Physiologie respiratoire, comportementale et morphofonctionnelle des ostracodes podocopes et myodocopes et d'un amphipode caprellide profond. Stratégies adaptives et implications évolutives.

Sur Terre, l'augmentation de la pression partielle d'O2 (PO2) de »1-3 à 21 kPa (valeur actuelle) a accompagné l'explosion de la vie au Cambrien, il y a plus de 500 millions d'années. Comprendre comment les premiers animaux ont pu s'adapter à ce changement majeur est un challenge important. Certains animaux, comme les ostracodes ont peu ou pas évolué depuis cette époque. Crustacés de petite taille (0,5 - 3 mm), ils vivent dans le sédiment, et/ou la colonne d'eau. Nous avons étudié la physiologie respiratoire d'ostracodes podocopes sans branchies, ni système circulatoire et d'ostracodes myodocopes, équipés de branchies et d'un système circulatoire. Nous montrons que lorsque l'oxygénation de l'eau varie, ces animaux sont incapables d'adapter leur ventilation et/ou leur activité cardiaque contrairement aux crustacés, poissons et mammifères actuels qui maintiennent ainsi une PO2 tissulaire originelle à 1-3 kPa. Par contre, ils adoptent une stratégie comportementale en migrant dans les sédiments (podocopes) où en fabriquant des nids (myodocopes), qui leur permettent de réguler indirectement l'oxygénation de leurs cellules. Les caprellidés, crustacés plus récents, colonisent à quelques millimètres près le même biotope. Nous les avons observés pour la 1ère fois vivant et montrés que, positionnés dans une eau où PO2 » 15 kPa, ils possèdent des branchies peu favorables aux échanges gazeux alors qu'O2 et CO2 doivent diffuser principalement à travers leur corps. C'est vraisemblablement l'intensité de leurs mouvements qui contrôle leurs échanges gazeux et l'oxygénation de leurs tissus. Deux types d'ostracodes sont utilisés en paléocéanographie en tant que paléomarqueurs d'oxygénation des fonds marins. Nous n'avons trouvé aucune base physiologique entre taille des vestibules de Krithes et stratégie d'oxygénation de l'animal. Par contre, les Cytherellidae possèderaient des caractéristiques ventilatoire et morpho-fonctionnelles qui peuvent rendre compte d'une résistance accrue aux faibles oxygénations de l'eau.On Earth, 500 million years ago, an O2 rise from a partial pressure (PO2) of »1-3 to 21 kPa (present value) accompanied the life explosion in the lower Cambrian. To understand how the first animals faced this major change is a fundamental challenge. Some animals, such as ostracods have been established since that time. They are minute crustaceans (0.5-3 mm), which are either living in the sediment and/or the water column. We studied the respiratory physiology of Podocopid ostracods, which lack gills and heart, and Myodocopid ostracods, equipped with gills, heart and circulatory system. We show that when water PO2 varies, these animals are unable to adapt their ventilation and/or cardiac activity contrary to modern crustaceans, fish and mammals that maintain an original tissue PO2 of »1-3 kPa. However, they regulate their tissue O2 status by behavioural adaptation: Podocops adjust their tissue O2 status by migrating to sediment layers where the pore water PO2 is 3-5 kPa; Myodocops build nests where they are rebreathing in an hypoxic environment during daytime. Caprellids are more recent crustaceans colonizing the same biotope at water PO2 »15 kPa. We present the 1st report on living animals. They have small gills unfavourable to gas exchange whereas O2 and CO2 must diffuse through their thin body wall. We suggest that their body movement likely controls gas exchanges. Finally, we studied two types of ostracods used in paleoceanography as paleo-markers for bottom water oxygenation. We did not find any physiological evidence for a direct relationship between Krithe vestibule size and O2-supply mechanisms. However, Cytherellidae possess ventilatory and morphofunctional characteristics which could explain an increased resistance to low O2 by comparison to other ostracods

New insights gained from museum collections: Deep-sea barnacles (Crustacea, Cirripedia, Thoracica) in the Museum National d'Histoire Naturelle, Paris, collected during the Karubar expedition in 1991

An examination of the deep-sea barnacles (Cirripedia, Thoracica) collected by the Karubar expedition to Indonesia (1991) and deposited in the Museum National d'Histoire Naturelle, Paris, identified 40 species contained in three families of stalked and five families of acorn barnacles. Information on these species is presented, including descriptions, updated distributions and images to aid species identification. Thirty of the species, treated herein, are new records for the Indonesian Kei Islands and Tanimbar Island, which increases the total number of species recorded from Kei Islands, Aru Island and Tanimbar Island to 40. This study demonstrates the value of museum collections as a resource in biodiversity science

A genetic fingerprint of Amphipoda from Icelandic waters – the baseline for further biodiversity and biogeography studies

Source at https://doi.org/10.3897/zookeys.731.19931.Amphipods constitute an abundant part of Icelandic deep-sea zoobenthos yet knowledge of the diversity of this fauna, particularly at the molecular level, is scarce. The present work aims to use molecular methods to investigate genetic variation of the Amphipoda sampled during two IceAGE collecting expeditions. The mitochondrial cytochrome oxidase subunit 1 (COI) of 167 individuals originally assigned to 75 morphospecies was analysed. These targeted morhospecies were readily identifiable by experts using light microscopy and representative of families where there is current ongoing taxonomic research. The study resulted in 81 Barcode Identity Numbers (BINs) (of which >90% were published for the first time), while Automatic Barcode Gap Discovery revealed the existence of 78 to 83 Molecular Operational Taxonomic Units (MOTUs). Six nominal species (Rhachotropis helleri, Arrhis phyllonyx, Deflexilodes tenuirostratus, Paroediceros propinquus, Metopa boeckii, Astyra abyssi) appeared to have a molecular variation higher than the 0.03 threshold of both p-distance and K2P usually used for amphipod species delineation. Conversely, two Oedicerotidae regarded as separate morphospecies clustered together with divergences in the order of intraspecific variation. The incongruence between the BINs associated with presently identified species and the publicly available data of the same taxa was observed in case of Paramphithoe hystrix and Amphilochus manudens. The findings from this research project highlight the necessity of supporting molecular studies with thorough morphology species analyses

Amphipod family distributions around Iceland

publishedVersio

Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution

BACKGROUND: We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS: The PO(2) of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2) of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2). Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2) levels. The PO(2) of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2). Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO(2) gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2). Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. CONCLUSIONS/SIGNIFICANCE: Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour

sFDvent: A global trait database for deep‐sea hydrothermal‐vent fauna

Motivation: Traits are increasingly being used to quantify global biodiversity patterns, with trait databases growing in size and number, across diverse taxa. Despite grow‐ ing 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 re‐ pository 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 – sFD‐ vent (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 da‐ tabase, describe our approach, and evaluate its scope. Finally, we compare the sFD‐ vent 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 spe‐ cies‐level identification present or in progress. Software format: .csv and MS Excel (.xlsx).This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

The World Amphipoda Database: history and progress

We provide an overview of the World Amphipoda Database (WAD), a global species database that is part of the World Register of Marine Species (WoRMS). Launched in 2013, the database contains entries for over 10,500 accepted species names. Edited currently by 31 amphipod taxonomists, following WoRMS priorities, the WAD has at least one editor per major group. All accepted species are checked by the editors, as is the authorship available for all of the names. The higher classification is documented for every species and a type species is recorded for every genus name. This constitutes five of the 13 priorities for completion, set by WoRMS. In 2015, five LifeWatch grants were allocated for WAD activities. These included a general training workshop in 2016, together with data input for the superfamily Lysianassoidea and for a number of non-marine groups. Philanthropy grants in 2019 and 2021 covered more important gaps across the whole group. Further work remains to complete the linking of unaccepted names, original descriptions, and environmental information. Once these tasks are completed, the database will be considered complete for 8 of the 13 priorities, and efforts will continue to input new taxa annually and focus on the remaining priorities, particularly the input of type localities. We give an overview of the current status of the order Amphipoda, providing counts of the number of genera and species within each family belonging to the six suborders currently recognized

Papuadocus blodiwai gen. nov., sp. nov. (Crustacea: Amphipoda: Maeridae), a new bathyal species associated with sunken wood in the Bismarck Sea (Papua New Guinea)

International audienceA new species belonging to a new genus of Maeridae, Papuadocus blodiwai gen. nov., sp. nov., is described from bathyal bottoms of the Bismarck Sea (Papua New Guinea). This genus/species can be distinguished from most other known maerids by right and left maxillas 1 with asymmetrical palps and by gnathopod 2 not sexually dimorphic. Its closest relative is the genus Bathyceradocus also characterized by asymmetrical maxillas 1, but differing by the presence of gill on coxae 7. These observations lead to the conclusion that the diagnosis of the family Maeridae has to be amended to receive both Bathyceradocus and Papuadocus genera. All the collected specimens lived in association with sunken wood, at 500–580 m depth

First observations of the behaviour of the deep-sea amphipod Dulichiopsis dianae sp. nov. (Senticaudata, Dulichiidae) in the TAG hydrothermal vent field (Mid-Atlantic Ridge)

International audienceA “tiny and mysterious creature swinging on a stem”: that was the first observation of the new species Dulichiopsis dianae sp. nov. made during the remotely operated vehicle (ROV) dive devoted to the exploration of the surroundings of the vent site TAG (BICOSE cruise, 3550–3650 m). The viewing and analysis of the high-definition pictures from several dives (PL570, PL573 and PL575) corresponding to five different locations around TAG revealed that these organisms were amphipods, hung on erected and flexible masts (5–7 cm length) attached to the underlying hard substratum. Two specimens were opportunely sampled during dive PL575 (3637 m) with the suction sampler of the ROV and were identified as a new species ascribed to the genus Dulichiopsis (family Dulichiidae). The present study provides the morphological description of this new species, coupled with in situ observations of its behaviour and lifestyle in the vicinity of the TAG vent field. Taxonomic and ecological aspects of the family Dulichiidae are proposed here, as well as a review of the amphipod diversity in hydrothermal environments

Anoplodactylus maritimus Hodgson 1914

Anoplodactylus maritimus Hodgson, 1914 Anoplodactylus maritimus Hodgson, 1914: 164. Anoplodactylus parvus Giltay, 1934a: 1–3, figs 1–5. Anoplodactylus maritumus – Hodgson 1915: 148; 1927: 357. — Marcus 1940: 60. — Child 1982b: 21; 1992b: 39 (key), 52–53, tab. 5, fig. 23; 2009: 820 (list). — Stock 1990: 229; 1992a: 131, 139; 1994: 19 (list), 61, 63. — Bamber & Costa 2009: 168 (list), 174, fig. 3d. — Bamber 2010: 16 (list), 200, fig. 236. — Turpaeva & Raiskiy 2014: 243. — Lucena & Christoffersen 2018a: 112; 2018b: 375 (key), 378–382. — Sabroux et al. 2019b: tab. 1. Anoplodactylus parvus – Hedgpeth 1948: 223–224, fig. 27e–f. — Stock 1951: 13, figs 14–16; 1954a: 127; 1957: 85; 1975a: 1069–1074, fig. 54. — Bourdillon 1955: 590–591, pl. 1 fig. 1. — Fage & Stock 1966: 326. — Kraeuter 1973: 494–495. — Ramírez-Tello et al. 2022: 161, 165, tab. 1. non? Anoplodactylus maritimus (= Anoplodactylus iuleus Stock, 1975) – Hedgpeth 1948: 230, fig. 29d–e. Type material Anoplodactylus maritimus Hodgson, 1914. Type(s): unknown. Type locality: Sargasso Sea. Anoplodactylus parvus Giltay, 1934. Holotype: USNM 72790 (not examined). Type locality: Bermuda. Material examined MARTINIQUE • 1 ♂; Presqu’Île de la Caravelle; 14°48.4ʹ N, 60°52.8ʹ W; depth 23–25 m; 20 Sep. 2016; st. AB197; MNHN-IU-2016-1140. Remarks This is the first record of this species in Martinique, sampled off Presqu’Île de la Caravelle. Distribution Amphi-Atlantic, including Virginia, Bermuda, the Caribbean, Gulf of Mexico, Brazil, Sargasso Sea, Middle Atlantic and Macaronesia (Madeira, Canary Islands, Azores). Depth range 0– 120 m.Published as part of Sabroux, Romain, Hassanin, Alexandre & Corbari, Laure, 2022, Sea spiders (Arthropoda: Pycnogonida) collected during the Madibenthos Expedition from Martinique shallow waters, pp. 1-141 in European Journal of Taxonomy 851 (1) on page 92, DOI: 10.5852/ejt.2022.851.1999, http://zenodo.org/record/742809