Soft robotics is an emerging technology that has shown considerable promise in deep-sea marine biological applications. It is particularly useful in facilitating delicate interactions with fragile ...marine organisms. This study describes the shipboard design, 3D printing and integration of custom soft robotic manipulators for investigating and interacting with deep-sea organisms. Soft robotics manipulators were tested down to 2224m via a Remotely-Operated Vehicle (ROV) in the Phoenix Islands Protected Area (PIPA) and facilitated the study of a diverse suite of soft-bodied and fragile marine life. Instantaneous feedback from the ROV pilots and biologists allowed for rapid re-design, such as adding "fingernails", and re-fabrication of soft manipulators at sea. These were then used to successfully grasp fragile deep-sea animals, such as goniasterids and holothurians, which have historically been difficult to collect undamaged via rigid mechanical arms and suction samplers. As scientific expeditions to remote parts of the world are costly and lengthy to plan, on-the-fly soft robot actuator printing offers a real-time solution to better understand and interact with delicate deep-sea environments, soft-bodied, brittle, and otherwise fragile organisms. This also offers a less invasive means of interacting with slow-growing deep marine organisms, some of which can be up to 18,000 years old.
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•Unambiguously resolved phylogenetic relationships among recalcitrant taxa with divergences >80 million years.•Objectively inferred robust species boundaries in a deep-sea octocoral ...genus by testing alternative delimitation hypotheses.•Present substantial evidence rejecting the current morphological species delimitation model for the genus.•Inferred the presence of cryptic deep-sea species associated with environmental variables.•Argue that the suitability limits of RAD-seq for phylogenetic inferences are contingent on taxon-specific factors.
Species delimitations is problematic in many cases due to the difficulty of evaluating predictions from species hypotheses. In many cases delimitations rely on subjective interpretations of morphological and/or DNA data. Species with inadequate genetic resources needed to answer questions regarding evolutionary relatedness and genetic uniqueness are particularly problematic. In this study, we demonstrate the utility of restriction site associated DNA sequencing (RAD-seq) to objectively resolve unambiguous phylogenetic relationships in a recalcitrant group of deep-sea corals with divergences >80 million years. We infer robust species boundaries in the genus Paragorgia by testing alternative delimitation hypotheses using a Bayes Factors delimitation method. We present substantial evidence rejecting the current morphological species delimitation model for the genus and infer the presence of cryptic species associated with environmental variables. We argue that the suitability limits of RAD-seq for phylogenetic inferences cannot be assessed in terms of absolute time, but are contingent on taxon-specific factors. We show that classical taxonomy can greatly benefit from integrative approaches that provide objective tests to species delimitation hypotheses. Our results lead the way for addressing further questions in marine biogeography, community ecology, population dynamics, conservation, and evolution.
The characterization of evolutionary and biogeographical patterns is of fundamental importance to identify factors driving biodiversity. Due to their widespread but discontinuous distribution, ...deep‐sea hydrothermal vent barnacles represent an excellent model for testing biogeographical hypotheses regarding the origin, dispersal and diversity of modern vent fauna. Here, we characterize the global genetic diversity of vent barnacles to infer their time of radiation, place of origin, mode of dispersal and diversification. Our approach was to target a suite of multiple loci in samples representing seven of the eight described genera. We also performed restriction‐site associated DNA sequencing on individuals from each species. Phylogenetic inferences and topology hypothesis tests indicate that vent barnacles have colonized deep‐sea hydrothermal vents at least twice in history. Consistent with preliminary estimates, we find a likely radiation of barnacles in vent ecosystems during the Cenozoic. Our analyses suggest that the western Pacific was the place of origin of the major vent barnacle lineage, followed by circumglobal colonization eastwards through the Southern Hemisphere during the Neogene. The inferred time of radiation rejects the classic hypotheses of antiquity of vent taxa. The timing and the mode of origin, radiation and dispersal are consistent with recent inferences made for other deep‐sea taxa, including nonvent species, and are correlated with the occurrence of major geological events and mass extinctions. Thus, we suggest that the geological processes and dispersal mechanisms discussed here can explain the current distribution patterns of many other marine taxa and have played an important role shaping deep‐sea faunal diversity. These results also constitute the critical baseline data with which to assess potential effects of anthropogenic disturbances on deep‐sea ecosystems.
Seamount systems that are geographically, hydrographically, topographically, and/or genetically "isolated" are likely to have developed highly endemic taxa and ecosystems. Although current estimates ...of endemism are challenged by inconsistencies in sampling approaches, the physical, biological, and geological processes intrinsic to seamount systems can undeniably serve to connect or isolate populations, stimulate genetic divergence, drive the formation of new species, and structure diversity and endemism. In fact, the large variety of interconnected mechanisms that promote or impede the genetic connectivity of seamount communities via dispersal (and the long-term maintenance of species or the subsequent divergence of populations leading to speciation) are key unknowns to understanding the fundamental evolutionary processes that structure both the diversity and biogeography of deep-sea fauna. Fortunately, the net results of these ecological interactions at seamounts are represented in the patterns of genetic connectivity of the constituent species. The conclusions of the relatively few genetic connectivity studies across seamount fish, coral, and invertebrates are largely inconsistent, reflecting the ecological and evolutionary complexities of seamount systems. Yet, identifying the "connectivity" of seamount populations and their diverse ecosystems, which are increasingly vulnerable to threats from destructive fisheries and mining practices, is vital for developing and evaluating conservation and management strategies for seamount resources. Integrated, multidisciplinary studies of the physical, chemical, geological, an ecological dynamics of seamounts will continue to reveal the value of seamounts as natural laboratories in which to gain insights into the factors that elucidate the role these systems play in the dispersal, evolution, and biodiversity of deep-sea fauna. These studies will also direct the management of seamount biological diversity, which is increasingly susceptible to anthropogenic disturbance.
To assess the potential impact of the Deepwater Horizon oil spill on offshore ecosystems, 11 sites hosting deep-water coral communities were examined 3 to 4 mo after the well was capped. Healthy ...coral communities were observed at all sites >20 km from the Macondo well, including seven sites previously visited in September 2009, where the corals and communities appeared unchanged. However, at one site 11 km southwest of the Macondo well, coral colonies presented widespread signs of stress, including varying degrees of tissue loss, sclerite enlargement, excess mucous production, bleached commensal ophiuroids, and covering by brown flocculent material (floc). On the basis of these criteria the level of impact to individual colonies was ranked from 0 (least impact) to 4 (greatest impact). Of the 43 corals imaged at that site, 46% exhibited evidence of impact on more than half of the colony, whereas nearly a quarter of all of the corals showed impact to >90% of the colony. Additionally, 53% of these corals’ ophiuroid associates displayed abnormal color and/or attachment posture. Analysis of hopanoid petroleum biomarkers isolated from the floc provides strong evidence that this material contained oil from the Macondo well. The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems. Our findings underscore the unprecedented nature of the spill in terms of its magnitude, release at depth, and impact to deep-water ecosystems.
The continental margin off the northeastern United States (NEUS) contains numerous, topographically complex features that increase habitat heterogeneity across the region. However, the majority of ...these rugged features have never been surveyed, particularly using direct observations. During summer 2013, 31 Remotely-Operated Vehicle (ROV) dives were conducted from 494 to 3271 m depth across a variety of seafloor features to document communities and to infer geological processes that produced such features. The ROV surveyed six broad-scale habitat features, consisting of shelf-breaching canyons, slope-sourced canyons, inter-canyon areas, open-slope/landslide-scar areas, hydrocarbon seeps, and Mytilus Seamount. Four previously unknown chemosynthetic communities dominated by Bathymodiolus mussels were documented. Seafloor methane hydrate was observed at two seep sites. Multivariate analyses indicated that depth and broad-scale habitat significantly influenced megafaunal coral (58 taxa), demersal fish (69 taxa), and decapod crustacean (34 taxa) assemblages. Species richness of fishes and crustaceans significantly declined with depth, while there was no relationship between coral richness and depth. Turnover in assemblage structure occurred on the middle to lower slope at the approximate boundaries of water masses found previously in the region. Coral species richness was also an important variable explaining variation in fish and crustacean assemblages. Coral diversity may serve as an indicator of habitat suitability and variation in available niche diversity for these taxonomic groups. Our surveys added 24 putative coral species and three fishes to the known regional fauna, including the black coral Telopathes magna, the octocoral Metallogorgia melanotrichos and the fishes Gaidropsarus argentatus, Guttigadus latifrons, and Lepidion guentheri. Marine litter was observed on 81% of the dives, with at least 12 coral colonies entangled in debris. While initial exploration revealed the NEUS region to be both geologically dynamic and biologically diverse, further research into the abiotic conditions and the biotic interactions that influence species abundance and distribution is needed.
Cirrate octopods (Cephalopoda: Cirrata) are among the largest invertebrates of the deep sea. These organisms have long been known to lay single, large egg capsules on hard substrates on the ocean ...bottom 1, including cold-water octocorals (Anthozoa: Octocorallia). The egg capsule is comprised of an external egg case as well as the chorion and developing embryo. Development in cirrates proceeds for an extended time without parental care 2. Although juveniles have previously been collected in the midwater 3, cirrate hatchlings have so far never been observed. Here, we provide the first video of a living hatchling and use magnetic resonance imaging (MRI) to analyze its anatomy and assign the specimen to the genus Grimpoteuthis, the so-called dumbo octopods. The specimen’s behavior and advanced state of organ development show that cirrate hatchlings possess all morphological features required for movement via fin-swimming, for visually and chemically sensing their environment, and for prey capture. In addition, the presence of a large internal yolk sac reduces the risk of failure at first feeding. These data provide evidence that dumbo octopods hatch as competent juveniles.
Shea et al. identify the egg case and hatchling of a rare cirrate or “dumbo” Grimpoteuthis octopod for the first time. The specimen’s extensive morphological development suggests that it hatched as a competent juvenile.
On April 20, 2010, the Deepwater Horizon (DWH) blowout occurred, releasing more oil than any accidental spill in history. Oil release continued for 87 d and much of the oil and gas remained in, or ...returned to, the deep sea. A coral community significantly impacted by the spill was discovered in late 2010 at 1,370 m depth. Here we describe the discovery of five previously unknown coral communities near the Macondo wellhead and show that at least two additional coral communities were impacted by the spill. Although the oil-containing flocullent material that was present on corals when the first impacted community was discovered was largely gone, a characteristic patchy covering of hydrozoans on dead portions of the skeleton allowed recognition of impacted colonies at the more recently discovered sites. One of these communities was 6 km south of the Macondo wellhead and over 90% of the corals present showed the characteristic signs of recent impact. The other community, 22 km southeast of the wellhead between 1,850 and 1,950 m depth, was more lightly impacted. However, the discovery of this site considerably extends the distance from Macondo and depth range of significant impact to benthic macrofaunal communities. We also show that most known deep-water coral communities in the Gulf of Mexico do not appear to have been acutely impacted by the spill, although two of the newly discovered communities near the wellhead apparently not impacted by the spill have been impacted by deep-sea fishing operations.
Most of our knowledge about deep-sea habitats is limited to bathyal (200–3000m) and abyssal depths (3000–6000m), while relatively little is known about the hadal zone (6000–11,000m). The basic ...paradigm for the distribution of deep seafloor biomass suggests that the reduction in biomass and average body size of benthic animals along depth gradients is mainly related to surface productivity and remineralisation of sinking particulate organic carbon with depth. However, there is evidence that this pattern is somewhat reversed in hadal trenches by the funnelling of organic sediments, which would result in increased food availability along the axis of the trenches and towards their deeper regions. Therefore, despite the extreme hydrostatic pressure and remoteness from the pelagic food supply, it is hypothesized that biomass can increase with depth in hadal trenches. We developed a numerical model of gravitational lateral sediment transport along the seafloor as a function of slope, using the Kermadec Trench, near New Zealand, as a test environment. We propose that local topography (at a scale of tens of kilometres) and trench shape can be used to provide useful estimates of local accumulation of food and, therefore, patterns of benthic biomass. Orientation and steepness of local slopes are the drivers of organic sediment accumulation in the model, which result in higher biomass along the axis of the trench, especially in the deepest spots, and lower biomass on the slopes, from which most sediment is removed. The model outputs for the Kermadec Trench are in agreement with observations suggesting the occurrence of a funnelling effect and substantial spatial variability in biomass inside a trench. Further trench surveys will be needed to determine the degree to which seafloor currents are important compared with the gravity-driven transport modelled here. These outputs can also benefit future hadal investigations by highlighting areas of potential biological interest, on which to focus sampling effort. Comprehensive exploration of hadal trenches will, in turn, provide datasets for improving the model parameters and increasing predictive power.
•We present a testable and tunable model of gravitational lateral sediment transports in a hadal setting.•The model predicts benthic standing stocks by accounting for vertical and lateral transport of organic sediments.•Model results highlight the potential role of local topography in determining biomass distribution.•Model results can help prioritize likely areas of high biomass in the trenches to guide future sampling.
In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. ...We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.
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