Now showing items 21-40 of 898

    • Disparities in the analysis of morphological disparity

      Guillerme, T; Cooper, N; Brusatte, SL; Davis, KE; Jackson, AL; Gerber, S; Goswami, A; Healy, K; Hopkins, MJ; Jones, MEH; et al. (The Royal Society, 2020-07-01)
      Analyses of morphological disparity have been used to characterize and investigate the evolution of variation in the anatomy, function and ecology of organisms since the 1980s. While a diversity of methods have been employed, it is unclear whether they provide equivalent insights. Here, we review the most commonly used approaches for characterizing and analysing morphological disparity, all of which have associated limitations that, if ignored, can lead to misinterpretation. We propose best practice guidelines for disparity analyses, while noting that there can be no ‘one-size-fits-all’ approach. The available tools should always be used in the context of a specific biological question that will determine data and method selection at every stage of the analysis.
    • Ineffectiveness of light emitting diodes as underwater deterrents for Long-tailed Ducks Clangula hyemalis

      Cantlay, JC; Bond, AL; Wells-Berlin, AM; Crawford, R; Martin, GR; Rouxel, Y; Peregoy, S; McGrew, KA; Portugal, SJ (Elsevier BV, 2020-09-01)
      Gillnet bycatch accounts for over 400,000 bird mortalities worldwide every year, affectinga wide variety of species, especially those birds that dive when foraging. Technologicalsolutions to improve gillnet visibility or deter birds from approaching nets, such as LEDlights, are essential for aiding diving birds to perceive nets as a hazard. Designing suchsolutions requires obtaining visual and behavioural ecology information from species toassess their ability to see the warning devices, and to examine their behavioural responsesto them. Seaducks, particularly Long-tailed DucksClangula hyemalis,have high bycatchmortality rates. We examined the visualfields of four Long-tailed Ducks to understandtheir three-dimensional view around the head. The visualfield characteristics of thisspecies indicate a reliance on visual guidance for foraging associated with their capture ofvaried, mobile prey in their generalist diet. We subsequently conducted dive tank trials totest the effectiveness of 12 different LED treatments as visual deterrents to the underwaterforaging behaviour of 8 Long-tailed Ducks. During each trial, ducks were offered foodrewards from a specific underwater location in a dive tank, having the choice of whether totake the food or not. At the same time, they were exposed to either one LED light or thecontrol (no light) to determine whether the presence of each light affected the foragingsuccess rate of dives compared to the control. Exposure of ducks to all 13 treatmentcombinations was randomised over the trial period. White lights with an increasingflashrate were shown to have a significant positive effect on foraging success, and likely acted asa visual attractant, rather than as a deterrent. No light treatment significantly reduced theforaging success of ducks. LED lights did not inhibit the feeding of Long-tailed Ducks. Suchlights may be ineffective as underwater visual deterrents when deployed on gillnets, whilewhiteflashing lights may make foraging sites more attractive to Long-tailed Ducks.
    • A revision of the Maechidiini Burmeister, 1855 (Coleoptera: Scarabaeidae: Melolonthinae) from the Indo-Australian transition zone, and the first record of the tribe west of Wallace’s Line

      Telnov, Dmitry (2020-10-19)
      Features of the Maechidiini (Scarabaeidae: Melolonthinae) genera Maechidius Macleay, 1819, Epholcis Waterhouse, 1875 and Paramaechidius Frey, 1969 are critically revised and a new synonymy is proposed: Maechidius = Epholcis syn. nov. = Paramaechidius syn. nov. A key to and an annotated checklist of Maechidiini from the Indo-Australian transition zone are presented for the first time. Thirty-five new species are described, namely Maechidius aiyura sp. nov., M. alesbezdeki sp. nov., M. awu sp. nov., M. babyrousa sp. nov., M. bintang sp. nov., M. boessnecki sp. nov., M. brocki sp. nov., M. caperatus sp. nov., M. ciliatus sp. nov., M. crypticus sp. nov., M. dani sp. nov., M. deltouri sp. nov., M. dendrolagus sp. nov., M. hamatus sp. nov., M. kazantsevi sp. nov., M. konjo sp. nov., M. lapsus sp. nov., M. legalovi sp. nov., M. leucopsar sp. nov., M. longipes sp. nov., M. mailu sp. nov., M. maleo sp. nov., M. merdeka sp. nov., M. miklouhomaclayi sp. nov., M. nepenthephilus sp. nov., M. owenstanleyi sp. nov., M. riedeli sp. nov., M. similis sp. nov., M. skalei sp. nov., M. sougb sp. nov., M. suwawa sp. nov., M. trivialis sp. nov., M. ursus sp. nov., M. weigeli sp. nov. and M. yamdena sp. nov. Six new synonyms are proposed: Maechidius Macleay, 1819 = Epholcis Waterhouse, 1875 syn. nov. = Paramaechidius Frey, 1969 syn. nov., Maechidius esau Heller, 1914 = M. setosus Moser, 1920 syn. nov. = M. setosellus Frey, 1969 syn. nov., Maechidius heterosquamosus Heller, 1910 comb. rest. = Paramaechidius clypeatus Frey, 1969 syn. nov. and Maechidius paupianus Heller, 1910 = M. arrowi Frey, 1969 syn. nov. The first records of Maechidiini from the Tanimbar Islands (Yamdena), Sangihe Islands (Sangir) and Lesser Sunda Islands (Bali) are documented, of which the latter two are the northern- and westernmost known records of Maechidius and of the tribe Maechidiini. Lectotypes are designated for 23 species. Fifteen new combinations are proposed and the original combination to Maechidius is restored for four species. Ecological data are presented for the first time for selected Papuan and Wallacean species. Type material of Wallacean and Papuan Maechidiini is depicted for the first time. A key to species is given. In total, 78 species of Maechidiini are confirmed for the Indo-Australian transition zone.
    • Eliopoulosite, V7S8, A New Sulfide from the Podiform Chromitite of the Othrys Ophiolite, Greece

      Bindi, L; Zaccarini, F; Bonazzi, P; Grammatikopoulos, T; Tsikouras, B; Stanley, Christopher; Garuti, G (MDPI AG, 2020-03-08)
      The new mineral species, eliopoulosite, V7S8, was discovered in the abandoned chromium mine of Agios Stefanos of the Othrys ophiolite, located in central Greece. The investigated samples consist of massive chromitite hosted in a strongly altered mantle tectonite, and are associated with nickelphosphide, awaruite, tsikourasite, and grammatikopoulosite. Eliopoulosite is brittle and has a metallic luster. In plane-reflected polarized light, it is grayish-brown and shows no internal reflections, bireflectance, and pleochroism. It is weakly anisotropic, with colors varying from light to dark greenish. Reflectance values of mineral in air (Ro, Re’ in %) are: 34.8–35.7 at 470 nm, 38–39 at 546 nm, 40–41.3 at 589 nm, and 42.5–44.2 at 650 nm. Electron-microprobe analyses yielded a mean composition (wt.%) of: S 41.78, V 54.11, Ni 1.71, Fe 1.1, Co 0.67, and Mo 0.66, totali 100.03. On the basis of Σatoms = 15 apfu and taking into account the structural data, the empirical formula of eliopoulosite is (V6.55Ni0.19Fe0.12Co0.07Mo0.04)Σ = 6.97S8.03. The simplified formula is (V, Ni, Fe)7S8 and the ideal formula is V7S8, which corresponds to V 58.16%, S 41.84%, total 100 wt.%. The density, based on the empirical formula and unit-cell volume refined form single-crystal structure XRD data, is 4.545 g·cm−3. The mineral is trigonal, space group P3221, with a = 6.689(3) Å, c = 17.403(6) Å, V = 674.4(5) Å3, Z = 3, and exhibits a twelve-fold superstructure (2a × 2a × 3c) of the NiAs-type subcell with V-atoms octahedrally coordinated by S atoms. The distribution of vacancies is discussed in relation to other pyrrhotite-like compounds. The mineral name is for Dr. Demetrios Eliopoulos (1947–2019), a geoscientist at the Institute of Geology and Mineral Exploration (IGME) of Greece and his widow, Prof. Maria Eliopoulos (nee Economou, 1947), University of Athens, Greece, for their contributions to the knowledge of ore deposits of Greece and to the mineralogical, petrographic, and geochemical studies of ophiolites, including the Othrys complex. The mineral and its name have been approved by the Commission of New Minerals, Nomenclature, and Classification of the International Mineralogical Association (No. 2019-96).
    • Reptile-like physiology in Early Jurassic stem-mammals

      Newham, E; Gill, Pamela; Brewer, Philippa; Benton, MJ; Fernandez, Vincent; Gostling, NJ; Haberthür, D; Jernvall, J; Kankaanpää, T; Kallonen, A; et al. (Springer Science and Business Media LLC, 2020-10-12)
      Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.
    • A new family of diprotodontian marsupials from the latest Oligocene of Australia and the evolution of wombats, koalas, and their relatives (Vombatiformes)

      Beck, RMD; Louys, J; Brewer, Philippa; Archer, M; Black, KH; Tedford, RH (Springer Science and Business Media LLC, 2020-06-25)
      We describe the partial cranium and skeleton of a new diprotodontian marsupial from the late Oligocene (~26–25 Ma) Namba Formation of South Australia. This is one of the oldest Australian marsupial fossils known from an associated skeleton and it reveals previously unsuspected morphological diversity within Vombatiformes, the clade that includes wombats (Vombatidae), koalas (Phascolarctidae) and several extinct families. Several aspects of the skull and teeth of the new taxon, which we refer to a new family, are intermediate between members of the fossil family Wynyardiidae and wombats. Its postcranial skeleton exhibits features associated with scratch-digging, but it is unlikely to have been a true burrower. Body mass estimates based on postcranial dimensions range between 143 and 171 kg, suggesting that it was ~5 times larger than living wombats. Phylogenetic analysis based on 79 craniodental and 20 postcranial characters places the new taxon as sister to vombatids, with which it forms the superfamily Vombatoidea as defined here. It suggests that the highly derived vombatids evolved from wynyardiid-like ancestors, and that scratch-digging adaptations evolved in vombatoids prior to the appearance of the ever-growing (hypselodont) molars that are a characteristic feature of all post-Miocene vombatids. Ancestral state reconstructions on our preferred phylogeny suggest that bunolophodont molars are plesiomorphic for vombatiforms, with full lophodonty (characteristic of diprotodontoids) evolving from a selenodont morphology that was retained by phascolarctids and ilariids, and wynyardiids and vombatoids retaining an intermediate selenolophodont condition. There appear to have been at least six independent acquisitions of very large (>100 kg) body size within Vombatiformes, several having already occurred by the late Oligocene.
    • Evaluation of DNA barcode libraries used in the UK and developing an action plan to fill priority gaps

      Price, BW; Briscoe, AG; Misra, Raju; Broad, G (Natural England, 2020-10)
      There are approximately 76,000 eukaryote species recognised in the UK, and while we know some of them in great detail, the majority of these species are poorly known, and hundreds of new species are discovered each year. DNA barcoding uses a short, standardised segment of an organism’s genome for identification by comparison to a reference library; however, the UK lags behind several countries in Europe and North America in that we lack trusted, reliable and openly accessible reference sequences for key UK taxa. This report is the first step in rectifying this by engaging diverse stakeholders to facilitate collaboration and coordination; providing robust stakeholder-based and independent assessment of the current state of reference libraries available for all known UK taxa; and prioritising key taxa. A survey was developed and shared with the UK research and end user community, receiving 80 responses from a wide range of stakeholders and covering the focal taxa / assemblages and habitats; the DNA reference libraries in use, their quality assurance and perceived coverage. A formal gap analysis of the public DNA data in major DNA reference libraries highlighted that an estimated 52% of UK species have publicly available DNA data of some sort; however, coverage in gene specific reference libraries varies greatly (eg 2 – 52%), as does the associated quality assurance. Priority taxa highlighted by end users had coverage in reference libraries ranging from almost complete, in the case of known invasive non-native species, to significant coverage (71%) for taxa with conservation designations. However, these data also vary by kingdom and reference library, as does the associated quality assurance. If taking a strict requirement of DNA data provided by UK specimens and held in UK repositories, for robust QC and QA, then the proportion of UK species with public DNA data in reference libraries falls to less than 4% in the largest reference library assessed (BOLD). While standard genes for DNA-based identification have essentially been established, more work is required to establish the priority taxa required for regulatory delivery in contrast to taxa that are surveyed in a non-regulatory framework. Several barriers to the development of barcode libraries were highlighted, the most relevant being sustained large scale funding, expertise, capacity, laboratory skills and equipment, quality control and assurance, collecting logistics (eg permits and access) and communication. Significant opportunities identified include a large network of interested experts, several organisations with significant delivery capabilities, current large-scale projects and funding opportunities, emerging technologies and the economy of scale for DNA sequencing. Following a stakeholder workshop, we have outlined a concise action plan to provide reliable, open access reference sequences, linked to open access vouchers, identified by known experts, to facilitate UK academic and regulatory aims.
    • Grammatikopoulosite, NiVP, a New Phosphide from the Chromitite of the Othrys Ophiolite, Greece

      Bindi, L; Zaccarini, F; Ifandi, E; Tsikouras, B; Stanley, Christopher; Garuti, G; Mauro, D (MDPI AG, 2020-01-31)
      Grammatikopoulosite, NiVP, is a new phosphide discovered in the podiform chromitite and hosted in the mantle sequence of the Othrys ophiolite complex, central Greece. The studied samples were collected from the abandoned chromium mine of Agios Stefanos. Grammatikopoulosite forms small crystals (from 5 μm up to about 80 μm) and occurs as isolated grains. It is associated with nickelphosphide, awaruite, tsikourasite, and an undetermined V-sulphide. It is brittle and has a metallic luster. In plane-polarized light, it is creamy-yellow, weakly bireflectant, with measurable but not discernible pleochroism and slight anisotropy with indeterminate rotation tints. Internal reflections were not observed. Reflectance values of mineral in air (R1, R2 in %) are: 48.8–50.30 at 470 nm, 50.5–53.5 at 546 nm, 51.7–55.2 at 589 nm, and 53.2–57.1 at 650 nm. Five spot analyses of grammatikopoulosite give the average composition: P 19.90, S 0.41, Ni 21.81, V 20.85, Co 16.46, Mo 16.39, Fe 3.83, and Si 0.14, total 99.79 wt %. The empirical formula of grammatikopoulosite—based on Σ(V + Ni + Co + Mo + Fe + Si) = 2 apfu, and taking into account the structural results—is (Ni0.57Co0.32Fe0.11)Σ1.00(V0.63Mo0.26Co0.11)Σ1.00(P0.98S0.02)Σ1.00. The simplified formula is (Ni,Co)(V,Mo)P and the ideal formula is NiVP, which corresponds to Ni 41.74%, V 36.23%, P 22.03%, total 100 wt %. The density, calculated on the basis of the empirical formula and single-crystal data, is 7.085 g/cm3. The mineral is orthorhombic, space group Pnma, with a = 5.8893(8), b = 3.5723(4), c = 6.8146(9) Å, V = 143.37(3) Å3, and Z = 4. The mineral and its name have been approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2019-090). The mineral honors Tassos Grammatikopoulos, geoscientist at the SGS Canada Inc., for his contribution to the economic mineralogy and mineral deposits of Greece.
    • “Hope” is the thing with feathers: how useful are cyclomethicones when cleaning taxidermy?

      Allington-Jones, L (NatSCA, 2020-10-01)
      Silicone solvents have extreme hydrophobicity so they can be used as a temporary barrier to aqueous cleaning solutions. They are characterised as having low odour, moderately low toxicity, low polarity and surface tension. They are 100% volatile so will leave no trace behind. Silicone solvents could potentially be used to flood the skin of taxidermy specimens, to provide a barrier whilst fur or feathers are cleaned, and even permit the use of heat treatments without causing damage to the skin. They will not cause drying or swelling and will not dissolve or mobilise any skin components such as dyes or fats, which would normally be adversely affected by water or other solvents. They are also, in theory, safe to use on skin which has suffered so much deterioration that the shrinkage temperature is close to room temperature. Different classes of silicone solvents have different working times and this article explores 3 of these, and their practical applicability when cleaning taxidermy.
    • Morphology, Development, and Sediment Dynamics of Elongating Linear Dunes on Mars

      Davis, Joel; Banham, Steven; M. Grindrod, P; Boazman, Sarah; Balme, Matthew; Bristow, Charlie (American Geophysical Union (AGU), 2020-05-24)
      Linear dunes occur on planetary surfaces, including Earth, Mars, and Titan, yet their dynamics are poorly understood. Recent studies of terrestrial linear dunes suggest they migrate by elongation only in supply‐limited environments. Here, we investigate elongating linear dunes in the Hellespontus Montes region of Mars which are morphologically similar to terrestrial systems. Multitemporal, high‐resolution orbital images show these linear dunes migrate by elongation only and that the fixed sediment source of the dunes probably restricts any lateral migration. Some linear dunes maintain their along‐length volume and elongate at rates comparable to adjacent barchans, whereas those which decrease in volume show no elongation, suggesting they are near steady state, matching morphometric predictions. Limited sediment supply may restrict Martian linear dunes to several kilometers, significantly shorter than many terrestrial linear dunes. Our results demonstrate the close similarities in dune dynamics across the two planetary surfaces.
    • The origin and diversification of pteropods precede past perturbations in the Earth’s carbon cycle

      Peijnenburg, KTCA; Janssen, AW; Wall-Palmer, D; Goetze, E; Maas, AE; Todd, JA; Marlétaz, F (Proceedings of the National Academy of Sciences, 2020-09-24)
      Pteropods are a group of planktonic gastropods that are widely regarded as biological indicators for assessing the impacts of ocean acidification. Their aragonitic shells are highly sensitive to acute changes in ocean chemistry. However, to gain insight into their potential to adapt to current climate change, we need to accurately reconstruct their evolutionary history and assess their responses to past changes in the Earth’s carbon cycle. Here, we resolve the phylogeny and timing of pteropod evolution with a phylogenomic dataset (2,654 genes) incorporating new data for 21 pteropod species and revised fossil evidence. In agreement with traditional taxonomy, we recovered molecular support for a division between “sea butterflies” (Thecosomata; mucus-web feeders) and “sea angels” (Gymnosomata; active predators). Molecular dating demonstrated that these two lineages diverged in the early Cretaceous, and that all main pteropod clades, including shelled, partially-shelled, and unshelled groups, diverged in the mid- to late Cretaceous. Hence, these clades originated prior to and subsequently survived major global change events, including the Paleocene–Eocene Thermal Maximum (PETM), the closest analog to modern-day ocean acidification and warming. Our findings indicate that planktonic aragonitic calcifiers have shown resilience to perturbations in the Earth’s carbon cycle over evolutionary timescales.
    • Adakite-like granitoids of Songkultau: A relic of juvenile Cambrian arc in Kyrgyz Tien Shan

      Konopelko, D; Seltmann, Reimar; Dolgopolova, Alla; Safonova, I; Glorie, S; De Grave, J; Sun, M (Elsevier BV, 2020-09-01)
      The early Paleozoic Terskey Suture zone, located in the southern part of the Northern Tien Shan domain in Kyrgyzstan, comprises tectonic slivers of dismembered ophiolites and associated primitive volcanics and deep-marine sediments. In the Lake Songkul area, early-middle Cambrian pillow basalts are crosscut by the Songkultau intrusion of coarse-grained gneissose quartz diorites and tonalites with geochemical characteristics typical for high-SiO2 adakites (SiO2 ​> ​56 ​wt.%, Al2O3 ​> ​15 ​wt.%, Na2O ​> ​3.5 ​wt.% and high Sr/Y and La/Yb ratios). The Songkultau granitoids have positive initial εNd (+3.8 to +6.4) and εHf (+12.3 to +13.5) values indicating derivation from sources with MORB-like isotopic signature. Volcanic formations, surrounding the Songkultau intrusion, have geochemical affinities varying from ocean floor to island arc series. This rock assemblage is interpreted as a relic of an early-middle Cambrian primitive arc where the adakite-like granitoids were derived from partial melting of young and hot subducted oceanic crust. An age of 505 ​Ma, obtained for the Songkultau intrusion, shows that hot subduction under the Northern Tien Shan continued until middle Cambrian. The primitive arc complexes were obducted onto the Northern Tien Shan domain, where the Andean type continental magmatic arc developed in Cambrian and Ordovician. Formation of the Andean type arc was accompanied by uplift, erosion and deposition of coarse clastic sediments. A depositional age of ca. 470 Ma, obtained for the gravellites in the Lake Songkul area, is in agreement with the timing of deposition for lower Ordovician conglomerates elsewhere in the Northern Tien Shan, and corresponds to the main phase of the Andean type magmatism. The Songkultau adakites in association with surrounding ocean floor and island arc formations constitute a relic of a primitive Cambrian arc and represent a juvenile domain of substantial size identified so far within the predominantly crustal-derived terranes of Tien Shan. On a regional scale this primitive arc can be compared with juvenile Cambrian arcs of Kazakhstan, Gorny Altai and Mongolia.
    • Climatic oscillations in Quaternary have shaped the co‑evolutionary patterns between the Norway spruce and its host‑associated herbivore

      Jakub, G; Andrzej, O; Robert, R; Igor, C; Katarzyna, M; Radosław, P; Matti, L; Mauro, G; Gernot, H; Vytautas, T; et al. (Springer Nature, 2020-10-05)
      During the Last Glacial Maximum in the Northern Hemisphere, expanding ice sheets forced a large number of plants, including trees, to retreat from their primary distribution areas. Many host-associated herbivores migrated along with their host plants. Long-lasting geographic isolation between glacial refugia could have been led to the allopatric speciation in separated populations. Here, we have studied whether the migration history of the Norway spruce Picea abies in Quaternary has affected its host-associated herbivorous beetle—Monochamus sartor. By using microsatellite markers accompanied by the geometric morphometrics analysis of wing venation, we have revealed the clear geographic structure of M. sartor in Eurasia, encompassing two main clusters: southern (Alpine–Carpathian) and eastern (including northeastern Europe and Asia), which reflects the northern and southern ecotypes of its host. The two beetles’ lineages probably diverged during the Pleniglacial (57,000—15,000 BC) when their host tree species was undergoing significant range fragmentation and experienced secondary contact during post-glacial recolonization of spruce in the Holocene. A secondary contact of divergent lineages of M. sartor has resulted in the formation of the hybrid zone in northeastern Europe. Our findings suggest that the climatic oscillations during the Pleistocene have driven an insect-plant co-evolutionary process, and have contributed to the formation of the unique biodiversity of Europe.
    • Observations of organic falls from the abyssal Clarion-Clipperton Zone in the tropical eastern Pacific Ocean

      Amon, Diva; Hilario, A; Arbizu, PM; Smith, CR (Springer Berlin Heidelberg, 2016-10-04)
      Organic falls can form nutrient-rich, ephemeral hotspots of productivity and biodiversity at the deep-sea floor, especially in food-poor abyssal plains. We report here the first wood falls and second carcass fall recorded from the Clarion-Clipperton Zone in the tropical eastern Pacific Ocean, an area that could be mined for polymetallic nodules in the future. A small cetacean fall in the mobile-scavenger stage likely recently arrived on the seafloor was observed, whereas most of the wood falls were highly degraded. There were multiple species in attendance at the wood falls including organic-fall specialists such as Xylophagaidae molluscs. Many of the taxa attending the carcass fall were known mobile scavengers that regularly attend bait parcels in the Pacific Ocean. These results further confirm that wood falls can occur at large distances (>1450 km) from major land masses, providing an adequate supply of wood to the abyssal seafloor for colonization by wood-boring molluscs and associated fauna. Organic falls may be regionally abundant and are likely to influence species and habitat diversity in the abyssal areas of the Clarion-Clipperton Zone.
    • Exploration of the Mid-Cayman Rise

      German, CR; Tyler, PA; McIntyre, C; Amon, Diva; Cheadle, M; Clarke, J; John, B; McDermott, JM; Bennett, SA; Huber, JA; et al. (The Oceanography Society, 2012)
    • Insights into the abundance and diversity of abyssal megafauna in a polymetallic-nodule region in the eastern Clarion-Clipperton Zone

      Amon, Diva; Ziegler, AF; Dahlgren, TG; Glover, AG; Goineau, A; Gooday, AJ; Wiklund, H; Smith, CR (Springer, 2016-07-29)
      There is growing interest in mining polymetallic nodules in the abyssal Clarion-Clipperton Zone (CCZ) in the Pacific. Nonetheless, benthic communities in this region remain poorly known. The ABYSSLINE Project is conducting benthic biological baseline surveys for the UK Seabed Resources Ltd. exploration contract area (UK-1) in the CCZ. Using a Remotely Operated Vehicle, we surveyed megafauna at four sites within a 900 km2 stratum in the UK-1 contract area, and at a site ~250 km east of the UK-1 area, allowing us to make the first estimates of abundance and diversity. We distinguished 170 morphotypes within the UK-1 contract area but species-richness estimators suggest this could be as high as 229. Megafaunal abundance averaged 1.48 ind. m−2. Seven of 12 collected metazoan species were new to science, and four belonged to new genera. Approximately half of the morphotypes occurred only on polymetallic nodules. There were weak, but statistically significant, positive correlations between megafaunal and nodule abundance. Eastern-CCZ megafaunal diversity is high relative to two abyssal datasets from other regions, however comparisons with CCZ and DISCOL datasets are problematic given the lack of standardised methods and taxonomy. We postulate that CCZ megafaunal diversity is driven in part by habitat heterogeneity.
    • Megafauna of the UKSRL exploration contract area and eastern Clarion-Clipperton Zone in the Pacific Ocean: Echinodermata

      Amon, Diva; Ziegler, AF; Kremenetskaia, A; Mah, CL; Mooi, R; O Hara, T; Pawson, DL; Roux, M; Smith, CR (Pensoft Publishers, 2017-05-11)
      Background: There is growing interest in mining polymetallic nodules from the abyssal Clarion-Clipperton Zone (CCZ) in the tropical Pacific Ocean. Despite being the focus of environmental studies for decades, the benthic megafauna of the CCZ remain poorly known. In order to predict and manage the environmental impacts of mining in the CCZ, baseline knowledge of the megafauna is essential. The ABYSSLINE Project has conducted benthic biological baseline surveys in the UK Seabed Resources Ltd polymetallic-nodule exploration contract area (UK-1). Prior to these research cruises in 2013 and 2015, no biological studies had been done in this area of the eastern CCZ. New information: Using a Remotely Operated Vehicle and Autonomous Underwater Vehicle, the megafauna within the UKSRL exploration contract area (UK-1) and at a site ~250 km east of the UK-1 area were surveyed, allowing us to make the first estimates of megafaunal morphospecies richness from the imagery collected. Here, we present an atlas of the abyssal echinoderm megafauna observed and collected during the ABYSSLINE cruises to the UK-1 polymetallic-nodule exploration contract area in the CCZ. There appear to be at least 62 distinct morphospecies (13 Asteroidea, 5 Crinoidea, 9 Echinoidea, 29 Holothuroidea and 6 Ophiuroidea) identified mostly by imagery but also using molecular barcoding for a limited number of animals that were collected. This atlas will aid the synthesis of megafaunal presence/absence data collected by contractors, scientists and other stakeholders undertaking work in the CCZ, ultimately helping to decipher the biogeography of the megafauna in this threatened habitat.
    • Characterization of methane-seep communities in a deep-sea area designated for oil and natural gas exploitation off Trinidad and Tobago

      Amon, Diva; Gobin, J; Van Dover, CL; Levin, LA; Marsh, L; Raineault, NA (Frontiers, 2017-10-30)
      Exploration of the deep ocean (>200 m) is taking on added importance as human development encroaches. Despite increasing oil and natural gas exploration and exploitation, the deep ocean of Trinidad and Tobago is almost entirely unknown. The only scientific team to image the deep seafloor within the Trinidad and Tobago Exclusive Economic Zone was from IFREMER in the 1980s. That exploration led to the discovery of the El Pilar methane seeps and associated chemosynthetic communities on the accretionary prism to the east of Trinidad and Tobago. In 2014, the E/V Nautilus, in collaboration with local scientists, visited two previously sampled as well as two unexplored areas of the El Pilar site between 998 and 1,629 m depth using remotely operated vehicles. Eighty-three megafaunal morphospecies from extensive chemosynthetic communities surrounding active methane seepage were observed at four sites. These communities were dominated by megafaunal invertebrates including mussels (Bathymodiolus childressi), shrimp (Alvinocaris cf. muricola), Lamellibrachia sp. 2 tubeworms, and Pachycara caribbaeum. Adjacent to areas of active seepage was an ecotone of suspension feeders including Haplosclerida sponges, stylasterids and Neovermilia serpulids on authigenic carbonates. Beyond this were large Bathymodiolus shell middens. Finally there was either a zone of sparse octocorals and other non-chemosynthetic species likely benefiting from the carbonate substratum and enriched production within the seep habitat, or sedimented inactive areas. This paper highlights these ecologically significant areas and increases the knowledge of the biodiversity of the Trinidad and Tobago deep ocean. Because methane seepage and chemosynthetic communities are related to the presence of extractable oil and gas resources, development of best practices for the conservation of biodiversity in Trinidad and Tobago waters within the context of energy extraction is critical. Potential impacts on benthic communities during oil and gas activities will likely be long lasting and include physical disturbance during drilling among others. Recommendations for the stewardship of these widespread habitats include: (1) seeking international cooperation; (2) holding wider stakeholder discussions; (3) adopting stringent environmental regulations; and (4) increasing deep-sea research to gather crucial baseline data in order to conduct appropriate marine spatial planning with the creation of marine protected areas.
    • ICDP workshop on the Lake Tanganyika Scientific Drilling Project: a late Miocene–present record of climate, rifting, and ecosystem evolution from the world's oldest tropical lake

      Russell, JM; Barker, P; Cohen, Andrew; Ivory, S; Kimirei, Ismael; Lane, C; Leng, Melanie; Maganza, N; McGlue, M; Msaky, E; et al. (Copernicus GmbH, 2020-05-27)
      The Neogene and Quaternary are characterized by enormous changes in global climate and environments, including global cooling and the establishment of northern high-latitude glaciers. These changes reshaped global ecosystems, including the emergence of tropical dry forests and savannahs that are found in Africa today, which in turn may have influenced the evolution of humans and their ancestors. However, despite decades of research we lack long, continuous, well-resolved records of tropical climate, ecosystem changes, and surface processes necessary to understand their interactions and influences on evolutionary processes. Lake Tanganyika, Africa, contains the most continuous, long continental climate record from the mid-Miocene (∼10 Ma) to the present anywhere in the tropics and has long been recognized as a top-priority site for scientific drilling. The lake is surrounded by the Miombo woodlands, part of the largest dry tropical biome on Earth. Lake Tanganyika also harbors incredibly diverse endemic biota and an entirely unexplored deep microbial biosphere, and it provides textbook examples of rift segmentation, fault behavior, and associated surface processes. To evaluate the interdisciplinary scientific opportunities that an ICDP drilling program at Lake Tanganyika could offer, more than 70 scientists representing 12 countries and a variety of scientific disciplines met in Dar es Salaam, Tanzania, in June 2019. The team developed key research objectives in basin evolution, source-to-sink sedimentology, organismal evolution, geomicrobiology, paleoclimatology, paleolimnology, terrestrial paleoecology, paleoanthropology, and geochronology to be addressed through scientific drilling on Lake Tanganyika. They also identified drilling targets and strategies, logistical challenges, and education and capacity building programs to be carried out through the project. Participants concluded that a drilling program at Lake Tanganyika would produce the first continuous Miocene–present record from the tropics, transforming our understanding of global environmental change, the environmental context of human origins in Africa, and providing a detailed window into the dynamics, tempo and mode of biological diversification and adaptive radiations.