Deep-Sea Research Part I-Oceanographic Research Papers最新文献

{"title":"Evolutionary affinity of a novel deep-sea coral from the Central Indian Ridge seamount, and its links to Pacific Ocean species","authors":"Rengaiyan Periasamy ,&nbsp;Baban Ingole","doi":"10.1016/j.dsr.2025.104543","DOIUrl":"10.1016/j.dsr.2025.104543","url":null,"abstract":"<div><div>The family Victorgorgiidae Moore et al., 2017 comprises deep-sea gorgonian corals typically characterized by purple colonies and distinctive josephinae clubs in their polyp tentacles. Despite this, the family exhibits low species diversity and the ones from the deep Indian Ocean remain poorly unknown, remarking the need for more research to better understand their ecological role and evolutionary history. A new species, <em>Victorgorgia indica</em> sp. nov., was discovered on a seamount along the Central Indian Ridge (CIR) at depths of 1917–2053 m, representing the first record of Victorgorgiidae in the Indian Ocean. Among the nine known species of <em>Victorgorgia</em> López-González and Briand, 2002), <em>V. indica</em> sp. nov. is morphologically most similar to <em>V. flabellata</em> Li et al., 2020 and <em>V. iocasica</em> Li et al., 2020, particularly in the arrangement of the calyx, which is mainly isolated in three sides of the branches. However, this arrangement can vary in different parts of a colony and may be influenced by local habitat conditions. <em>V. indica</em> sp. nov. differs from these species by having tuberculate rods, a thorn club in the tentacle rachis, and curved rodlets with tall tubercules along their edges in the pinnules. Phylogenetic analysis at the family level using the MutS-like protein (MutS) gene supports Victorgorgiidae as a monophyletic group. The evolutionary relationships of the new CIR species suggest a close affinity with its Pacific Ocean congeners, including <em>V. flabellat</em><em>a</em>, <em>V. iocasica</em> and <em>V. eminens</em> Moore et al., 2017. This points to the CIR seamount system potentially acting as a link for gene flow between the Indian and Pacific Oceans. Analyses of the reproductions of these species showed that <em>V. indica</em> sp. nov. is a brooder, with planula larvae developing within clumped autozooids—the only mature polyps—and settling on dead deep-sea coral. Here we presented also the complete mitochondrial genome of <em>V. indica</em> sp. nov., which is 18,715 base pairs in size, and includes 14 protein-coding genes (PCGs), two ribosomal RNA genes (rrnS and rrnL), and one transfer RNA gene. The gene order of the mitogenome is identical to that of other sequenced Victorgorgiidae species.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104543"},"PeriodicalIF":2.3,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144502790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Megafauna of the RMS Titanic shipwreck and a nearby seamount ridge in the deep sea of the western North Atlantic","authors":"Jason Cleland ,&nbsp;Anna Gebruk ,&nbsp;J. Murray Roberts ,&nbsp;Dmitry Aleynik ,&nbsp;Beverly McClenaghan ,&nbsp;Rod Mather ,&nbsp;Bridget Buxton ,&nbsp;Steve W. Ross","doi":"10.1016/j.dsr.2025.104544","DOIUrl":"10.1016/j.dsr.2025.104544","url":null,"abstract":"<div><div>The biology of shipwrecks and hard substrata in the deep sea remains poorly explored. These complex habitats alter biodiversity on the deep seafloor and facilitate connecting populations over large distances. We analysed biological and environmental data collected at the RMS <em>Titanic</em> wreck site (3800 m) and a seamount ridge (2900 m) during the 2022 <em>Titanic</em> Expedition (15 June–25 July). The ridge is part of Seamount U, approximately 40 km southeast of the <em>Titanic,</em> and was explored for the first time on July 23, 2022. We analysed megafaunal occurrence across 920 images of the wreck site and 169 images of the ridge site, from digital video. The most common megafauna overall were Ophiuroidea, <em>Munidopsis</em> sp., Cushion-Encrusting Porifera, <em>Geodia</em> spp., and cold-water corals including Keratoisididae and Pennatuloidea. We describe the patterns in community composition across five benthic habitats, likely controlled by substrate type, local hydrodynamics, and food availability. The ridge yielded a higher number of observed megafauna and higher Shannon diversity (n = 73; H = 2.89) than the wreck (n = 21; H = 1.39). The communities associated with the ridge showed high dissimilarity to those at the wreck. We also explored the temporal variability of biofouling organisms on the <em>Titanic</em> using video from 1986 to 2022. We observed a net increase in <em>Chrysogorgia</em> sp. and <em>Lepidisis</em> sp. coral colonies over time with estimated average linear growth rates of up to 10 mm/yr and linear rusticle extensions of up to 14 mm/yr, raising questions about the wreck's ecological succession as it deteriorates.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104544"},"PeriodicalIF":2.3,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144480960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional and microbial insights into the gill symbiosis and metal tolerance of the cold seep mussel Gigantidas haimaensis","authors":"Xuanguang Liang ,&nbsp;Mingmin Du ,&nbsp;Yuxin Qin ,&nbsp;Wenlong Cai ,&nbsp;Junrou Huang ,&nbsp;Genmei Lin ,&nbsp;Jianguo Lu","doi":"10.1016/j.dsr.2025.104545","DOIUrl":"10.1016/j.dsr.2025.104545","url":null,"abstract":"<div><div>Deep-sea cold seeps that discharge fluids rich in methane, hydrogen sulfide, and heavy metals present extreme conditions under which only a few organisms, such as deep-sea mussels, can survive. Deep-sea mussels exploit chemosynthetic energy via symbiotic microorganisms. This study compared environmental sensing and stress responses in different tissues of <em>Gigantidas haimaensis</em> from the Haima cold seep through transcriptome and microbiome sequencing, biochemistry index measurements and metal content assessments to decipher its adaptive mechanisms. Transcriptomic analysis revealed distinct expression patterns among three tissues, with more genes expressed in the gill. Compared to the mantle and adductor muscle, the gill had 2519 and 4508 differentially expressed genes (DEGs), respectively, while 1453 DEGs were identified between the mantle and the adductor muscle. Up-regulated DEGs in the gill were associated with symbiont acquisition, pathogen recognition, pathogen removal, symbiotic substance exchange, and oxidative stress response. Meanwhile, the gill microbiota was dominated by methanotrophic Methylomonaceae (&gt;85 % relative abundance). Of the 13 metals analyzed, Zn, Fe, and Cu exhibited the highest concentrations. Genes associated with distinct metal-binding pathways were expressed in different tissues. The gill also showed heightened antioxidant capacity and metal accumulation, underscoring its role in the stress response. The up-regulated genes in the adductor muscle were related to muscle contraction, while in the mantle, the up-regulated protease inhibitors were linked to humoral immunity. This study demonstrates the gill's crucial functions in symbiont and pathogen regulation as well as metal stress response, thus extending our understanding of the adaptive mechanism of <em>G. haimaensis</em> inhabiting cold seeps.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104545"},"PeriodicalIF":2.3,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144279541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of eddy merging in maintaining the quasi-permanent Ulleung Eddy","authors":"Guoqing Han ,&nbsp;Wang Zhu ,&nbsp;Yaofeng Wang ,&nbsp;Xiayan Lin ,&nbsp;Juncheng Xie ,&nbsp;Yu Liu","doi":"10.1016/j.dsr.2025.104542","DOIUrl":"10.1016/j.dsr.2025.104542","url":null,"abstract":"<div><div>Eddy merging plays a crucial role in maintaining the lifetimes of quasi-permanent eddies. This study used satellite observations and 3D reanalysis data to investigate the eddy merging process of a quasi-permanent eddy, known as the Ulleung Eddy, in the Ulleung Basin (UB) of the Sea of Japan. The results showed that the number of cyclonic eddies in the Sea of Japan was greater than that of anticyclonic eddies. However, regarding long-lived eddies (&gt;360 days), which were mostly distributed in UB, the number of anticyclonic eddies was greater than that of cyclonic eddies. The eddy merging process is beneficial for strengthening the Ulleung Eddy and maintaining its quasi-permanent state. Through a case analysis of 3D reanalysis data, considerable instability was observed during the merging of the Ulleung Eddy. During the eddy merging process, energy conversion associated with baroclinic instability is dominant. In particular, 95.8 % of the eddy merging processes exhibited a conversion from mean potential energy to eddy potential energy, whereas 83.3 % of the eddy merging processes demonstrated a conversion from mean kinetic energy to eddy kinetic energy. The merging of the Ulleung Eddy is conducive to its maintenance and development.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104542"},"PeriodicalIF":2.3,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144271478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A video dataset for hadal snailfish along with the benchmark","authors":"Jiushuang Zhang,&nbsp;Yong Wang","doi":"10.1016/j.dsr.2025.104517","DOIUrl":"10.1016/j.dsr.2025.104517","url":null,"abstract":"<div><div>Application of deep learning technology for deep-sea ecological studies is still in its infancy stage especially in the field of automatic taxonomic identification and statistics. In this study, we created a novel dataset containing annotated videos for the rare species of hadal snailfish inhabiting in depth below 6000 meters, and conducted control experiments by combining models of different specifications and adding different attention mechanisms. We successfully generated a set of benchmark test data from a quantitative perspective. In addition, based on out of set data with completely different data distributions from the training and validation sets, the generalization ability of the model trained on the new dataset in real-world scenarios was qualitatively analyzed. Other researchers can continue to expand and supplement the dataset based on our benchmarks, or directly apply our results to actual deep-sea videos collected, and accurately identify and capture deep-sea snailfish in the videos. With this deep learning video processing technology, distribution pattern and biodiversity of the deep-sea organisms will be accomplished efficiently.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104517"},"PeriodicalIF":2.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144271459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial variation of micrometeorite abundance in global ocean","authors":"V.P. Singh ,&nbsp;N.G. Rudraswami","doi":"10.1016/j.dsr.2025.104533","DOIUrl":"10.1016/j.dsr.2025.104533","url":null,"abstract":"<div><div>Annually, Earth accumulates ∼40,000 tons of cosmic dust, with ∼4000–6000 tons reaching the surface as micrometeorites (MMs). This study analyzes ∼3 tons of wet sediments and ∼5000 MMs from the Central Indian Ocean Basin, using a machine learning algorithm based on terrestrial sedimentation rate (TSR) and MM abundance to identify optimal collection regions. Deep-sea sediments (TSR &lt;0.01 cm/kyr) contain ∼50 MM/kg of dry sediments, yet remain largely unexplored. Moderately deep-sea sediments (0.01 &lt; TSR &lt;0.1 cm/kyr), like those in this study, average ∼15 MM/kg, while shallow-sea sediments yield far fewer. Modelling indicates that ocean regions between 45° N and 45° S latitude are ideal for MM collection. The eastern Pacific Ocean (10-40° N and 10-30° S) and the Central Indian Ocean (0-45° S) are particularly suitable. Apart from deep-sea collection, ancient rocks deposited in calm environments with low TSR (e.g. shale, claystone, mudstone, chert, and limestone) are promising for collecting fossil MMs. Overall, this research enhances micrometeorite collection strategies, enabling more accurate flux estimation and providing a foundation for researchers to effectively target specific ocean areas and ancient rock formations, thereby facilitating investigations into extraterrestrial activities and their impacts on Earth's processes.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"222 ","pages":"Article 104533"},"PeriodicalIF":2.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144167724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The roles of benthic diversity and environmental factors in nutrient and macrofaunal dynamics within the oxygen minimum zone of the British Columbia continental slope","authors":"Alessia C. Ciraolo ,&nbsp;Paul V.R. Snelgrove ,&nbsp;Marta M. Cecchetto ,&nbsp;Andrew K. Sweetman","doi":"10.1016/j.dsr.2025.104530","DOIUrl":"10.1016/j.dsr.2025.104530","url":null,"abstract":"<div><div>Global warming has expanded oxygen minimum zones (OMZs), or oceanic “dead zones”. Despite their ecological significance, the diversity, and functional roles of benthic organisms in nutrient cycling and carbon (C) uptake in OMZ remain understudied. In this study, we focused on the Northeast Pacific continental slope OMZ (600–1200 m depth) off Vancouver Island, Canada, along an oxygen and depth transect (∼77, 40, and 10 μmol ‧ l⁻¹ at 200-, 475-, 850-m depth, respectively). Using a multicorer we collected sediment cores and performed shipboard incubations to examine organic matter remineralization and nutrient flux rates. In parallel, we performed pulse-chase tracer incubations with isotopically labeled algae (<em>Phaeodactylum</em> sp.) at the 475- and 850-m sites, to assess macrofaunal C uptake and benthic nutrient flux responses to fresh phytodetritus. Our results revealed no clear influence of decreasing oxygen on macrofaunal abundances, nutrient regeneration, or on the role of infauna in organic matter remineralization. Nontheless, organic matter quantity and quality strongly influenced macrofaunal community structure. Despite differences in community composition among sites, we also observed no clear relationship between macrofaunal community composition and nutrient fluxes, with phytoplankton-based food as a key food source for oxygen-deficient-adapted infauna. The highest C uptake rate and highest net nutrient influxes at the 475 m site contrasted lower rates at 850 m site, where only one flabelligerid and one cirratulid polychaete species ingested the organic matter, followed by amphipods, cumaceans, unidentified crustaceans, and bivalves, all primarily in the upper 2 cm of sediment. Our findings highlight the complex interplay of oxygen, depth, and organic matter, suggesting that organic matter quality and quantity may obscure oxygen effects on benthic biodiversity and ecological processes.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"222 ","pages":"Article 104530"},"PeriodicalIF":2.3,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pathways and impacts of ENSO-induced oceanic variability in the southern Indian Ocean investigated with high-resolution model simulations","authors":"Yanan Zhu ,&nbsp;Yuanlong Li ,&nbsp;Yilong Lyu ,&nbsp;Fan Wang","doi":"10.1016/j.dsr.2025.104532","DOIUrl":"10.1016/j.dsr.2025.104532","url":null,"abstract":"<div><div>Pacific Ocean water masses can reach the Atlantic through the Indonesian Throughflow (ITF) and Agulhas Current (AC) leakage, constituting an essential route of the global ocean conveyor belt. However, whether the oceanic variability induced by El Niño-Southern Oscillation (ENSO) can efficiently penetrate through this route remains largely uncertain. In this study, we utilize experiments of a high-resolution (0.1° in horizontal resolution) ocean model to revisit pathways of Pacific-origin oceanic signals and their impacts on the Southern Indian Ocean (SIO) circulation. The experiments are performed for the 2014–2022 period to cover the 2015–2016 super El Niño and the 2020–2022 consecutive La Niña. Our results reveal a main pathway of Pacific-origin baroclinic Rossby waves stretching from the Maritime Continent to Madagascar, with ENSO signatures weakening rapidly as proceeding westward. The Pacific-origin oceanic signals explain ∼95 % of the strength variability in the ITF outflow at 116°E, ∼66 % of that in the South Equatorial Current (SEC) and ∼17 % of that in the Northeast Madagascar Current (NEMC) during 2014–2022. Through this “oceanic channel” mechanism, the 2015–2016 El Niño led to a strengthened NEMC in 2016 and a weakened Southeast Madagascar Current (SEMC) in 2017. By contrast, this oceanic channel effect is generally negligible for the AC system which is dominated by ocean internal variability. These results constrain the extent of ENSO's modulation effect on the SIO circulation and imply that effective ocean-channel communication between the Pacific and the Atlantic has to occur on decadal or longer timescales.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"222 ","pages":"Article 104532"},"PeriodicalIF":2.3,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping suitable thermal migration corridors for western Alaska chum salmon in the North Pacific","authors":"Emily Lemagie ,&nbsp;Ed Farley ,&nbsp;Joseph A. Langan ,&nbsp;Phyllis J. Stabeno","doi":"10.1016/j.dsr.2025.104531","DOIUrl":"10.1016/j.dsr.2025.104531","url":null,"abstract":"<div><div>It is evident that warming North Pacific Ocean (NPO) temperatures are impacting salmon fitness and survival. Record-low western Alaska chum salmon run sizes were recorded in the Yukon River during 2020 and 2021. Based on recent analyses of Pacific salmon species-specific ocean temperature preferences, chum salmon have the widest thermal preference range; we focus on chum because they may have the greatest resilience to temperature variability and if their range is impacted, it is likely other species will respond to observed warming as well. Thermal suitability was mapped along the seasonal migration based on swimming rates to examine potential interannual range or distribution shifts. Two individual-based models of salmon migration driven by surface temperatures and geostrophic currents were run to test the impact of ocean physics on migration and distribution. We found that in the last decade ocean temperatures have similar magnitude and variability as projected through 2050. Since around 2013, the high suitability migration corridor has shifted northwards into the Bering Sea, but the seasonal migration may not be driven primarily by temperature or ocean currents. Warmer ocean temperatures, marine heatwaves, and loss of seasonal sea ice are likely to have the greatest impacts on western Alaska chum salmon where thermal suitability is lowest–in the Bering Sea in winter, and in the eastern Gulf of Alaska in summer. The impacts at the margins of their habitat range may lead to poor condition, a northward domain shift, and more fish entering the Arctic Ocean.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"222 ","pages":"Article 104531"},"PeriodicalIF":2.3,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diversity and distribution of Tanaidacea (Crustacea: Peracarida) in the abyssal polymetallic nodule fields of the eastern Clarion-Clipperton Fracture Zone","authors":"Chee Kong Chim ,&nbsp;Koh Siang Tan","doi":"10.1016/j.dsr.2025.104521","DOIUrl":"10.1016/j.dsr.2025.104521","url":null,"abstract":"<div><div>Tanaidaceans comprise a significant macrofaunal component of the abyssal plains in the Clarion-Clipperton Fracture Zone (CCFZ), Pacific Ocean. A large amount of tanaid material were examined from the eastern end of CCFZ, specifically the OMS (Singapore) and UK-I (United Kingdom) exploration areas and one of the nearest Area of Particular Environmental Interest APEI-6. Some 1800 individuals were collected from 89 stations at 4016–4336 m depth primarily using the box corer, epibenthic sled and multiple corer during three research cruises conducted between 2013 and 2020. Based on morphological characters, a total of 98 species and morphospecies belonging to 12 families were identified from these specimens, of which 85 % are undescribed. Only seven of the 35 described tanaid species previously recorded from CCFZ were rediscovered in this study. The OMS and UK-I areas recorded 85 and 71 species, respectively, and these high species richness as compared to values reported in other exploration areas could be due to greater sampling effort. Despite the close geographical proximity of OMS and UK-I, only 59 % of recorded species were common between the areas. Differences were observed in tanaid density, species richness and species composition between the northern and southern stations in the combined areas of OMS and UK-I. Interestingly, the relatively distant APEI-6 recorded 11 species, all of which were also present in OMS and UK-I. This study did not detect any relationship between tanaid community measures and abiotic factors. Another important outcome of this study is that the addition of the 250 μm mesh to the usual 300 μm mesh increased the total number of individuals retained on the sieves by 25–32 %, but not the total number of species. Even though the 0–2 cm sediment layer contained 1.4–3.0 times and 2.1–8.3 times more individuals than the 2–5 cm and 5–10 layers, respectively, no species was found exclusively at the top layer.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"222 ","pages":"Article 104521"},"PeriodicalIF":2.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}