expedições científicas. Como dados ambientais foram utilizados variáveis de terreno calculadas com uma abordagem multi‐escala a partir de uma grelha de batimetria com 100 m de resolução, e dados de oceanografia física obtidos com o modelo VIKING20X, a uma resolução nativa de 1/20°. Duas técnicas de modelação (Generalized Additive Models (GAM) e Random Forest) foram usadas e resultados de modelos individuais foram combinados, através da média ponderada, num modelo final Ensemble. O desempenho dos modelos foi validado usando diferentes métricas através de técnicas de validação cruzada. Resultados A orientação do terreno, a larga escala, apresentou uma das maiores contribuições relativas para os modelos de distribuição de todos os CWCs, sugerindo que interações de hidrodinâmica com topografia beneficiam os corais, possivelmente pelo aumento da disponibilidade de alimento. No entanto, mudanças na morfologia de terreno a escalas mais finas e salinidade foram importantes para diferenças entre a distribuição de espécies específicas. O modelo Ensemble projetou a presença de indicadores de VMEs em todos os montes submarinos e, consistentemente, apresentou métricas de desempenho mais altas, superando modelos individuais. No entanto, medidas de extrapolação e incerteza foram elevadas, especialmente em áreas menos estudadas, destacando claramente a necessidade de recolher mais dados. Conclusão O nosso estudo mostra como áreas com poucos dados podem ser avaliadas quanto à probabilidade de VMEs e fornece informações importantes para guiar futuras investigações em Cabo Verde, sendo fundamental para aconselhar planos de conservação em curso.

Northern coastlines face increasing challenges in marine conservation as climate change, shifting ocean currents, and human activities place pressure on sensitive benthic ecosystems. Nunatsiavut, a sovereign Inuit region in Labrador, Canada, has over 17,000 km of coastline made up of dynamic landscapes featuring high marine biodiversity. There, swift currents, restrictive weather, a prolonged sea ice season, and uncharted seafloors make benthic studies of nearshore areas using conventional scientific methods difficult and costly. Therefore, most studies that have been conducted in Nunatsiavut catalogue the benthos in deeper waters away from the coastline, but not where Labrador Inuit most often interact with the benthos. This study helps to fill critical knowledge gaps in benthic community composition in a culturally appropriate manner that reinforces the relationships between community members, the benthos, and researchers. To do this, we used GoPro cameras and participatory mapping to better understand benthic communities in coastal Nunatsiavut, as well as the relationships between the benthos and Labrador Inuit. We identified 60 taxa comprising seven near-shore benthic community assemblages in areas that are challenging to access using more conventional scientific benthic survey methods, doing so at a fraction of the cost and with greater community engagement in the research project. By identifying these species through methodology centered on the relationships between Labrador Inuit and the benthos, the results can be instrumental in informing resiliency plans, especially as they relate to food security in the face of climate change.