Deep-sea Research Part Ii-topical Studies in Oceanography最新文献

{"title":"A prior-knowledge-integrated downscaling approach for subsurface thermal structure reconstruction in the tropical Indian Ocean","authors":"Zhongkun Feng ,&nbsp;Jifeng Qi ,&nbsp;Bowen Xie ,&nbsp;Yuan Cao ,&nbsp;Delei Li ,&nbsp;Chuanyu Liu ,&nbsp;Baoshu Yin","doi":"10.1016/j.dsr2.2025.105589","DOIUrl":"10.1016/j.dsr2.2025.105589","url":null,"abstract":"<div><div>Accurately obtaining high-resolution ocean subsurface thermal structure (OSTS) is essential for resolving mesoscale dynamics in the tropical Indian Ocean (TIO), yet observations remain sparse and uneven. We present a Transformer-based neural network model, the Downscaling Vision Transformer (DSVIT), which integrates prior knowledge to reconstruct high-resolution OSTS in the TIO. Inputs include sea surface temperature (SST), absolute dynamic topography (ADT), and wind stress curl (WSC), as well as temporal, geographic, and climatological information. DSVIT enhances a standard Vision Transformer (ViT) with a geographic positional prior and a physics-aware loss that emphasizes thermocline and surface variability. On an independent test set, DSVIT achieves a Root Mean Square Error (RMSE) of 0.29 °C and a Coefficient of Determination (R²) of 0.9962 for reconstructed subsurface temperature, outperforming traditional recurrent neural network (RNN) and convolutional neural network (CNN) models. Moreover, a key innovation of this study lies in its novel downscaling strategy, which effectively improves the EN4 subsurface temperature resolution from 1° to 1/4° by altering the input segmentation. Compared with traditional interpolation and assessed against independent high-resolution products, the downscaled outputs exhibit lower RMSE and higher R², indicating enhanced physical consistency and mesoscale representation. SHapley Additive exPlanations (SHAP) analysis further reveals that climatology and SST are the dominant predictors, followed by ADT. This study provides a novel approach for downscaling OSTS and offers valuable insights for advancing oceanic and climatic research.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105589"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938589","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":"Primary productivity and N2-fixation in the eastern Indian ocean: Bottom-up support for an ecologically and economically important ecosystem","authors":"Sven A. Kranz ,&nbsp;Jared M. Rose ,&nbsp;Michael R. Stukel ,&nbsp;Karen E. Selph ,&nbsp;Natalia Yingling ,&nbsp;Michael R. Landry","doi":"10.1016/j.dsr2.2025.105570","DOIUrl":"10.1016/j.dsr2.2025.105570","url":null,"abstract":"<div><div>Oligotrophic ocean regions are characterized by strong nutrient limitation, low standing phytoplankton biomass, and highly efficient nutrient recycling. During the BLOOFINZ-IO expedition (February 2022), we quantified nutrient inventories, primary productivity and N₂ fixation in the Argo Basin of the eastern Indian Ocean, the sole known spawning ground for Southern Bluefin Tuna. Low concentrations of surface nitrate (&lt;0.02 μmol L⁻¹) and persistent residual phosphate indicated N as the limiting macronutrient, with photophysiological indices consistent with iron colimitation. Depth-integrated net primary production (NPP), from ¹⁴C-based <em>in-situ</em> incubations during 4 Lagrangian experiments, averaged ∼460 mg C m⁻²d⁻¹, generally agreeing with mean satellite-based NPP estimates (459 mg C m⁻²d⁻¹) but with spatial discrepancies. Nitrogen fixation provided a consistent new nitrogen source, contributing ∼16 % to local NPP in the upper euphotic zone. Gross primary production (GPP), from fast-repetition-rate-fluorometry-based estimates of electron transport, revealed significant autotrophic respiration losses, with mean GPP:NPP ratios of ∼1.8 consistent with metabolic costs under nutrient limitation. Net community production (NCP) from O₂/Ar ratios averaged ∼20 % of NPP in the upper 30 m. This result, in combination with N₂ fixation measurement, indicates that N₂ fixation supports most of the export production in the region. Together, the multi-method approach revealed a recycling-dominated ecosystem affected by episodic mixing events, where primary productivity is maintained primarily through efficient nitrogen recycling and physiological photoacclimation. These results provide a comprehensive baseline of bottom-up support of ecosystem productivity for the Argo Basin for assessing future climate-driven changes in stratification, nutrient cycling, and food-web dynamics.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105570"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692362","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":"Subsurface mixing and ventilation of oxygen minimum zone waters in the southern Bay of Bengal during summer monsoon","authors":"Rajdeep Roy ,&nbsp;P.N. Vinayachandran ,&nbsp;Jenson George ,&nbsp;Amit Sarkar ,&nbsp;Chandanlal Parida","doi":"10.1016/j.dsr2.2025.105584","DOIUrl":"10.1016/j.dsr2.2025.105584","url":null,"abstract":"<div><div>During the summer monsoon, the influence of the cyclonic curl of local wind forcing around Sri Lanka causes the formation of a cold dome called the Sri Lanka Dome (SLD), which upwells subsurface water. To the east of SLD, the summer monsoon Current (SMC) flows into the Bay of Bengal (BoB), transporting Arabian Sea high salinity water. We show that SMC, alongside the upwelled waters of SLD, is ventilated episodically during the summer monsoon in the southern BoB, leading to a net exchange of low oxygen subsurface waters with the oxygen-saturated surface mixed layers. We observed the presence of a hypoxic boundary &lt;63 μmol kg⁻¹ very close to the surface. Within the SLD, it shoaled between 35 and 40 m with oxygen concentrations reaching as low as 6 μmol kg⁻¹ at the bottom of the thermocline. Negative fluxes representing the in-gassing rates ranged between (-0.33 to - 9.43 μmol m⁻² sec⁻¹) within SLD and SMC. We emphasize that episodic ventilation observed during this investigation may lead to disequilibrium in the surface mixed layers and can contribute to mid-depth oxygen enrichment. Our present study possibly illustrates a likely mechanism that contributes to preventing denitrification in this region.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105584"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836522","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":"Trophic specialization enhances growth performance in larvae of southern bluefin, albacore, and skipjack tunas from the eastern Indian ocean","authors":"Raúl Laiz-Carrión ,&nbsp;Ricardo Borrego-Santos ,&nbsp;José María Quintanilla ,&nbsp;Claudio Quezada- Romegialli ,&nbsp;Estrella Malca ,&nbsp;Rasmus Swalethorp ,&nbsp;Francisco Abascal ,&nbsp;María Grazia Pennino ,&nbsp;Manuel Vargas-Yáñez ,&nbsp;Carolina Johnstone ,&nbsp;Miguel Ángel Godoy-Bermúdez ,&nbsp;David Die ,&nbsp;Michael R. Landry","doi":"10.1016/j.dsr2.2025.105585","DOIUrl":"10.1016/j.dsr2.2025.105585","url":null,"abstract":"<div><div>We examined trophic ecology and its influence on larval growth variability for three scombrids, southern bluefin (<em>Thunnus maccoyii</em>, SBT), albacore (<em>T. alalunga</em>, ALB), and skipjack tunas (<em>Katsuwonus pelamis</em>, SKJ), that share a common spawning ground in the eastern Indian Ocean. We combined otolith-based ageing with bulk nitrogen and carbon stable isotope analysis (SIA) of individual larva. Significant interspecific differences in δ¹⁵N and δ¹³C indicate adaptive resource partitioning that allows these tunas to coexist during early ontogeny. Trophic position and isotopic niche were estimated with both frequentist and Bayesian approaches, enabling the evaluation of ontogenetic isotope shifts, niche overlap, and resource use in relation to growth. ALB grew fastest, had the highest trophic position, and the broadest isotopic niche. Optimally growing tuna larvae occupied the narrowest trophic niche and had lower trophic positions for all three species, supporting the hypothesis that strong trophic specialization supports better growth performance and that feeding on more efficient shorter food chains (e.g., microbial loop via appendicularians) can enhance larval fitness. Using lower C:N ratio as a proxy of larval condition found in optimal growing groups supports the broader hypothesis that growth potential is closely tied to energy allocation strategies during early ontogeny. A detailed understanding of how larval trophodynamics, niche breadth, and resource partitioning interact with growth and survival during these vulnerable stages is essential for ecosystem-based management, particularly in systems where growth rate modulates predation risk and competitive fitness.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105585"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836523","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 distribution and environmental drivers of meiofaunal communities in the Persian Gulf: insights into biodiversity and sediment dynamics","authors":"Narges Badri ,&nbsp;Behrooz Abtahi ,&nbsp;Abolfazl Saleh ,&nbsp;Homira Agah ,&nbsp;Hans-Peter Grossart","doi":"10.1016/j.dsr2.2025.105571","DOIUrl":"10.1016/j.dsr2.2025.105571","url":null,"abstract":"<div><div>Unlike earlier studies conducted in shallow coastal areas, this study is the first to examine the vertical distribution of meiofaunal communities at depths ranging from 10 to 93 m at five stations in the northern semi-enclosed Persian Gulf. Among the sampled stations, the highest meiofauna density was observed at Station 2, with an average of 2398 ± 921.4 individuals per 10 cm², while the lowest abundance was recorded at Station 4, amounting to 444.3 ± 96.2 individuals per 10 cm². A comprehensive analysis of 20311 meiofauna individuals representing 29 taxa revealed several dominant groups. Free-living nematodes (51.98 %), foraminifera (27.88 %), copepods (4.9 %), juvenile bivalves (2.79 %), polychaetes (2.76 %), and oligochaetes (2.39 %) comprised together 93 % of the community. The vertical distribution profile indicated that 91 % of the Persian Gulf meiofauna were concentrated in the top 2–3 cm sediment layer, although some were found at depths exceeding 5 cm. The nematode complex exhibited a diverse composition, with 90 genera from 30 families and 7 orders identified across the study sites. Environmental parameters, including sediment characteristics, i.e., dissolved oxygen (DO) as the strongest driver, total organic matter (TOM), grain size, and water depth, emerged as critical factors influencing meiofaunal abundance and diversity. Based on the Environmental Quality Standards (EQS) classification, the sampling stations demonstrated high to good EQS compliance.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105571"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692359","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 nitrogen in a tropical river-sea continuum: a seasonal view on the distribution and transformation","authors":"Longyun Lai ,&nbsp;Moritz Müller ,&nbsp;Rahayu Sukmaria Sukri ,&nbsp;Changi Wong ,&nbsp;Aazani Mujahid ,&nbsp;Sumei Liu ,&nbsp;Zhaomeng Xu ,&nbsp;Tim Rixen ,&nbsp;Thorsten Warneke ,&nbsp;Justus Notholt ,&nbsp;Shan Jiang","doi":"10.1016/j.dsr2.2025.105583","DOIUrl":"10.1016/j.dsr2.2025.105583","url":null,"abstract":"<div><div>The Belait River is a typical blackwater river in Brunei, characterized by deep tea-brown water rich in dissolved organic matter (DOM) derived from surrounding peat swamps and rainforests. This study provides a systematic assessment of the chemical composition, transformation, and transport processes of dissolved nitrogen (N) in the Belait River during alternating wet and dry seasons by integrating nitrate (NO₃⁻) stable isotope techniques with microbial analyses. Results indicate that dissolved organic nitrogen (DON) constitutes the primary component of total dissolved nitrogen (TDN), with its seasonal dynamics significantly controlled by hydrological climate and microbial activity. Along the salinity gradient, DON decreases due to dilution and degradation, while ammonium (NH₄⁺) and NO₃⁻ accumulate significantly in densely populated areas owing to anthropogenic inputs. The extremely low dissolved inorganic phosphorus (DIP) concentrations in the Belait River highlight the crucial role of P limitation in maintaining the system's oligotrophic state. Through the investigation in this representative blackwater system, this study highlights complex N cycling mechanisms in blackwater and provides a critical gauge in land-ocean material fluxes at the Indo-Pacific Convergence Area.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"225 ","pages":"Article 105583"},"PeriodicalIF":3.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747822","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":"Temporal stability in genetic origin of juvenile green turtle recruits at remote western Indian Ocean islands","authors":"Jérôme Bourjea ,&nbsp;Quentin Schull ,&nbsp;Sylvie Lapègue ,&nbsp;Corinne Bouvier ,&nbsp;Stéphane Ciccione ,&nbsp;Claire Jean ,&nbsp;Katia Ballorain ,&nbsp;Phillipe Gaspar ,&nbsp;Julien Temple Boyer ,&nbsp;Christopher Jones ,&nbsp;Annabelle Constance ,&nbsp;Mayeul Dalleau ,&nbsp;Michael Jensen","doi":"10.1016/j.dsr2.2025.105545","DOIUrl":"10.1016/j.dsr2.2025.105545","url":null,"abstract":"<div><div>The increasing anthropogenic and climatic pressures on marine ecosystems raise concerns about the sustainability of their functions, uses and conservation. Marine megafauna such as marine turtles are particularly vulnerable to these pressures due to their life cycle and the variability of habitats they occupy during their life cycle. Understanding how juvenile population dynamics respond to environmental conditions is crucial for designing effective conservation strategies. The present study investigates whether the genetic composition of juvenile green turtles at recruitment sites changes over time. A total of 346 juveniles were sampled at four key recruitment sites in the South Western Indian Ocean - SWIO (Glorieuses, Mayotte, Reunion and Aldabra) during two sampling phases at an interval between 6 and 17 years depending on the site. Based on mtDNA control region sequences, genetic structures were compared between periods within each site. Even if subtle changes in genetic composition may not be detectable with current genetic resolution, our results suggest that the structure of the juvenile green turtle population has not significantly changed over the course of the study period. Such stability in population structure may be correlated with the stability of regional oceanic currents over the last decades in the SWIO, as well as the dynamics of nesting populations in the different regional genetic stocks contributing in regional juvenile green turtle production.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"224 ","pages":"Article 105545"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145263171","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":"Implications of gear selection for monitoring benthic fish communities in the Beaufort Sea","authors":"Duane E. Stevenson ,&nbsp;Stan Kotwicki ,&nbsp;Brenda Norcross ,&nbsp;Andrew Majewski","doi":"10.1016/j.dsr2.2025.105561","DOIUrl":"10.1016/j.dsr2.2025.105561","url":null,"abstract":"<div><div>A series of bottom-trawl surveys were conducted in the Beaufort Sea in the years 2012–2014 to compare catch characteristics among gear types using paired research trawls. In the western Beaufort Sea, an American team compared two types of benthic beam trawls, while in the eastern Beaufort Sea, a Canadian team compared a benthic beam trawl with a larger Otter trawl. These surveys documented a relatively low-diversity community of primarily benthic and demersal fishes, which consisted of primarily small (&lt;20 cm TL) individuals. Catch biomass in the eastern Beaufort Sea was dominated by Arctic cod, while in the western Beaufort Sea the biomass was more evenly distributed among Arctic cod, skates, eelpouts, and other species. Large gadids (&gt;20 cm TL) were notably absent from all catches. Size selectivity among the two benthic beam trawls in the western Beaufort Sea was similar. However, the plumb-staff beam trawl captured a higher proportion of the smallest specimens and had a higher probability of detection than the high-rise benthic beam trawl throughout the size range of fish specimens encountered. Selectivity differences between the beam trawl and Otter trawl in the eastern Beaufort Sea were more pronounced, as the benthic beam trawl captured a greater proportion of smaller fishes, but the Otter trawl captured a much higher proportion of larger fishes. Probability of detection was notably higher for the Otter trawl throughout the size range. These results confirm that estimates of diversity, biomass, and size distribution produced from trawl surveys are highly dependent on gear type.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"224 ","pages":"Article 105561"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575905","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":"Microbial food web dynamics in tropical waters of the bluefin tuna spawning region off northwestern Australia","authors":"Michael R. Landry ,&nbsp;Michael R. Stukel ,&nbsp;Natalia Yingling ,&nbsp;Karen E. Selph ,&nbsp;Sven A. Kranz ,&nbsp;Christian K. Fender ,&nbsp;Rasmus Swalethorp ,&nbsp;Ria I. Bhabu","doi":"10.1016/j.dsr2.2025.105547","DOIUrl":"10.1016/j.dsr2.2025.105547","url":null,"abstract":"<div><div>Whereas recruitment success for many fisheries depends on coincident timing of larvae with abundance peaks of their prey, less can be more in the tropical/subtropical spawning areas of bluefin tunas if lower but steady food resources are offset by reduced larval vulnerability to pelagic predators. To understand larval habitat characteristics for Southern Bluefin Tuna (SBT), we quantified microbial community carbon flows based on growth and grazing rates from depth profiles of dilution incubations and carbon biomass assessments from microscopy and flow cytometry (FCM) during their peak spawning off NW Australia (Indian Ocean) in February 2022. Two Chl<em>a</em>-based estimates of phytoplankton production gave differing offsets due to cycling or mixotrophy, exceeding ¹⁴C net community production on average (677 ± 98 versus 447 ± 43 mg C m⁻² d⁻¹). Productivity was higher than in the Gulf of Mexico spawning area for Atlantic Bluefin Tuna but less than similar studies of oceanic upwelling regions. Microzooplankton grazing averaged 482 ± 63 mg C m⁻² d⁻¹ (71 ± 13 % of production). Two measurement variables for <em>Prochlorococcus</em> gave average production and grazing rates of 282 ± 36 and 248 ± 32 mg C m⁻² d⁻¹ (86 ± 6 % grazed). <em>Prochlorococcus</em> comprised almost half of production and grazing fluxes in the upper (0–25 m) euphotic zone where SBT larvae reside. <em>Prochlorococcus</em> declined and eukaryotic phytoplankton and heterotrophic bacteria increased in relative importance in the lower euphotic zone. These results describe relatively classic open-ocean oligotrophic conditions as the food web base for nutritional flows to SBT larvae.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"224 ","pages":"Article 105547"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107591","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":"Plastic pollution: A potential vector of both pathogens and probiotics for corals on the Mascarene Ridge, Indian Ocean","authors":"Vyctoria Marillac ,&nbsp;Philippe Jourand ,&nbsp;Pierre-Louis Stenger ,&nbsp;Gwennais Fustemberg ,&nbsp;Julie Gindrey ,&nbsp;Margot Thibault","doi":"10.1016/j.dsr2.2025.105556","DOIUrl":"10.1016/j.dsr2.2025.105556","url":null,"abstract":"<div><div>In marine environments, plastic debris serves as a vector for pathogenic bacteria that can negatively impact marine fauna, including corals. The Saya de Malha and Nazareth Banks, located in the Indian Ocean, harbor an extensive area of coral reefs that may be susceptible to diseases associated with plastic pollution. In this context, we aimed to determine whether plastic debris in this region can act as a vector for coral-associated pathogenic bacteria. During the \"Indian Ocean mission 2022,\" floating plastic debris (&gt;500 μm) was collected from the Saya de Malha region using manta trawling. The collected debris were quantified, classified by type, size, and weighed. The associated microbiome, along with the viable bacterial communities attached to the plastic, were analyzed using 16S rDNA high-throughput sequencing and traditional molecular and microbiological techniques. A high concentration of plastic debris was recorded both on Saya de Malha and Nazareth Bank, with 10⁵ items.km⁻². The mean viable bacterial count was 15,519 ± 9340 CFU/g of plastic debris. Nine bacterial phyla were identified, with Firmicutes (58 % of the total) and Proteobacteria (42 %) being the dominant groups. The bacterial diversity on the plastic was measured at 0.92, including coral pathogens, such as <em>Acinetobacter</em> (27 %), <em>Psychrobacter</em> (2 %), and <em>Pseudomonas</em> (2 %). In addition, probiotic bacteria such as <em>Exiguobacterium</em> (58 %), <em>Rheinheimera</em> (1 %), and <em>Idiomarina</em> (1 %) were also detected. This preliminary study states the presence of both pathogenic and probiotic coral-associated fixed to plastic. Further research is needed to confirm their direct effect on coral reef disease. Nevertheless, these findings add to the growing evidence of the widespread presence of plastic debris floating in the region.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"224 ","pages":"Article 105556"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412760","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}