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Most animal species have a singular developmental pathway and adult ecology, but developmental plasticity is well-known in some such as honeybees where castes display profoundly different morphology and ecology. An intriguing case is the Atlantic deep-sea hydrothermal vent shrimp pair Rimicaris hybisae and R. chacei that share dominant COI haplotypes and could represent very recently diverging lineages or even morphs of the same species. Rimicaris hybisae is symbiont-reliant with a hypertrophied head chamber (in the Mid-Cayman Spreading Centre), while R. chacei is mixotrophic with a narrow head chamber (on the Mid-Atlantic Ridge). Here, we use X-ray micro-computed tomography and fluorescence in situ hybridization to show that key anatomical shifts in both occur during the juvenile–subadult transition, when R. hybisae has fully established symbiosis but not R. chacei. On the Mid-Atlantic Ridge, the diet of R. chacei has been hypothetically linked to competition with the obligatorily symbiotic congener R. exoculata , and we find anatomical evidence that R. exoculata is indeed better adapted for symbiosis. We speculate the possibility that the distinct development trajectories in R. hybisae and R. chacei may be determined by symbiont colonization at a "critical period" before subadulthood, though further genetic studies are warranted to test this hypothesis along with the true relationship between R. hybisae and R. chacei. [ABSTRACT FROM AUTHOR]

The Southwest Indian Ridge is an ultraslow-spreading mid-ocean ridge with numerous poorly-explored seamounts. The benthic fauna of seamounts are thought to be highly heterogeneous, within even small geographic areas. Here we report observations from a two-year opportunistic experiment, which was comprised of two deployments of mango wood and whale bones. One was deployed at 732 m on Coral Seamount (~32 °S) and the other at 750 m on Atlantis Bank (~41 °S), two areas with little background faunal knowledge and a significant distance from the continental shelf. The packages mimic natural organic falls, large parcels of food on the deep-sea floor that are important in fulfilling the nutritional needs and providing shelter and substratum for many deep-sea animals. A large number of species colonised the deployments: 69 species at Coral Seamount and 42 species at Atlantis Bank. The two colonising assemblages were different, however, with only 11 species in common. This is suggestive of both differing environmental conditions and potentially, barriers to dispersal between these seamounts. Apart from Xylophaga and Idas bivalves, few organic-fall specialists were present. Several putative new species have been observed, and three new species have been described from the experiments thus far. It is not clear, however, whether this is indicative of high degrees of endemism or simply a result of under-sampling at the regional level. [ABSTRACT FROM AUTHOR]

Hydrothermal vents on mid-oceanic ridges are patchily distributed and host many taxa endemic to deep-sea chemosynthetic environments, whose dispersal may be constrained by geographical barriers. The aim of this study was to investigate the connectivity of three populations of the 'scaly-foot gastropod' ( Chrysomallon squamiferum Chen et al., 2015), a species endemic to hydrothermal vents in the Indian Ocean, amongst two vent fields on the Central Indian Ridge (CIR) and Longqi field, the first sampled vent field on the Southwest Indian Ridge (SWIR). Connectivity and population structure across the two mid-oceanic ridges were investigated using a 489-bp fragment of the cytochrome oxidase c subunit I (COI) gene. Phylogeographical approaches used include measures of genetic differentiation ( F), reconstruction of parsimony haplotype network, mismatch analyses and neutrality tests. Relative migrants per generation were estimated between the fields. Significant differentiation ( F = 0.28-0.29, P < 0.001) was revealed between the vent field in SWIR and the two in CIR. Signatures were detected indicating recent bottleneck events followed by demographic expansion in all populations. Estimates of relative number of migrants were relatively low between the SWIR and CIR, compared with values between the CIR vent fields. The present study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. The phylogeography revealed for C. squamiferum indicates low connectivity between SWIR and CIR vent populations, with implications for the future management of environmental impacts for seafloor mining at hydrothermal vents in the region, as proposed for Longqi. [ABSTRACT FROM AUTHOR]

Few species of reptant decapod crustaceans thrive in the cold-stenothermal waters of the Southern Ocean. However, abundant populations of a new species of anomuran crab, Kiwa tyleri, occur at hydrothermal vent fields on the East Scotia Ridge., As a result of local thermal conditions at the vents, these crabs are not restricted by the physiological limits that otherwise exclude reptant decapods south of the polar front., We reveal the adult life history of this species by piecing together variation in microdistribution, body size frequency, sex ratio, and ovarian and embryonic development, which indicates a pattern in the distribution of female Kiwaidae in relation to their reproductive development., High-density ' Kiwa' assemblages observed in close proximity to sources of vent fluids are constrained by the thermal limit of elevated temperatures and the availability of resources for chemosynthetic nutrition. Although adult Kiwaidae depend on epibiotic chemosynthetic bacteria for nutrition, females move offsite after extrusion of their eggs to protect brooding embryos from the chemically harsh, thermally fluctuating vent environment. Consequently, brooding females in the periphery of the vent field are in turn restricted by low-temperature physiological boundaries of the deep-water Southern Ocean environment. Females have a high reproductive investment in few, large, yolky eggs, facilitating full lecithotrophy, with the release of larvae prolonged, and asynchronous. After embryos are released, larvae are reliant on locating isolated active areas of hydrothermal flow in order to settle and survive as chemosynthetic adults. Where the cold water restricts the ability of all adult stages to migrate over long distances, these low temperatures may facilitate the larvae in the location of vent sites by extending the larval development period through hypometabolism., These differential life-history adaptations to contrasting thermal environments lead to a disjunct life history among males and females of K. tyleri, which is key to their success in the Southern Ocean vent environment., We highlight the complexity in understanding the importance of life-history biology, in combination with environmental, ecological and physiological factors contributing to the overall global distribution of vent-endemic species. [ABSTRACT FROM AUTHOR]

Introduction: The 'scaly-foot gastropod' (Chrysomallon squamiferum Chen et al., 2015) from deep-sea hydrothermal vent ecosystems of the Indian Ocean is an active mobile gastropod occurring in locally high densities, and it is distinctive for the dermal scales covering the exterior surface of its foot. These iron-sulfide coated sclerites, and its nutritional dependence on endosymbiotic bacteria, are both noted as adaptations to the extreme environment in the flow of hydrogen sulfide. We present evidence for other adaptations of the 'scaly-foot gastropod' to life in an extreme environment, investigated through dissection and 3D tomographic reconstruction of the internal anatomy. Results: Our anatomical investigations of juvenile and adult specimens reveal a large unganglionated nervous system, a simple and reduced digestive system, and that the animal is a simultaneous hermaphrodite. We show that Chrysomallon squamiferum relies on endosymbiotic bacteria throughout post-larval life. Of particular interest is the circulatory system: Chrysomallon has a very large ctenidium supported by extensive blood sinuses filled with haemocoel. The ctenidium provides oxygen for the host but the circulatory system is enlarged beyond the scope of other similar vent gastropods. At the posterior of the ctenidium is a remarkably large and well-developed heart. Based on the volume of the auricle and ventricle, the heart complex represents approximately 4 % of the body volume. This proportionally giant heart primarily sucks blood through the ctenidium and supplies the highly vascularised oesophageal gland. Thus we infer the elaborate cardiovascular system most likely evolved to oxygenate the endosymbionts in an oxygen poor environment and/or to supply hydrogen sulfide to the endosymbionts. Conclusions: This study exemplifies how understanding the autecology of an organism can be enhanced by detailed investigation of internal anatomy. This gastropod is a large and active species that is abundant in its hydrothermal vent field ecosystem. Yet all of its remarkable features—protective dermal sclerites, circulatory system, high fecundity—can be viewed as adaptations beneficial to its endosymbiont microbes. We interpret these results to show that, as a result of specialisation to resolve energetic needs in an extreme chemosynthetic environment, this dramatic dragon-like species has become a carrying vessel for its bacteria. [ABSTRACT FROM AUTHOR]

Radiation of dramatically disparate forms among the phylum Mollusca remains a key question in metazoan evolution, and requires careful evaluation of homology of hard parts throughout the deep fossil record. Enigmatic early Cambrian taxa such as Halkieria and W iwaxia (in the clade Halwaxiida) have been proposed to represent stem-group aculiferan molluscs ( Caudofoveata + Solenogastres + Polyplacophora), as complex scleritomes were considered to be unique to aculiferans among extant molluscs. The 'scaly-foot gastropod' ( Neomphalina: Peltospiridae) from hydrothermal vents of the Indian Ocean, however, also carries dermal sclerites and thus challenges this inferred homology. Despite superficial similarities to various mollusc sclerites, the scaly-foot gastropod sclerites are secreted in layers covering outpockets of epithelium and are largely proteinaceous, while chiton ( Polyplacophora: Chitonida) sclerites are secreted to fill an invaginated cuticular chamber and are largely calcareous. Marked differences in the underlying epithelium of the scaly-foot gastropod sclerites and operculum suggest that the sclerites do not originate from multiplication of the operculum. This convergence in different classes highlights the ability of molluscs to adapt mineralized dermal structures, as supported by the extensive early fossil record of molluscs with scleritomes. Sclerites of halwaxiids are morphologically variable, undermining the assumed affinity of specific taxa with chitons, or the larger putative clade Aculifera. Comparisons with independently derived similar structures in living molluscs are essential for determining homology among fossils and their position with respect to the enigmatic evolution of molluscan shell forms in deep time. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 949-954. [ABSTRACT FROM AUTHOR]

Elucidation of life-history traits is essential to understand larval dispersal and population dynamics in marine benthic assemblages. This study is the first investigation of the life history of a recently described hippolytid shrimp from a deep-sea chemosynthetic environment, Lebbeus virentova Nye, Copley, Plouviez and Van Dover, at the Von Damm Vent Field (18°22N, 81°47W, ~2,300 m depth, Mid-Cayman Spreading Centre, Caribbean), using samples collected in February and June 2013. Lebbeus virentova is gonochoric and iteroparous. The sex ratio of L. virentova was significantly female biased (1:3) in February and June. The sampled population of L. virentova had a unimodal size-frequency distribution pattern in February and June, consistent with continuous recruitment and mortality. Continuous reproduction is indicated by a lack of synchrony in oocyte size-frequency distributions within both months, and asynchronous development of embryos among females, which may result in asynchronous larval release. A large embryo size in this species (2.65 ± 0.28 mm diameter) compared with other caridean shrimps suggests possible abbreviated larval development, as described in other species of the genus from non-chemosynthetic environments. Fecundity (26-94 embryos female) was lower and embryo size larger in L. virentova compared with alvinocaridids at chemosynthetic environments. This suggests that there are phylogenetic constraints on reproductive features of decapods at hydrothermal vents. [ABSTRACT FROM AUTHOR]

Abstract: Eleven specimens representing two hippolytid genera, EualusThallwitz, 1892 and LebbeusWhite, 1847 were sampled recently from the Scotia Sea (1517–2598m). Seven specimens are described and illustrated as Eualus amandae sp. nov., and its morphology is compared with those of previously described species. Four female specimens, morphologically consistent with Lebbeus antarcticus (Hale, 1941), are described and illustrated to supplement previous descriptions of this rarely collected bathyal species. Partial COI mtDNA and 18S rDNA sequences were generated for both species. Only limited DNA sequences are available for the Hippolytidae. COI phylogenetic trees are presented to illustrate that the new species is genetically distinct from all other species in GenBank. This record enhances existing knowledge of Antarctic invertebrate biodiversity and species richness of decapod crustaceans in the Southern Ocean. [Copyright &y& Elsevier]

Abstract: Direct visual observations from submersible vehicles at hydrothermal vents typically only reveal a fraction of the vent environment at any one time. We describe the use of precision Remotely Operated Vehicle (ROV) videography to produce extensive mosaic images of hydrothermal vent chimneys and surrounding seafloor areas (c. 250m2), with sufficient resolution to determine distributions of macro- and megafauna. Doppler velocity log navigation (DVLNAV) was used to follow overlapping vertical survey lines in a fixed plane facing a vent chimney, while acquiring high-definition video imagery using a forward-looking camera. The DVLNAV also enabled the vehicle to follow overlapping horizontal survey lines while acquiring seafloor imagery from a downward-looking video camera and mapping variations in seawater temperature. Digital stills images extracted from video were used to compile high-resolution composite views of the surveyed areas. Applying these image acquisition techniques at vent fields on the East Scotia Ridge, Southern Ocean, revealed consistent patterns of faunal zonation around vent sources, variations in proportions of faunal assemblage types on different faces of a vent chimney, and differences in proportions of faunal assemblages between two different vent fields. The technique can therefore be used to determine the composition and spatial distribution of fauna across complex areas of topography, such as vent fields, where mosaic images of vertical structures cannot currently be acquired using other platforms such as autonomous underwater vehicles (AUVs). These image acquisition techniques, demonstrated here in the first ROV dives at newly discovered vent fields, may offer an appropriate technology for rapid baseline studies required by the potential mining of seafloor massive sulfides (SMS). [Copyright &y& Elsevier]

The dynamics and microdistribution of faunal assemblages at hydrothermal vents often reflect the fine-scale spatial and temporal heterogeneity of the vent environment. This study examined the reproductive development and population structure of the caridean shrimp Rimicaris hybisae at the Beebe and Von Damm Vent Fields (Mid-Cayman Spreading Centre, Caribbean) using spatially discrete samples collected in January 2012. Rimicaris hybisae is gonochoric and exhibits iteroparous reproduction. Oocyte size-frequency distributions (21-823 µm feret diameters) varied significantly among samples. Embryo development was asynchronous among females, which may result in asynchronous larval release for the populations. Specimens of R. hybisae from the Von Damm Vent Field (2294 m) were significantly larger than specimens from the Beebe Vent Field. Brooding females at Von Damm exhibited greater size-specific fecundity, possibly as a consequence of a non-linear relationship between fecundity and body size that was consistent across both vent fields. Samples collected from several locations at the Beebe Vent Field (4944–4972 m) revealed spatial variability in the sex ratios, population structure, size, and development of oocytes and embryos of this mobile species. Samples from the Von Damm Vent Field and sample J2-613-24 from Beebe Woods exhibited the highest frequencies of ovigerous females and significantly female-biased sex ratios. Environmental variables within shrimp aggregations may influence the distribution of ovigerous females, resulting in a spatially heterogeneous pattern of reproductive development in R. hybisae, as found in other vent taxa. [ABSTRACT FROM AUTHOR]

Alvinocaridid shrimps are endemic and globally widespread in chemosynthetic ecosystems such as hydrothermal vents and hydrocarbon seeps. Though the biology of Atlantic alvinocaridid species have received considerable attention, little is known about their Pacific relatives. Here we described population structures and reproductive biology of three Pacific alvinocaridid species—Shinkaicaris leurokolos, Opaepele loihi, Alvinocaris longirostris—with notes on a fourth species—A. dissimilis—from several chemosynthetic ecosystems around Japan and compared their size frequency distributions and reproductive outputs. We showed that population demographics differ among these species, including a significantly larger proportion of juveniles in O. loihi and spatial variation of sex ratio in S. leurokolos, but all shared sex ratios biased toward females. The three shrimp species were characterized by relatively small sizes at onset of maturity, although this varied among sites for A. longirostris. Overall, size-specific fecundities and egg volumes of A. longirostris, O. loihi and S. leurokolos were in a similar range to Atlantic alvinocaridids. In addition, we performed egg incubation experiments of O. loihi under different temperature conditions to characterize thermal physiology during its brooding period. This confirmed a strong influence of temperature on both brooding duration and hatching rate, with a thermal preference that differs from previously published data for A. longirostris and S. leurokolos. Finally, our results indicated that these alvinocaridid species from the northwestern Pacific likely differ in reproductive timing, either through distinct brooding durations and/or distinct brooding periodicity, although further investigations are required to confirm these patterns. [ABSTRACT FROM AUTHOR]

Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal vents, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered vent fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of vent biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal activity in a vent field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal activity, and a mosaic image of >250 m² of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from vent sources and peak temperatures. Assemblages closest to vent sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m²), followed by a peltospiroid gastropod (>1,500 individuals m-2), eolepadid barnacle (>1,500 individuals m-2), and carnivorous actinostolid anemone (>30 individuals m-2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of activity suggests a possible successional sequence for vent fauna in this new biogeographic province. An increase in δ34 S values of primary consumers with distance from vent sources, and variation in their δ13 C values also indicate possible zonation of nutritional modes of the vent fauna. By using ROV videography to obtain a high-resolution representation of a vent environment over a greater extent than previous studies, these results provide a baseline for determining temporal change and investigations of processes structuring faunal assemblages at Southern Ocean vents. [ABSTRACT FROM AUTHOR]

Podcasting has become a popular medium for accessing and assimilating information and podcasts are increasingly being used to deliver audio recordings of lectures to campus-based students. This paper describes a simple, cost-effective and file size-efficient method for producing video podcasts combining lecture slides and audio without a requirement for any specialist software. The results from a pilot scheme delivering supplementary lecture materials as audio and video podcasts are also presented, including data on download patterns and responses to a survey of students on podcast use. These results reveal students' enthusiasm for podcast recordings of lecture materials and their primary use by students in revision and preparation for assessments. Survey responses also suggest little likely impact on lecture attendance as a consequence of podcasting, but indicate that podcast recordings of lectures may not be effective in facilitating mobile learning. [ABSTRACT FROM AUTHOR]

This paper evaluates the dynamics of two faunal assemblages colonizing high- and low-temperature habitats of the TAG hydrothermal mound on the Mid-Atlantic Ridge. Timelapse video and photographic transects were used to monitor changes in shrimp and anemone populations from June 1994 to March 1995. During this period, holes were drilled in the vicinity of the target populations by the Ocean Drilling Program (ODP). The a priori expectation of a rapid redistribution of motile alvinocaridid shrimp to occupy the optimal thermal and chemical habitat in response to changes in the pattern of hydrothermal activity was met by the observation of an increase in hydrothermal activity and shrimp population density at the site where a timelapse video system was deployed. The importance of hydrothermal activity as a control on the distribution of vent shrimp is suggested by tidal variations in the distribution of shrimp on a minidiffuser chimney. Sediment deposition during ODP drilling resulted in a temporary disturbance of the shrimp occupying the flat part of the mound surface seen by the timelapse video. In contrast to the changes observed in shrimp distribution, little change was observed in the distribution of anemones across the mound in two photographic transects 10 months apart, with the exception of a localized disturbance where anemones were buried by sediment around an ODP hole. Differences in the response of the shrimp and anemones to changes in the hydrothermal system may result from differences in their motility and rates of biological activity, or reflect a lower trophic position in the case of the shrimp. [ABSTRACT FROM AUTHOR]

The biodiversity of deep-sea hydrothermal vents in the Indian Ocean remains poorly characterised compared with that of their Pacific and Atlantic counterparts. Although the Longqi hydrothermal vent field is the most extensively explored vent site on the ultra-slow-spreading Southwest Indian Ridge, it is still a source of new discoveries. Here, we report and formally describe a new peltospirid snail from Longqi – Lirapex felix sp. nov. Known from only two specimens, it differs from other named Lirapex species by a depressed spire and the lack of coil loosening on the body whorl. Examinations of the external anatomy and radular characteristics agree with its placement in Lirapex, which is also supported by a molecular phylogeny reconstructed using the barcoding fragment of the mitochondrial cytochrome c oxidase I (COI) gene. This is the fifth peltospirid snail known to inhabit the Longqi field, three of which (including Lirapex felix sp. nov.) have been found nowhere else. There is growing evidence that the Longqi field represents a biogeographically unique site among Indian Ocean vents. The discovery of Lirapex felix sp. nov. adds to the unique biodiversity of Longqi field, with implications for conservation in the light of potential deep-sea mining. This work is registered in ZooBank under: [ABSTRACT FROM AUTHOR]

The recent discovery and exploration of deep-sea hydrothermal vent fields in the Mid-Cayman Spreading Centre, Caribbean Sea (Beebe Vent Field, 4956–4972 m depth) and the East Scotia Ridge, Southern Ocean (E2 and E9 vent fields, 2394–2641 m depth) have yielded extensive collections of two new provannid species, Provanna beebei n. sp. and P. cooki n. sp. Morphological and molecular taxonomy (530 bp of the mitochondrial cytochrome c oxidase subunit I gene) confirm P. beebei n. sp. and P. cooki n. sp. as distinct species; these species are formally described, and details are provided of their distribution, habitat and species associations. Bayesian and maximum likelihood analyses support the placement of P. beebei n. sp. and P. cooki n. sp within the genus Provanna and show that these two new deep-sea species form a well-supported clade with the abyssal West Pacific P. cingulata. Provanna beebei n. sp. and P. cooki n. sp. represent the first records of Provanna from hydrothermal vents in the Caribbean Sea and Southern Ocean, respectively, and extend the known geographic range of the genus. For the first time, intraspecific phenotypic variation in size and sculpture has been reported for Provanna. At the East Scotia Ridge, shell-size frequency distributions and median shell size of P. cooki n. sp. varied significantly between the E2 and E9 vent fields, as well as between diffuse flow and high-temperature venting habitats within each field. The variation in shell sculpture in relation to habitat was also observed in P. cooki n. sp. [ABSTRACT FROM AUTHOR]

The vestimentiferan tubeworm genera Lamellibrachia and Escarpia inhabit deep-sea chemosynthesis-based ecosystems, such as seeps, hydrothermal vents and organic falls, and have wide distributions across the Pacific, Atlantic and Indian Oceans. In 2010–2012 during initial explorations of hydrothermal vents of the Mid-Cayman Spreading Centre (MCSC), both genera were found to co-occur at the Von Damm Vent Field (VDVF), a site characterised by diffuse flow, therefore resembling a 'hydrothermal seep'. Here, we erect two new vestimentiferan tubeworm species from the VDVF, Lamellibrachia judigobini sp. nov. and Escarpia tritentaculata sp. nov. Lamellibrachia judigobini sp. nov. differs genetically and morphologically from other Lamellibrachia species, and has a range that extends across the Gulf of Mexico, MCSC, off Trinidad and Tobago, and Barbados, and also across both vents and seeps and 964–3304-m water depth. Escarpia tritentaculata sp. nov. is distinguished from other Escarpia species primarily based on morphology and is known only from vents of the MCSC at 2300-m depth. This study highlights the incredible habitat flexibility of a single Lamellibrachia species and the genus Escarpia , and historic biogeographic connections to the eastern Pacific for L. judigobini sp. nov. and the eastern Atlantic for E. tritentaculata sp. nov. ZooBank: urn:lsid:zoobank.org:pub:D9F72BD4-FDE1-4C0A-B84B-A08D06F2A981 Sessile vestimentiferan tubeworms inhabit chemosynthetic environments, such as hydrothermal vents or methane seeps. The new species described here, Lamellibrachia judigobini sp. nov. and Escarpia tritentaculata sp. nov., both from seep-dwelling genera, were discovered at a unique 'hydrothermal seep' of the Mid-Cayman Spreading Centre. We show an incredible habitat flexibility of a single Lamellibrachia species and the genus Escarpia , and historic biogeographic connections to the eastern Pacific for L. judigobini and the eastern Atlantic for E. tritentaculata. [ABSTRACT FROM AUTHOR]

The 'scaly-foot gastropod' is widely recognized as an iconic species of deep-sea hydrothermal vent ecosystems in the Indian Ocean. Uniquely among gastropods, this species carries hundreds of dermal sclerites on its foot and these scales can be covered in iron sulphide that also covers its shell, making it the only extant metazoan known to utilize iron sulphide as part of its skeleton. It has not been formally named, despite attracting great attention from both scientists and the general public alike, although a manuscript name has occasionally been used in various sources. The RRS James Cook JC67 expedition in 2011 sampled the biota of the Longqi vent field (37847.0270S, 49838.9630E), Southwest Indian Ridge, for the first time, revealing a previously unknown population of the 'scaly-foot gastropod'. The present study gives a formal name to the 'scaly-foot gastropod', Chrysomallon squamiferum n. gen., n. sp. with Longqi vent field as the type locality. The erection of the new monotypic genus is supported by both morphological and molecular characterization, differentiating it from existing genera of the family Peltospiridae. Analysis of the cytochrome c oxidase subunit I gene reveals a 24-26% pairwise distance between Chrysomallon and five other genera of Peltospiridae, while the range among those five genera is 14-25%. The new genus is placed in the family Peltospiridae based on morphological characteristics, including lack of sexual dimorphism, no copulatory organ, the distal end of marginal teeth being subdivided into many denticles and the ventral margin of the gill leaflets carrying a series of bulges. A fivegene Bayesian phylogenetic reconstruction does not contradict the placement within Peltospiridae. [ABSTRACT FROM AUTHOR]

"Mating stacks" have been widely documented in calyptraeid slipper limpets, which are protandric and exhibit sequential hermaphroditism. Gigantopelta is a genus of peltospirid snails endemic to deep-sea hydrothermal vents containing two species, one distributed on the East Scotia Ridge in the Southern Ocean and another on the Southwest Indian Ridge in the Indian Ocean. Here, we report the observation that both species form extensive (often >15 individuals) "snail chains". These chains are potentially analogous to 'mating stacks' of calyptraeids, or alternatively, maybe a behaviour to facilitate spermatophore transfer. Both Gigantopelta species apparently have separate sexes and are sexually mature at a small size. However, it remains unclear whether they undergo sex change during their life. [ABSTRACT FROM AUTHOR]

Abstract: A new population of Ophiolimna antarctica (Lyman, 1879) was discovered at 1546m in Kemp Caldera, a topographic feature with active hydrothermal venting at the southern end of the South Sandwich Islands, Southern Ocean. The distribution, population structure, reproduction, and diet of O. antarctica were investigated. O. antarctica were found predominantly on basalt with an over-dispersed distribution. The mean density was 17 individuals m−2 with a range of 9–24 individuals m−2. There was a bimodal population structure, with separate juvenile and adult peaks. Sexes were separate and the sex ratio was not significantly different from equality. The maximum oocyte diameter was 520μm, suggesting direct or lecithotrophic development, whilst individual females reproduced asynchronously. Stomach contents included crustacean fragments, flocculate material, diatoms, forams, fish scales, and ophiuroid tissues and spines, which was indicative of omnivory. There was no apparent influence of hydrothermal vents <500m away on the diet of Ophiolimna antarctica. The ecology of Ophiolimna antarctica is consistent with what is known for other Antarctic and deep-sea ophiuroid species. [Copyright &y& Elsevier]

We consider the opportunities and challenges associated with organizing a conference online, using a case study of a medium-sized (approx. 400 participants) international conference held virtually in August 2020. In addition, we present quantifiable evidence of the participants' experience using the results from an online post-conference questionnaire. Although the virtual meeting was not able to replicate the in-person experience in some aspects (e.g. less engagement between participants) the overwhelming majority of respondents found the meeting an enjoyable experience and would join similar events again. Notably, there was a strong desire for future in-person meetings to have at least some online component. Online attendance by lower-income researchers was higher compared with a past, similar-themed in-person meeting held in a high-income nation, but comparable to one held in an upper-middle-income nation. This indicates that online conferences are not a panacea for diversity and inclusivity, and that holding in-person meetings in developing economies can be at least as effective. Given that it is now relatively easy to stream contents of meetings online using low-cost methods, there are clear benefits in making all presented content accessible online, as well as organizing online networking events for those unable to attend in person. [ABSTRACT FROM AUTHOR]

Motivation: Traits are increasingly being used to quantify global biodiversity patterns, with trait databases growing in size and number, across diverse taxa. Despite growing interest in a trait‐based approach to the biodiversity of the deep sea, where the impacts of human activities (including seabed mining) accelerate, there is no single repository for species traits for deep‐sea chemosynthesis‐based ecosystems, including hydrothermal vents. Using an international, collaborative approach, we have compiled the first global‐scale trait database for deep‐sea hydrothermal‐vent fauna – sFDvent (sDiv‐funded trait database for the Functional Diversity of vents). We formed a funded working group to select traits appropriate to: (a) capture the performance of vent species and their influence on ecosystem processes, and (b) compare trait‐based diversity in different ecosystems. Forty contributors, representing expertise across most known hydrothermal‐vent systems and taxa, scored species traits using online collaborative tools and shared workspaces. Here, we characterise the sFDvent database, describe our approach, and evaluate its scope. Finally, we compare the sFDvent database to similar databases from shallow‐marine and terrestrial ecosystems to highlight how the sFDvent database can inform cross‐ecosystem comparisons. We also make the sFDvent database publicly available online by assigning a persistent, unique DOI. Main types of variable contained: Six hundred and forty‐six vent species names, associated location information (33 regions), and scores for 13 traits (in categories: community structure, generalist/specialist, geographic distribution, habitat use, life history, mobility, species associations, symbiont, and trophic structure). Contributor IDs, certainty scores, and references are also provided. Spatial location and grain: Global coverage (grain size: ocean basin), spanning eight ocean basins, including vents on 12 mid‐ocean ridges and 6 back‐arc spreading centres. Time period and grain: sFDvent includes information on deep‐sea vent species, and associated taxonomic updates, since they were first discovered in 1977. Time is not recorded. The database will be updated every 5 years. Major taxa and level of measurement: Deep‐sea hydrothermal‐vent fauna with species‐level identification present or in progress. Software format:.csv and MS Excel (.xlsx). [ABSTRACT FROM AUTHOR]

Recently discovered hydrothermal vent fields on the East Scotia Ridge ( ESR, 56-60° S, 30° W), Southern Ocean, and the South West Indian Ridge ( SWIR, 37° S 49° E), Indian Ocean, host two closely related new species of peltospirid gastropods. Morphological and molecular (mitochondrial cytochrome c oxidase subunit I, COI) characterization justify the erection of G igantopelta gen. nov. within the Peltospiroidae with two new species, G igantopelta chessoia sp. nov. from ESR and G igantopelta aegis sp. nov. from SWIR. They attain an extremely large size for the clade Neomphalina, reaching 45.7 mm in shell diameter. The oesophageal gland of both species is markedly enlarged. Gigantopelta aegis has a thick sulphide coating on both the shell and the operculum of unknown function. The analysis of a 579-bp fragment of the COI gene resulted in 19-28% pairwise distance between Gigantopelta and six other genera in Peltospiridae, whereas the range amongst those six genera was 12-28%. The COI divergence between the two newly described species of Gigantopelta was 4.43%. Population genetics analyses using COI (370 bp) of 30 individuals of each species confirmed their genetic isolation and indicate recent rapid demographic expansion in both species. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

We report the discovery of three new species of Osedax in the deep Southern Ocean, expanding the diversity and geographical range of this genus of bone-eating worms. Osedax rogersi sp. n. and Osedax crouchi sp. n. were found on a whale skeleton at 1444 m in the Kemp Caldera in the East Scotia Sea during the Chemosynthetic Ecosystems of the Southern Ocean (ChEsSo) project. The recently described species, Osedax antarcticus, found on whale bones implanted at a depth of 550-650 m off Smith Island in the Bransfield Strait, was also found inhabiting the whale skeleton in the Kemp Caldera. Osedax crouchi as well as another new species Osedax nordenskjoeldi sp. n. have also been found on the implanted whale bones off Smith Island. These two localities are approximately 1800 km apart demonstrating a wide distribution of species within the genus. We describe the three new species, O. rogersi, O. crouchi and O. nordenskjoeldi and report the second record of O. antarcticus. We also present a new phylogenetic analysis for Osedax, including data examining genetic connectivity between the Scotia Arc and the Bransfield Strait. [ABSTRACT FROM AUTHOR]

Abstract: Large cetacean carcasses at the deep-sea floor, known as ‘whale falls’, provide a resource for generalist-scavenging species, chemosynthetic fauna related to those from hydrothermal vents and cold seeps, and remarkable bone-specialist species such as Osedax worms. Here we report the serendipitous discovery of a late-stage natural whale fall at a depth of 1444m in the South Sandwich Arc. This discovery represents the first natural whale fall to be encountered in the Southern Ocean, where cetaceans are abundant. The skeleton was situated within a seafloor caldera, in close proximity (<250m) to active hydrothermal vents. We used a DNA barcoding approach to identify the skeleton as that of an Antarctic minke whale (Balaenoptera bonaerensis). The carcass was in an advanced state of decomposition, and its exposed bones were occupied by a diverse assemblage of fauna including nine undescribed species. These bone fauna included an undescribed species of Lepetodrilus limpet that was also present at the nearby hydrothermal vents, suggesting the use of whale-fall habitats as stepping stones between chemosynthetic ecosystems. Using Remotely Operated Vehicle (ROV) videography, we have quantified the composition and abundance of fauna on the whale bones, and tested a hypothesis that varying concentrations of lipids in the bones of whales may influence the microdistribution of sulfophilic whale-fall fauna. Our data supported the hypothesis that more lipid-rich bones support a greater abundance of sulfophilic bacterial mats, which are also correlated with the abundance of grazing limpets (Pyropelta sp.). The abundance of Osedax sp. on bones however, showed a negative correlation with the bacterial-mat percentage cover, and hence greatest abundance on bones predicted to have lowest lipid content. [Copyright &y& Elsevier]

A correction is presented to the article "Moving conferences online: lessons learned from an international virtual meeting."