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

{"title":"Descriptions of two new deep-sea nemertean species from the genera Alvinonemertes and Sagornya gen. nov. (Hoplonemertea, Oerstediina) with discussion on close genetic relationship between deep-sea species","authors":"Alexei V. Chernyshev,&nbsp;Vasiliy G. Kuznetsov","doi":"10.1016/j.dsr.2024.104439","DOIUrl":"10.1016/j.dsr.2024.104439","url":null,"abstract":"<div><div>In a recent study by Sagorny et al. (2022), nine new species of deep-sea hoplonemerteans, including five from the new genus <em>Alvinonemertes</em> Sagorny, von Döhren, Rouse &amp; Tilic, 2022, have been described from off the Pacific coast of Costa Rica and the Oregon margin. The new species <em>Alvinonemertes tilici</em> sp. nov., found during the research cruise #94 aboard the R/V <em>Akademik M.A. Lavrentyev</em> in the Emperor Seamounts, has proven to be very close morphologically and genetically to <em>A. dariae</em> Sagorny et al., 2022 from the methane Parrita Seep, off Costa Rica. As a phylogenetic analysis based on five gene markers (cytochrome <em>c</em> oxidase subunit I, 1<em>6S</em> rRNA, <em>18S</em> rRNA, <em>28S</em> rRNA, and histone H3) has shown, the genus <em>Alvinonemertes</em> is not monophyletic. Four species of <em>Alvinonemertes</em> are here segregated into a new genus, <em>Sagornya</em> gen. nov. The new species <em>Sagornya iturupica</em> sp. nov. is described based a specimen collected from the bathyal zone in the Sea of Okhotsk. This species is close genetically to <em>S. tatjanae</em> (Sagorny et al., 2022) comb. n. from seeps along the Oregon margin. The family Oerstediidae is divided into two sister groups: the subfamilies Oerstediinae and Tetranemertinae subfam. nov. To date, the new clade <em>Gononemertes</em> is the largest clade in the family Oerstediinae in terms of number of deep-sea and symbiotic species. Examples of close genetic similarity between deep-sea species from the genera <em>Nemertovema</em>, <em>Tetrastemma, Alvinonemertes, Sagornya</em>, and <em>Carinina</em> are considered. The study has shown that the genetic differences between deep-sea hoplonemerteans from the western and eastern Pacific Ocean are lower than those between sibling hoplonemertean species from Pacific shallow waters off North America and Asia. A hypothesis is advanced here that species with limited geographical ranges are frequently found among deep-sea nemerteans. The wide distribution of deep-sea hoplonemerteans can be provided by long-swimming lecithotrophic larvae, as in Cratenemertidae sp. MCZ IZ 45644.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"216 ","pages":"Article 104439"},"PeriodicalIF":2.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143092860","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":"Vertical and seasonal variations in stable oxygen isotope ratio of living planktonic foraminifera and estimation of habitat depth in the western tropical Pacific","authors":"Tae Wook Ko ,&nbsp;Kyung Eun Lee ,&nbsp;Ryoung Ah Kim","doi":"10.1016/j.dsr.2024.104440","DOIUrl":"10.1016/j.dsr.2024.104440","url":null,"abstract":"<div><div>To verify the habitat depth of planktonic foraminifera, the variability of foraminiferal δ¹⁸O (δ¹⁸O_pforam) by depth, season, day and night was investigated over a water depth of 0–600 m in the western tropical Pacific region. Species that inhabit the surface mixed layer in April include <em>Globigerinoides sacculifer, Globigerinoides ruber</em> white<em>, Globigerinoides conglobatus, Globigerinella siphonifera,</em> and <em>Orbulina universa</em> (δ¹⁸O_pforam, −2.2‰ to –2.9‰). Meanwhile, <em>Globorotalia hirsuta</em> and <em>Globorotaloides hexagonus</em> inhabit the upper thermocline (δ¹⁸O_pforam, −0.3‰to –1.2‰) and lower thermocline (δ¹⁸O_pforam, 1.2‰), respectively. In August, various species inhabit the uppermost thermocline during the day (<em>G. sacculifer</em>, <em>G. ruber</em> white, <em>G. siphonifera</em>, <em>G. conglobatus</em>, <em>O. universa</em>, <em>Globorotalia menardii</em>, <em>Hastigerina pelagica</em>, <em>Neogloboquadrina dutertrei</em>, <em>Pulleniatina obliquiloculata</em>, and <em>Globoquadrina conglomerata</em>) (δ¹⁸O_pforam, −2.2‰ to –3.2‰). At night, <em>G. sacculifer</em> without sac and <em>G. menardii</em> appear to inhabit the surface mixed layer (δ¹⁸O_pforam, −2.9‰ to –3.4‰). <em>G. hexagonus</em> inhabits the lower thermocline (δ¹⁸O_pforam, 1.3‰) in August. The vertical distribution of δ¹⁸O_pforam in December was similar to that of April δ¹⁸O_pforam. The habitat depths inferred from δ¹⁸O_pforam were mostly consistent with those estimated from species abundance. Species that did not match were <em>Globorotalia truncatulinoides</em> (in April), <em>Globigerinoides elongatus</em> (in December), <em>G. hirsuta</em> (in August), and <em>G. hexagonus</em> (in December). The results of δ¹⁸O analysis suggest that <em>G. truncatulinoides</em> lives in the uppermost thermocline, and <em>G. elongatus</em> in the surface mixed layer. In the case of <em>G. hirsuta</em> and <em>G. hexagonus</em>, they inhabit the upper thermocline and lower thermocline, respectively. Our results contribute to research on reconstructing past thermocline structure using geochemical analysis of planktonic foraminifera in marine sediments in this region.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"216 ","pages":"Article 104440"},"PeriodicalIF":2.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143092859","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":"Investigation of the influence of stratification and background currents on Internal Solitary Waves in the northern South China Sea based on the Wavefront model","authors":"Zijian Cui ,&nbsp;Chujin Liang ,&nbsp;Beifeng Zhou ,&nbsp;Feilong Lin ,&nbsp;Tao Ding ,&nbsp;Weifang Jin","doi":"10.1016/j.dsr.2025.104442","DOIUrl":"10.1016/j.dsr.2025.104442","url":null,"abstract":"<div><div>Internal Solitary Waves (ISWs) are nonlinear internal waves generated within vertically stratified oceans, characterized by large amplitudes and strong destructive capabilities. Previous studies have shown that background currents significantly affect the propagation process of ISWs. However, the background currents can also induce changes in stratification, and the specific manner in which they influence ISWs remains unclear. This study, based on the Wavefront model, independently investigates the effects of oceanic stratification and background currents on the nonlinear phase velocity, crest line morphology, and energy distribution of ISWs in the northern South China Sea. The results show that compared to stratification, background currents are more likely to alter the nonlinear phase speed of ISWs. The background currents also significantly alter the generation locations and propagation directions of ISWs. Furthermore, this study analyzes the propagation characteristics of ISWs under different Kuroshio circulation patterns and points out that the Kuroshio primarily regulates ISWs through background currents. The Wavefront model serves as a powerful tool for accurately forecasting ISWs in the northern South China Sea and holds great potential for studying other characteristics of ISWs.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"216 ","pages":"Article 104442"},"PeriodicalIF":2.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143092920","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":"Modeling mesoscale circulation and potential fish larvae transport at the entrance of a semi-enclosed sea under different periods","authors":"Laura Sánchez-Velasco ,&nbsp;Jorge Montes-Arechiga ,&nbsp;Emmanuel Romero ,&nbsp;Erick D. Ruvalcaba-Aroche ,&nbsp;Victor M. Godínez ,&nbsp;Leonardo Tenorio-Fernández ,&nbsp;Emilio Beier ,&nbsp;Lydia B. Ladah","doi":"10.1016/j.dsr.2024.104430","DOIUrl":"10.1016/j.dsr.2024.104430","url":null,"abstract":"<div><div>Data from three oceanographic cruises at the entrance to the Gulf of California (April 2012, June 2015, and October 2020) were used to model the transport of preflexion fish larvae associated with the mesoscale eddies that dominated the surface circulation during the study periods. Hydrographic transects crossed sections of various eddies of different life histories (origin, rotation, dimensions). A lagrangian particle tracking model (HYCOM) was applied to a cross-Gulf transect using six key locations over the mesoscale structures. The 14-day simulations showed that most particles were retained within the eddies. In April 2012, 85% of the particles remained at the entrance to the Gulf of California until day 7, and one week later, 34% arrived at the north side of the boundary between the entrance to the Gulf of California and the southern Gulf (with no free transport to north). In October 2022, no particles arrived at the southern Gulf of California during the 14 days. In June 2015, however, &gt;90% of the particles were transported to the north by day 14, and 56% of these, to the southern Gulf of California, corresponding with the detection of the poleward Mexican Coastal Current on the mainland side. Dominant fish species in the region with seasonal changes in abundance included <em>Benthosema panamense</em> (mesopelagic), <em>Auxis</em> spp. (epipelagic), <em>Bregmaceros bathymater</em> (pelagic neritic) and <em>Syacium ovale</em> (soft-demersal). Extrapolating the modeling results to preflexion fish larvae distributions, it appears that these mesoscale structures may trap most of the larvae spawned in the Gulf of California entrance. June 2015 was the exception when the fish larvae could disperse from the entrance to the Gulf of California towards the north, corresponding with the period of spawning for some soft-demersal fish species in the region. We conclude that the high mesoscale activity that occurs most of the year at the entrance to the Gulf of California might be a dynamic barrier that controls the dispersal of fish larvae and other planktonic organisms in the region, and might occur in other semi-enclosed seas as well.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"216 ","pages":"Article 104430"},"PeriodicalIF":2.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143092913","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":"Forecasting summer marine heatwaves in the South China Sea using explainable machine learning models","authors":"Chaorong Mi ,&nbsp;An Yi ,&nbsp;Jingyuan Xue ,&nbsp;Changming Dong ,&nbsp;Haixia Shan","doi":"10.1016/j.dsr.2025.104457","DOIUrl":"10.1016/j.dsr.2025.104457","url":null,"abstract":"<div><div>Marine Heatwaves (MHWs), classified as extreme oceanographic meteorological phenomena, have profound effects on ecological systems and socio-economic activities within the South China Sea (SCS). Multiple machine learning (ML) algorithms, specifically Random Forest (RF) and Ridge models, are employed to predict summer Sea Surface Temperature Anomalies (SSTA) and occurrence of MHWs in the SCS. The ML forecast results are also compared with climatology forecasts, persistence forecasts, and the European Centre for Medium-Range Weather Forecasts Sub-seasonal to Seasonal (ECMWF S2S) hindcasts. The results reveal that for regression forecasting with a one-week lead time, the Ridge model performs the best among all models. However, for longer lead times, all models tend towards climatology forecasts. When it comes to the classification forecasting, the RF model demonstrates superior performance to predict extreme MHWs compared to typical MHWs. Moreover, the feature importance is measured via the mean decrease in impurity (MDI) incorporated in the RF model to identify the predictors that contribute to predicting the MHWs. The SHapley Additive exPlanation (SHAP) algorithm is additionally employed to evaluate both the positive and negative impacts of these predictors on the model. SSTA and the Indian Ocean Basin-Wide (IOBW) index are the most two critical forecasting factors influencing the occurrence of MHWs, exhibiting a pronounced positive contribution to the model. The insights derived from this study are expected to provide strong support for the MHWs early warning system in the SCS and provide essential information for the conservation of marine ecosystems and the management of fisheries resources.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"218 ","pages":"Article 104457"},"PeriodicalIF":2.3,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429057","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":"Interaction between the M2 internal tides and typhoon-induced near-inertial waves near the Luzon Strait","authors":"Anzhou Cao ,&nbsp;Zheng Guo ,&nbsp;Xu Chen ,&nbsp;Xinyu Guo ,&nbsp;Jinbao Song","doi":"10.1016/j.dsr.2025.104452","DOIUrl":"10.1016/j.dsr.2025.104452","url":null,"abstract":"<div><div>The South China Sea is abundant with intense internal tides (ITs) and typhoon-induced near-inertial waves (NIWs), which inevitably interact with each other. Based on the numerical simulation results, the interaction between the M₂ ITs and typhoon Megi-induced NIWs in the deep ocean near the Luzon Strait is studied. The interaction gives rise to sum- and difference-frequency waves, denoted as the <em>f</em>M₂ and M₂-<em>f</em> waves. Results of this study highlight the contribution of the M₂-<em>f</em> waves to shear enhancement: The kinetic energy of the M₂-<em>f</em> waves is one order of magnitude smaller than that of the M₂ ITs, but the domain-averaged vertical shear squared caused by the M₂-<em>f</em> waves is comparable to that of the M₂ ITs. The IT-NIW interaction is dominated by the product of vertical internal tidal velocity and vertical shear of horizontal near-inertial velocity, which is followed by the product of horizontal near-inertial velocity and horizontal shear of horizontal internal tidal velocity. The IT-NIW interaction influences the evolution of near-inertial kinetic energy through modulating the energy exchange and near-inertial energy flux, which are site-dependent. In the modulation of energy exchange, the terms associated with horizontal shear of horizontal internal tidal velocity play crucial roles. Whereas in the modulation of near-inertial energy flux, the terms associated with vertical shear of horizontal near-inertial velocity are dominant.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"217 ","pages":"Article 104452"},"PeriodicalIF":2.3,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133978","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":"Rock bottom: Colonization patterns of deep-sea Arctic and subarctic dropstones (200–1300 m)","authors":"Sophie Wolvin ,&nbsp;Jean-François Hamel ,&nbsp;Annie Mercier","doi":"10.1016/j.dsr.2025.104454","DOIUrl":"10.1016/j.dsr.2025.104454","url":null,"abstract":"<div><div>Hard substrata of allochthonous origin, such as ice-rafted dropstones, can provide essential habitat for benthic communities in the polar and subpolar deep sea, acting as “islands” in otherwise finer-grained sedimentary environments. The present study explored the diversity and distribution patterns of morphospecies (msp/mspp) present on dropstones collected at depths of ∼200–500 m in the Labrador Sea (LAB) and ∼700–1300 m in Baffin Bay (BAF), respectively spanning subarctic and Arctic regions of eastern Canada. Specifically, the zonation, intra- and interspecific interactions, and succession of all colonizers were examined. Based on <em>in</em>-<em>situ</em> images, dropstones exhibited ∼94% greater epibenthic megafaunal richness than similar surfaces of the substratum immediately surrounding them. Analysis of three dropstones collected from each of six sites documented a total of 101 sessile and motile taxa spanning 10 phyla. Across sites, bryozoans dominated at all depths and locations (27 mspp, plus 3 dead) followed by poriferans (27 mspp), 19 cnidarians, eight arthropods, eight annelids, five chordates (tunicates), three echinoderms, three molluscs, and one foraminifer. There were 19 mspp that spanned both LAB and BAF, with greater overall richness in the subarctic region (62 vs 26 mspp). A total of 64 sessile mspp occurred above the stone-sediment interface (e.g., cnidarians and poriferans), whereas 22 mspp (mostly bryozoans) occurred at the stone-sediment interface; one morphospecies of polychaete occurred below. The most abundant morphospecies was an arborescent bryozoan, while two encrusting bryozoans covered the most surface area. Eight morphospecies occurred as just one individual or colony per stone, and 35 mspp appeared to maintain an exclusion zone between conspecifics (e.g., tube-dwelling annelids, hydrozoans, and anthozoans). Conversely, in 51 mspp conspecifics occurred abutting one another (e.g., bryozoans and poriferans). Allospecific exclusion zones appeared to occur in 27 mspp (e.g., bryozoans and annelids), whereas 59 allospecifics (e.g., poriferans, cnidarians, and chordates) occurred within touching distance. Secondary colonization (including cases of epibiosis) was observed in 83 mspp, documenting 204 unique pairings of hosts and colonizers. The number and diversity of morphospecies colonizing dropstones in the deep sea of the eastern Canadian Arctic and subarctic support the role of dropstones as oases that facilitate connectivity in an otherwise poorly diversified epibenthic environment.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"217 ","pages":"Article 104454"},"PeriodicalIF":2.3,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strong magnetism and geochemical characteristics of sediment in Challenger Deep and their indications for sources","authors":"KaiWei Wang ,&nbsp;YongHong Wang ,&nbsp;QiuYu Yue ,&nbsp;XiaoHua Zhang ,&nbsp;JiWen Liu ,&nbsp;Chunhui Xiao ,&nbsp;Toshiya Kanamatsu ,&nbsp;Michael Strasser ,&nbsp;Rui Bao","doi":"10.1016/j.dsr.2025.104455","DOIUrl":"10.1016/j.dsr.2025.104455","url":null,"abstract":"<div><div>Understanding the properties of trench sediments is an important aspect of comprehending the sources and transport variations of trench sediments. This study seeks to identify the sources of sediment and understand the mechanisms driving sediment source variation in the Challenger Deep, based on the environmental magnetic characteristics and geochemical properties of the MT20-750 core retrieved from a depth of 10,815 m in the Mariana Trench. The proximal sediment source of the MT20-750 core comprises mainly altered bedrock components from the southern Pacific Plate and volcanic eruption materials from the northern Philippine Plate, while the distal source is primarily aeolian dust input, with biogenic materials also contributing. The overall magnetic susceptibility values of the sediments in the Challenger Deep are significantly higher, reaching 3–5 times that of other regions in the Pacific Ocean. The strong magnetic properties of these sediments are primarily due to the enhanced alteration of the southern subducting plate rocks, which are mainly composed of basalt rich in iron and magnesium (mafic basalt), under the action of Pacific bottom water. This represents a normal state when sediments are funneled into the trench axis and preserved in an oxidizing environment. However, the sediments from the northern Philippine Sea Plate, mainly composed of tuffaceous rocks with lower Fe, Mg, and Ti content, intermittently enter the trench during seismic events or turbidity flows. These events alter the sediment composition in the trench, leading to a decrease in magnetic susceptibility values, with the change in provenance primarily driven by the varying intensity of geological processes and the specific conditions of sediment transport.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"217 ","pages":"Article 104455"},"PeriodicalIF":2.3,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133521","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":"Vertical variations in zooplankton size spectra down to 3,000 m depth and significant effects of the sizes of Calanoida and Ergasilida across the subarctic, transitional, and subtropical regions of the western North Pacific","authors":"Dongwoo Kim ,&nbsp;Sota Komeda ,&nbsp;Kohei Matsuno ,&nbsp;Atsushi Yamaguchi","doi":"10.1016/j.dsr.2025.104445","DOIUrl":"10.1016/j.dsr.2025.104445","url":null,"abstract":"<div><div>Zooplankton size spectra are crucial for evaluating marine ecosystem structure, with copepods being the predominant taxa within the marine zooplankton communities. Among copepods, Calanoida and Ergasilida are the two numerically dominant taxa. Despite their importance, limited information exists regarding the effects of these two taxa on the overall zooplankton size spectra. This study aimed to comprehensively evaluate the regional and vertical changes in zooplankton size spectra, normalised biomass size spectrum (NBSS), and size diversity across subarctic, transitional, and subtropical regions of the western North Pacific Ocean. Additionally, the study aimed to investigate the effects of size variations in two dominant copepod taxa, Calanoida and Ergasilida, on the overall zooplankton size spectra. To achieve this, vertically stratified zooplankton samples were collected from 12 layers, ranging from the sea surface to a depth of 3000 m, at five stations across the subtropical to subarctic western North Pacific. The samples were analysed using ZooScan to assess the overall zooplankton size spectra and the effects of Calanoida and Ergasilida on it. Across all stations, the NBSS slopes became moderate, and the size diversity increased with increasing depth, particularly evident for the oxygen minimum layer (OML) at approximately 1000 m depth. These patterns reflect a high proportion of large-sized zooplankton in the deeper layers and a lower predation pressure from micronektonic fish around the OML. Calanoida and Ergasilida accounted for 43.3% and 24.6% of the mean zooplankton abundance, respectively. Among the two taxa, Calanoida exhibited significant changes in body size depending on the station and depth, being larger in the subarctic region and deeper layers. Ergasilida showed minimal changes in body size relative to location and depth. The body size of Calanoida significantly influenced the overall zooplankton size spectra. Therefore, the dominance of large-sized Calanoida induced a moderate NBSS slope and high size diversity in the overall zooplankton size spectra. The results of this study indicate that the size of Calanoida, the dominant taxon in the zooplankton community, primarily governs the size spectra of the overall zooplankton community.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"217 ","pages":"Article 104445"},"PeriodicalIF":2.3,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interannual variability in surface mesozooplankton in the Western Antarctic Peninsula during two anomalous years","authors":"Camila Máximo Leonor ,&nbsp;Erik Muxagata","doi":"10.1016/j.dsr.2025.104444","DOIUrl":"10.1016/j.dsr.2025.104444","url":null,"abstract":"<div><div>Zooplankton play a key role in the Southern Ocean, are closely linked to oceanographic variations and are highly sensitive to environmental changes. The Western Antarctic Peninsula (WAP) is a critical global climate hotspot where the variability and vulnerability of marine ecosystems are particularly evident. This study aims to characterize the variability of surface mesozooplankton across the Gerlache (GS) and Bransfield (BS) straits. Data were collected with a continuous plankton recorder (CPR) during the austral summer of 2016 (CPR-34 route) and 2017 (CPP-35 route), enabling extensive spatial mapping of zooplankton communities. In 2016, the average sea surface temperature (SST) was 0.57 °C, whereas in 2017, it increased to a maximum of 2.13 °C. The surface salinity (SS) was lower in 2017 (average 33.86). High chlorophyll-<em>a</em> values were recorded in the GS in 2016 (43.78 mg m⁻³). PERMANOVA revealed significant differences in community composition between the year and location site. Beta diversity analysis revealed nestedness in 2016, with Copepoda dominating the mesozooplankton community, particularly <em>Metridia gerlachei</em> and <em>Metridia longa,</em> which accounted for 85% of the total abundance of Copepoda. In 2017, events of replacement, known as turnover, were observed, with a shift from copepods to salps along with lower local diversity. The BS had a relatively high abundance in both years, reflecting the sampling periods and dial migration patterns. CCA revealed positive correlations between salps and temperature and negative correlations between salinity and copepods. These findings highlight distinct community structure patterns driven by specific environmental conditions linked to major climatic events, i.e., the ENSO and SAM, offering insights into zooplankton responses to anomalous oceanographic conditions in the WAP.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"217 ","pages":"Article 104444"},"PeriodicalIF":2.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133980","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}