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Bamboo corals are distinguished from most other octocorals by an articulated skeleton. The nodes are proteinaceous and sclerite-free while the internodes are composed of non-scleritic calcium carbonate. This articulation of the skeleton was thought to be unique and a strong synapomorphy for the family Isididae. Our phylogeny, based on the amplification of mtMutS and 18S, shows an articulating skeleton with sclerite-free nodes has arisen independently at least five times during the evolutionary history of Octocorallia rather than being a synapomorphy characteristic of a monophyletic bamboo coral clade. The family Isididae is currently composed of four subfamilies (Circinisidinae, Isidinae, Keratoisidinae, and Mopseinae). Not only is the family polyphyletic, but our genetic analyses suggest also the subfamily Isidinae is polyphyletic based on current taxonomic classifications, and Mopseinae is not monophyletic. The type, Isis, is found outside of the well-supported Calcaxonia – Pennatulacea clade where the other members of Isididae cluster. The current classification of the family Isididae does not reflect the evolutionary history of an articulated skeleton. To better reflect the evolutionary history of these taxa we propose that three of the four the subfamilies, the genus Isidoides, and genera within the subfamily Isidinae, be elevated to family level to produce a classification with five families with a bamboo-like skeleton: Chelidonisididae, Isididae, Isidoidae, Keratoisididae, and Mopseidae.

A new species of Aborjinia Özdikmen, 2010 is described from the tissues of the cold-water bamboo coral Acanella arbuscula (Johnson) from the northwest Atlantic. Aborjinia corallicolasp. n. is characterized by 18.4–33.2 mm long body in adults; outer labial and cephalic sensilla papilliform and located 14–21 µm from anterior end, amphideal aperture located 22–41 µm from anterior end, excretory pore indistinct, rectum and anal opening functional, convex-conoid tail with broadly rounded terminus, spinneret subventral. It is placed in the genus Aborjinia based on the combination of the following characters: outer labial and cephalic sensilla papilliform in shape and located in one circle, contrary to Marimermis Rutsov & Platonova, 1974 (outer labial and cephalic sensilla setiform) and Ananus Rubtsov, 1977 and Thalassonema Ward, 1933 (outer labial and cephalic sensilla in separate circles, if known). From Aborjinia eulagiscae Tchesunov & Spiridonov, 1985 the new species differs in much shorter body, much shorter tail, presence of caudal glands and spinneret in adults, different host species. Our finding represents the first report of a nematode in a parasitic relationship with a cold-water octocoral. Phylogenetic relationships between Aborjinia and other nematodes are analyzed based on 18S rDNA sequences. Summary of all presently known species and genera of the family Marimermithidae is also given.

The genus Lepidisis was established by Verrill in 1883 for three species collected from the continental slope in the western North Atlantic Ocean. Over the intervening years, several species were assigned to this genus using conflicting characters taken from Verrill's original description. Using what remains of Verrill's syntype specimens and a new specimen collected from off of the coast of the New England region, USA, we show that Verrill made a serious mistake in his description of the type species, and that mistake has caused some of the confusion surrounding this genus. We redescribe the type species, then use that description to evaluate the other species currently assigned to the genus.

6 pages, 2 figures, 2 tables, supplementary information https://doi.org/10.1186/s41200-021-00210-y, The living and dead fauna of Valencia Seamount, a deep promontory in the middle of the Balearic Basin which summit is at ca. 1100 m depth, is described by first time based in a rock dredge perfomed in a sedimentary area of the summit Mount. Surface-feeder polychaetes (the Paraonidae Levinsenia gracilis and Terebellidae as dominant), and taxodont bivalves (Ledella messanensis and Yoldiella ovulum) were the main species of benthos. We found alive remains of the bamboo coral Isidella elongata, a vulnerable, habitat-forming species in the deep Mediterranean. Benthos density was low (0.6 organisms/2 dm3 mud). Thanatocoenosis evidenced a rather moderate diversity of benthic bivalves (11 species) and gastropods (9 species) also dominated by surface deposit feeders. Fish (identified/quantified from sedimented otoliths) showed diversified and abundant mesopelagic fauna, mainly Myctophidae. More interestingly, we highlighted among benthopelagic fish the occurrence of recruits of Merluccius merluccius, Micromesistius poutassou, or Hymenocephalus italicus, all species that live in the neighboring slopes of the Iberian Peninsula and the Balearic Islands at quite shallower depths (at 100-700 m) than their distribution in the Valencia Seamount summit (1102–1130 m) based on the deposited otoliths found. Some ecological aspects were discussed and the necessity to consider the deep Valencia Seamount as a potential area that should be under protection, The study was financed by the MICYT project RECOMARES (RTI2018-094066-B-I00) funded by Ministerio de Ciencia e Innovación, MICYIT. [...]. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI), With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

The subfamily Muricellisidinae was erected by Kükenthal in 1915 and placed in the family Isididae in order to accommodate an unusual species collected in Sagami Bay, Japan. In 1931, Thomson and Dean added a second species collected in Indonesia during the Siboga Expedition. The holotypes of both species have been re-examined. Muricellisis echinata was found to be an anthothelid living on the axis of a keratoisid bamboo coral and M. cervicornis is a melithaeid. Both species are redescribed.

The relationships between infaunal diversity and ecosystem function of biogenic structures in the Eastern Canadian Arctic remain poorly documented. Our study investigated the influence of sponge gardens at the Frobisher Bay site (137 m) and bamboo corals at the Baffin Bay site (1007 m) on the infaunal community structure and benthic ecosystem functioning. The occurrence of both types of biogenic structure type enhanced particular taxa and/or feeding guilds. A large density of suspension filter feeders was observed in bamboo coral sediment, whereas bare sediment exhibited a large proportion of nematodes and deposit-detritus feeders. Sponge gardens’ sediment showed a high proportion of isopods, Paraonidae polychaetes and up/down conveyors whereas bare sediment exhibited a large density of filter feeders. Through incubation cores, we measured ex situ benthic nutrient and oxygen fluxes at the sediment-water interface in each habitat and site. Biogeochemical fluxes varied significantly between habitats in the Baffin Bay site with a significant impact of bamboo coral habitat on nutrient fluxes (nitrate, ammonium, and silicate). Surprisingly, the sediment hosting bamboo corals acted as a source of nitrate and ammonium reaching values similar or higher to the Frobisher site despite the difference in water depth, and thus food supply between the two sites. These significant releases could derive from (i) a high organic matter deposition in bamboo coral habitat, allowed by their erected structure, (ii) a high efficiency of bioturbators (surficial modifiers and burrowers) mixing the surface layer of the sediment, and (iii) the difference in sediment type. Our study highlighted that, compared to its adjacent habitat, the presence of bamboo corals appeared to enhance the infaunal density and nutrient release of its sediment. In contrast, the impact of sponge gardens was not as clear as for bamboo coral habitat, likely due to the relatively significant presence of megabiota in the sponge garden adjacent habitat. Thus, our results based on a relatively small sample size, indicate that the bamboo coral habitat seems to increase the efficiency of deep-benthic ecosystem functioning, while that of sponge garden on the shallow ecosystem functioning remains uncertain.

Environmental conditions of deep-sea corals were monitored with instruments placed in and adjacent to three Hawaiian deep-sea coral patches dominated by gorgonian octocorals and zoanthid gold coral. Temperature, backscatter, and flow differed among and within the patches and highlighted distinctions in distribution of focus taxa (Hemicorallium laauense, Pleurocorallium secundum, Narella spp., Acanella dispar, Kulamanamana haumeaae). Two of the patches (Barbers Pt., Makapuʻu Pt.) had more than double the sustained mean flow of the third patch (Keahole Pt.), where backscatter levels of the passing water mass showed scattering strengths a third higher, suggesting greater food supply in the water at the Keahole Pt. patch. Further, spectral analysis of flow speed and direction suggests that flow at the first two high-flow sites (Barbers Pt., Makapuʻu Pt.) are dominated by semi-diurnal tidal forcing (flow changing 4x daily, direction 2x daily), while Keahole Pt. patch shows a distinct pattern more typical of diurnal forcing. Of the focus taxa, the two coralliids occupied a similar temperature range but differed in dominance between sites along a flow/scatter gradient, with the “red” coral, Hemicorallium laauense, found at the site with low flow (0.5-4.9 cm/s) and higher scatter (-28 dB) and the “pink” coral, Pleurocorallium secundum, seen at the patch with higher sustained flow (12.6-18.4 cm/s) and lower backscatter (-43 dB). Narella spp. spanned a 10 °C temperature range but were found more frequently at sites with the highest mean flow (18.4-21.7 cm/s). The final two corals, the parasitic zoanthid “gold” coral, Kulamanamana haumeaae, and its most common host, bamboo coral, Acanella dispar, were found at all three sites over a wide temperature range with flow ranging from 2.8 to 18.9 cm/s. The number of gold colonies was negatively correlated with flow even though that relationship was not apparent for the bamboo coral. These patterns were considered in relation to what is known about the life history of deep-sea corals and how they might influence community settlement, growth, and diversity.

Despite growing interest in ocean-climate interactions in response to recent anthropogenic warming, historical hydrographic data with which to assess changes in the deep ocean over the last century are limited. With their robust calcium carbonate skeletons, deep-sea corals, especially long-lived bamboo corals, serve as a potential archive for reconstructing continuous high-resolution paleoceanographic records extending back hundreds to even thousands of years.Here we use deep-sea bamboo corals collected between 800 and 2000 m water depth in the eastern equatorial Atlantic to reconstruct the ventilation history over the last century. Deep-sea bamboo corals have a jointed axis consisting of organic nodes and internodes composed of calcium carbonate. The radiocarbon content of the organic nodes documents the radiocarbon of surface water and likely records the distinctive bomb 14C signal that can be used to generate a chronology for each coral specimen. By contrast, the radiocarbon content of calcite internodes records the radiocarbon signature of deep water over the lifetime of the coral. The reconstructed calcite radiocarbon record shows a quasi-periodic cycle of about two-decades, which is likely linked to multidecadal fluctuations in North Atlantic climate influencing the ventilation state of the water mass. In addition to radiocarbon records, we show that trace metal compositions of bamboo coral also provides key information with regard to both biomineralization processes, past environmental conditions, and chemistry of seawater. By combining radiocarbon and elemental composition of bamboo coral, we are building a set of tools with which to reconstruct deep ocean dynamics over the last century.

We evaluated disturbance and damage to deep-sea corals and sponges (DSCS) in areas of longtime (> 65 years) bottom trawling off southern Oregon and northern California. The incidence of disturbance was quantified from video and still images collected along strip transects conducted with underwater vehicles operating at depths of 600–2100 m. All DSCS were identified, counted, and measured, condition (healthy, unhealthy, or dead) was determined, and associated seafloor substratum types were designated. Physical disturbance and damage were classified as DSCS with broken or missing parts, overturned, or detached from the seafloor. Overall frequency of disturbance to DSCS throughout the study area was 2% of the total number observed; most of these were coral colonies while sponges were rarely damaged. There was notable disturbance to corals, particularly to bamboo corals of the family Isididae (45% of 873 colonies were impacted), at depths of 1100–1150 m in our most northern study site off southern Oregon and the southern site off Cape Mendocino, California. Nearly 20% (n = 78) of disturbed bamboo corals were sheared off at the base, leaving only small stumps to be counted. Height of intact undisturbed bamboo coral colonies ranged from 5 to 185 cm. The Mendocino Ridge area had the highest incidence of coral bycatch in research bottom trawls conducted between 2001 and 2015. Using visual survey tools, we now have a better understanding of the extent of damage and disturbance to DSCS. Conservation areas have been implemented off the U.S. West Coast to protect seafloor habitats, but DSCS in our study site remain vulnerable to impacts from bottom-contact fishing gears.

Trace elemental ratios preserved in the calcitic skeleton of bamboo corals have been shown to serve as archives of past ocean conditions. The concentration of dissolved barium (BaSW), a bioactive nutrientlike element, is linked to biogeochemical processes such as the cycling and export of nutrients. Recent work has calibrated bamboo coral Ba/Ca, a new BaSW proxy, using corals spanning the oxygen minimum zone beneath the California Current System. However, it was previously unclear whether Ba/Cacoral records were internally reproducible. Here we investigate the accuracy of using laser ablation inductively coupled plasma mass spectrometry for Ba/Cacoral analyses and test the internal reproducibility of Ba/Ca among replicate radial transects in the calcite of nine bamboo corals collected from the Gulf of Alaska (643–720 m) and the California margin (870–2054 m). Data from replicate Ba/Ca transects were aligned using visible growth bands to account for nonconcentric growth; smoothed data were reproducible within ~4% for eight corals (n = 3 radii/coral). This intracoral reproducibility further validates using bamboo coral Ba/Ca for BaSW reconstructions. Sections of the Ba/Ca records that were potentially influenced by noncarbonate bound Ba phases occurred in regions where elevated Mg/Ca or Pb/Ca and coincided with anomalous regions on photomicrographs. After removing these regions of the records, increased Ba/Cacoral variability was evident in corals between ~800 and 1500 m. These findings support additional proxy validation to understand BaSW variability on interannual timescales, which could lead to new insights into deep sea biogeochemistry over the past several centuries.

13 pages, 8 figures, 5 tables, 1 appendix, We present an initial reconstruction of recent (last few centuries) mud-bottom faunal communities on the upper slope (398–667 m) of the continental margin off Catalonia (western Mediterranean), including periods free of any trawling impact. Radiometric dating of marine sediments and identification of faunal remains (e.g., fish otoliths, pteropod shells, coral sclerites) were performed to obtain a sediment geochronology in a 56 cm sediment core (MC4) taken at 398 m off the Ebro Delta in 2011. Core MC4 was especially rich in faunal remains, including, for example, 247 identifiable otoliths. A fine-scale chronology of MC4 was not possible due to sediment mixing. However, the depth of 210Pbxs penetration (20–22 cm) identified sediments older (below 22 cm depth) and younger (from core top to 22 cm) than ca. 100 years. Mass Accumulation Rate (MAR) from the 210Pbxs profile was estimated as 0.23±0.02 g cm−2 y−1. A significant peak of sclerites of the bamboo coral Isidella elongata was found between 4 and 8 cm in MC4, with remains of the axes and bases of Isidella colonies exclusively found at core depths >8–10 cm, which would correspond (MAR results) to the period 1980–1985. Such structures were not found in the 0–8 cm layer, likely an effect of trawling that started in the area in the 1980s. Other changes both in benthos (corals and cirripedes) and zooplankton (pteropods) seemed to be related with Ebro river discharge, with changes coinciding with massive damming of the Ebro and tributary rivers in the 1950s and until 1965. Mesopelagic fish also showed temporal oscillations in MC4. Abundance of some myctophid remains (Lampanyctus croccodilus and Benthosema glaciale) was related with positive NAO periods and with rather high temperature in Levantine Intermediate Waters. By contrast, periods of higher dominance of Ceratoscopelus maderensis off Catalonian coasts could indicate lower salinity during the past and a progressive degree of eutrophication in intermediate waters in recent decades. A general decline in myctophids otolith abundance during the last ca. 100 years could be related to changes in the temperature and salinity of deep-water masses and a decline in ocean productivity that would also have affected open-water fish stocks, This study was financed within the framework of the MICYT project ANTROMARE, but it was especially possible thanks to the multi-methological work designed in proposals like TRENDSEAS and PELMAR (CTM2014-54018-C3, which were not funded by Ministerio de Economía y Competitividad)

Bamboo corals represent an intriguing paleoceanographic archive with the potential to reconstruct variations throughout the water column over multiple centuries. Realizing this potential partially depends on if, and at what resolution, timeseries of variability can be generated. Recent work demonstrates that bamboo coral growth temperature, averaged over its entire lifespan, can be derived from linear correlations in its carbon and oxygen isotope composition (δ13C, δ18O) when the apparent equilibrium fractionations for a coral's growth rate and calcifying pH are used. Building on this method, this study applies it to coeval coral skeleton to assess the possibility of extracting paleoceanographic timeseries from bamboo coral skeletons. Using boron isotope (δ11B) based pH estimates, micromilled samples yield accurate paleotemperatures with uncertainties of 2 °C. This is attributed to the inability to measure δ13C and δ18O in exactly the same skeleton, as is the case for micromilled samples. A micromilled sampling strategy is therefore likely the most practical means of applying the method. Carbonate clumped isotopes (∆47) estimate temperatures slightly warmer than observed, suggesting they may not accurately record the subtle variations of the latest Holocene. When interpreted in conjunction, δ18O, δ11B and ∆47 data suggest that pH up-regulation plays a role in generating linear δ13C-δ18O trends. However, oxygen isotope fractionation and ∆47 are lower than would be predicted by pH alone. Potential explanations for this discrepancy include biological processes that favor the incorporation of carbonate ion into coral skeleton, uncertainties in the δ11B-pH proxy, the influence of magnesium on calcite-fluid isotope fractionation, or uncertainties in the fractionation factors used to calculate apparent equilibrium. Despite some remaining uncertainties, the method can resolve many observed decadal-scale thermocline temperature anomalies, suggesting that appropriately located bamboo corals could help constrain the behavior of similar temporal variability prior to instrumental monitoring.

Seamounts represent ecologically important marine environments and undeniably play a crucial role in the functioning of the deep-sea ecosystems, thanks primarily to their contribution in supporting offshore benthic and pelagic biodiversity. In the last decades, these features have received attention in all oceans of the world, but they were relatively overlooked in the Mediterranean Sea. In particular, the Ligurian Sea hosts six major structures, whose summits, ranging from 150 to nearly 2000 m depth, are virtually unknown from the biological point of view. The summit region of the Janua Seamount, located approximately at 40 nautical miles off the harbour of Genoa at 810 m depth, was explored for the first time using Remotely Operated Vehicles. The sea bed topography is characterized by a heterogeneous hard bottom, dominated by sub-fossil thanatocoenoses of Lophelia pertusa (Linnaeus, 1758) covered in a thick Ferrous-Manganese crust, and colonized by a scattered bathyal assemblage dominated by hexactinellids and benthic cnidarians showing a distinct regionalization around the summit. Cnidarians observed in this site include a rare Atlantic bamboo coral (Isididae, Chelidonisis aurantiaca Studer, 1890), described herein for the first time for the Mediterranean Basin. These findings provide new information on the biogeographic patterns of colonization of the bathyal Mediterranean fauna but also highlight the large knowledge gap that still exists for deep-sea biodiversity of this basin.

The ocean’s physicochemical variability is not well understood despite its importance for the world’s climate because of rare instrumental time series. This issue can be resolved through natural archives that recorded past environmental conditions such as corals. Bamboo corals, thriving in water depths down to 4000 m, offer the potential to record environmental parameters over a wide range of oceanic conditions. This dissertation provides a detailed look into the chemical composition of bamboo coral skeletons to distinguish between environmental and biomineralisation controls over the skeletal composition. The ability of bamboo corals to record seawater temperature and nutrient availability was investigated by measuring the distribution of Mg and Ba, respectively, in the internode of an Atlantic specimen. The mean Mg/Ca composition of a bamboo coral can be used to reconstruct the ambient seawater temperature while mean Ba/Ca was found to record [Ba]SW. Conversely, the micron-scale skeletal Mg and Ba composition is strongly impacted by coral physiology. The use of skeletal Na and S concentrations as environmental proxies in marine calcifiers is debated and was therefore evaluated in two Atlantic bamboo corals. The microscale distribution of Na and S can show a concentric structure and zig zag patterns as found for Mg. The heterogeneity indicates a main control of the coral physiology over the skeletal composition. The B elemental as well as its isotopic composition in calcium carbonates have been used to study the ambient pH of the corals’ calcifying fluid (CF). The B/C and B isotopic spatial distribution in an Atlantic and a Pacific bamboo coral were measured in the bulk internode material and the purified calcite fraction. Our results suggest that besides CF pH, the skeletal boron isotopic composition of bamboo corals might be influenced by isotopically light borate influx to the CF, organic matter induced isotope fractionation or kinetic isotope effects.

A deep-water coral forest, characterized by slender and whip-shaped bamboo corals has been discovered from water depths of 1200–1380 m at the western edge of the Xisha (Paracel Islands) area in the South China Sea. The bamboo corals are often accompanied by cold-water gorgonian “sea fan” corals: Anthogorgia sp. and Calyptrophora sp., as well as assemblages of sponges, cirrate octopuses, crinoids and other animals. The coral density increased toward the shallower areas from 24.8 to 220 colonies per 100 m2 from 1380 m to 1200 m water depth. This is the first set of observations of deep-water bamboo coral forests in Southeast Asia, opening a new frontier for systematic, ecological and conservation studies to understand the deep-coral ecosystem in the region.

Keratoisis grayi is one of the most abundant large gorgonian corals found off Newfoundland and Labrador, yet we know little regarding the factors influencing its distribution, abundance, and condition. We employed remotely operated vehicle (ROV) transect data collected in three canyons off the Grand Banks, Newfoundland to quantitatively examine the influence of depth, bottom type, canyon, and trawling intensity on K. grayi abundance, height, and condition at small spatial scales. While surveying 105 km of seafloor with a ROV, we observed 5770 K. grayi colonies and 167 trawl marks. We found that K. grayi were significantly more likely to occur in boulder areas than in cobble or gravel. Bottom depth related positively and significantly with colony height and our models predict that the largest bamboo coral colonies occur in boulders in Halibut Channel, and in boulders and cobble in Haddock Channel. The majority of colonies observed were alive and undamaged, but tipped, broken, dead and partially dead colonies were also recorded. K. grayi were more likely to occur in trawled areas, but these colonies were more likely to be damaged, broken, smaller in size, and less abundant than colonies outside trawled areas. These results demonstrate a negative impact of bottom trawling on K. grayi colonies off Newfoundland and Labrador and that fishers may specifically target areas where these corals occur.

We test for trace element proxies in the high-magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen-mean compositions of 73 corals that were live-caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the Antarctic slope. Comparisons were done at a large geographic scale (LGS) and for a well sampled area south of Australia, across depths at a single site, in order to help separate the effects of environmental variables that co-vary at one spatial scale, but not the other. Thirty-seven trace elements were measured using solution-based Sector Field ICP-MS, of which seventeen were significantly detected in more than a third of the specimens. Only eight element/calcium ratios correlated significantly with any environmental variable at the large geographic scale, and only four did so at the local level. At the LGS, the highest correlation was between ambient temperature and Mg/Ca, which accounted for 89% of the variance across specimens, spanned all four Isidid sub-families and was independently significant in the two best sampled sub-families. The predictive (geometric mean) relationship is T ( ° C ) = - 23.9 ( ± 2.46 ) + 0.34 ( ± 0.25 ) Mg / Ca ( mmol / mol ) spanning a temperature range of −1.9 to 26.8 °C, Mg/Ca ratios from 58.6 to 155.1 mmol/mol, and an uncertainty (RMS) of 2.78 °C. The numbers in parentheses are 95% CIs. The slope of the regression does not differ significantly from that of abiotic high-Mg calcites, which suggests that the temperature-dependent incorporation of Mg into the carbonate results from kinetic reactions at the crystal surface. Analysis at the SH scale for the sub-set of specimens for which we had data suggests is also affected by growth rates. There were no obvious trace element correlates at either spatial scale of salinity or oxygen levels that could not be accounted for by covariance between these environmental parameters and, in most cases, temperature. Single and multiple correlation analyses also confirm previous suggestions that Ba/Ca in bamboo coral calcite is a proxy for seawater barium and hence refractory nutrients, suggest that Sr/Ca is influenced by specimen-mean Mg/Ca ratios and water temperature as well as possibly seawater Sr/Ca, and falsify for bamboo corals P/Ca (as well as P/Cd and Cd/Ca) as a proxy for seawater phosphate levels. The predictive relationship between Isidid skeletal-mean Ba/Ca and seawater silicate concentrations appears to be linear, and is given by silicate ( μ mol kg - 1 ) = - 56.7 ( ± 20.8 ) + 9217 ( ± 1632 ) Ba / Ca ( mmol / mol ) spanning a silicate range of 0.5 to 120 μmol kg−1, a Ba/Ca range of 0.0042 to 0.0195 mmol/mol, and with an uncertainty (RMS) of 33.1 μmol kg−1. Mn/Ca differences among specimens and sites are highly significant and appear to reflect seawater Mn, suggesting a proxy for this micronutrient. The compilation of growth rate data across 34 specimens indicates a wide range of growth rates even among con-familial specimens from within a single habitat, and suggests both ambient temperature and food availability underlie at least part of this variability.

Bamboo corals represent an emerging paleoclimate archive with the potential to record variability at intermediate depths throughout much of the global ocean. Realizing this potential has been complicated by biologically mediated vital effects, which are evident in linear correlations of skeletal carbon (δ13C) and oxygen (δ18O) isotope composition. Previous efforts to develop a bamboo coral δ18O paleothermometer by accounting for such vital effects have not been completely successful as they still rely on empirical calibrations that are offset from the temperature dependence of abiogenic experiments. Here we describe an approach that better corrects for bamboo coral vital effects and allows paleotemperatures to be calculated directly from the abiogenic temperature dependence. The success of the method lies in calculating apparent equilibrium carbon and oxygen isotope fractionation at the temperature, pH, and growth rate of each coral, as well as in the use of model II regressions. Rigorous propagation of uncertainty suggests typical errors of ±2–3°C, but in select cases errors as low as ±0.98°C can be achieved for densely sampled and strongly correlated data sets. This lower limit approaches the value attributed to uncertainty in pH and growth rate estimates alone, as predicted by a series of pseudoproxy experiments. The incorporation of isotopically light metabolic CO2 appears to be negligible in most Pacific corals, but may be significant in Atlantic specimens, potentially requiring an additional correction. The success of the method therefore hinges on how well complex environmental systems and biomineralization strategies are constrained, with the most reliable temperatures occurring when calcifying fluid pH, growth rate, and incorporation of metabolic carbon into skeletal calcite are constrained using multiple geochemical proxies.

The bamboo coral Isidella elongata is a key structuring species on deep muddy bottoms, which has suffered severe consequences from bottom-fishing activities, as it often co-occurs with precious fishery resources such as red shrimps. A five-year series of data collected during a scientific trawl survey was used to localize the presence and to characterize the associated megafauna over a wide spatial scale in the Western and Central Mediterranean (Sardinia, South-Central Tyrrhenian, Western Ionian and Southern Adriatic). In addition, the overlap of I. elongata hotspots with nursery and spawning areas of three selected species (Aristaeomorpha foliacea, Aristeus antennatus and Galeus melastomus) was analysed. The sizes of the colonies were analysed in the South-Central Tyrrhenian and the Southern Adriatic. No significant variation over time was observed in the former, while in the latter, the colonies were bigger but showed a decreasing trend over time.

During two expeditions to seamounts near the Mariana Trench in the tropical western Pacific, several trochiform shells from the upper bathyal zone were sampled. Morphological observations of these specimens suggest that they represent two new species that belong to the family Trochidae, but the shell morphology, radular plan, and external anatomy differ considerably from those of closely related genera. A new subfamily, Carinotrochinae subfam. nov., and a new genus, Carinotrochus gen. nov., are proposed herein to accommodate these two species. Carinotrochus marianaensis sp. nov., the type species, was associated with coral debris at a depth of 865 m, and Carinotrochus williamsae sp. nov. was discovered crawling on a hydroid Stegolaria sp. that was attached to a dead bamboo coral at a depth of 1332 m. Genertic analysis of mitochondrial COI, 16S rRNA, and nuclear 28S rRNA genes using maximum likelihood, Bayesian inference, and pairwise uncorrected p-distances confirmed that the new taxa are trochids but do not belong to any existing defined subfamily. Molecular clock analysis based on concatenated sequences (COI, 16S, and 28S) indicated that Carinotrochinae subfam. nov. split from its shallow water sister subfamily Trochinae roughly 80 Mya during the Late Cretaceous.

Bamboo corals are the representatives of the Gorgonacea order within Isidids octocorals. Opposed to corals from the Scleractinia order, in which the biomineralization process has been well evaluated, the mineralization in the Isididae corals is still not fully understood. The interspace mineralization process in the deep-sea bamboo corals bilayered organic matrix is described and analyzed.

A mono-specific population of Isidella elongata in the Ventotene Basin (Pontine Islands, western Mediterranean Sea) was recently revealed by ROV survey. This vulnerable marine community was found on top of a 3.6 km long morphological high, in water depths between 510 and 560 m. Side scan sonar data showed the presence of several trawl marks suggesting a high anthropogenic impact of the study area. Furthermore, multibeam and high-resolution seismic data revealed the presence of widespread pockmarks, indicating occurrence of fluids in the sub-seafloor.

The deep ocean was once assumed to be lifeless and barren. Today we know that even the deepest waters teem with living creatures, some of them thought to be little changed from when life itself first appeared on the planet. The deep ocean is also essential to the earth’s biosphere—it regulates global temperatures, stores carbon, provides habitat for countless species, and cycles nutrients for marine food webs.1 Currently stressed by pollution, industrial fishing, and oil and gas development, these cold, dark waters now face another challenge: mining. With land-based mineral sources in decline, seabeds offer a new and largely untapped frontier for mineral extraction, and companies are gearing up to mine a treasure trove of copper, zinc, gold, manganese, and other minerals from the ocean floor.2,3 The ocean floor is home to a wealth of species, some of which—such as this bamboo coral (Isidella tentaculum)—have only recently been discovered. Proponents of seabed mining claim it causes less ecological damage than terrestrial extraction. ... Scientists, regulators, and mining companies are now collaborating on frameworks and strategies for mining the seabed responsibly. Cindy Van Dover, director of the Duke University Marine Laboratory and chair of the school’s Division of Marine Science and Conservation, says that’s encouraging, given that seabed mining appears to be inevitable. “There’s been a lot of engagement on the environmental side,” Van Dover says. “A hundred years from now, people will look back and ask if we got this right. We need to be sure that we do.” Copper grades, or the percentage of copper per unit of mined substrate, have declined with steadily rising extraction, from a high of 10–20% during the late nineteenth century to less than 1% today.4 By contrast, copper grades in seabeds slated for exploitation in 2018 by the Canadian mining company Nautilus Minerals, lying under 1,600 m of water off Papua New Guinea, average 7.2%.5 It’s estimated that 500 billion metric tons of polymetallic nodules—mineral clumps loaded with varying levels of manganese, cobalt, nickel, and copper—lie scattered under waters up to 6,000 m deep in the Pacific, Atlantic, and Indian oceans.6 Proponents of seabed mining assert that extracting minerals from the deep ocean will inflict less environmental damage than mining on land, which displaces communities, removes entire ecosystems, exacerbates erosion, and pollutes groundwater, rivers, and streams. But according to Craig Smith, a professor of biological oceanography at the University of Hawai‘i at Mānoa, seabed mining will also stir up vast plumes of sediments, some of which could resettle over areas much larger than the mine sites themselves. Scientists worry the plumes could cause widespread ecological damage and kill off deep-sea fauna that they know little about. Without appropriate regulations, they say, seabed mining will further erode the ocean’s capacity to provide essential ecological services, adding to what are already acute concerns for the ocean’s overall health. “Deep-ocean ecosystems can be incredibly fragile,” Smith says. “And it’s possible that after the mining starts, huge areas could be impacted before any one of them has a chance to bounce back.”

Deep-sea bamboo corals (Family Isididae: subfamily Keratoisidinae) are a widely distributed group of gorgonian octocorals, commonly found in the deep sea below 200 m, with the deepest specimen to date collected at 4700 m. Two specimens were collected from the seamounts off Tasmania at depths of 3065 to 3950 m. In situ high-definition images, compound microscopy of preserved specimens, and Scanning Electron Microscopy (SEM) provided morphological data on distinguishing morphological characters such as colony shape and branching pattern, polyp arrangement, composition of the axial skeleton, and shape and arrangement of the sclerites. The genus Bathygorgia Wright, 1885 is resurrected and distinguished from Keratoisis, and two new species, B. abyssicola and B. tasmaniensis are added.

The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed ‘ocean acidification’). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal understanding on the rate and magnitude of deep ocean acidification. Here we investigate boron, carbon, and oxygen isotopes on live-collected deep-sea bamboo corals (genus Keratoisis) from a pHtot range of 7.5–8.1. These analyses are used to explore the potential for using bamboo coral skeletons as archives of past deep-sea pH and to trace anthropogenic acidification in the subsurface North Atlantic Ocean (850–2000 m water depth). Boron isotope ratios of the most recently secreted calcite of bamboo coral skeletons are close to the calculated isotopic composition of borate anion in seawater (δ11Bborate) for North Atlantic corals, and 1–2‰ higher than δ11Bborate for Pacific corals. Within individual coral skeletons, carbon and oxygen isotopes correlate positively and linearly, a feature associated with vital effects during coral calcification. δ11B variability of 0.5–2‰ is observed within single specimens, which exceeds the expected anthropogenic trend in modern North Atlantic corals. δ11B values are generally elevated in Pacific corals relative to δ11Bborate, which may reflect pH-driven physiological processes aiding coral calcification in environments unfavorable for calcite precipitation. Elevated δ11B values are also observed proximal to the central axis in multiple Atlantic and Pacific specimens, relative to δ11Bborate, which might reflect ontogenetic variability in calcification rates. Although the observed boron isotope variability is too large to resolve the present anthropogenic ocean acidification signal at the studied depths in the North Atlantic (∼0.03–0.07 pH units), pH changes ⩾0.1 units might still be reconstructed using δ11B measurements in bamboo corals.

Special issue Bridging the gap between the shallow and deep oceans: The key role of submarine canyons.-- 13 pages, 9 figures, 2 tables, The impacts of fishing activities on ecosystems represent an acknowledged environmental issue, especially considering the increasing demands for the conservation of biodiversity. Submarine canyons are complex environments that can harbor high biodiversity of benthic ecosystems and high biomass of fish species, thus representing preferential fishing areas for bottom trawling fleets. The effects of bottom trawling on the benthic epifauna were investigated over the soft-bottom margins of the Gioia Canyon (Southeastern Tyrrhenian Sea) by means of quantitative analysis of Remote Operated Vehicle (ROV) video transects and compared with the recent pattern of trawling intensity, reconstructed through processing of data collected with the Vessel Monitoring System (VMS). Four ROV transects were then performed at 320–540 m depth in areas affected by different trawling pressure. The analysis was focused on the bamboo coral Isidella elongata and the sea pen Funiculina quadrangularis, which are considered indicator taxa of Vulnerable Marine Ecosystems (VMEs) and relevant in terms of sustainable management priorities. I. elongata only occurred at the two deeper stations, below 400 m depth. This species showed a clear relationship with trawling intensity, since its abundance was significantly higher under low trawling intensity, where coexistence of large (>20 cm height) and small colonies was observed. The relatively high prevalence of small colonies in areas exposed to higher trawling effort was interpreted as a consequence of the trawling activity that removed the larger colonies. However, the frequent occurrence of dead colonies and the diffuse presence of epibionts (e.g. the anemone Amphianthus dohrnii and the hydroid Clytia linearis) on living colonies indicate stressful conditions for I. elongata even in areas where trawling intensity was lower. Conversely, the relationship between trawling intensity and species abundance was not straightforward for F. quadrangularis; despite the lowest abundance of this species was recorded in areas subject to high trawling intensity, relatively high abundances were observed in areas with intermediate trawling effort. Although such distribution may be driven by other environmental factors, it suggests that vulnerability to bottom trawling can be different for the two species

The powder infrared spectra of a sulfate-bearing calcitic coral sample are recorded at room temperature in attenuated total reflectance (ATR) geometry and at low temperature in transmission geometry. The comparison of ATR spectra recorded with diamond or Ge crystal confirms that the width and the shape of the prominent absorption bands, related to CO 3 groups, are dominantly affected by macroscopic electrostatic interactions. In contrast, the temperature-dependence of the position and width of weak and narrow absorption bands, related to CO 3 or SO 4 groups, can be interpreted in terms of thermal expansion, anharmonic coupling, and local strain fluctuations. The three SO 4 stretching bands display a contrasted thermal behavior, the frequency of one of them increasing with temperature. Based on first-principles calculation, this unusual temperature dependence is traced back to the anisotropy of calcite thermal expansion. These results sustain the previously proposed atomic-scale model of sulfate in calcite and attest to a dominantly structural nature of sulfate in the investigated sample. Accordingly, structurally substituted sulfur in deep-sea calcitic bamboo coral could be used as proxy of seawater sulfate.

Keratoisis is a genus of bamboo coral commonly reported in the northwest (NW) Atlantic as a result of fishing bycatch or by in situ observations. In 1999, a scientific trawl survey recovered fragments of Keratoisis sp. in southeast Baffin Bay (NW Atlantic), but colonies had never been seen in situ at this location until 2013, when a remotely operated vehicle (ROV) was used to survey this location. Here we report the presence of dense forests of Keratoisis sp. in a muddy environment at depths >900 m. Colonies were found as dense patches up to ~55 m long along the ROV track and were estimated to reach ~1 m in height. At this location, Keratoisis sp. appears to have branched root-like structures probably used for anchorage on mud. The majority of colonies were alive, but fragments of dead colonies were also observed, especially in the path of the 1999 bottom trawl tow. Based on visual observation, the dense stands of Keratoisis sp. in this environment seem to form structure and habitat for other invertebrates and fishes in an otherwise mainly muddy environment.

Deep-sea bamboo corals (order Gorgonacea, family Isididae) are known to record changes in water mass chemistry over decades to centuries. These corals are composed of a two-part skeleton of calcite internodes segmented by gorgonin organic nodes. We examine the spatial variability of bamboo coral organic node 13C/12C and 15N/14N from 13 bamboo coral specimens sampled along the California margin (37–32° N, 792–2136 m depth). Radiocarbon analyses of the organic nodes show the presence of the anthropogenic bomb spike, indicating the corals utilize a surface-derived food source (pre-bomb D14C values of ∼−100‰, post-bomb values up to 82‰). Carbon and nitrogen isotope data from the organic nodes (δ13C = −15.9‰ to −19.2‰; δ15N = 13.8‰ to 19.4‰) suggest selective feeding on surface-derived organic matter or zooplankton. A strong relationship between coral δ15N and habitat depth indicates a potential archive of changing carbon export, with decreased δ15N values reflecting reduced microbial degradation (increased carbon flux) at shallower depths. Using four multi-centennial-length coral records, we interpret long-term δ15N stability in the California Current. Organic node δ15C values record differences in carbon isotope fractionation dictated by nearshore vs. offshore primary production. These findings imply strong coupling between primary production, pelagic food webs, and deep-sea benthic communities.

Reconstruction of past seawater δ 138 / 134 BaNIST (barium-isotopic compositions) can augment existing proxies of water mass provenance and deep-ocean circulation. Deep-sea bamboo corals are uniquely poised to record Ba-isotopic variations, given their widespread oceanographic distribution and incorporation of ambient Ba in approximate proportion to that in surrounding seawater. However, the utility of such records requires knowing: the phases hosting Ba in deep-sea coral skeletons, that specimens faithfully capture modern Ba-isotopic chemistry, and that internal skeletal variability relates principally to historical variations in the composition of ambient seawater. We investigated each of these requirements using a stepped cleaning experiment, a ‘core-top’ comparison of eight live-collected specimens from the California margin (870–2,055 m) against ambient seawater, and through examination of historical variability in skeletal Ba chemistry, respectively. First, we report that non-carbonate phases minimally contribute to bamboo coral Ba/Ca, obviating the need for chemical cleaning of live-collected specimens. Second, using newly-obtained profiles of northeast Pacific Ba-isotopic chemistry, we observe that bamboo corals faithfully reflect ambient seawater with a taxonomically- and environmentally-invariant Ba-isotopic offset, Δ 138 / 134 Bacoral–SW, of −0.37±0.03‰ (±2 SD, n = 8 ). The partition coefficient for Ba, K D Ba, is similarly insensitive to taxonomy, but linearly decreases with depth. The driving mechanism is unresolved. Third, we find minimal Ba/Ca and Ba-isotopic variability in historical growth representing the past century. We interpret this invariance as evidencing the overall fidelity of deep-sea bamboo corals for ambient Ba chemistry over their long lifespans. The insensitivity of Δ 138 / 134 Bacoral–SW to environmental gradients indicates that the Ba-isotopic composition of bamboo corals can be solely interpreted in terms of seawater composition, which should find myriad applications to the study of past ocean circulation over a range of timescales.

The critically endangered “bamboo coral” Isidella elongata is a near-endemic protected species for which limited information exists in the Eastern Mediterranean Sea. The aim of this work was to update the known geographical distribution of I. elongata in the Eastern Mediterranean by combining literature data with unpublished records (from experimental fisheries surveys and ROV observations) made within the last two decades. Our study revealed 35 records of I. elongata occurrence spanning across the entire Aegean ecoregion. It has been found at a depth range of 126–1125 m. A considerable number of records, in some cases with multiple colonies, were identified in the North Aegean Sea and the Hellenic Trench. This study showed that the distribution range of this key species in the Eastern Mediterranean Sea is wider than previously thought and provides a baseline for future research and conservation initiatives in Eastern Mediterranean deep waters.

Trace elements and stable isotopes (δ 13 C and δ 15 N) in deep-sea coral have been used as proxies to reconstruct past climate, and to investigate food web structure. However, there is a paucity of information regarding the effect of preservation on the chemical integrity of archived coral. In this study a live-caught colony of Bamboo coral (southern Australia), genus ( Lepidisis ), was sectioned into three pieces and stored for approximately one year to investigate the influence of preservation in ethanol and preservation in seawater, that mimics the early stages of fossilization, against a dry preserved control. Storage and preservation have no significant effect on the isotopic signature of Δ 14 C, bulk δ 15 N, δ 15 N and δ 13 C of individual amino acids, or C:N in the fibrillar protein matrix, with the only offset (~0.2‰) being observed in part of the δ 13 C record. In the high-magnesium calcite lattice Ba/Ca appears to be significantly different after storage in ethanol, whereas Δ 14 C, B/Ca, Mg/Ca, Sr/Ca, and U/Ca remain largely unaltered. Possible mechanisms responsible for these observed differences center around the decomposition, or contamination, by organics and we recommend further investigation, and caution when comparing samples with differing preservation histories.

This study presents the results of seafloor habitat identification and mapping of a NE Atlantic deep seamount. An “assemble first, predict later” approach has been followed to identify and map the benthic habitats of the Galicia Bank (NW Iberian). Biotic patterns inferred from the survey data have been used to drive the definition of benthic assemblages using multivariate tools. Eight assemblages, four hard substrates and four sedimentary ones, have been described from a matrix of structural species. Distribution of these assemblages was correlated with environmental factors (multibeam and backscatter data) using binomial GAMs. Finally, the distribution model of each assemblage was applied to produce continuous maps and pooled in a final map with the distribution of the main benthic habitats. Depth and substrate type are key factors when determining soft bottom communities, whereas rocky habitat distribution is mainly explained by rock slope and orientation. Enrichment by northern water masses (LSW) arriving to GB and possible zooplankton biomass increase at vertical-steep walls by “bottom trapping” can explain the higher diversity of habitat providing filter-feeders at slope rocky breaks. These results concerning vulnerable species and habitats, such as Lophelia and Madrepora communities and black and bamboo coral aggregations were the basis of the Spanish proposal of inclusion within the Natura 2000 network. The aim of the present study was to establish the scientific criteria needed for managing and protecting those environmental values, This study was financed by the EC contract INDEMARES-LIFE (07/NAT /E/000732)

It is poorly understood how intermediate water masses are affected by decadal scale climate via biogeochemical cycling, export production, and changes in circulation/ventilation. To this end, a geochemical nutrient proxy from deep-sea bamboo corals would provide decadal to centennial scale records of deep and intermediate-water nutrient dynamics. Seawater barium (BaSW) has a nutrient-like distribution in the water-column (similar to silicate), so Ba/Ca records in foraminifera, shallow water surface corals, and other deep-sea corals have been used to trace refractory nutrients. Here we present the first calibration of a nutrient proxy from skeletal barium preserved in the calcitic internodes of deep-sea bamboo corals, collected from intermediate water depths. A calibration was calculated from a broadly distributed suite of Isidella and Keratoisis corals spanning a silicate and BaSW gradient (n = 33 corals; 300–2800 m): Ba / Ca b a m b o o c o r a l μmol/mol = 0.079 ± 0.008 ∗ Ba SW nmol/kg + 4.205 ± 0.870 r 2 = 0.77 ; n = 33 The strong linear correlation between Ba/Cabamboo coral and BaSW suggests that coral Ba/Ca is a reliable recorder of seawater barium (and, therefore, silicate). We find a distribution coefficient (DBa) for Ba/Cabamboo coral of 1.3 ± 0.2, similar to that of other corals (surface and deep-sea dwelling) and inorganic calcium carbonate precipitation experiments (DBa = 1.2–1.5). This suggests that Ba incorporation is primarily driven by cationic substitution in bamboo corals and holds promise as a globally applicable refractory nutrient proxy. We find interannual–decadal scale variability in a Ba/Cabamboo coral timeseries from a California Margin coral (San Juan Seamount; 1295 m). These data suggest that additional high-resolution Ba/Cabamboo coral records may reveal a connection between regional-scale intermediate water biogeochemistry and low-latitude surface ocean/atmospheric climate.

Sampling along the New England Seamount Chain has produced a large number of new octocoral species, especially of the bamboo corals in the subfamily Keratoisidinae. The new genus described here is unusual in that it branches from the internodes yet has sclerites at the base of the polyp body that are arranged obliquely, and in having tentacles that can be pulled completely into the top of the polyp over the retracted oral disk. The genus and species are characterized using both morphological and molecular data.

In previous studies on the secondary metabolites of the Taiwanese octocoral Isis hippuris, specimens have always been collected at Green Island. In the course of our studies on bioactive compounds from marine organisms, the acetone-solubles of the Taiwanese octocoral I. hippuris collected at Orchid Island have led to the isolation of five new polyoxygenated steroids: hipposterone M-O (1-3), hipposterol G (4) and hippuristeroketal A (5). The structures of these compounds were determined on the basis of their spectroscopic and physical data. The anti-HCMV (human cytomegalovirus) activity of 1-5 and their cytotoxicity against selected cell lines were evaluated. Compound 2 exhibited inhibitory activity against HCMV, with an EC(50) value of 6.0 μg/mL.

Bamboo corals (Order Gorgonacea, Family Isididae) are attractive prospects for deep-sea paleoceanographic reconstruction, capturing trace elements in their calcitic skeletons that may serve as environmental proxies with subdecadal resolution over multi-century timescales. We study the reproducibility and fidelity of trace-element profiles (Ba, Mg, Sr, Mn, U, Pb) in a 420-year-old specimen of the bamboo coral Keratoisis sp. from the SE USA. Using laser-ablation ICP-MS to obtain multiple replicate profiles, we use spectral techniques to distinguish noise and irreproducible variations from fully reproducible geochemical fluctuations that are candidates for environmental signals. By quantifying variability between profiles, we assess the fidelity with which the corals potentially record environmental information. Barium is the most reproducible element in the skeleton, with large fluctuations along different growth radii reproducing to within 4%. Both Mg and Sr have very uniform levels within the coral, but display low-amplitude irreproducible variations that might represent an internal biological process. In the case of Mg, which has been proposed as a paleotemperature proxy, this irreproducibility would represent an intrinsic uncertainty of ∼±0.1 to 0.4 °C. Both Mn and Pb contain some irreproducibility superimposed upon broad reproducible profiles that may be environmental signals. Some of the irreproducible Pb fluctuations correlate with cracks and dark bands in the sample suggesting detrital or surface contamination. Uranium displays large amplitude variations which are not reproducible along different radii. This suggests that uranium cannot be used for paleoenvironmental reconstruction, and may show signs of early diagenesis – a possibility that could complicate attempts to date young Keratoisis sp. samples by U-series geochemistry. The highly reproducible Ba signal allows precise alignment of profiles and thus we can show that growth rate along one radius can vary by a factor of two relative to growth along a different radius. There is no evidence that this large variation in relative growth rate affects either the Mg or Sr incorporation. In addition, geochemical anomalies in Ba and Mg indicate that the very central axis of the specimen may represent a different mode of growth. This study suggests that Keratoisis sp. corals are imperfect recorders of geochemical information, but do contain reproducible variations which are good candidates for environmental signals.