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

{"title":"Functional group dynamics and environmental forcing of microphytoplankton in the Persian Gulf: Temporal patterns from Khark and Qeshm Islands","authors":"Emad Koochaknejad,&nbsp;Abolfazl Saleh","doi":"10.1016/j.dsr2.2025.105534","DOIUrl":"10.1016/j.dsr2.2025.105534","url":null,"abstract":"<div><div>Phytoplankton communities play a crucial role in marine ecosystem resilience and biogeochemical cycling, yet their functional responses to environmental fluctuations in extreme environmental conditions like the Persian Gulf remain poorly understood. This study investigates the temporal and spatial structuring of microphytoplankton communities around Khark and Qeshm Islands in the Persian Gulf over an annual cycle (November 2021 to December 2022), integrating taxonomic diversity with a trait-based functional approach to assess adaptive strategies under varying physicochemical conditions. Monthly sampling was conducted at six stations (three per island), and phytoplankton functional diversity was quantified based on nine key traits: photosynthetic pigment composition, growth form, body size, motility, nitrogen-fixing ability, trophic strategy, cell wall composition, long projections, and vertical migration. The results reveal distinct ecological regimes between the two islands. The phytoplankton communities in Qeshm Island are taxonomically diverse but functionally stable, reflecting ecological stability under relatively constant environmental conditions. In contrast, the Khark phytoplankton communities exhibit pronounced seasonal shifts in functional diversity shaped by fluctuations in salinity, carbonate chemistry, and nutrient availability. Clustering analysis identified six functional groups with two dominant assemblages: Group 6 (<em>Trichodesmium erythraeum</em>, a diazotrophic cyanobacterium) and Group 4 (chain-forming diatoms such as <em>Chaetoceros</em> spp.). Carbonate saturation state, nitrate availability, and temperature were identified as key environmental factors shaping both taxonomic and functional community composition (as indicated by Canonical Correspondence Analysis (CCA) and Fourth-Corner Analysis). Furthermore, large-scale <em>Trichodesmium erythraeum</em> blooms in Khark during summer and early autumn significantly altered carbonate system equilibrium, a novel insight into phytoplankton trait-environment relationships in the Persian Gulf, highlighting the capacity of diazotrophic cyanobacteria to drive biogeochemical feedback loops through nitrogen fixation, pH modulation, and shifts in carbonate saturation state, with potential implications for regional carbon cycling.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105534"},"PeriodicalIF":3.0,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890810","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":"Invariable nickel dynamics in the Peru, Benguela and Mauritania oxygen minimum zones","authors":"Mark J. Hopwood ,&nbsp;Martha Gledhill ,&nbsp;Eric P. Achterberg ,&nbsp;Yuanyuan Gu ,&nbsp;Ali A. Al-Hashem ,&nbsp;Leila R. Kittu ,&nbsp;Stephan Krisch ,&nbsp;Insa Rapp","doi":"10.1016/j.dsr2.2025.105531","DOIUrl":"10.1016/j.dsr2.2025.105531","url":null,"abstract":"<div><div>Nickel (Ni) is a bio-essential trace metal used in urease, hydrogenase and superoxide dismutase enzymes. The concentration of dissolved (&lt;0.2 μm) Ni (dNi) in the surface ocean is rarely depleted below ∼2 nM globally. This is in stark contrast to the concentrations of many other bio-essential trace metals such as iron (Fe), cobalt (Co) and manganese (Mn). Both complexation with strong ligands, potentially rendering dNi unavailable to marine organisms, and slow depletion of dNi because of low cellular demand compared to other trace metals have been invoked to explain this peculiar elemental distribution. Here we report new measurements of pelagic dNi concentrations (n = 1094) from four cruises (M135-M138) in the Eastern Tropical South Pacific (ETSP) to evaluate dNi dynamics under variable biogeochemical conditions in a highly productive shelf region. We additionally report total and labile particulate Ni concentrations along two cross-shelf sections at 16° S and 17° S. The ETSP features a productive Eastern Boundary Upwelling System along the Peruvian-Chilean shelf. This coincides with an extensive underlying Oxygen Minimum Zone which leads to persistently high phosphate and intermittently high Fe conditions.</div><div>The vast majority of dNi concentrations measured across the Peruvian shelf were within the range 2.2–10.8 nM dNi with highly reproducible depth profiles compared to prior cruises in different seasons, years, and El Niño–Southern Oscillation phases. Evidence of lower dNi concentrations was only found at one inshore location with dNi as low as 1.3 nM. Such low dNi concentrations appear to be rare. Whilst biogenic Ni associated with diatom detritus is buried in Peruvian shelf sediments, biological dNi demand on the Peruvian shelf is &lt;30 % of the annual upwelled dNi flux and burial in shelf sediments accounts for approximately 1–3 % of the upwelled dNi flux. Total particulate Ni concentrations measured on two cross-shelf sections ranged from below detection to 1.2 nM and were consistently low relative to dNi concentrations. On average, total particulate Ni (TpNi) was 2.6 % of dNi + TpNi with labile particulate Ni (LpNi) and TpNi remaining tightly coupled (R² = 0.99). As is the case elsewhere in the global ocean, dNi remained tightly correlated with phosphate and silicic acid concentrations. Limited biological demand for Ni relative to the upwelled dNi supply explains why dNi profiles in general were quite homogenous across the Peruvian coastal, shelf and offshore regions. Finally, profiles of dNi suggested a slightly lower than average dNi:phosphorous ratio (0.673 mmol (mol P)⁻¹) in the upper water column. Similar distributions of dNi and dNi:phosphorous ratios were found for the Benguela and Mauritania shelves reinforcing the relatively invariable nature of dNi profiles even in extremely productive shelf environments.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105531"},"PeriodicalIF":3.0,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889522","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":"Live and dead zooplankton distributions within the Humboldt current system during upwelling and downwelling events","authors":"Sonia Yáñez ,&nbsp;Pamela Hidalgo ,&nbsp;Paula Ruz-Moreno ,&nbsp;Kam W. Tang","doi":"10.1016/j.dsr2.2025.105530","DOIUrl":"10.1016/j.dsr2.2025.105530","url":null,"abstract":"<div><div>Traditional field sampling assumes all zooplankton collected are originally alive, but ignoring even a small percentage of dead zooplankton can result in large errors in predicting population dynamics and secondary production. We tested a protocol for Neutral Red staining and live/dead sorting of zooplankton samples from upwelling zones within the Humboldt Current System. In laboratory tests, live individuals of diverse copepod species including eggs, naupliar and advanced stages, as well as several gelatinous zooplankton groups, were stained readily and the staining efficiency was better than 94.6 %. Larval fish and crabs were only weakly stained. Once validated, we applied the staining method in field sampling in Mejillones Bay and Concepcion during upwelling and downwelling periods. Both abundances and percentages of zooplankton carcasses were significantly higher during upwelling events, and carcasses were mostly concentrated within the Oxygen Minimum Zone, suggesting that intrusion of oxygen-poor water during upwelling led to higher non-predatory mortality especially among species sensitive to hypoxia. Carcass abundances also varied between developmental stages, likely a result of differences in low-oxygen tolerance as well as <em>in situ</em> abundances between stages. Incorporation of Neutral Red staining method into routine sampling will generate live/dead zooplankton distribution data that will improve understanding of zooplankton population dynamics, secondary production, trophic link to fisheries, and zooplankton responses to environmental changes.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105530"},"PeriodicalIF":3.0,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893005","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":"MaxEnt modeling for predicting the present-day and future potential geographical distribution of coral/algae in the Persian Gulf under climate change","authors":"Amir Ghazilou","doi":"10.1016/j.dsr2.2025.105529","DOIUrl":"10.1016/j.dsr2.2025.105529","url":null,"abstract":"<div><div>The Persian Gulf forms a natural geographic barrier to coral reef communities. This study employs MaxEnt modeling with environmental data from Bio-ORACLE to assess the potential distributions of coral/algae and microalgal mats under present conditions and future (2090–2100) scenarios for SSP1, SSP3, and SSP5. Maximum temperature and mixed layer depth were found as the key environmental variables defining habitat suitability. Present-day suitable habitat for coral/algae totals approximately 94,161 km². Under SSP1, a moderate decline of 2.29 % (to ∼92,002 km²) in habitat area is projected. SSP3 scenario shows an increase of 14.32 % (up to ∼107,651 km²), potentially due to local adaptation. In comparison, SSP5 projects a severe 18.14 % decrease (∼77,072 km²) with fragmentation and isolation characterized by a 40 % drop in effective mesh size and 130 % increase in edge density. Microalgal mats exhibited an increasing area and connectivity under more severe scenarios, with the total core area rising from ∼5.2 million to over 16.7 million square units. The largest patch index exceeded 82 %, and the aggregation index peaked near 95 %. Biotic velocity metrics suggested that microalgal mats require movements exceeding 1400 m/year, which is higher than those of coral/algae. North-south direction dominates patterns of change in distribution. These results underscore the need for targeted conservation that prioritizes connectivity and scenario-sensitive management actions in response to climate change in the Persian Gulf.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105529"},"PeriodicalIF":3.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841760","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 cost-effective, open-source laboratory system for 3D photogrammetric analysis of corals","authors":"Alvaro Romo ,&nbsp;Cristina Gutiérrez-Zárate ,&nbsp;Meri Bilan ,&nbsp;Andrea Gori ,&nbsp;Alfredo Veiga ,&nbsp;Rodrigo Pérez ,&nbsp;Maria Rakka ,&nbsp;António Godinho ,&nbsp;Timm Schoening ,&nbsp;Andrew Carey ,&nbsp;Marina Carreiro-Silva ,&nbsp;Covadonga Orejas","doi":"10.1016/j.dsr2.2025.105525","DOIUrl":"10.1016/j.dsr2.2025.105525","url":null,"abstract":"<div><div>Three-dimensional photogrammetry is a method used to measure 3D reconstructions created from 2D images. The precision of this method makes it widely used for studying ecosystem engineers such as corals. Although photogrammetry has been used to study both tropical and cold-water corals in situ, very few studies, with certain limitations including potential coral stress or low replicability, use photogrammetry to study corals in aquaria. For accurate 3D photogrammetric measurements of corals under laboratory conditions, we present the “Coruña 3D system” and the two prototypes that served as input for the development of the final setup. The “Coruña 3D system” is presented as a publicly accessible cost-effective setup used to obtain a complete set of images of a coral in an aquarium and create accurate 3D reconstructions. Using photogrammetry to study corals in aquaria enables the measurement and monitoring of different variables over both, short and long periods of time. The effectiveness of the system was assessed with a total of 120 3D reconstructions of cold-water corals. The system has resulted in a highly accurate tool, creating 3D reconstructions with a total scale error of 0.048 ± 0.079 mm (mean ± SD). Moreover, this open-source, cost-effective (&lt;3000 €) system provided precise results overcoming the limitations of previous prototypes and mechanisms used in other studies. The adaptability of the \"Coruña 3D system\" according to the needs of the study makes it a versatile and useful tool to measure corals as well as other benthic marine species.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105525"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912276","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 vertical profiles of the tidal constituents and bed-induced dissipation of tidal signals in the Persian Gulf","authors":"Morteza Keshtgar ,&nbsp;Seyed Mostafa Siadatmousavi ,&nbsp;Jafar Azizpour","doi":"10.1016/j.dsr2.2025.105528","DOIUrl":"10.1016/j.dsr2.2025.105528","url":null,"abstract":"<div><div>This study evaluates the hydrodynamic and tidal dynamics of the Persian Gulf using the Finite Volume Community Ocean Model (FVCOM) under two distinct forcing configurations: wind-and-tide and tide-only. A comprehensive statistical assessment was conducted to validate the model's performance in replicating tidal elevation and flow velocity against in-situ data as well as TPXO10 tidal predictions. Co-tidal maps revealed that semi-diurnal constituents (e.g., M2, S2) exhibit pronounced phase transitions, particularly at the Strait of Hormuz, highlighting the influence of regional bathymetry on tidal propagation. Diurnal constituents (e.g., K1, O1) showed more uniform phase distributions, suggesting reduced sensitivity to topographic constraints. The analysis of tidal amplitudes underscored the dominance of the M2 and K1 constituents. Vertical analyses of current speeds revealed distinct patterns of tidal attenuation between diurnal and semi-diurnal constituents. The diurnal constituents undergo greater amplitude reductions with depth compared to semi-diurnal constituents, indicating stronger bottom interaction processes for longer-period tides. While the M2 constituent demonstrated minimal sensitivity to wind forcing, diurnal constituents like K1 showed significant attenuation influenced by seasonal stratification and atmospheric conditions. These findings underscore the critical interplay between wind forcing, tidal dynamics, and seasonal variability in shaping the hydrodynamics of the Persian Gulf.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105528"},"PeriodicalIF":3.0,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144826357","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":"Assessing the ecological preferences of planktic foraminifera from the south-eastern Arabian Sea","authors":"Kumari Anjali ,&nbsp;Thejasino Suokhrie ,&nbsp;Rajeev Saraswat ,&nbsp;Sujata R. Kurtarkar ,&nbsp;Dinesh Kumar Naik ,&nbsp;Dharmendra Pratap Singh ,&nbsp;Rupal Dubey","doi":"10.1016/j.dsr2.2025.105527","DOIUrl":"10.1016/j.dsr2.2025.105527","url":null,"abstract":"<div><div>The south-eastern Arabian Sea (SEAS) witnesses the confluence of the Arabian Sea and the Bay of Bengal waters along with an influence from both the summer and winter monsoon. As a result, the distinct hydrographic parameters are expected to modulate the diversity and abundance of planktic foraminifera in this region. Hence, 91 surface sediment samples covering a depth range from 25 m to 3150 m were analysed to establish region-specific planktic foraminiferal ecology. Overall, the water depth, seasonal chlorophyll-a and the mixed layer parameters significantly influence the planktic foraminiferal abundance in the SEAS. A total of 31 species of planktic foraminifera belonging to 17 genera were found. We report <em>Globigerina bulloides</em> as the most dominant species, preferring high productivity regions. <em>Globigerina bulloides</em> and <em>Globigerinoides ruber</em> exhibited opportunistic distribution patterns while region-specific preferences were observed for <em>Globigerinita glutinata, N. dutertrei, Globorotalia cultrata</em> and <em>Trilobatus sacculifer. Globigerinita glutinata</em> show a restricted seasonal occurrence while <em>G. hexagonus</em> is reported as a ubiquitous species. The ecological preferences of the planktic foraminifera inferred from the SEAS will help in reconstructing the past climatic conditions from this region.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105527"},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864097","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":"Establishment of a Global Coral Biobank: Implementation of the protocols from coral collection to long distance shipping and long-term maintenance in public aquariums","authors":"Olivier Brunel ,&nbsp;Dominique Barthelemy ,&nbsp;Max Janse ,&nbsp;Renaud Herbert ,&nbsp;Nienke Klerks ,&nbsp;Maureen Midol ,&nbsp;Bruno Piguet ,&nbsp;Christophe Cavelli ,&nbsp;Silvia Vimercati ,&nbsp;Frauke Fleischer-Dogley ,&nbsp;Annabelle Constance ,&nbsp;Didier Zoccola","doi":"10.1016/j.dsr2.2025.105516","DOIUrl":"10.1016/j.dsr2.2025.105516","url":null,"abstract":"<div><div>The World Coral Conservatory (WCC) has initiated a pioneering global biobank to conserve coral species in response to accelerating reef degradation. This paper reports on the first coral collection mission at Aldabra Atoll, Seychelles, undertaken during the Monaco Explorations Indian Ocean expedition in October 2022. Fifty-eight colonies, representing 21 species, were successfully collected, transported, and distributed across European aquariums. We detail the methodologies for coral collection, transport, and in-tank maintenance, ensuring genetic diversity and coral health preservation.</div><div>Post-arrival monitoring revealed an 88 % survival rate over an 18-months period, despite challenges such as bleaching and bacterial infections. The success of this mission validates the feasibility of long-term coral conservation in aquaria and sets the stage for future expeditions and advanced genetic research.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105516"},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889523","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":"Disentangling upwelling: how light and nutrient supply shape primary producers and stoichiometry in the Humboldt upwelling system","authors":"Antonia U. Thielecke ,&nbsp;Mar Fernández-Méndez ,&nbsp;Javier Arístegui ,&nbsp;Moritz Baumann ,&nbsp;Jacqueline Behncke ,&nbsp;Stella A. Berger ,&nbsp;Veit Dausmann ,&nbsp;Silvia Georgieva ,&nbsp;Silvan U. Goldenberg ,&nbsp;Gonzalo V. Gomez-Saez ,&nbsp;Michelle Graco ,&nbsp;Toralf Heene ,&nbsp;Leila Richards Kittu ,&nbsp;Jeffrey W. Krause ,&nbsp;Andrea Ludwig ,&nbsp;Jana Meyer ,&nbsp;Volker Mohrholz ,&nbsp;Jens C. Nejstgaard ,&nbsp;Joaquin Ortiz-Cortes ,&nbsp;Kai G. Schulz ,&nbsp;Ulf Riebesell","doi":"10.1016/j.dsr2.2025.105522","DOIUrl":"10.1016/j.dsr2.2025.105522","url":null,"abstract":"<div><div>The Humboldt upwelling system (HUS) is known for its extraordinary productivity due to wind-driven upwelling of nutrient-rich deep water, resulting in the highest fish catches per unit area worldwide. However, contrary to other Eastern boundary upwelling systems, upwelling intensity is highest in winter, while primary productivity reaches its peak during the summer months. Our current understanding of the counterintuitive relationship between upwelling intensity and productivity is insufficient to predict the consequences of climate change on this ecosystem. To elucidate the drivers of the upwelling-productivity relationship in the HUS, we tested the hypothesis that low light availability limits primary productivity in winter despite strong upwelling intensity supplying plenty of nutrients into the surface layer, while light availability in the shallower mixed layer in summer enables an effective use of the upwelled nutrients. To disentangle the interactive effects of light and nutrients on primary production and carbon cycling, we enclosed natural plankton communities off the coast of Callao (Peru) during a 35-day mesocosm experiment by recreating summer-time high light and winter-time low light conditions under different upwelling intensities (0 %, 15 %, 30 %, 45 % and 60 %). Primary productivity and phytoplankton biomass scaled with both nitrate and light availability. Comparing the same upwelling intensity at different light levels, our data confirmed the hypothesis that light limitation due to deepening of the mixed layer is a key driver for the out-of-phase observations in primary productivity in the Humboldt upwelling system. Under light limiting conditions phytoplankton had low POC:Chl<em>a</em> ratios indicating photoacclimation and low POC:PON ratios indicating light limitation of nitrate uptake which leads to increased food quality for grazers in winter. Our study indicates that small seasonal changes in phytoplankton biomass (estimated using Chl<em>a</em>) might hide larger changes in primary productivity (carbon uptake), and highlights the importance of combining satellite studies with in situ observations and experimental studies to predict the fate of upwelling systems in a changing ocean. Increased stratification caused by global warming in upwelling systems such as the HUS would lead to less phytoplankton biomass with higher POC:Chl<em>a</em> and POC:PON ratios. This phytoplankton community would have lower food quality for grazers and might lead to a decline in the transfer to higher trophic levels, but at the same time might lead to increased CO₂ drawdown in an otherwise CO₂ emitting ecosystem. Understanding the unique relationship between upwelling intensity and productivity in the HUS contributes to predicting the reaction of this valuable ecosystem for fisheries to the impacts of climate change.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105522"},"PeriodicalIF":3.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771646","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":"Sedimentary phosphorus in the Persian Gulf and the Gulf of Oman: Geochemical fractionation, seasonal variations, potential bioavailability, and ecological risk","authors":"Kamalodin Kor,&nbsp;Hamid Ershadifar,&nbsp;Abolfazl Saleh","doi":"10.1016/j.dsr2.2025.105524","DOIUrl":"10.1016/j.dsr2.2025.105524","url":null,"abstract":"<div><div>Phosphorus is a vital macronutrient that regulates marine biogeochemical cycles and ecosystem production. This is the first thorough investigation of phosphorus geochemistry in surface sediments of the Persian Gulf (PG) and the Gulf of Oman (GO), quantifying its fractions, potential ecological risks and potential bioavailability. Five forms of phosphorus were quantified using a sequential extraction technique. TP ranged from 636.0 to 1341.3 μg/g and 599.6–1354.1 μg/g in the summer and winter, respectively. Calcium-bound phosphorus (Ca-P) and detrital phosphorus (De-P) were the dominant forms of TP in surface sediments, with following descending order to other forms: O-P &gt; Fe-P &gt; Ad-P. Inorganic phosphorus (P) comprised over 83 % of the TP in the study area's sediments, indicating a low contribution from organic phosphorus. A mean of 29.1 % and 25.3 % of TP was found to be bioavailable phosphorus during the summer and winter sampling periods, respectively. Phosphorus pollution index exceeded one at most stations in both seasons, indicating sediment phosphorus pollution. Effective management of phosphorus inputs and maintenance of phosphorus balance are recommended to prevent eutrophication and HABs in the PG and GO.</div></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"223 ","pages":"Article 105524"},"PeriodicalIF":3.0,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739307","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}