Journal of Marine Systems最新文献

{"title":"Sources of organic carbon in surface sediments of Hangzhou Bay and Zhejiang coastal area: Implication from total organic carbon, lignin and algal pigments","authors":"Yuhao Xue ,&nbsp;Qianqian Wang ,&nbsp;Xiaoyong Duan ,&nbsp;Dahai Zhang ,&nbsp;Xianguo Li","doi":"10.1016/j.jmarsys.2025.104062","DOIUrl":"10.1016/j.jmarsys.2025.104062","url":null,"abstract":"<div><div>In this study, surface sediment samples (<em>n</em> = 49) were collected from Hangzhou Bay and Zhejiang coastal area. We combine bulk parameters (total organic carbon, TOC and stable carbon isotope signature, <em>δ</em>¹³C) with both terrestrial (lignin) and marine (pigments) sources' biomarkers to elucidate the sources of organic carbon. The high contents of TOC were related to inputs from Ou River, Hangzhou Bay, Changjiang Diluted Water and Yong River. Stable carbon isotope signature (<em>δ</em>¹³C) and C/N ratio of the bulk organic matter indicated that the organic carbon in these samples was mainly derived from marine organic matters together with a little contribution from terrestrial sources. The eight lignin-phenols normalized to organic carbon (<em>Λ</em>₈) in this study were relatively low, which was attributed to the strong tidal forces in Hangzhou Bay and the shallow water depth in coastal areas. The S/V and C/V ratios of lignin-phenols demonstrated that lignin in our research area was mainly derived from angiosperms, with a small contribution from gymnosperms. The concentrations of nine pigments detected in this study were relatively low, and the concentration of fucoxanthin reduces with distance from the shoreline (in the southern area of 29°N), while the case was in the contrary for prasinoxanthin and zeaxanthin. Chlorophyll <em>a</em> was only detected in a few samples with the lowest average concentration. There was no obvious distribution characteristic of organic carbon, lignin and pigments from north to south of the entire study area, accompanied with some partial distribution features, which could be attributed to the complicated hydrodynamic conditions and diverse organic carbon sources.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104062"},"PeriodicalIF":2.7,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644537","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":"30 years of sea surface temperature and salinity observations crossing the Southern Ocean near 140°E: Trends and rollercoaster variability","authors":"Rosemary Morrow,&nbsp;Elodie Kestenare","doi":"10.1016/j.jmarsys.2025.104048","DOIUrl":"10.1016/j.jmarsys.2025.104048","url":null,"abstract":"<div><div>Observations of high-resolution sea surface temperature, salinity and density are analysed over 30 years along a transect crossing the Southern Ocean from Tasmania to Antarctica near 140°E during austral summer. Three dynamical regions are investigated in fixed latitude bands. The Subtropical and Subantarctic Zones show a surface warming trend of 0.33 °C/decade in accord with previous studies, and surface salinity has increased by 0.05/decade. This trend towards warmer, saltier surface waters is mostly density compensated; the large trend dominates over the interannual variability. The increased presence of warm, salty subtropical waters is linked to the poleward shift in the Subtropical Front which is now located 160 km further south than in the early 1990s, whereas the Subantarctic Front and Polar Front positions remain stable. This reduces the effective summer surface area of the Subantarctic Zone by one-third over 30 years. Interannual changes in the influx of subtropical waters across 140°E are linked to the main climate modes. Austral summers having warmer, saltier conditions occur during the positive Southern Annular Mode (SAM) and La Nina phases; cooler fresher conditions occur during negative SAM and El Nino. In the Antarctic Zone south of the Polar Front, the freshening trend reported over the 1990s and 2000s has stabilized. The mean austral SSS increased slightly over the last decade, and the 30-year trend in surface salinity is now zero. The Sea-Ice Zone south of 60°S around 140°E was largely impacted by the Mertz Glacier calving in 2010, releasing a large volume of sea-ice over the following years. Interannual changes in summer surface salinity are anti-correlated with the available sea-ice the previous spring. Over the 30-year period, the region south of 60°S has freshened by 0.012 per decade, and cooled by 0.06 °C per decade. Coastal waters off Antarctica show the largest impact: here surface waters have freshened by 0.1 over three decades, even as the summer sea-ice concentration has been reduced by 2.5 %. The Subantarctic Zone and the Sea-Ice Zone exhibit a rollercoaster of large interannual changes since 2017, and continued monitoring is required to understand the long-term effects of this recent increased variability.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104048"},"PeriodicalIF":2.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619531","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":"Trend analysis of time series variations in the marine environments and size-fractionated chlorophyll a in the coastal areas of eastern Hokkaido, southwestern Okhotsk Sea","authors":"Akihiro Shiomoto ,&nbsp;Kosuke Inoue ,&nbsp;Takeshi Okunishi","doi":"10.1016/j.jmarsys.2025.104052","DOIUrl":"10.1016/j.jmarsys.2025.104052","url":null,"abstract":"<div><div>The coastal areas of eastern Hokkaido, located in the southwestern part of the Okhotsk Sea, are unique areas where the Soya Warm Current Water (SWCW) and the East Sakhalin Current Water (cold water) alternate seasonally. They are important sea areas for Japanese fishery production. Observational results off Cape Notoro, eastern Hokkaido, over the last 10 years (2011−2022), showed that the influence of the Tsushima Warm Current Water (TWCW), the origin of the SWCW, has become stronger. The TWCW is dominated by small phytoplankton. An increase in their impact will have a similar effect on the ecosystem in the SWCW, where large phytoplankton dominate, as the shift to small phytoplankton occurs owing to global warming. Although the change in small phytoplankton observed in the current study was not statistically significant, the standing stock of small phytoplankton has been high over the past few years. An increase in the influence of the TWCW and a shift to small phytoplankton were observed in Saroma-ko Lagoon (2009–2022), the largest brackish-water lake in eastern Hokkaido. Data from the past 35 years (1987–2021) indicated a significant increase in the surface water temperature. Furthermore, off Shibetsu in the Nemuro Strait on the east side of the Okhotsk Sea across the Shiretoko Peninsula (2009–2022), the influence of the TWCW strengthened and indications of a shift to small phytoplankton were found. This study showed that in the phytoplankton community, the significance of small phytoplankton as primary producers has risen in response to environmental changes such as global warming and the growing inflow of the TWCW, in the coastal areas of eastern Hokkaido in the Okhotsk Sea. There have been concerns regarding future changes in the ecosystems and fishery production. Therefore, it is essential to continue monitoring studies for sustainable fishery production.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104052"},"PeriodicalIF":2.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593031","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":"Climate-driven warming, deoxygenation, and desertification in large marine ecosystems","authors":"Roberto Mario Venegas ,&nbsp;Malika Kheireddine ,&nbsp;Juan Pablo Rivera Caicedo ,&nbsp;Eric A. Treml","doi":"10.1016/j.jmarsys.2025.104053","DOIUrl":"10.1016/j.jmarsys.2025.104053","url":null,"abstract":"<div><div>This study explores Large Marine Ecosystems (LME) impacts caused by climate-induced changes in sea surface temperature (SST), surface dissolved oxygen concentrations (O₂), and surface phytoplankton concentrations (CHL). It spans pre-industrial (1850–1900) to future (2015–2099) epochs under Shared Socioeconomic Pathways (SSPs) medium (SSP-2.45) and high (SSP-5.85) CO₂ emission scenarios. Across the 66 LMEs, we observed consistent warming, deoxygenation, and desertification, with more pronounced changes in SSP-5.85. SST trends (°C/decade) varied from 0.04 to 0.29 (SSP-2.45) and 0.12 to 0.63 (SSP-5.85), resulting in net increases from &gt;3 °C (SSP-2.45) to &gt;4.5 °C (SSP-5.85). O₂ exhibited trends (μmol/kg/decade) of −0.04 to −1.97 (SSP-2.45), with substantial declines in SSP-5.85 (−0.86 to −3.93), and significant net decreases (μmol/kg) of &gt;−18 (SSP-2.45) and &gt;−25 (SSP-5.85). CHL showed significant decreases (kg/m³) up to −0.31 (SSP-2.45) and −0.36 (SSP-5.85), with negative trends (kg/m³/decade) up to −0.0097 (SSP-2.45) and −0.0159 (SSP-5.85), except the Black Sea and Antarctica which exhibited positive trends. Climate indices reveal that LMEs experiencing the least impacts across all indicators occur in the East Siberian Sea, Faroe Plateau, Central Arctic, and Gulf of Mexico, in both scenarios. However, under the SSP-2.45 scenario, additional the Laptev Sea, Insular Pacific-Hawaiian also experienced lower impacts. In SSP-5.85, reduced impacts are observed in the South Brazil Shelf, East Brazil Shelf, Agulhas Current, West Central Australian Shelf, and Canadian High Arctic-North Greenland. Conversely, the most impacted LMEs, including the Barents Sea, Norwegian Sea, Oyashio Current, West Bering Sea, and the Aleutian Islands are affected in both scenarios. Additionally, the Pacific Central-American Coastal region, the Gulf of Alaska, Benguela Current, and the Sea of Japan are affected in the SSP-2.45 scenario. Only the Scotian Shelf experienced high impacts in SSP-5.85. Antarctica exhibited low impacts in both scenarios but substantial increases in SST, O₂, and CHL.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104053"},"PeriodicalIF":2.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580593","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":"Global surface ocean calcite saturation (Ωcal) estimation using satellite and in-situ observations","authors":"Ibrahim Shaik ,&nbsp;P.V. Nagamani ,&nbsp;Sandesh Yadav ,&nbsp;Yash Manmode","doi":"10.1016/j.jmarsys.2025.104054","DOIUrl":"10.1016/j.jmarsys.2025.104054","url":null,"abstract":"<div><div>Calcite saturation (Ω_<em>cal</em>) in global surface ocean waters is a crucial parameter for assessing marine ecosystem health. This study presents a multiparametric linear regression (MLR) model integrating satellite and in-situ observations to estimate global surface ocean Ω_<em>cal</em>. The model was developed using in-situ measurements of sea surface temperature (SST), sea surface salinity (SSS), total alkalinity (TA), dissolved inorganic carbon (DIC) and Ω_<em>cal</em> obtained from the National Center for Environmental Information (NCEI), combined with satellite derived chlorophyll concentrations (Chla). Model validation demonstrated strong agreement with in-situ data, indicating high accuracy of estimation. Satellite derived Ω_<em>cal</em> estimates also showed robust correlations with in-situ measurements, confirming the MLR model reliability. Sensitivity analysis highlighted the model resilience to variations in input parameters. This study reveals significant spatiotemporal variability in Ω_<em>cal</em>, driven by physical, chemical, and biological processes, including seasonal patterns and climate phenomena like the El Nino Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). Analysis of interannual trends and the rate of change in Ω_<em>cal</em> emphasize the impacts of ocean acidification, revealing a declining trend that poses challenges to marine ecosystems. The proposed approach offers a valuable tool for monitoring global ocean carbonate chemistry, providing insights into the long term impacts of environmental changes on marine health and enabling informed decision making for ecosystem management.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104054"},"PeriodicalIF":2.7,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552997","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":"Phytoplankton photosynthetic parameters and primary production in some Arctic regions during the summer of 2020","authors":"Tatiana Efimova ,&nbsp;Tatiana Churilova ,&nbsp;Elena Skorokhod ,&nbsp;Anatoly Buchelnikov ,&nbsp;Nataliia Moiseeva","doi":"10.1016/j.jmarsys.2025.104050","DOIUrl":"10.1016/j.jmarsys.2025.104050","url":null,"abstract":"<div><div>In August 2020, during the 80th cruise of the R/V “Akademik Mstislav Keldysh”, phytoplankton photosynthetic parameters were measured in the Norwegian Sea, the Barents Sea and the adjacent area of the Arctic Ocean. Primary production in the Arctic area was estimated using full spectral approach that took into account quantum yield of photosynthesis (ϕ), phytoplankton spectral light absorption coefficient and spectral downwelling irradiance. Total light absorption by all optically active components except water influenced spectral features of downwelling irradiance: increase of the total non-water light absorption at the sea surface layer resulted in a shift of the wavelength of the downwelling irradiance spectrum maximum to the longer wavelength (from 500 ± 7 nm to 530 ± 5 nm). Phytoplankton photosynthetic parameters (maximum quantum yield (ϕ_max) and light intensity saturating photosynthesis) were depth-dependent variables due to phytoplankton photoacclimation. Relationships between photosynthetically available radiation (PAR) vs. ϕ_max and PAR vs. ϕ were described. Although chlorophyll-<em>a</em> specific photosynthetic rate (P^B) ranged from 0.5 to 1.5 mgC/mgChl-<em>a</em>/h in the surface layer, daily primary production (1.1 mgC/m³/d - 32 mgC/m³/d) was correlated to chlorophyll-<em>a</em> concentration (Chl-<em>a</em>) (<em>r</em> = 0.97, <em>n</em> = 22, <em>p</em> &lt; 0.0001), which is likely to be caused by higher variability of Chl-<em>a</em> (0.07 mg/m³–1.5 mg/m³) compared to P^B. The full spectral approach developed for the Black Sea is relevant for correct assessment of primary production in the Arctic area.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"248 ","pages":"Article 104050"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518930","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 how eutrophication in northern Baltic coastal zone is driven by new nutrient inputs, internal loading, and 3D hydrodynamics","authors":"Risto Lignell ,&nbsp;Elina Miettunen ,&nbsp;Harri Kuosa ,&nbsp;Janne Ropponen ,&nbsp;Laura Tuomi ,&nbsp;Irma Puttonen ,&nbsp;Kaarina Lukkari ,&nbsp;Marie Korppoo ,&nbsp;Markus Huttunen ,&nbsp;Karel Kaurila ,&nbsp;Jarno Vanhatalo ,&nbsp;Frede Thingstad","doi":"10.1016/j.jmarsys.2025.104049","DOIUrl":"10.1016/j.jmarsys.2025.104049","url":null,"abstract":"<div><div>The nutrient load and the resulting eutrophication responses in the Archipelago Sea, a northern Baltic Sea basin, were assessed by developing the FICOS model system (Finnish Coastal Nutrient Load Model). FICOS includes a simple but sufficiently mechanistic biogeochemical (BGC) model with two functional phytoplankton groups (strict autotrophs and diazotrophic N₂ fixing cyanobacteria) accounting for key processes in the Baltic nitrogen‑phosphorus cycle. The BGC model is linked to a high-resolution 3D hydrodynamic coastal model and includes all important nutrient sources. We applied Bayesian inference on time series of dissolved inorganic phosphorus (DIP), dissolved inorganic nitrogen (DIN), chlorophyll <em>a</em> (Chla), and algal biomass observations to estimate five unknown phytoplankton growth parameters of the BGC model, and the uncertainties associated with them, as well as to calibrate the model predictions. In general, the calibrated BGC model simulated well the time courses of the observations at three intensive monitoring stations in the Archipelago Sea.</div><div>Main sources of new nutrients to the Archipelago Sea include catchment area, atmosphere, point load (e.g. fish farming), N₂ fixation by cyanobacteria and background transport from open sea. An important and characteristic additional nutrient source in the shallow area is recycling from bottom sediments. During the season of phytoplankton growth, this internal load was the most important DIP source for the productive surface layer. In the sheltered basin coupled with the main river Aurajoki (area 1221 km²), about half of the DIP released from sediments was transported to the surface. For DIN in the Aurajoki basin, atmospheric deposition and catchment load were the most important sources for phytoplankton, both accounting for about 30 % of total surface inputs. In the whole Archipelago Sea, annual inputs of DIP and total P were dominated by internal load while atmospheric load was the most important DIN source. Import from the northern Baltic proper was the other main source of both forms of N and P.</div><div>During the growth season in the Aurajoki basin, high internal DIP load led to low surface DIN:DIP input ratio, indicating primary N-limitation of phytoplankton. The internal DIP load and catchment area DIN load were the local inputs with the widest impact areas in model simulations, suggesting that local inorganic nutrient loads were exhausted within the coastal zone during the growth season. Furthermore, Bayesian uncertainty analysis of nutrient load scenario predictions suggested that good environmental status (below 2.5–3.0 μg Chla L⁻¹) is achievable in the Aurajoki basin only with drastic reductions in practically all anthropogenic loads.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104049"},"PeriodicalIF":2.7,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644536","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":"Spatial and seasonal variability of Arctic phytoplankton communities in conditions of interaction with Atlantic origin waters in the St. Anna Trough (Kara Sea)","authors":"Valentina M. Sergeeva ,&nbsp;Svetlana V. Stepanova ,&nbsp;Mikhail V. Flint ,&nbsp;Irina N. Sukhanova ,&nbsp;Alexey V. Fedorov ,&nbsp;Vladimir A. Artemiev","doi":"10.1016/j.jmarsys.2025.104051","DOIUrl":"10.1016/j.jmarsys.2025.104051","url":null,"abstract":"<div><div>For the first time, seasonal changes in phytoplankton communities were described in the Kara Sea region, which is influenced by modified Atlantic water through the St. Anna Trough. The study focused on June, when the sea ice began to retreat, July after three weeks without sea ice, and September, when Siberian river discharge had a widespread surface impact. In all seasons, the structure of the phytoplankton community differed significantly on the outer shelf of the Kara Sea and the slope of the St. Anna Trough. This boundary was caused by changes in the hydrophysical structure and was located approximately at 76.5 N, with a width of about 20 km. The highest phytoplankton abundance, biomass and photosynthetic activity were observed on the outer Kara Sea shelf in the cold winter layer with temperature ranging from −1.7 to −0.5 °C and salinity ranging from 32.5 to 33.7. In June and July, the layer was located in conditions with sufficient underwater irradiance and nutrient supply. The integral abundance and biomass of algae differed 10–20 times between the outer shelf of the Kara Sea and the slope of the St. Anna Trough, where this layer was not present. In September, stratification on the Kara Sea shelf increased under the influence of pronounced river runoff, and the cold winter layer became thinner and deeper, with a significant decrease in phytoplankton abundance. Despite the high similarity (61–64 %) in species composition between the outer shelf and slope of St. Anna, there were differences in dominant species between the areas each month. In June the spring diatoms <em>Chaetoceros socialis</em>, Fragilariopsis spp. (<em>F. cylindrus</em>, <em>F. oceanica</em>) and <em>Navicula pelagica</em> mass developed on the Kara Sea outer shelf, while <em>Phaeocystis pouchetii</em> did on the slope of the St. Anna Trough. In July, resting spores of <em>Chaetoceros socialis</em>, as well as Apedinella radiance, and Choanoflagellates prevailed on the shelf, but <em>Dicrateria</em> sp. was the most abundant in the St. Anna Trough. In September <em>Leptocylindrus danicus</em>, <em>Peridiniella catenata</em> and <em>Thalassionema nitzschioides</em> were the base of community on the outer shelf, however <em>Thalassiosira</em> cf. <em>levanderii</em>, <em>Leptocylindrus minimus</em>, <em>Nephroselmis</em> sp. dominated on the slope. The “Atlantification” through the St. Anna Trough in June and July had a similar effect on the phytoplankton in the Kara Sea's outer shelf as it did on the phytoplankton communities in the Polar Front area of the Barents Sea during April–May.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"249 ","pages":"Article 104051"},"PeriodicalIF":2.7,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580592","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":"Coastal zooplankton in the Palmer Archipelago, Western Antarctica Peninsula: Influence of environmental conditions at short-term scale during austral summer","authors":"Benjamín Rodríguez-Stepke ,&nbsp;Claudia Morales ,&nbsp;Manuel I. Castillo ,&nbsp;Ángela Rodríguez ,&nbsp;Manuel I. Castillo ,&nbsp;César A. Cárdenas ,&nbsp;Mario La Mesa ,&nbsp;Mathias Hüne ,&nbsp;Mauricio F. Landaeta","doi":"10.1016/j.jmarsys.2025.104047","DOIUrl":"10.1016/j.jmarsys.2025.104047","url":null,"abstract":"<div><div>Seasonal and inter-annual fluctuations in the zooplankton composition and abundance from West Antarctica are relatively well known. Nonetheless, there is scarce information about the zooplankton structure in Antarctic waters at shorter time and spatial scales. In this study, we analyzed short-term (i.e., days) temporal and spatial (i.e., km) variation in mesozooplankton from a shallow embayment (South Bay, Doumer Island, 64°52′S, 63°35′W) and surrounding zones off the Western Antarctic Peninsula (WAP), during the austral summer 2022. A total of 110 taxonomic groups were identified in the samples. Meroplankton (Asteroidea, Polychaeta, and Nemertea larvae) was more abundant inside the bay, while the opposite trend was observed for the holoplankton (Copepoda, Appendicularia, and Chaetognatha). Copepods numerically dominated the samples, particularly <em>Oithona</em> spp., <em>Calanoides acutus</em>, and <em>Paraeuchaeta</em> sp. Only meroplankton showed significant differences in the composition and abundance between zones, although alpha-diversity indices showed similar values inside and outside the bay. A Multivariate Regression Tree indicated that the pH (node 1) was the primary predictor separating zooplankton assemblages, followed by the east–west wind stress (Tau-U, node 2), and water stability (node 3). This study highlights the importance of shallow bays in the WAP for the aggregation of planktonic stages of benthic and demersal taxa.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"248 ","pages":"Article 104047"},"PeriodicalIF":2.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487838","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":"Impact of coral bleaching on symbiotic microbial communities and carbon fixation pathways in the South China Sea","authors":"Fulin Sun ,&nbsp;Hongqiang Yang ,&nbsp;Xiyang Zhang ,&nbsp;Fei Tan ,&nbsp;Guan Wang ,&nbsp;Qi Shi","doi":"10.1016/j.jmarsys.2025.104046","DOIUrl":"10.1016/j.jmarsys.2025.104046","url":null,"abstract":"<div><div>Microorganisms play a crucial role in supplying essential nutrients to corals, thereby enhancing their survival under environmental stress. However, the diversity and ecological functions of carbon-fixing microorganisms in coral symbiosis remain poorly understood. In this study, we employed metagenomic analysis to investigate microbial responses to coral bleaching and their impact on carbon fixation pathways in the South China Sea. Principal coordinates Analysis (PCoA) revealed that both bleaching and coral species significantly influenced the symbiotic microbial community composition. Bleached corals exhibited a substantial increase in heterotrophic microorganisms. The findings demonstrated the presence of complete photosynthetic and prokaryotic carbon fixation pathways within coral holobionts, with a clear shift in microbial carbon metabolism following bleaching. Function analysis shows a decrease in key enzymes of photosynthetic carbon fixation and an increase in prokaryotic carbon fixation enzymes in bleached corals, indicating the activation of the prokaryotic carbon fixation pathway in bleached corals. In addition to Symbiodiniaceae, other microbial taxa contributed to carbon fixation, with Suessiales, Cladophorales, Oscillatoriales, Rhodospirillales, and Rhodobacterales identified as the major contributors. Notably, Cladophorales (<em>Boodlea</em> and <em>Botryococcus</em>) emerged as key contributors to RuBP carboxylase activity in bleached corals. These results highlight the significant role of microbial carbon fixation within coral holobionts and provide a foundation for future research on lineage-specific carbon-fixing microorganisms.</div></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"248 ","pages":"Article 104046"},"PeriodicalIF":2.7,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445501","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}