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Sponges play vital roles in the ecosystem function of the deep sea. Some species, such as the birds' nest sponge Pheronema carpenteri , can form highly structured and dense habitats (i.e., aggregations), which contribute to the increase of nearby biodiversity. Climate change is expected to have a pronounced impact on the deep sea, particularly on Vulnerable Marine Ecosystems such as those formed by the glass sponge Pheronema carpenteri. These ecosystems are especially vulnerable to climate change and other anthropogenic activities since they are formed by sensitive species with slow growth rates and limited dispersal capability, which can hinder their adaptive capability and recovery after disturbance. The impact that climate change will have on Pheronema carpenteri remains unclear, although it is expected to influence the species' available suitable habitat and distribution range. The aim of this study was to predict the distribution of the glass sponge Pheronema carpenteri both for present day and under several future climate scenarios in the North Atlantic. An ensemble modelling approach was employed, combining Maximum Entropy, Generalized Additive Models and Random Forest techniques. Changes in available suitable habitat were projected to present day and to three future climatic scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). Depth, temperature and dissolved oxygen were identified as the key predictor variables of habitat suitability, which patterns suggest a strong influence of the Mediterranean Outflow Water in shaping the present day distribution of the species, particularly in the eastern North Atlantic. Our results indicate a potential expansion of available suitable habitat in the northernmost region of the study area, with a contraction at lower latitudes, more prominent in the Portuguese archipelago of the Azores. Under the worst-case scenario (RCP 8.5), the area of suitable habitat will likely double compared to present, occupying approximately 6% of the total study area. The management and conservation of areas where Pheronema aggregations can occur should be articulated between different countries, particularly in the Northeast Atlantic since, cumulatively, most of Pheronema's climate refugia occurs within their EEZs. Nonetheless, a significant proportion of the species' climate refugia is located in areas within the High Seas (i.e., Rockall plateau). • P. carpenteri suitable habitat may increase up to 2 times under climate change. • Suitable habitat likely shifts towards higher latitudes. • 74.7% of climate refugia falls within EEZs. • The largest reduction in suitable habitat may occur in the Azores archipelago. • Management and conservation of this species will require concerted international efforts. [ABSTRACT FROM AUTHOR]

We report on a hexactinellid sponge new to science, Walteria demeteraesp. nov., which was collected from the northwestern Pacific seamounts at depths of 1 271–1 703 m. Its tubular and basiphytous body, extensive lateral processes, numerous oval lateral oscula which are irregularly situated in the body wall, the presence of microscleres with oxyoidal, discoidal and onychoidal outer ends, and the absence of anchorate discohexasters, indicate it belongs to the genus Walteria of family Euplectellidae, which is also supported by molecular phylogenetic evidence from 18S, 28S, 16S rRNA and cytochrome c oxidase subunit I (COI) gene sequences. The unique morphotype, which is structured by a thin and rigid framework of body wall and lateral processes consisting of diactins, characterizes it as a new species. Local aggregations of individuals of this new species coupled with their associated macrofauna in the Suda Seamount are reported, highlighting its functional significance in providing biogenic microhabitats in the deep sea. [ABSTRACT FROM AUTHOR]

Identifying vulnerable marine habitats is fundamental to promote evidence-based management and a sustainable use of our oceans. Although progress in the mapping of marine benthic habitats has been made, complex ecosystems such as submarine canyons remain largely unexplored, hampering evidence-based management from taking place in these ubiquitous features worldwide. Data from a remotely operated vehicle (ROV) survey in the upper São Vicente Submarine Canyon in southwestern Portugal from 2011, was analysed to carry out a comprehensive assessment of megabenthic habitats, particularly those of conservation concern occuring between 90 and 560 m. Underwater videos from three exploratory dives, covering a total of 8.8 kilometers, were analyzed through multivariate and visual assessments, and the identified habitats were assessed against a set of criteria derived from current definitions of priority habitats. Thirteen potential priority habitats were characterized, out of which four distinct “coral gardens” and one “deep-sea sponge aggregation” are aligned with OSPAR definitions of priority habitats, and one corresponds to the habitat of a strictly protected sea urchin listed in the Habitats Directive. Three circalittoral sponge aggregations were also suggested based on the abundance of indicator species. The specific composition and diversity of priority habitats as described here, has not yet been described in any other canyon in the NE Atlantic region. Depth was revealed to be particularly important for the distribution of habitats, followed by relief and substratum. The approach presented in this study contributes to improve the understanding about submarine canyons, which is paramount to implement knowledge-based protection measures. Furthermore, it can be used to support future mapping efforts of deep-sea environments such as submarine canyons.

This study analyzes the fauna composition of the community of brittle and sea stars associated with sponge aggregations located in Avilés Canyons System and El Cachucho, Marine Protected Area (MPA). Diverse sampling methods were used depending on bottom morphology, such as rock dredges and specific samplers for sedimentary bottoms, mainly beam trawl models. These banks are made up of sponge and coral species that build a very appropriate substrate for the proliferation of benthic species, which together create Vulnerable Marine Ecosystems that are highly relevant for management and conservation. Among these benthic species, echinoderms are of great interest due to their value as indicators of good habitat. In total, 1261 specimens were collected (934 brittle stars and 327 starfishes), belonging to 42 species (28 ophiuroids and 14 asteroids) from INDEMARES AVILÉS, ECOMARG, and SponGES project surveys. Specimens were distributed among four sponge aggregations (F: fields) that were considered according to the sponge records obtained in the same stations (36). These fields were defined and named based on the five most common sponge species: Aphrocallistes beatrix and Regadrella phoenix (F1: Avilés Canyon); Pheronema carpenteri (F2: Intraslope basin of Le Danois Bank); Asconema setubalense (F3: Le Danois Bank); and Neoschrammeniella aff. bowerbankii (F4: Corbiro Canyon). Faunistic results show that Ophiactis abyssicola (55.55% occurrence), Brisinga endecacnemos, Ophiolycus purpureus, and Peltaster placenta (33.33%) were the most frequently found species in F1; Psilaster andromeda (80%), Pseudarchaster parelii (60%), and Nymphaster arenatus (46.67%) in F2; Ophiura carnea (71.43%) and Ophiacantha smitti (42.86%) in F3; and Ophiacantha densa, and Henricia caudani (100%) in F4. The asteroid and ophiuroid species collected seem to be composed of four different communities that fit to areas with particular morphological and biological features, related to the presence of species specialized in the use of the resources they can find there. In general, the abiotic factor controlling this structure is depth. This assemblage structure, which favors the dissimilarity between the canyons and the bank, is not so clear, since the deepest stations are located on the intraslope basin of El Cachucho, Marine Protected Area (MPA), therefore, using it a priori could lead to misunderstandings. Once the structure of the echinoderm community was known, we compared the expected and obtained results to analyze evidence which should prove the existence of any association between echinoderms and sponges, which enabled us to refute the incongruous hypothesis.

In the deep waters of the Nordic Seas and adjacent areas, several benthic habitats such as cold-water coral reefs, coral gardens, and deep-sea sponge aggregations have been classified as vulnerable marine ecosystems (VMEs), due to their uniqueness, limited spatial extent, physical fragility, and slow recovery rate. In the last decade observations carried out by habitat mapping programmes in Norway, Iceland, and more recently in the Faroe Islands have substantially increased knowledge on the distribution of VMEs in the Nordic Seas. Nevertheless, large areas have not been explored due to the cost and logistics of obtaining observations in the deep-sea. Species distribution models can be used to predict the distribution of VMEs and their indicator species. Here we present the predicted distribution of 44 VME indicator taxa including 20 sponges, 17 cold-water corals, and 7 seapens in the Nordic Seas based on data compiled and models developed by the NovasArc project (2016–2018). Models for 44 VME indicator species were developed using the maximum entropy algorithm MaxEnt, using an extensive database compiled from habitat mapping surveys, by-catch data from bottom fish surveys, and records from reports and peer reviewed publications. Modeled distributions showed good agreement with observations. Niche overlap measures were used to identify seven groups and four subgroups of VME indicator taxa that co-occur. These were consistent with the species composition of known biotopes in the study area. A VME Index that combine the predictions for all VME indicator species was computed to identify particularly valuable and vulnerable ecosystems that should be targets of further exploration and conservation efforts. Such areas were identified at shelf break and slope off Iceland, the Faroe Islands, and central Norway, and the continental shelf off southern Greenland. The predicted distribution of VMEs in Arctic and sub-Arctic waters allows for the evaluation of interactions with fisheries and other anthropogenic activities and provides an important input for managers.

Mud volcanoes are singular seafloor structures classified as 'sensitive habitats'. Here we report on the sponge fauna from a field of eight mud volcanoes located in the Spanish margin of the northern Gulf of Cadiz (North-eastern Atlantic), at depths ranging from 380 to 1146 m. Thirty-eight beam-trawl samplings were conducted (covering over 61,000 m2) from 2010 to 2012, in the frame of a EC-LIFE + INDEMARES grant. A total of 1659 specimens were retrieved, belonging to 82 species, from which 79 were in the Class Demospongiae and three in Hexactinellida. Two species were new to science (Jaspis sinuoxea sp. nov.; Myrmekioderma indemaresi sp. nov.) and three others recorded for the first time in the Atlantic Ocean (Geodia anceps , Coelosphaera cryosi and Petrosia raphida). Five additional species were 'Atlantic oddities', since this study provides their second record in the Atlantic Ocean (Lanuginella cf. pupa , Geodia cf. spherastrella , Cladocroce spathiformis , Cladocroce fibrosa and Haliclona pedunculata). Basic numerical analyses indicated a significant linear relationship between the species richness per m2 and the number of sponge individuals per m2, meaning that in most volcanoes many species occur in equivalent, moderate abundance. Likewise, sponge species richness increased with depth, while the abundance of hard substrata resulting from carbonate precipitation and the fishing activities around the volcanoes had no detectable effect on the sponge fauna. However, in the latter case, a negative trend – lacking statistical support – underlaid the analyses, suggesting that a more extensive sampling would be necessary to derive more definitive conclusions in this regard. [ABSTRACT FROM AUTHOR]

Abstract Deep-sea sponge aggregations have been identified as potential Vulnerable Marine Ecosystems under United Nations General Assembly Resolution 61/105. Understanding the distribution of these habitats is critical to future spatial management efforts, and central to this understanding are quantitative data on the environmental drivers of that distribution. Accumulations of large suspension feeders are hypothesised to aggregate in regions of internal wave formation. The causal link is thought to be an increase in the supply of food related to the incidence of internal waves, which results in resuspension of particulate organic matter on which the sponges feed. There is, however, almost no empirical evidence to support this hypothesis for deep-sea sponge aggregations, although there is strong circumstantial evidence. We tested the relationship between sponge density and 1) temperature range (as a measure of internal wave presence in this region), and 2) optical backscatter (a measure of particulate flux) for a known sponge aggregation in the Faroe-Shetland Channel where internal wave interaction with the slope is further well-documented. 25 benthic video transects, ranging from 422 to 979 m water depth were conducted in the study region. 225 images were analysed and all taxa identified to morphotypes and quantified. Temperature and optical backscatter data were drawn from archived CTD data, and data from long term (4 months) and 2 seasonal short term (11 days) mooring deployments from the region. A generalised linear model was used to test the relationship between sponge density and temperature range (ΔT), and sponge density and optical backscatter. The results showed a statistically significant positive relationship between sponge density and temperature range, with the highest sponge densities occurring at depths of greatest temperature range. They showed a statistically significant positive relationship between sponge density and optical backscatter for long term and one short term seasonal deployment (Sep–Oct), but a weak negative relationship for the other short term mooring deployment (April-May). We conclude that sponge aggregations in the Faroe-Shetland Channel are associated with slope regions that are subjected to abrupt and pronounced changes in temperature due to intensified internal wave activity over the slope between depths of 400–600 and that lead to intensified near-bed currents and elevated resuspension of particulate. Our data provide empirical evidence of the relationship between internal wave processes and deep-sea sponge aggregations. These data modify current theory on drivers of deep sea sponge aggregation distribution, suggesting aggregations also occur directly within regions of internal wave breaking, rather than simply proximal to these regions. Highlights • Deep-sea sponge aggregation occurs in area of greatest variation in temperature. • There is a log-linear relationship between sponge abundance and temperature variability. • Temperature variability is attributed to internal wave activity in the study area. • Sponge abundance is related to long term (132 days) mean suspended particulate matter. [ABSTRACT FROM AUTHOR]

Identifying and understanding environmental drivers of deep-sea sponge aggregations is critical for effective protection and management. Current literature suggests an association between internal wave activity, regions of enhanced currents, and the distribution of deep-sea sponge aggregations. It is hypothesised that sponges utilise particulate organic matter associated with internal waves and enhanced currents and therefore aggregate in these regions. Random Forest algorithms – as well as preliminary Generalised Additive Models (GAMs) – were fitted to the presence-pseudo-absence and density datasets to characterise the relationship with each environmental variable. Additionally, residual autocovariate variables were calculated and included in models to account for spatial autocorrelation. All variables were statistically significant when GAMs were fitted to the presence-pseudo-absence datasets, but spatial autocorrelation could not be successfully accounted for. In contrast, a Random Forest model was fitted that also successfully accounted for spatial autocorrelation. No relationships were detected when GAMs were fitted to the density dataset – results confirmed by a poorly performing Random Forest model. Our findings suggest that average temperature variability is an important driver of P. carpenteri distribution and should be incorporated into habitat suitability models. However, available environmental data do not capture key drivers of P. carpenteri density, limiting our ability to model, and therefore identify areas where aggregations are likely to occur. This may reflect a mismatch in the spatial scales in which environmental and biological processes occur. We conclude that further research is required, particularly into feeding strategy and reproduction, to identify missing drivers of P. carpenteri density. • Temperature variability is an important driver of P. carpenteri distribution. • Temperature variability should be incorporated into habitat suitability models. • Environmental variables did not explain P. carpenteri density. • The underlying drivers of P. carpenteri density are poorly understood. [ABSTRACT FROM AUTHOR]

The importance of cold-water coral (CWC) mounds and sponge-beds as habitat for demersal fish was examined in the Træna Deep marine protected area and adjacent areas of the Norwegian continental shelf. Standardised longline fishing was conducted twice, in June and March, and predetermined fishing effort was allocated to multiple plots with varying densities of small CWC mounds and sponges, plus control plots with neither of these habitats. Catches within all examined habitats were dominated by the commercially exploited Brosme brosme (representing 4 70% of the total catch) followed by Galeus melastomus, Chimaera monstrosa, Etmopterus spinax and the commercially exploited Molva molva. Positive correlations were found between catch rates of B. brosme, G. melastomus and C. monstrosa and the density of small CWC mounds at one or both sampling occasions. No correlations were found between the catch rates of the same three species and sponge density; thus the sponge-beds did not seem to represent an ecologically equivalent habitat to the CWCs. On a local scale the CWC habitat appeared to attract higher abundances of B. brosme, G. melastomus and C. monstrosa; however, the differences in catch rates between coral and non-coral areas were quite low (2–4 times) and for most species the fish–habitat relationships varied temporarily and with the spatial scale used to delineate the habitat. Based on the methods and the results of this study and the fact that CWCs only occupy a very small proportion of the Norwegian shelf, the importance of CWCs as habitat for the populations of the demersal fish species examined is judged as marginal. [ABSTRACT FROM AUTHOR]