Progress in Oceanography最新文献

{"title":"Global-scale biogeography of the pelagic polychaete family Tomopteridae (Annelida) revealed by DNA barcoding and genome-wide single nucleotide polymorphisms","authors":"Kanako Amei ,&nbsp;Junya Hirai ,&nbsp;Erica Goetze ,&nbsp;Yuichiro Nishibe","doi":"10.1016/j.pocean.2026.103689","DOIUrl":"10.1016/j.pocean.2026.103689","url":null,"abstract":"<div><div>Zooplankton are essential members of marine ecosystems that respond sensitively to environmental changes. While the distribution patterns of zooplankton have been extensively investigated in the global ocean, pelagic polychaetes, particularly the Tomopteridae family, are underexplored in diversity and biogeography, due to their fragile bodies and subtle morphological traits. In the current study, mitochondrial cytochrome <em>c</em> oxidase subunit I (mtCOI), nuclear 28S rRNA, and genome-wide single-nucleotide polymorphisms (SNPs) were analyzed to characterize the diversity and distribution of tomopterid species globally. Phylogenetic analyses of mtCOI were conducted for 603 specimens collected from 54 stations across the global ocean. Concordance was detected between 14 mitochondrial lineages and their genome-wide SNPs, while species-level operational taxonomic units (OTUs) were defined based on mtCOI sequence similarity (≥ 2.4%) supported by genome-wide SNPs. The comprising the global dataset contained 35 OTUs and 17 singletons, representing at least 52 tomopterid species. The number of species we assumed in this study exceeds previous morphological reports from certain ocean regions, including the eastern and western North Pacific Ocean (18 OTUs:11 species and 9 OTUs:7 species, respectively), suggesting the existence of previously unrecognized species. No specimens in this study were classified to species by morphotaxonomy. Tomopterids exhibited distribution patterns that corresponding to the general biogeography of other zooplankton, including subarctic/boreal, subarctic/bipolar, temperate–subtropical/circumglobal, temperate-subtropical/Indo-Pacific, equatorial, and upwelling region distributions. As this is the first species-level study of the global-scale biogeography of Tomopteridae, the findings provide fundamental information for future ecological and evolutionary studies on tomopterids.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"243 ","pages":"Article 103689"},"PeriodicalIF":3.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134967","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":"Potential impact of seamount on the mild oxygen minimum zone (OMZ) in the Western Pacific","authors":"Jun Ma ,&nbsp;Lilian Wen ,&nbsp;Xuegang Li ,&nbsp;Kuidong Xu ,&nbsp;Jiajia Dai ,&nbsp;Yi Sun ,&nbsp;Guorong Zhong ,&nbsp;Detong Tian ,&nbsp;Huamao Yuan ,&nbsp;Liqin Duan ,&nbsp;Jinming Song","doi":"10.1016/j.pocean.2025.103666","DOIUrl":"10.1016/j.pocean.2025.103666","url":null,"abstract":"<div><div>Seamount and the oxygen minimum zone (OMZ) are often two typical habitats coexisting in the deep sea, and studying the relationship between the “seamount effect” and OMZ is of great significance to improve the cognitive level of the two typical deep-sea habitats. Based on the investigation of the two cruises in the M4 seamount of the Western Pacific, this study revealed the “seamount effect”, explored the impact of seamount and environmental parameters on OMZ. The results showed that the uplifts of the isohaline, isotherm and isopycnal occurred near the summit in the two cruises, and the isolines of NO₃-N, PO₄-P and NO₂-N were also elevated near the summit. Meanwhile, the ratio of the average concentration of POC near the summit for cruise 1 to cruise 2 can reach up to about 2 times. This may indicate that there was a “seamount effect” in both cruises, and it was stronger in cruise 1. The range and intensity of OMZ in both cruises were similar, with the range of 550–1100 m and (330–380, 850–1100) m, respectively. The impact of seamount on OMZ may be reflected in two aspects. One possible mechanism was that the hydrological phenomena such as upwelling near the summit may raise the isolines of low concentration DO in 200–300 m, increasing the range of the upper boundary of OMZ; Another possibility was that the biological activities of seamount sediments continuously may consume DO, such as in 1000 m at station A7 of cruise 1, increasing the intensity of OMZ. In addition, the temperature below 1000 m directly controlled the upper boundary of OMZ, while the decomposition of organic matter in 75–300 m above the OMZ consumed DO, which also had an important impact on the range and intensity of the OMZ.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103666"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940881","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 connectivity of deep-sea Amphipoda of the Bering Sea and the Aleutian Trench revealed with DNA barcoding","authors":"Anna M. Jażdżewska ,&nbsp;Anne Helene S. Tandberg ,&nbsp;Wiktor Leszczyński","doi":"10.1016/j.pocean.2025.103655","DOIUrl":"10.1016/j.pocean.2025.103655","url":null,"abstract":"<div><div>Amphipoda are speciose and abundant in all marine habitats and are proven to be important food source for higher trophic levels. These crustaceans are brooders with no planktonic larval stage, so migration of species depend mainly on swimming capacities of adult animals.</div><div>The aims of the present work were: 1) characterizing the diversity of abyssal and hadal amphipods of the Bering Sea (BS) and the Aleutian Trench (AT), 2) studying the amphipod species distribution as well as 3) inferring the connectivity between North East Pacific amphipod fauna and the other deep-sea regions of the world ocean.</div><div>The material was collected with and epibenthic sledge from two stations in the South East BS, three stations on the northern slope of the AT, three stations on the southern slope of the AT and six stations in the hadal of the AT. A representation of all collected amphipods was initially sorted into families and preferably morphospecies and subjected to cytochrome <em>c</em> oxidase subunit I gene (COI) barcoding.</div><div>The barcoding of 575 individuals resulted in 460 sequences that were ascribed to 182 Molecular Operational Taxonomic Units (MOTUs). At least 25 families, 31 genera and six known species were identified. The families (or groups of families) that dominated barcoded material in terms of abundance were: Oedicerotidae (76 ind.), Eusiridae (75 ind.) and Lysianassoidea indet. (61 ind.), while the most speciose groups were: Lysianassoidea indet. (31 MOTUs), followed by Pardaliscidae (29 MOTUs) and Oedicerotidae (28 MOTUs). Almost three quarters of all MOTUs were singletons or doubletons, however as many as 46 MOTUs appeared to be shared with other regions of the World Ocean. The Bering Sea and both slopes of the trench appeared to harbour significantly higher number of amphipod MOTUs (51–61 MOTUs) than the hadal zone of the AT (33 MOTUs). The highest faunal exchange appeared to be between abyssal and hadal zones of the AT and similar depth zones of the Kuril-Kamchatka Trench (39 MOTUs), the second most connected region was the abyss of Clarion-Clipperton Zone (11 MOTUs). The BS fauna demonstrated high uniqueness with only four MOTUs shared with AT abyss and hadal as well as with four MOTUs shared with NW Pacific.</div><div>The study confirmed high species richness of another deep-sea region of the World, formerly almost completely unknown.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103655"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785681","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":"Beyond temperature: predictive modelling of range shifts in benthic peracarids across the northern North Pacific under future climate scenarios","authors":"Stefanie Kaiser ,&nbsp;Anna M. Jażdżewska ,&nbsp;Sarah Gerken ,&nbsp;Anne Helene S. Tandberg ,&nbsp;Chih-Lin Wei ,&nbsp;Davide Di Franco ,&nbsp;Hanieh Saeedi ,&nbsp;Hannah Owens ,&nbsp;Henry Knauber ,&nbsp;Emma Palacios Theil ,&nbsp;Angelika Brandt ,&nbsp;Pedro Martinez Arbizu ,&nbsp;Jens Oldeland","doi":"10.1016/j.pocean.2025.103657","DOIUrl":"10.1016/j.pocean.2025.103657","url":null,"abstract":"<div><div>Accelerating climate change driven by greenhouse gas emissions is profoundly impacting marine biodiversity. Some species are shifting their geographic ranges toward more favourable environments, while others lose suitable habitat and face extinction. We examined the effects of climate change on selected benthic peracarid species (Amphipoda, Cumacea, and Isopoda) in the Pacific Arctic, Pacific Subarctic, and North Pacific temperate ecosystems—regions characterized by environmental sensitivity and unique topography. Using Maximum Entropy (MaxEnt) modelling, we identified key environmental drivers of species occurrence and projected horizontal and vertical shifts until 2050 and 2100 under RCP 2.6 and 8.5 scenarios. We further analysed how ecological traits such as diet, mobility, and life habit correlate with distributional responses. While most species shifted northward, some exhibited unexpected directional changes, likely due to regional differences in climate velocity, environmental change, and species-specific responses. Temperature emerged as a primary determinant for many species, with dissolved oxygen and salinity also playing critical roles. Our findings indicate that traits—particularly diet and bathymetric distribution—affect potential habitat expansions or contractions, categorizing species as potential “winners” or “losers.” Despite challenges including deep-sea data limitations and complex trait interactions, our study provides vital insights into future peracarid distributions. These results underscore the need for refined predictive models and targeted conservation strategies to enhance ecosystem resilience and sustainable resource management in a warming ocean.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103657"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145844678","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 re-evaluation of Atlantic bluefin tuna (Thunnus thynnus) spawning distribution in the western Atlantic Ocean","authors":"David E. Richardson ,&nbsp;Katrin E. Marancik ,&nbsp;Malgorzata Adamus ,&nbsp;Elisabeth A. Broughton ,&nbsp;Robert K. Cowen ,&nbsp;Trika Gerard ,&nbsp;Christina M. Hernández ,&nbsp;John J. Hoey ,&nbsp;Joel K. Llopiz ,&nbsp;Molly E. Lutcavage ,&nbsp;Estrella Malca ,&nbsp;Debra L. Palka ,&nbsp;Lourdes Vásquez-Yeomans ,&nbsp;Harvey J. Walsh ,&nbsp;C. Michelle Willis ,&nbsp;Glenn A. Zapfe","doi":"10.1016/j.pocean.2026.103687","DOIUrl":"10.1016/j.pocean.2026.103687","url":null,"abstract":"<div><div>There is currently a lack of consensus on the spatial, seasonal and decadal-scale patterns of Atlantic bluefin tuna (<em>Thunnus thynnus</em>) spawning in the western Atlantic Ocean. We compiled ichthyoplankton and reproductive data to characterize bluefin spawning patterns and the uncertainty in these patterns. Ichthyoplankton data indicates that bluefin spawn in the Gulf of America/Gulf of Mexico, northwest Caribbean Sea, north of the Bahamas, along the inshore edge of the Florida Current off the Carolinas and in the western Slope Sea. Reproductive studies identified these same spawning areas, as well as the Windward Passage and waters east of the Bahamas. We used regional sea surface temperature cycles and the distribution of electronically tagged bluefin to identify potentially undocumented spawning areas and times. The northwest Sargasso Sea may also support spawning in June but has not been sampled. Our data is consistent with Atlantic bluefin tuna having a continuous spawning distribution that starts in April in the northwest Caribbean and southern Gulf, progresses through the western Sargasso Sea in June and finishes in early-August in the Slope Sea. The northern Gulf and western Slope Sea are identified as the two most prominent spawning locations across this distribution and spawning in the Sargasso Sea needs to be further evaluated. We could not resolve decadal-scale changes in spawning distribution or timing, but an earlier seasonal timing of optimum temperatures for spawning is evident in all areas. Future work to understand bluefin population structure and migrations will benefit from the data compiled during this study.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103687"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072661","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":"Dissolved organic matter (DOC, CDOM, FDOM) in the western Tropical South Pacific: Depth- and subregion-resolved variability, and hydrothermal influence","authors":"Marc Tedetti ,&nbsp;Catherine Guigue ,&nbsp;Léo Mahieu ,&nbsp;Pauline L. Martinot ,&nbsp;Mar Benavides ,&nbsp;Cécile Dupouy ,&nbsp;Sandra Nunige ,&nbsp;Elvira Pulido-Villena ,&nbsp;Céline Dimier ,&nbsp;Chloé Tilliette ,&nbsp;Sophie Bonnet ,&nbsp;Cécile Guieu ,&nbsp;Dominique Lefèvre","doi":"10.1016/j.pocean.2025.103664","DOIUrl":"10.1016/j.pocean.2025.103664","url":null,"abstract":"<div><div>The Western Tropical South Pacific has recently been identified as a global hotspot for microbial dinitrogen fixation and shallow hydrothermal activity, yet the dynamics of dissolved organic matter (DOM) in this ecosystem remains understudied. During the TONGA cruise (2019), we investigated the distribution of dissolved organic carbon (DOC), chromophoric DOM (CDOM) and fluorescent DOM (FDOM) from Melanesian waters to the South Pacific Gyre, including the Lau Basin/Tonga-Kermadec Volcanic Arc. DOC concentration, CDOM absorption [a_CDOM(254)], the CDOM spectral slope (S_275-295) and tyrosine-like fluorescence decreased from surface to deep waters across subregions. In contrast, apparent oxygen utilization (AOU), nutrients, a_CDOM(350), specific UV absorbance (SUVA₂₅₄), humic-like fluorescence, humification (HIX) and combustion (COX) indices increased with depth. These distributions reveal 1) the production of labile, low molecular weight DOM by phytoplankton, and photobleaching in the photic layer, and 2) the production of higher molecular weight, bio-refractory DOM from the remineralization of sinking particulate organic carbon and DOC in deeper waters. Also, the tryptophan-like fluorescence peaks at depth could be associated with the presence of sinking <em>Trichodesmium</em> spp. Regional variations in DOM characteristics were less pronounced than water-mass-related differences but revealed subtle trends along the west-east gradient, with overall higher DOC, CDOM and FDOM levels in the Melanesian and Lau Basin/Arc subregions compared to the South Pacific Gyre. At 200-m depth near the Arc, the release of hydrothermal fluids altered the DOM composition close to the vent, with significant increases in a_CDOM(254) and tyrosine-like material, and significant decreases in HIX and COX indices. We further show an indirect, large-scale impact of shallow hydrothermal vents on the DOM stock in the 0–50-m surface layer, driven by the iron fertilization-induced stimulation of planktonic activity in the photic zone. The increased DOM stocks were observed mostly in the Lau Basin/Arc subregion but extending to Melanesian waters and the western edge of South Pacific Gyre. Collectively, these processes shape the optical properties and biogeochemical behavior of DOM, highlighting the importance of hydrothermal systems in the oceanic carbon cycle.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103664"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979188","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":"Circadian particulate organic carbon driven by size-fractionated microbial communities in northern South China Sea","authors":"Xinxin Li ,&nbsp;Yifan Qi ,&nbsp;Ziyan Wang ,&nbsp;Wenpeng Li ,&nbsp;Hongwei Chen ,&nbsp;Xin Zhao","doi":"10.1016/j.pocean.2026.103681","DOIUrl":"10.1016/j.pocean.2026.103681","url":null,"abstract":"<div><div>Circadian POC-diurnal and nocturnal cycling of particulate organic carbon (POC)- could influence their seasonal and interannual biogeochemical patterns. In order to understand circadian POC in oligotrophic northern South China Sea, this study conducted a continuous 24 h time-series sampling across four depths (5 m, chlorophyll maximum depth, 200 m, and 662 m) of one site on the continental slope and analyzed optical properties of suspended particulate matter (SPM), POC properties, microbial community abundance and respiration rate (MCR) of size-fractionated microorganisms, and their dark carbon fixation rates (DCF). The results suggested varying degrees of coupling among SPM, POC, MCR, microbial abundance, and light intensity, associated with different primary production and diel vertical migration patterns. Size-fractionated analysis revealed three distinct metabolic patterns but no significant differences in their contribution to total MCR: synchronized variations between abundance of small phytoplankton and bacterioplankton organisms (0.2–0.8 μm) followed a “fast carbon cycling mode”; medium organisms (0.8–3.0 μm) showed significant correlations between bacterial abundance, POC, and MCR, functioning as primary POC decomposers; and large organisms (&gt;3.0 μm) displayed decoupled metabolic patterns, potentially utilizing non-primary productivity carbon sources. Dark carbon fixation (56.9 ± 9.2 mg C m⁻² d^-1) was an important POC supply besides export production and lateral transport in the deep ocean. The study emphasized the critical importance of considering the science of circadian POC when assessing biological carbon pump efficiency in oligotrophic marginal seas.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103681"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001419","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":"Seasonal dynamics and forcing mechanisms of the Cape Horn Current: insights from reanalysis data and hydrographic observations","authors":"José Garcés-Vargas ,&nbsp;Andrea Piñones ,&nbsp;Wolfgang Schneider ,&nbsp;Mauricio F. Landaeta ,&nbsp;Manuel I. Castillo ,&nbsp;Natalia Cisternas ,&nbsp;Carmen Barrios-Guzmán ,&nbsp;Fernanda Barilari","doi":"10.1016/j.pocean.2025.103665","DOIUrl":"10.1016/j.pocean.2025.103665","url":null,"abstract":"<div><div>Circulation along the west coast of South America originates from the eastward-flowing South Pacific Current, which bifurcates around 40-45°S. Its northern branch forms the Humboldt Current (HC), while the southern branch continues along the continental shelf as the Cape Horn Current (CHC). Despite significant scientific efforts to understand the HC, the CHC has received considerably less attention. This study investigates the spatial structure, seasonal variability, and forcing mechanisms of the CHC using a combination of reanalysis data (GLORYS12, ERA5) and <em>in-situ</em> observations. Our results reveal that the CHC’s dynamics are governed by the superposition of two distinct physical mechanisms with different vertical structures: a surface-intensified response to direct wind forcing, and a vertically-coherent geostrophic flow driven by sea surface height gradients. This dual structure explains both the year-round persistence of the current, due to its deep geostrophic core, and its seasonal cycle. The current exhibits a modest but consistent intensification during austral summer and spring, with mean velocities increasing from ∼ 16 cm s⁻¹ in autumn/winter to ∼ 18 cm s⁻¹ in the warmer seasons, a variability primarily associated with the surface wind-driven component. Correlation analysis confirms that wind and sea surface height gradients are the dominant forcings, particularly in the CHC core region (51°–56°S). Furthermore, the underlying physical mechanism is consistent with a coastal downwelling process, where persistent alongshore winds ultimately maintain the large-scale pressure gradient. In comparison with the Alaska Current, the CHC shows similarities in its wind-driven dynamics but differs in its largely barotropic geostrophic structure, in contrast to the strong baroclinic influence of freshwater in the Gulf of Alaska. Our findings clarify the dual nature of the CHC, highlighting its role as a key pathway in the Patagonian shelf-break region, which in turn influences regional climate, marine ecosystems, and biogeochemical cycles. Future research should focus on the interaction of these components using high-resolution hydrodynamic models to better elucidate its variability.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103665"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145903480","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":"Halocline as an environmental barrier for the larvae of Arctic marine benthic invertebrates","authors":"Weronika Patuła ,&nbsp;Marta Ronowicz ,&nbsp;Piotr Kukliński ,&nbsp;Agata Weydmann-Zwolicka","doi":"10.1016/j.pocean.2025.103649","DOIUrl":"10.1016/j.pocean.2025.103649","url":null,"abstract":"<div><div>Many marine benthic invertebrates possess a pelagic larval life stage (meroplankton) that is highly sensitive to environmental changes, influencing their spatial distribution, survival, and settlement. This study was conducted on the adjacent shelf and in Kongsfjorden, a high-Arctic fjord system in Svalbard, where the Kongsfjorden Transect (KT), influenced by Arctic and Atlantic oceanic regimes, shows strong variability in physico-chemical conditions. Consequently, changes in environmental conditions, including the depth of the halocline, can act as a physical barrier for organisms, affecting local biodiversity. We, investigated meroplankton vertical distribution in relation to the halocline, and hypothesized that the salinity gradient acts as a barrier for larvae, influencing their movements, distribution and diversity. We identified 25 meroplankton morphotypes along the KT, with Bivalvia veligers as the dominant taxon. Taxonomic assemblages differed significantly between above (AH) and below (BH) the halocline. More abundant Echinodermata larvae characterized the AH assemblage, which remained compositionally similar throughout the studied transect. In contrast, Polychaeta larvae were characteristic of the BH assemblage with greater spatial variability, consistent with decreasing temperature, salinity, and chlorophyll <em>a</em> concentration, towards the inner part of the fjord. By integrating detailed morphotype analysis with hydrographic data, we showed that the halocline is a barrier for meroplankton larvae, defining their vertical distribution, abundance, and taxonomic composition; we also present the indicator taxa of the AH and BH assemblages. Our results emphasize the role of the salinity gradient in shaping larval communities and support their potential role as early indicators of environmental change in the Arctic fjords.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103649"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759816","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":"Chlorophyll response and High Productivity Zone contraction in northern Perú during the 2017 Coastal El Niño","authors":"Rodrigo Mogollón ,&nbsp;Dante Espinoza-Morriberón ,&nbsp;Oswaldo Velasquez ,&nbsp;Guisela Yabar ,&nbsp;Manuel Villena ,&nbsp;Jorge Tam","doi":"10.1016/j.pocean.2026.103679","DOIUrl":"10.1016/j.pocean.2026.103679","url":null,"abstract":"<div><div>The 2017 Marine Heatwave event was characterized by significant positive sea surface temperature anomalies driven by weakened and reversed wind patterns, from mid-January to mid-April. The wind reversal during the Coastal El Niño favored downwelling processes, limiting the upward transport of nutrient-rich waters and causing a rapid collapse in surface phytoplankton biomass. Additionally, reduced latent heat flux and increased shortwave radiation further exacerbated surface warming. From February to March 2017, chlorophyll-a concentrations showed strong negative anomalies (more than −3 mg m⁻³), with the High Productive Zone (HPZ) contracting significantly, from 300 km offshore in January to nearly 25 km from the coast during this two-months period, while the total HPZ area decreased by up to 130,000 km² in March, demonstrating a sharp decline in surface chlorophyll-a concentration. However, as physical drivers tend to return to typical seasonal values by April, upwelling resumed, positive chlorophyll-a anomalies emerged indicating a relatively rapid recovery of phytoplankton biomass, and the HPZ re-expanded toward climatological levels. These findings emphasize the sensitivity of the northern Peruvian marine ecosystem to short-term climate variability. Given the increasing frequency of these climatic events, understanding the physical drivers of ecosystem changes is critical for predicting future impacts and informing adaptive management strategies.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103679"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995700","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}