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Across the world's oceans, our knowledge of the habitats on the seabed is limited. Increasingly, video/imagery data from remotely operated underwater vehicles (ROVs) and towed and drop cameras, deployed from vessels, are providing critical new information to map unexplored benthic (seabed) habitats. However, these vessel-based surveys involve considerable time and personnel, are costly, require favorable weather conditions, and are difficult to conduct in remote, offshore, and deep marine habitats, which makes mapping and surveying large areas of the benthos challenging. In this study, we present a novel and efficient method for mapping diverse benthic habitats on the continental shelf, using animal-borne video and movement data from a benthic predator, the Australian sea lion (Neophoca cinerea). Six benthic habitats (between 5-110m depth) were identified from data collected by eight Australian sea lions from two colonies in South Australia. These habitats were macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate reef and invertebrate boulder habitats. Percent cover of benthic habitats differed on the foraging paths of sea lions from both colonies. The distributions of these benthic habitats were combined with oceanographic data to build Random Forest models for predicting benthic habitats on the continental shelf. Random forest models performed well (validated models had a >98% accuracy), predicting large areas of macroalgae reef, bare sand, sponge/sand and invertebrate reef habitats on the continental shelf in southern Australia. Modelling of benthic habitats from animal-borne video data provides an effective approach for mapping extensive areas of the continental shelf. These data provide valuable new information on the seabed and complement traditional methods of mapping and surveying benthic habitats. Better understanding and preserving these habitats is crucial, amid increasing human impacts on benthic environments around the world. [ABSTRACT FROM AUTHOR]

Across the world’s oceans, our knowledge of the habitats on the seabed is limited. Increasingly, video/imagery data from remotely operated underwater vehicles (ROVs) and towed and drop cameras, deployed from vessels, are providing critical new information to map unexplored benthic (seabed) habitats. However, these vessel-based surveys involve considerable time and personnel, are costly, require favorable weather conditions, and are difficult to conduct in remote, offshore, and deep marine habitats, which makes mapping and surveying large areas of the benthos challenging. In this study, we present a novel and efficient method for mapping diverse benthic habitats on the continental shelf, using animal-borne video and movement data from a benthic predator, the Australian sea lion (Neophoca cinerea). Six benthic habitats (between 5-110m depth) were identified from data collected by eight Australian sea lions from two colonies in South Australia. These habitats were macroalgae reef, macroalgae meadow, bare sand, sponge/sand, invertebrate reef and invertebrate boulder habitats. Percent cover of benthic habitats differed on the foraging paths of sea lions from both colonies. The distributions of these benthic habitats were combined with oceanographic data to build Random Forest models for predicting benthic habitats on the continental shelf. Random forest models performed well (validated models had a >98% accuracy), predicting large areas of macroalgae reef, bare sand, sponge/sand and invertebrate reef habitats on the continental shelf in southern Australia. Modelling of benthic habitats from animal-borne video data provides an effective approach for mapping extensive areas of the continental shelf. These data provide valuable new information on the seabed and complement traditional methods of mapping and surveying benthic habitats. Better understanding and preserving these habitats is crucial, amid increasing human impacts on benthic environments around the world.

Introduction: The Arctic sea ice extent in September (when it is at its lowest) has declined 13% Q10 per decade, and the Arctic Ocean is becoming a more Atlantic-influenced system. Rapid climate-forced changes are taking place in many high-latitude marine ecosystems. The Barents Sea is one such highlatitude shelf ecosystem, between approximately 70° and 80°N in the Norwegian Arctic. The purpose of the current study was to estimate zoobenthic blue carbon across multiple habitats within the Barents Sea (trough, basin, shelf, and shallows), potentially providing values to aid ecosystem-based management of these areas under future climate change scenarios. Method: We tested this by capture and analysis of 947 high-resolution (each 405.7 × 340.6 mm, 12 MB, 5 megapixels) seabed images at 17 sites with latitudinal cline, linked to a collection of corresponding oceanographic data. Biotas within these images were identified to one of the 14 functional groups and the density was calculated. Mean stored carbon per individual was assigned by ash mass (AM) and ash-free dry mass (AFDM) of individuals caught within Agassiz trawl deployments at the same sites. Results: Trough sites, except for one site (B16), have a low quantity of zoobenthic blue carbon compared with the shallow, shelf, and basin habitats. Discussion: The results of a previous study focused entirely on trough habitats and are therefore difficult to scale up as the basis for a meaningful estimate of across-habitat zoobenthic blue carbon in the Barents Sea. Compared with the trough and the basin, the shelf and shallow habitats of the Barents Sea are also subjected to more trawling events through demersal fisheries and showed higher zoobenthic blue carbon stock values. [ABSTRACT FROM AUTHOR]

IntroductionThe Arctic sea ice extent in September (when it is at its lowest) has declined 13% Q10 per decade, and the Arctic Ocean is becoming a more Atlantic-influenced system. Rapid climate-forced changes are taking place in many high-latitude marine ecosystems. The Barents Sea is one such high-latitude shelf ecosystem, between approximately 70° and 80°N in the Norwegian Arctic. The purpose of the current study was to estimate zoobenthic blue carbon across multiple habitats within the Barents Sea (trough, basin, shelf, and shallows), potentially providing values to aid ecosystem-based management of these areas under future climate change scenarios.MethodWe tested this by capture and analysis of 947 high-resolution (each 405.7 × 340.6 mm, 12 MB, 5 megapixels) seabed images at 17 sites with latitudinal cline, linked to a collection of corresponding oceanographic data. Biotas within these images were identified to one of the 14 functional groups and the density was calculated. Mean stored carbon per individual was assigned by ash mass (AM) and ash-free dry mass (AFDM) of individuals caught within Agassiz trawl deployments at the same sites.ResultsTrough sites, except for one site (B16), have a low quantity of zoobenthic blue carbon compared with the shallow, shelf, and basin habitats.DiscussionThe results of a previous study focused entirely on trough habitats and are therefore difficult to scale up as the basis for a meaningful estimate of across-habitat zoobenthic blue carbon in the Barents Sea. Compared with the trough and the basin, the shelf and shallow habitats of the Barents Sea are also subjected to more trawling events through demersal fisheries and showed higher zoobenthic blue carbon stock values.

Benthic macroinvertebrate protocols, in the United States, have been integral in the implementation of the Clean Water Act (33 U.S.C. §1251 et seq. (1972)). The methods in these protocols are designed to describe patterns of biological water quality and ecological condition relevant to legislative oversight, and require a tradeoff between taxonomic precision and protocol simplicity. The global similarity of ecological and evolutionary responses to the challenges of life in flowing waters, by stream organisms, has greatly facilitated the development and implementation of biological data from freshwater mussels, fishes and aquatic insects into streamlined regulatory frameworks. Unfortunately, the factors that expedite the use of benthic data into ecological descriptions sufficient for regulatory processes (taxonomic generalizations, standardization of sampling procedures to focus on a narrow subset of available habitats) also limit the utility of these methods in the conservation of benthic macroinvertebrate species (the large majority of which are insects). Using simple hypothetical simulations, some examples from a taxonomic and ecological database of one state in the USA (Illinois), and data from a large-scale inventory of aquatic insect species in a network of US National Parks, I illustrate how these methods are limited in their ability to effectively describe ecological patterns relevant to the conservation of aquatic insect species. I identify, challenge, and explore three basic assumptions implicit to the genus- and family-level identification methods widely used in freshwater benthic science, then discuss how the failure of these assumptions may create empirical, theoretical and philosophical obstacles to the interpretation of data and certainly hinder the conservation of species. I offer some hopeful suggestions for improving aquatic insect species conservation that are within the reach of all benthic freshwater ecologists.

Sessile marine invertebrate (biofouling) communities have served as an important model in ecology for evaluating fundamental patterns and processes, including invasion dynamics, which vary at broad spatial and temporal scales. Here, we tested for differences in biofouling community development among three biogeographically distinct bays in North America (Chesapeake Bay, Tampa Bay, and San Francisco Bay), exploring possible explanations for differential non-native species success. In particular, we aimed to examine if San Francisco Bay (a global hotspot for non-native species richness) differed in composition and space occupation, especially since open space can facilitate colonization. Additionally, we explored how biogeography, assembly and succession dynamics over the short and long term, and space availability affect marine communities across broad spatial scales. Patterns of community assembly differed among bays, with more bare space and less secondary cover (species settling on species) in San Francisco Bay. San Francisco Bay was also distinguished by a higher percent cover of Tunicata (almost all of which are non-native and historically absent) over multiple time scales. Cirripedia recruited on bare panels in all three Bays but cover increased only in Tampa Bay, as soak time increased. Tube-dwelling Polychaeta distinguished Chesapeake Bay from Tampa Bay and San Francisco Bay. Low-salinity events temporarily restructured the communities in all three bays. Whether differences among bays reflect coastal versus bay-specific patterns remains to be tested.

Biogeographic studies aim to understand species distributions and are becoming increasingly relevant to establish baselines to monitor ecological change. The NW Atlantic coast hosts a cold-temperate biota, although knowledge about its biogeography is patchy. This study documents for the first time biogeographic variation at mid-to-high intertidal elevations in wave-exposed rocky intertidal habitats along the open Atlantic coast of Nova Scotia (Canada), a hydrographically distinct subregion of this cold-temperate region. For this goal, we measured the summer abundance of algae and invertebrates at the same nine locations over four consecutive years (2014 to 2017) spanning 415 km of coastline, which allowed us to examine latitudinal and interannual patterns. In addition, we looked for mensurative evidence on possible drivers underlying these patterns, focusing on sea surface temperature, daily maximum and minimum temperature (which often happen at low tides at thus differ from sea surface temperature), pelagic food supply for intertidal filter-feeders (phytoplankton abundance and particulate organic carbon), drift sea ice during the cold season (which can cause intertidal disturbance), and species associations. Our field surveys revealed that northern locations can be severely disturbed by ice scour when drift ice is abundant and, while biological recolonization occurs over the years, it differs in pace among locations. Southern locations, instead, did not experience ice scour during our study and, thus, generally exhibited a higher species richness and abundance than northern locations. Multivariate analyses indicated that the aforementioned expressions of temperature and pelagic food supply explained together 32–55% of the variation in alongshore biogeographic pattern, depending on the year. Species association analyses suggest that algal foundation species (generally more abundant at southern locations) contribute to increase location-wise species richness. Mensurative evidence for bottom-up forcing in seaweed–herbivore and filter-feeder–predator systems differed greatly among years. Overall, in addition to its inherent value to advance NW Atlantic intertidal biogeography, our species distribution database should be valuable to assess ecological change decades into the future as climate change and other anthropogenic influences unfold.

The current article focuses on the morphological and molecular characterization of the often inconspicuous genus Amicula. This recently erected genus from brackish and marine sediments was monotypic but here we describe two new tropical species: Amicula micronesica sp. nov. and Amicula vermiculata sp. nov. Once considered an incertae sedis genus regarding its higher rank taxonomy, its position among the family Diploneidaceae is proposed here by molecular phylogenetics. The complete plastid and mitochondrial genomes of Amicula micronesica sp. nov. are also presented here. It appears that the 177614-bp long mitogenome is the biggest yet recorded among stramenopiles, due to its invasion by 57 introns. Moreover, it utilizes the genetic code 4 for translation instead of the code 1 usually found among diatoms.

Large structures are introduced into deep-water marine environments by several industrial activities, including hydrocarbon exploitation. Anthropogenic structures can alter ecosystem structure and functioning in many marine ecosystems but the responses on continental margins are poorly known. Here, we investigate the short-term response of benthic megafauna to the installation of a 56 km-long 30 cm diameter pipeline on the Angolan Margin (Block 31) from 700 to 1800 m water depth using remotely operated vehicle imagery. Clear depth-related patterns exist in the density, diversity and community structure of megafauna observed in 2013 prior to pipeline installation. These patterns are altered in a subsequent survey in 2014, three-months after pipeline installation. Significant increases in density, particularly in mid-slope regions are observed. Diversity is generally, but not consistently, enhanced, particularly in the shallower areas in 2014. Clear changes are noted in community structure between years. These changes are primarily caused by increases in the abundance of echinoderms, particularly the echinoid Phormosoma sp. indet. There was no evidence of colonisation of the pipeline in three months by visible fauna. The few large anemones observed attached to the pipe may be able to move as adults. The pipeline appeared to trap organic material and anthropogenic litter, and may enhance available food resources locally as well as providing hard substratum. These results indicate complex and ecosystem-dependent responses to structure installation and caution against simplistic approaches to environmental management.

Post-collapse of seasonal blooms of gelatinous zooplankton (Cnidaria, Ctenophora, and Thaliacea) sinking carcasses transports labile carbon (jelly-C) to benthic continental margins and the deep sea. In recent decades, bloom frequency and intensity have increased globally; however, how sinking jelly-C affects benthic communities is poorly known. Further, as climate change and other anthropogenic impacts may increase gelatinous blooms in the future, understanding the contributions and impacts of jelly-C upon benthic communities is of pivotal importance. Thus, in this study, we assessed jelly-C deposits post-intense blooming of a pelagic species of marine colonial gelatinous tunicate in the Thaliacean class, Pyrosoma atlanticum. We studied the seabed using a remotely operated vehicle (ROV) from 26 to 1,276 m, documenting jelly-C deposits and species of the megafaunal benthic community. Environmental variables from water column profiles at transects near our own off the Ivory Coast of West Africa were used in assessments. Jelly-C biomass peaked at 400 m (1,500 grC 100 m−2) and remained at the average (300 grC 100 m−2) through 1,276 m. Typically, in depth strata between 300 and 800 m, peaks in jelly-C biomass (500 to 1,500 grC 100 m−2) corresponded to areas with significantly reduced benthic megafaunal species abundances as well as diversity. From 800 to 1,276 m, we noted patchier jelly-C biomass deposits where individual megafauna species abundances and diversity correspondingly increased, yet total organism counts remained low. We observed 11 species from 5 phyla directly feeding on jelly-C and 10 single-species aggregations triggering megafaunal dominance events at various localized depth strata. Although such dynamics have been hypothesized and examined for some time with respect to phytodetritus biomass, they have been rarely described for jelly-C. Thus, our novel findings for jelly-C dynamics in the offshore regions can help to provide a better understanding of the ecological role that this component plays in marine benthic ecosystems and continental margins.

In marine environments, poaching can become a key threat to marine ecosystem conservation. Poaching can occur in marine protected areas and/or in fishery management areas. Unfortunately, understanding the magnitude and characteristics of poaching under community based and co-management governance schemes in coastal and marine environments, has not received the attention it deserves. In Chile, a system of Territorial Users Rights for Fisheries (TURF) has been recognized as one of the largest experiences of small-scale fisheries co-management at a global scale. Currently, poaching is one of the main threats to the TURF system in Chile. In this article, we assessed poaching of a highly valuable benthic resource (Concholepas concholepas) from TURF management areas. We estimated artisanal fisher association leaders’ perceptions of poaching within their TURFs and explore determinants of poaching for Concholepas concholepas. Poaching of Concholepas concholepas showed differences along the studied sites. As expected, the greater abundance of Concholepas concholepas in the management areas generates an increased incentive to poach. Areas that make the greatest investment in surveillance are those most affected by poaching. However, our study cannot determine the effectiveness of current levels of surveillance on illegal extraction. Results show older areas tend to reduce the levels of illegal extraction, which could indicate a greater capacity and experience to control poaching. Supporting fisher associations in enforcing TURFs and following up on sanctions against perpetrators are conditioning factors, highlighted by fisher leaders, for TURF sustainability. The approach used in this study provides insights to prioritize geographies and opportunities to address poaching in small-scale co-managed fisheries.

We investigated the use of eDNA metabarcoding for supplementing traditional diver-based monitoring of biodiversity of marine boulder reefs within the photic zone. The applied sampling design made it possible to evaluate the usefulness of eDNA monitoring as a supplement for traditional monitoring. Specifically, this study aimed to (1) assess the local influence of boulder reefs on biodiversity across the North Sea to Baltic Sea transition zone and (2) investigate the importance of environmental gradients for patterns in community structure. On samples collected during August 2020, we compared the composition and abundance of species associated with nine reefs, representing an environmental gradient of salinity (16–33 psu), water temperature (16–21°C) and water depth (6–29 m). At each reef site, water was sampled near the bottom just above the reef and on average 2.6 km upstream and downstream (location) and sequenced with metabarcoding using COI, 18S and 12S rDNA primers. eDNA identified 400 species, diver-based observations identified 184 with an overlap of 70 species (12%) and 81 genera (18%). While eDNA identified many infaunal species, it did not detect several macroalgal species which dominated in the diver-based observations. Multivariate analysis of eDNA and diver-based community structure both distinguished between reef communities, with a significant match between patterns observed by the two methods (r = 0.37, p = 0.02). Furthermore, the eDNA approach made it possible to identify significant differences in species composition between upstream, above-reef and downstream locations, suggesting that eDNA leaves a local footprint in benthic habitats. Patterns in both eDNA and diver-based species composition and richness were significantly related to geographical distance, salinity, water temperature and water depth. Despite of low detection of macroalgae, the eDNA sampling provided a substantial supplement to traditional diver-based monitoring of biodiversity around benthic hotspots in the Danish marine waters and therefore we recommend to add eDNA methods to conventional monitoring programs in the future.

The sulfonamide antibiotics sulfamethoxazole (SMX) and sulfamethazine (SMZ) are regularly detected in surface sediments of contaminated hydrosystems, with maximum concentrations that can reach tens of μg kg–1 in stream and river sediments. Little is known about the resulting effects on the exposed benthic organisms. Here we investigated the functional response of stream sediment microbial communities exposed for 4 weeks to two levels of environmentally relevant concentrations of SMX and SMZ, tested individually. To this end, we developed a laboratory channel experiment where natural stream sediments were immersed in water contaminated with nominal environmental concentrations of 500 and 5,000 ng L–1 of SMX or SMZ, causing their accumulation in surface sediments. The mean maximum concentrations measured in the sediment (about 2.1 μg SMX kg–1 dw and 4.5 μg SMZ kg–1 dw) were consistent with those reported in contaminated rivers. The resulting chronic exposure had various effects on the functional potential of the sediment microbial communities, according to the substance (SMX or SMZ), the type of treatment (high or low) and the measured activity, with a strong influence of temporal dynamics. Whereas the SMZ treatments resulted in only transient effects on the five microbial activities investigated, we observed a significant stimulation of the β-glucosidase activity over the 28 days in the communities exposed to the high concentration of SMX. Together with the stimulation of aerobic respiration at low SMX concentrations and the reduced concentration observed in the last days, our results suggest a potential biodegradation of sulfonamides by microbial communities from sediments. Given the key functional role of surface sediment microbial communities in streams and rivers, our findings suggest that the frequently reported contamination of sediments by sulfonamides is likely to affect biogeochemical cycles, with possible impact on ecosystem functioning. [ABSTRACT FROM AUTHOR]

Climate change is driving dramatic variability in sea ice dynamics, a key driver in polar marine ecosystems. Projected changes in Antarctica suggest that regional warming will force dramatic shifts in sea ice thickness and persistence, altering sea ice-associated primary production and deposition to the seafloor. To improve our understanding of the impacts of sea ice change on benthic ecosystems, we directly compared the benthic microbial communities underlying first-year sea ice (FYI) and multi-year sea ice (MYI). Using two tractable coastal habitats in McMurdo Sound, Antarctica, where FYI (Cape Evans) and MYI (New Harbour) prevail, we show that the structure and composition of the benthic microbial communities reflect the legacy of sea ice dynamics. At Cape Evans, an enrichment of known heterotrophic algal polysaccharide degrading taxa (e.g., Flavobacteriaceae , unclassified Gammaproteobacteria , and Rubritaleaceae) and sulfate-reducing bacteria (e.g., Desulfocapsaceae) correlated with comparatively higher chlorophyll a (14.2±0.8μgg−1) and total organic carbon content (0.33%±0.04), reflecting increased productivity and seafloor deposition beneath FYI. Conversely, at New Harbour, an enrichment of known archaeal (e.g., Nitrosopumilaceae) and bacterial (e.g., Woeseiaceae and Nitrospiraceae) chemoautotrophs was common in sediments with considerably lower chlorophyll a (1.0±0.24μgg−1) and total organic carbon content (0.17%±0.01), reflecting restricted productivity beneath MYI. We also report evidence of a submarine discharge of sub-permafrost brine from Taylor Valley into New Harbour. By comparing our two study sites, we show that under current climate-warming scenarios, changes to sea ice productivity and seafloor deposition are likely to initiate major shifts in benthic microbial communities, with heterotrophic organic matter degradation processes becoming increasingly important. This study provides the first assessment of how legacy sea ice conditions influence benthic microbial communities in Antarctica, contributing insight into sea ice–benthic coupling and ecosystem functioning in a polar environment. [ABSTRACT FROM AUTHOR]

The sulfonamide antibiotics sulfamethoxazole (SMX) and sulfamethazine (SMZ) are regularly detected in surface sediments of contaminated hydrosystems, with maximum concentrations that can reach tens of μg kg–1 in stream and river sediments. Little is known about the resulting effects on the exposed benthic organisms. Here we investigated the functional response of stream sediment microbial communities exposed for 4 weeks to two levels of environmentally relevant concentrations of SMX and SMZ, tested individually. To this end, we developed a laboratory channel experiment where natural stream sediments were immersed in water contaminated with nominal environmental concentrations of 500 and 5,000 ng L–1 of SMX or SMZ, causing their accumulation in surface sediments. The mean maximum concentrations measured in the sediment (about 2.1 μg SMX kg–1 dw and 4.5 μg SMZ kg–1 dw) were consistent with those reported in contaminated rivers. The resulting chronic exposure had various effects on the functional potential of the sediment microbial communities, according to the substance (SMX or SMZ), the type of treatment (high or low) and the measured activity, with a strong influence of temporal dynamics. Whereas the SMZ treatments resulted in only transient effects on the five microbial activities investigated, we observed a significant stimulation of the β-glucosidase activity over the 28 days in the communities exposed to the high concentration of SMX. Together with the stimulation of aerobic respiration at low SMX concentrations and the reduced concentration observed in the last days, our results suggest a potential biodegradation of sulfonamides by microbial communities from sediments. Given the key functional role of surface sediment microbial communities in streams and rivers, our findings suggest that the frequently reported contamination of sediments by sulfonamides is likely to affect biogeochemical cycles, with possible impact on ecosystem functioning.

Climate change is driving dramatic variability in sea ice dynamics, a key driver in polar marine ecosystems. Projected changes in Antarctica suggest that regional warming will force dramatic shifts in sea ice thickness and persistence, altering sea ice-associated primary production and deposition to the seafloor. To improve our understanding of the impacts of sea ice change on benthic ecosystems, we directly compared the benthic microbial communities underlying first-year sea ice (FYI) and multi-year sea ice (MYI). Using two tractable coastal habitats in McMurdo Sound, Antarctica, where FYI (Cape Evans) and MYI (New Harbour) prevail, we show that the structure and composition of the benthic microbial communities reflect the legacy of sea ice dynamics. At Cape Evans, an enrichment of known heterotrophic algal polysaccharide degrading taxa (e.g., Flavobacteriaceae, unclassified Gammaproteobacteria, and Rubritaleaceae) and sulfate-reducing bacteria (e.g., Desulfocapsaceae) correlated with comparatively higher chlorophyll a (14.2±0.8μgg−1) and total organic carbon content (0.33%±0.04), reflecting increased productivity and seafloor deposition beneath FYI. Conversely, at New Harbour, an enrichment of known archaeal (e.g., Nitrosopumilaceae) and bacterial (e.g., Woeseiaceae and Nitrospiraceae) chemoautotrophs was common in sediments with considerably lower chlorophyll a (1.0±0.24μgg−1) and total organic carbon content (0.17%±0.01), reflecting restricted productivity beneath MYI. We also report evidence of a submarine discharge of sub-permafrost brine from Taylor Valley into New Harbour. By comparing our two study sites, we show that under current climate-warming scenarios, changes to sea ice productivity and seafloor deposition are likely to initiate major shifts in benthic microbial communities, with heterotrophic organic matter degradation processes becoming increasingly important. This study provides the first assessment of how legacy sea ice conditions influence benthic microbial communities in Antarctica, contributing insight into sea ice–benthic coupling and ecosystem functioning in a polar environment.

Traditionally, deep-sea ecosystems have been considered to be insulated from the effects of modern climate change, but with the recognition of the importance of food supply from the surface ocean and deep-sea currents to sustaining these systems, the potential for rapid response of benthic systems to climate change is gaining increasing attention. However, very few ecological time-series exist for the deep ocean covering the twentieth century. Benthic responses to past climate change have been well-documented using marine sediment cores on glacial-interglacial timescales, and ocean sediments have also begun to reveal that planktic species assemblages are already being influenced by global warming. Here, we use benthic foraminifera found in mid-latitude and subpolar North Atlantic sediment cores to show that, in locations beneath areas of major surface water change, benthic ecosystems have also changed significantly over the last ∼150 years. The maximum benthic response occurs in areas which have seen large changes in surface circulation, temperature, and/or productivity. We infer that the observed surface-deep ocean coupling is due to changes in the supply of organic matter exported from the surface ocean and delivered to the seafloor. The local-to-regional scale nature of these changes highlights that accurate projections of changes in deep-sea ecosystems will require (1) increased spatial coverage of deep-sea proxy records, and (2) models capable of adequately resolving these relatively small-scale oceanographic features.

The global COVID-19 pandemic of 2020 has forced small island states to make rapid changes to the way they manage their marine estates following changes in global shipping practices and access which are essential for the supply of food items and island’s infrastructure. Following the closure of the border of neighboring French Polynesia, changes had to be made to the Pitcairn Islands’ sole supply vessel route, which resulted in the vessel requiring to set anchor on arrival at the island to conserve fuel. Considering this change and to ensure the continued protection of vulnerable coral habitats the local government has had to make swift decisions to identify anchoring zones that minimize seabed disturbance. Data collected in January 2020, just prior to the pandemic, were assessed using a rapid assessment method and combined with earth observation data to create the first shallow water (

The deep sea is the largest environment on Earth, comprising important resources of commercial interest. It is composed of a wide variety of ecosystems, which is home to often unique organisms that are yet to be described. The deep-sea is one of the least studied environments, where research is strongly linked to technological access and advances. With the recent advances in the next-generation sequencing and bioinformatics tools, there is an enhanced understanding of microbial diversity and ecological functions in deep sea. Multidisciplinary programs are being undertaken to investigate into microbial communities in diverse marine environments. As compared to other Oceans, the deeper parts of Indian Ocean are still poorly sampled and studied for bacterial, and more so fungal diversity. The studies reporting usage of modern sequencing tools to describe uncultured microbial diversity have seen a rise in numbers in the last decade. In this review, we summarize the important findings of research works carried on bacterial and fungal diversity from the abyssal regions of the Indian Ocean and provide our views on possible future paths.

The Prince Gustav Channel is a narrow seaway located in the western Weddell Sea on the northeastern-most tip of the Antarctic Peninsula. The channel is notable for both its deep (>1200 m) basins, and a dynamic glacial history that most recently includes the break-up of the Prince Gustav Ice Shelf, which covered the southern portion of the channel until its collapse in 1995. However, the channel remains mostly unsampled, with very little known about its benthic biology. We present a preliminary account of the benthic annelid fauna of the Prince Gustav Channel in addition to samples from Duse Bay, a sheltered, glacier-influenced embayment in the northwestern portion of the channel. Samples were collected using an Agassiz Trawl, targeting megafaunal and large macrofaunal sized animals at depths ranging between 200–1200 m; the seafloor and associated fauna were also documented in situ using a Shallow Underwater Camera System (SUCS). Sample sites varied in terms of depth, substrate type, and current regime, and communities were locally variable across sites in terms of richness, abundance, and both taxonomic and functional composition. The most diverse family included the motile predator/scavenger Polynoidae, with 105 individuals in at least 12 morphospecies, primarily from a single site. This study provides first insights into diverse and spatially heterogeneous benthic communities in a dynamic habitat with continuing glacial influence, filling sampling gaps in a poorly studied region of the Southern Ocean at direct risk from climate change. These specimens will also be utilized in future molecular investigations, both in terms of describing the genetic biodiversity of this site and as part of wider phylogeographic and population genetic analyses assessing the connectivity, evolutionary origins, and demographic history of annelid fauna in the region.

We introduce and test the subhabitat dependence hypothesis (SDH) in biogeography. This hypothesis posits that biogeographic pattern within a region differs when determined with species abundance data from different subhabitat types. It stems from the notion that the main abiotic factors that drive species distribution in different subhabitat types across a biogeographic region often vary differently across space. To test the SDH, we measured the abundance of algae and sessile invertebrates in two different subhabitats (high intertidal zone and mid-intertidal zone) at eight locations along the Atlantic Canadian coast. We conducted multivariate analyses of the species abundance data to compare alongshore biogeographic pattern between both zones. For both subhabitat types, location groupings based on community similarity not always responded to geographic proximity, leading to biogeographic patchiness to some extent. Nonetheless, both biogeographic patterns were statistically unrelated, thus supporting the SDH. This lack of concordance was most evident for southern locations, which clustered together based on high-intertidal data but showed considerable alongshore patchiness based on mid-intertidal data. We also found that the ordination pattern of these eight locations based on sea surface temperature data was significantly related to biogeographic pattern for the mid-intertidal zone but not for the high intertidal zone. This finding supports the rationale behind the SDH due to the longer periods of submergence experienced by the mid-intertidal zone. Overall, we conclude that biogeographic pattern within a region can depend on the surveyed subhabitat type. Thus, biological surveys restricted to specific subhabitats may not properly reveal biogeographic pattern for a biota as a whole or even just for other subhabitats. As many studies generate biogeographic information with data only for specific subhabitats, we recommend testing the SDH in other systems to determine its domain of application.

The Deepwater Horizon (DWH) oil spill significantly impacted the northern Gulf of Mexico (nGoM) deep benthos (>125 m water depth) at different spatial scales and across all community size and taxa groups including microbes, foraminifera, meiofauna, macrofauna, megafauna, corals, and demersal fishes. The resilience across these communities was heterogeneous, with some requiring years if not decades to fully recover. To synthesize ecosystem impacts and recovery following DWH, the Gulf of Mexico Research Initiative (GOMRI) Core 3 synthesis group subdivided the nGoM into four ecotypes: coastal, continental shelf, open-ocean, and deep benthic. Here we present a synopsis of the deep benthic ecotype status and discuss progress made on five tasks: (1) summarizing pre- and post-oil spill trends in abundance, species composition, and dynamics; (2) identifying missing data/analyses and proposing a strategy to fill in these gaps; (3) constructing a conceptual model of important species interactions and impacting factors; (4) evaluating resiliency and recovery potential of different species; and (5) providing recommendations for future long-term benthic ecosystem research programs. To address these tasks, we assessed time series to detect measures of population trends. Moreover, a benthic conceptual model for the GoM deep benthos was developed and a vulnerability-resilience analysis was performed to enable holistic interpretation of the interrelationships among ecotypes, resources, and stressors. The DWH oil spill underscores the overall need for a system-level benthic management decision support tool based on long-term measurement of ecological quality status (EQS). Production of such a decision support tool requires temporal baselines and time-series data collections. This approach provides EQS for multiple stressors affecting the GoM beyond oil spills. In many cases, the lessons learned from DWH, the gaps identified, and the recommended approaches for future long-term hypothesis-driven research can be utilized to better assess impacts of any ecosystem perturbation of industrial impact, including marine mineral extraction.

Dinothrix paradoxa and Gymnodinium quadrilobatum are benthic dinoflagellates possessing diatom-derived tertiary plastids, so-called dinotoms. Due to the lack of available genetic information, their phylogenetic relationship remains unknown. In this study, sequencing of 18S ribosomal DNA (rDNA) and the rbcL gene from temporary cultures isolated from natural samples revealed that they are close relatives of another dinotom, Galeidinium rugatum. The morphologies of these three dinotoms differ significantly from each other; however, they share a distinctive life cycle, in which the non-motile cells without flagella are their dominant phase. Cell division occurs in this non-motile phase, while swimming cells only appear for several hours after being released from each daughter cell. Furthermore, we succeeded in isolating and establishing two novel dinotom strains, HG180 and HG204, which show a similar life cycle and are phylogenetically closely related to the aforementioned three species. The non-motile cells of strain HG180 are characterized by the possession of a hemispheroidal cell covered with numerous nodes, while those of the strain HG204 form aggregations consisting of spherical smooth-surface cells. Based on the similarity in life cycles and phylogenetic closeness, we conclude that all five species should belong to a single genus, Dinothrix, the oldest genus within this clade. We transferred Ga. rugatum and Gy. quadrilobatum to Dinothrix, and described strains HG180 and HG204 as Dinothrix phymatodea sp. nov. and Dinothrix pseudoparadoxa sp. nov.

The Northeast Canyons and Seamounts Marine National Monument (NECSMNM) was designated by President Barack Obama in 2016, using his authority under the Antiquities Act of 1906. The Act allows a President to proclaim as national monuments “historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest” that are “upon the lands owned or controlled” by the United States but to reserve each designation to “the smallest area compatible with the proper care and management of the objects to be protected.” Protection in general excludes commercial scale extraction and is in perpetuity. Here we present analyses of physiographic and ecological datasets that facilitated assessment of the conservation benefits of protections for a new monument. We also review and synthesize the ecological literature to describe processes that operate in continental margin and deep-sea settings, in order to demonstrate the monument area is bounded for proper management and is an object of scientific interest. Results indicate that the current monument designation is an area of high diversity and ecological connectivity across depths and along the continental margin. The monument boundaries contain hot spots (areas of high abundance and species richness) for seafloor communities (inclusive of benthic invertebrate and demersal fish) as well as marine mammals in the epipelagic. Many species are sensitive to disturbance and vulnerable to human activities (e.g., deep-sea corals and sponges) with very long recovery times and extremely low resilience. The monument contains at least nine exemplars of offshore northwest Atlantic marine wildlife communities and habitats (e.g., deep shelf invertebrates, shelf fish, deep sea corals and sponges in canyons and on seamounts, deep sea fish, chemosynthetic communities, deep sea soft sediment, shelf edge cetaceans, and seabirds). The region is relatively undisturbed and can serve as a reference site to focus future research on ecological processes in an increasingly industrialized ocean and one subject to the synergies of regional climate effects. These results suggest that there is great potential for discovery and novel research in this first Atlantic Ocean Marine National Monument.

Dinothrix paradoxa and Gymnodinium quadrilobatum are benthic dinoflagellates possessing diatom-derived tertiary plastids, so-called dinotoms. Due to the lack of available genetic information, their phylogenetic relationship remains unknown. In this study, sequencing of 18S ribosomal DNA (rDNA) and the rbc L gene from temporary cultures isolated from natural samples revealed that they are close relatives of another dinotom, Galeidinium rugatum. The morphologies of these three dinotoms differ significantly from each other; however, they share a distinctive life cycle, in which the non-motile cells without flagella are their dominant phase. Cell division occurs in this non-motile phase, while swimming cells only appear for several hours after being released from each daughter cell. Furthermore, we succeeded in isolating and establishing two novel dinotom strains, HG180 and HG204, which show a similar life cycle and are phylogenetically closely related to the aforementioned three species. The non-motile cells of strain HG180 are characterized by the possession of a hemispheroidal cell covered with numerous nodes, while those of the strain HG204 form aggregations consisting of spherical smooth-surface cells. Based on the similarity in life cycles and phylogenetic closeness, we conclude that all five species should belong to a single genus, Dinothrix , the oldest genus within this clade. We transferred Ga. rugatum and Gy. quadrilobatum to Dinothrix , and described strains HG180 and HG204 as Dinothrix phymatodea sp. nov. and Dinothrix pseudoparadoxa sp. nov. [ABSTRACT FROM AUTHOR]

General studies on benthic microbial communities focus on fundamental biogeochemical processes or the most abundant constituents. Thereby, minor fractions such as the Rhodobacteraceae are frequently neglected. Even though this family belongs to the most widely distributed bacteria in the marine environment, their proportion on benthic microbial communities is usually within or below the single digit range. Thus, knowledge on these community members is limited, even though their absolute numbers might exceed those from the pelagic zone by orders of magnitudes. To unravel the distribution and diversity of benthic, metabolically active Rhodobacteraceae, we have now analyzed an already existing library of bacterial 16S rRNA transcripts. The dataset originated from 154 individual sediment samples comprising seven oceanic regions and a broad variety of environmental conditions. Across all samples, a total of 0.7% of all 16S rRNA transcripts was annotated as Rhodobacteraceae. Among those, Sulfitobacter, Paracoccus, and Phaeomarinomonas were the most abundant cultured representatives, but the majority (78%) was affiliated to uncultured family members. To define them, the 45 most abundant Rhodobacteraceae-OTUs assigned as “uncultured” were phylogenetically assembled in new clusters. Their next relatives particularly belonged to different subgroups other than the Roseobacter group, reflecting a large part of the hidden diversity within the benthic Rhodobacteraceae with unknown functions. The general composition of active Rhodobacteraceae communities was found to be specific for the geographical location, exhibiting a decreasing richness with sediment depth. One-third of the Rhodobacteraceae-OTUs significantly responded to the prevailing redox regime, suggesting an adaption to anoxic conditions. A possible approach to predict their physiological properties is to identify the metabolic capabilities of their nearest relatives. Those need to be proven by physiological experiments, as soon an isolate is available. Because many uncultured members of these subgroups likely thrive under anoxic conditions, in future research, a molecular-guided cultivation strategy can be pursued to isolate novel Rhodobacteraceae from sediments.

Oil and gas pipelines that lie exposed on the seabed can function as “artificial reefs,” providing habitat for fish and benthic species, including some that are listed under conservation designations. As the offshore hydrocarbon industry matures, operators and national governments must decide whether decommissioned pipelines should be left in situ or removed for onshore disposal. In most jurisdictions, there is a requirement to evaluate the environmental consequences of different pipeline decommissioning options in a comparative assessment. To do this effectively requires an understanding of the associations between pipelines and fauna. Pipeline operators routinely collect video footage for inspection and maintenance purposes using remotely operated vehicles (ROV). This footage has the potential to provide insight into interactions between the marine environment and offshore pipelines. This study uses inspection footage from eight pipelines to quantify the presence and abundance of species and features listed under a number of EU and United Kingdom conservation designations; 12 such features and species were observed on the pipelines or neighboring sediments. The soft coral Alcyonium digitatum was present in the highest densities on pipelines located on mud, while Sabellaria sp. and Echinus esculentus were more common on pipelines in sand. Gadoids, anemones and hermit crabs were also frequently observed around pipelines. The study identifies the limitations to the use of industry ROV footage for ecological purposes, but shows that with consideration of taxon size, image resolution, ROV speed and altitude, this can be a valuable approach to gain additional insights into environment-infrastructure interactions. The results suggest that removal of pipelines will remove established colonies of epibenthic species, some of which have conservation value. The ecological significance of this loss, however, must be weighed against the broader considerations during pipeline decommissioning including cost, technical feasibility and impacts to other marine users.

Cephalopods' visually driven, dynamic, and diverse skin display makes them a key animal model in sensory ethology and camouflage research. Development of novel methods is critically important in order to monitor and objectively quantify cephalopod behavior. In this work, the development of Cephalopod Experimental Projected Habitat (CEPH) is described. This newly developed experimental design bridges computational and ethological sciences, providing a visually controlled arena which requires limited physical space and minimal previous technical background. Created from relatively inexpensive and readily available materials, the experimental apparatus utilizes reflected light which closely resembles natural settings. Preliminary results suggest the experimental design reproducibly challenges marine organisms with visually dynamic surroundings, including videos of prey and predator. This new approach should offer new avenues for marine organism sensory research and may serve researchers from various fields.

Research on benthic communities in the deep sea has focused largely on habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. The present study aimed to determine the structural differences in benthic communities of continental slope, seamount, canyon, vent, and seep habitats, and assess their relative vulnerabilities to disturbance from bottom trawling and potential seabed mining. Megafaunal invertebrate communities of these habitats were sampled in two regions off New Zealand, in four depth strata between 700 and 1500 m, using an epibenthic sled and a beam trawl. Patterns of community and trophic structure, and the potential influence of environmental variables, were determined using multivariate analyses. The difference in community structure between regions was greater than among habitats and depth strata. Levels of food availability may explain regional differences in community structure, although some influence of fishing disturbance is also possible. Differences in community and trophic structure were most pronounced between the chemosynthetic vent and seep habitats, and other habitats. Differences among these other habitats within a region were inconsistent, except that canyon and slope communities always differed from each other. Community and trophic structural patterns were partly explained by the environmental differences observed among habitats. The relative vulnerabilities of benthic communities to human disturbance in the two regions were determined based on patterns of abundance and feeding mode of the megafauna. Communities of vent and seep habitats were assessed to be more vulnerable to disturbance than those of the other habitats based on a number of habitat-related attributes. However, the relative vulnerability of megafaunal communities at slope, canyon, and seamount habitats could not confidently be assessed on a habitat basis alone. The results of the present study have implications for how regional and habitat differences in benthic communities are incorporated into spatial management options for the deep sea.

The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of twelve meltwater ponds in the McMurdo Sound of Antarctica were investigated to examine variation between pond microbial communities and their biogeography. Geochemically comparable but geomorphologically distinct ponds were selected from Bratina Island (ice shelf) and Miers Valley (terrestrial) (

From photographic samples, we describe the benthic megafaunal communities in two north Svalbard fjords and on the adjacent continental shelf. We analyze the fauna in relation to abiotic factors of depth, bottom water temperature, percent cover of hard substratum, heterogeneity of stone size, and bottom-water turbidity to explore how these factors might affect the fauna and how they are related to the functional traits (size, morphology, mobility, colonial/solitary, and feeding type) of the megabenthos. Depth and bottom water temperature were consistently the strongest correlates with faunal composition and functional traits of the constituent species. A greater proportion of the variability in the functional traits of the megabenthos could be explained by abiotic factors rather than faunal composition, indicating that the abiotic factors of depth and temperature were strongly related to the functional traits of the megabenthos. On a local scale, stone size heterogeneity explained most variation in the functional traits of the megabenthos in one fjord. The results of this case study show a significant relationship between bottom water temperature and the functioning of north Svalbard megabenthic communities. Warming temperatures in the Arctic will likely decrease the variety of functional traits represented in Svalbard megabentos, resulting in scavenger-dominated communities. A reduction in megabenthic biomass may also result, reducing energy availability to higher trophic levels.

Marine litter is a global challenge that has recently received policymakers’ attention, with new environmental targets in addition to changes to old legislation. There are no global estimates of benthic litter because of the scarcity of data and only patchy survey coverage. However, estimates of baseline abundance and composition of litter are vital in order to implement litter reduction policies and adequate monitoring schemes. Two large-scale surveys of submarine geomorphological features in the Indian and Atlantic Oceans reveal that litter was found at all locations, despite their remoteness. Litter abundance was patchy, but both surveyed oceans had sites of high litter density. There was a significant difference in the type of litter found in the two oceans, with the Indian Ocean sites being dominated by fishing gear, whereas the Atlantic Ocean sites displayed a greater mix of general refuse. This study suggests that seabed litter is ubiquitous on raised benthic features, such as seamounts. It also concludes that the pattern of accumulation and composition of the litter is determined by a complex range of factors both environmental and anthropogenic. We suggest that the tracing of fishing effort and gear type would be an important step to elucidate hotspots of litter abundance on seamounts, ridges and banks.