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There is increased interest in using nickel aluminum bronze (NAB) alloys in large-scale directed energy deposition additive manufacturing (DEDAM) processes for maritime applications, but one challenge lies in the component distortion that results from residual stress generated during fabrication. This paper describes the development and evaluation of thermo-mechanical simulations for laser hot wire (LHW) DEDAM of NAB to predict part distortion. To account for the dearth of temperature-dependent properties for NAB C95800 in open literature and public databases, temperature-dependent material and mechanical properties for NAB C95800 were experimentally measured using test specimens fabricated with a variety of DEDAM processes. Autodesk's Netfabb Local Simulation software, a commercial finite-element based AM solver, was employed but with its heat source model modified to accommodate LHW DEDAM's oscillating laser path and additional energy input supplied by the preheated wire feedstock. Thermo-mechanical simulations were conducted using both the acquired temperature-dependent material and mechanical properties and the constant room-temperature properties to assess the impact on simulation accuracy. The usage of constant properties in the thermo-mechanical analysis resulted in significantly different predicted distortion compared to those using the temperature-dependent properties, at times even predicting substrate displacement in an opposite direction. [ABSTRACT FROM AUTHOR]

SYNOPSIS. The primary ecosystem-structuring organisms at many hydrothermal vents and cold seeps are phylogenetically related and quite similar physiologically and anatomically. Vestimentiferan tube worms and Vesicomyid clams in particular all rely on chemoautotrophic sulfur-oxidizing symbionts and have blood which binds sulfide with high affinity and capacity. However, there are significant differences between cold seep and hydrothermal vent environments, including large differences in flow rate of the emitted fluid and the chemistry of that fluid. Here we review extant data on the hydrothermal vent species, present new data on the physiologically relevant chemical microhabitat of cold seep vestimentiferans and vesicomyids, and compare the physiological ecology of the seep species to their hydrothermal vent relatives [ABSTRACT FROM PUBLISHER]

Deep-sea hydrothermal vents are populated by dense communities of animals that form symbiotic associations with chemolithoautotrophic bacteria. To date, our understanding of which factors govern the distribution of host/symbiont associations (or holobionts) in nature is limited, although host physiology often is invoked. In general, the role that symbionts play in habitat utilization by vent holobionts has not been thoroughly addressed. Here we present evidence for symbiont-influenced, regional-scale niche partitioning among symbiotic gastropods (genus Alviniconcha) in the Lau Basin. We extensively surveyed Alviniconcha holobionts from four vent fields using quantitative molecular approaches, coupled to characterization of high-temperature and diffuse vent-fluid composition using gastight samplers and in situ electrochemical analyses, respectively. Phylogenetic analyses exposed cryptic host and symbiont diversity, revealing three distinct host types and three different symbiont phylotypes (one ε-proteobacteria and two γ-proteobacteria) that formed specific associations with one another. Strikingly, we observed that holobionts with ε-proteobacterial symbionts were dominant at the northern fields, whereas holobionts with γ-proteobacterial symbionts were dominant in the southern fields. This pattern of distribution corresponds to differences in the vent geochemistry that result from deep subsurface geological and geothermal processes. We posit that the symbionts, likely through differences in chemolithoautotrophic metabolism, influence niche utilization among these holobionts. The data presented here represent evidence linking symbiont type to habitat partitioning among the chemosynthetic symbioses at hydrothermal vents and illustrate the coupling between subsurface geothermal processes and niche availability., Organismic and Evolutionary Biology

The article "Metabolomic richness and fingerprints of deep-sea coral species and populations", written by Samuel A. Vohsen, Charles R. Fisher and Iliana B. Baums, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 02 March, 2019 without open access. With the author(s)' decision to opt for Open Choice the copyright of the article changed on 30 March, 2019 to © The Author(s) 2019 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The original article has been corrected. [ABSTRACT FROM AUTHOR]

Introduction: From shallow water to the deep sea, corals form the basis of diverse communities with significant ecological and economic value. These communities face many anthropogenic stressors including energy and mineral extraction activities, ocean acidification and rising sea temperatures. Corals and their symbionts produce a diverse assemblage of compounds that may help provide resilience to some of these stressors. Objectives: We aim to characterize the metabolomic diversity of deep-sea corals in an ecological context by investigating patterns across space and phylogeny. Methods: We applied untargeted Liquid Chromatography-Mass Spectrometry to examine the metabolomic diversity of the deep-sea coral, Callogorgia delta, across three sites in the Northern Gulf of Mexico as well as three other deep-sea corals, Stichopathes sp., Leiopathes glaberrima, and Lophelia pertusa, and a shallow-water species, Acropora palmata. Results: Different coral species exhibited distinct metabolomic fingerprints and differences in metabolomic richness including core ions unique to each species. C. delta was generally least diverse while Lophelia pertusa was most diverse. C. delta from different sites had different metabolomic fingerprints and metabolomic richness at individual and population levels, although no sites exhibited unique core ions. Two core ions unique to C. delta were putatively identified as diterpenes and thus may possess a biologically important function. Conclusion: Deep-sea coral species have distinct metabolomic fingerprints and exhibit high metabolomic diversity at multiple scales which may contribute to their capabilities to respond to both natural and anthropogenic stressors, including climate change. [ABSTRACT FROM AUTHOR]

The article discusses the highlights of the 2015 Ecosystem Impacts of Oil and Gas Inputs to the Gulf (ECOGIG) expedition at the west of the Macondo well in lease block Mississippi Canyon in the Gulf of Mexico in the U.S. Also cited are the expedition's aim to study the effects of oil and dispersant on corals and communities affected by the 2010 Deepwater Horizon oil spill, and such activities as the metabolic analysis of coral tissues.

The article discusses the research findings on the lifestyle of the tubeworm Riftia pachyptila. Riftia is commonly found in hydrothermal vents and depends on intracellular chemoautotrophic symbionts which fill a large internal organ called the trophosome for nutrition. These symbionts generate organic carbon as a food source for their worm host. Some researchers had used a proteomic approach to examine protein expression in Riftia symbionts to gain new insights into their biochemistry and metabolism.

Abstract: Deepwater coral communities are hotspots of diversity and biomass. Most deep‐sea coral species are long‐lived and slow‐growing and are, thus, expected to recover slowly after disturbance. A better understanding of the recovery potential of these organisms is necessary to make appropriate management decisions. We used data from high‐resolution monitoring of individual coral colonies that were impacted by the Deepwater Horizon oil spill (April 2010) to parameterize and validate an annual, impact‐dependent, state‐structured matrix model to estimate the time to recovery for each coral colony. We projected the dynamics of three branch states: visibly healthy, unhealthy and hydroid‐colonized. Although we implicitly included branch loss in the model, we focused on the short‐term return of extant, damaged branches to a visibly healthy state and did not consider the far longer term regrowth of lost branches. Our model estimates that, depending on the initial level of impact, corals impacted by the spill will take up to three decades to recover to a state where all remaining branches appear healthy, though the majority of corals are projected to reach that state within a decade. By that time, some of these colonies will have lost a significant number of branches, leading to approximately 10% reduction in total biomass at all impacted sites. Overall, our model overestimates recovery, but branch loss estimates were reliable. Thus, the available growth rate data suggest that hundreds of years may be necessary for impacted communities to grow back to their initial biomass. Policy implications. Our study quantifies the very slow recovery rate of deep‐sea corals impacted by the Deepwater Horizon oil spill and demonstrates the imperative of prioritizing a precautionary approach for deep‐sea ecosystems over restoration after the fact. As anthropogenic pressure on the deep sea is likely to increase, we suggest the establishment of coral monitoring sites implemented as part of Marine Protected Areas to limit and detect impact to deep‐sea corals. Furthermore, our model may be used to plan shorter‐ and longer‐term monitoring programmes after impact and to provide a timeline for policy. [ABSTRACT FROM AUTHOR]

Cold seeps in the deep sea harbor various animals that have adapted to utilize seepage chemicals with the aid of chemosynthetic microbes that serve as primary producers. Corals are among the animals that live near seep habitats and yet, there is a lack of evidence that corals gain benefits and/or incur costs from cold seeps. Here, we focused on Callogorgia delta and Paramuricea sp. type B3 that live near and far from visual signs of currently active seepage at five sites in the deep Gulf of Mexico. We tested whether these corals rely on chemosynthetically‐derived food in seep habitats and how the proximity to cold seeps may influence; (i) coral colony traits (i.e., health status, growth rate, regrowth after sampling, and branch loss) and associated epifauna, (ii) associated microbiome, and (iii) host transcriptomes. Stable isotope data showed that many coral colonies utilized chemosynthetically derived food, but the feeding strategy differed by coral species. The microbiome composition of C. delta, unlike Paramuricea sp., varied significantly between seep and non‐seep colonies and both coral species were associated with various sulfur‐oxidizing bacteria (SUP05). Interestingly, the relative abundances of SUP05 varied among seep and non‐seep colonies and were strongly correlated with carbon and nitrogen stable isotope values. In contrast, the proximity to cold seeps did not have a measurable effect on gene expression, colony traits, or associated epifauna in coral species. Our work provides the first evidence that some corals may gain benefits from living near cold seeps with apparently limited costs to the colonies. Cold seeps provide not only hard substrate but also food to cold‐water corals. Furthermore, restructuring of the microbiome communities (particularly SUP05) is likely the key adaptive process to aid corals in utilizing seepage‐derived carbon. This highlights that those deep‐sea corals may upregulate particular microbial symbiont communities to cope with environmental gradients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Magnetic susceptibility measurement without SQUID magnetometry shape requirements. [•] Method evaluated with Cu–Sn solid solution alloys of 1.5–7% Sn at 4.7 and 11.1T. [•] Less than 3.1% difference between proposed MR method and SQUID magnetometry. [•] Method can be used to guide fabrication of tissue susceptibility-matched devices. [ABSTRACT FROM AUTHOR]

Abstract: Vestimentiferan tubeworms are a group of large sessile marine polychaete annelids (family Siboglinidae) found in the regions of hydrothermal venting or seepage of the reduced chemical hydrogen sulfide. Hydrocarbon seeps on the Louisiana Slope of the Gulf of Mexico support large communities of the co-occurring vestimentiferan species Lamellibrachia luymesi and Seepiophila jonesi. These sessile species have the opportunity to disperse between the patchy sites of active seepage on the seafloor during a planktonic larval stage. However, it is unclear whether dispersal occurs at a local or global scale. Four (L. luymesi) and seven (S. jonesi) microsatellite loci were used to test for population substructure among ten hydrocarbon seep sites on the Louisiana Slope. Both species showed high levels of allelic diversity, averaging 18.5 (L. luymesi) and 22 (S. jonesi) alleles/locus, respectively, and high observed heterozygosity at all microsatellite loci (0.71–0.9 in L. luymesi, 0.27–0.84 in S. jonesi). The two species showed a significant deficiency in heterozygotes compared to that predicted under the Hardy–Weinberg equilibrium. L. luymesi showed a small but significant amount of population structure, with a positive correlation between genetic and geographic distance among the sample sites spanning 540km. S. jonesi, in contrast, showed no evidence for isolation by distance, but did show a significant genetic difference between aggregations of different ages. These results suggest that these two species differ in how larvae are able to colonize new seep sites through space (L. luymesi) and though time (S. jonesi). [ABSTRACT FROM AUTHOR]

Abstract: The sulfide-oxidizing symbiotic tubeworm Lamellibrachia luymesi is a dominant member of deep-sea hydrocarbon seep ecosystems on the Gulf of Mexico seafloor. This tubeworm forms large aggregations that can live for centuries and provide habitat for an assortment of associated fauna. Previous studies have suggested that persistence of these tubeworms for such long time periods is contingent upon their ability to supply sediments with sulfate. To examine this hypothesis, we characterized the tubeworm’s geochemical environment using pore water peepers and compared the measured depth profiles with those predicted by a sulfur diffusion–reaction–supply model. We found a large range of sulfide concentrations in the tubeworm habitat, indicating that this species can live under conditions of both high and low sulfide availability. In sediments rich in hydrocarbons, we found compelling evidence that tubeworms enhance microbial sulfide production, likely through a combination of sulfide uptake and sulfate release through their root-like structures buried in the sediment. Our in situ empirical data combined with the results of the geochemical model corroborate previous physiological studies that indicate that tubeworms release between 70% and 90% of the sulfate produced during sulfide oxidation by their symbionts across their roots into the surrounding sediment. In sediments low in hydrocarbon content, sulfide production is hydrocarbon-limited rather than sulfate-limited, and our model predicts that tubeworm growth could be limited by low sulfide availability. [Copyright &y& Elsevier]