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

{"title":"Algal contribution to organic carbon sequestration and its signatures in a tropical seagrass meadow","authors":"Natasha Arina ,&nbsp;Nur Hidayah ,&nbsp;Nur Hazlin Hazrin-Chong ,&nbsp;Mohammad Rozaimi","doi":"10.1016/j.dsr2.2023.105307","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105307","url":null,"abstract":"<div><p>Algae form prolific coastal habitats and contribute the largest carbon dioxide (CO₂<span>) flux globally. Most of the algal biomass is transported to the coastal ocean as particulate organic matter<span><span> (OM), of which the contribution of carbon occurs mainly in depositional environments<span>. Identifying the algal contribution alongside other major sources of organic carbon (OC) is crucial for determining allochthonous and autochthonous contributions in blue carbon habitats. In this study, we identified the algal contribution to OC storage in the </span></span>seagrass meadow of Tanjung Adang Shoal (Johor, Malaysia) using dual-stable isotope measurements (δ</span></span>¹³C and δ¹⁵<span><span>N) and environmental DNA (eDNA) analysis. Stable isotope analysis showed that mangrove plants are the largest contributor to organic carbon pool in the sediments, followed by seston, </span>macroalgae<span>, epiphytes<span> and seagrasses. The combined proportions of sestonic, macroalgal and epiphytic inputs as algal-derived organic matter had contributed a cumulative of 41.4–55.4% of organic matter in the bulk sediment. The eDNA method was used to examine bulk sediments and determine the types of algae present in the seagrass meadow at the genus/family level. Results showed that the main macroalgae present were from member of Coralinalles, Cladophoraceae and Ulvaceae<span>, while diatoms were the predominant microalgae found in the sediment. These findings shed light on the importance of algae in carbon sequestration in the seagrass ecosystem. Understanding the role of algae in carbon storage and their interactions with sediment is crucial in the face of global and local environmental changes.</span></span></span></span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105307"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194589","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":"Habitat and benthic fauna of the Wallaby-Cuvier escarpment, SE Indian ocean","authors":"Todd Bond ,&nbsp;Yakufu Niyazi ,&nbsp;Jessica L. Kolbusz ,&nbsp;Alan J. Jamieson","doi":"10.1016/j.dsr2.2023.105299","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105299","url":null,"abstract":"<div><p><span><span>The Wallaby-Cuvier Escarpment is a 700 km long, NW-SE trending linear </span>geological feature<span> that marks the southern boundary of the Cuvier Plateau. The Plateau rises from the adjacent 5500 m deep abyssal plain to a topographical high of 3000 m, approximately 450 km off the coast of Western Australian. In 2021, a 50 km long segment of the escarpment, covering an area of 1700 km</span></span>², was mapped by a high-resolution full-ocean depth multibeam echosounder. The habitat of the study area was explored during two video surveys undertaken using the crewed submersible <em>Limiting Factor</em><span><span>. Using Benthic Terrain Modeler (BTM), we classified the seabed into five geomorphological classes; flat plains, depressions, broad slopes, steep slopes, and crest. Video footage was used to classify habitat types and to record benthic </span>megafauna<span><span> occurrences which revealed highly heterogeneous and rapidly changing habitats. Six habitats were proposed based on the nature of geomorphology, slope, and substrate textures. A total of 202 organisms comprising 52 morphotaxa were scored during 198 min of survey that included at least eight phyla and 29 families. Despite a high number of morphotaxa, the total abundance of organisms is considered low which we attribute to oligotrophic surface waters. However, the distribution of organisms and their feeding strategies were well-aligned with habitat type. This study documents faunal distribution and habitat diversity of a rarely explored type of deep-sea </span>geomorphological feature, and in a largely unexplored area and depth of the Indian Ocean.</span></span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105299"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194590","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":"Carbon budgets of Scotia Sea mesopelagic zooplankton and micronekton communities during austral spring","authors":"Kathryn B. Cook ,&nbsp;Anna Belcher ,&nbsp;Daniel Bondyale Juez ,&nbsp;Gabriele Stowasser ,&nbsp;Sophie Fielding ,&nbsp;Ryan A. Saunders ,&nbsp;Mohamed A. Elsafi ,&nbsp;George A. Wolff ,&nbsp;Sabena J. Blackbird ,&nbsp;Geraint A. Tarling ,&nbsp;Daniel J. Mayor","doi":"10.1016/j.dsr2.2023.105296","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105296","url":null,"abstract":"<div><p>Zooplankton form an integral component of epi- and mesopelagic ecosystems, and there is a need to better understand their role in ocean biogeochemistry. The export and remineralisation of particulate organic matter at depth plays an important role in controlling atmospheric CO₂ concentrations. Pelagic mesozooplankton and micronekton communities may influence the fate of organic matter in a number of ways, including: the consumption of primary producers and export of this material as fast-sinking faecal pellets, and the active flux of carbon by animals undertaking diel vertical migration (DVM) into the mesopelagic. We present day and night vertical biomass profiles of mesozooplankton and micronekton communities in the upper 500 m during three visits to an ocean observatory station (P3) to the NW of South Georgia (Scotia Sea, South Atlantic) in austral spring, alongside estimates of their daily rates of ingestion and respiration throughout the water column. Day and night community biomass estimates were dominated by copepods &gt;330 μm, including the lipid-rich species, <em>Calanoides acutus</em> and <em>Rhincalanus gigas</em>. We found little evidence of synchronised DVM, with only <em>Metridia</em> spp. and <em>Salpa thompsoni</em> showing patterns consistent with migratory behaviour. At depths below 250 m, estimated community carbon ingestion rates exceeded those of metabolic costs, supporting the understanding that food quality in the mesopelagic is relatively poor, and organisms have to consume a large amount of food in order to fulfil their nutritional requirements. By contrast, estimated community rates of ingestion and metabolic costs at shallower depths were approximately balanced, but only when we assumed that the animals were predominantly catabolising lipids (i.e. respiratory quotient = 0.7) and had relatively high absorption efficiencies. Our work demonstrates that it is possible to balance the metabolic budgets of mesopelagic animals to within observational uncertainties, but highlights the need for a better understanding of the physiology of lipid-storing animals and how it influences carbon budgeting in the pelagic.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105296"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194588","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":"Sea surface temperature predictability assessment with an ensemble machine learning method using climate model simulations","authors":"Fabio Boschetti ,&nbsp;Ming Feng ,&nbsp;Jason R. Hartog ,&nbsp;Alistair J. Hobday ,&nbsp;Xuebin Zhang","doi":"10.1016/j.dsr2.2023.105308","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105308","url":null,"abstract":"<div><p>Ensemble models, statistical analysis and machine learning (ML) can be used to predict novel conditions in a rapidly changing ocean. Traditionally, ML has been understood as a purely data-driven approach and has been used on both observational and model data to forecast Sea Surface Temperature (SST) anomalies. Here we use ML trained only on climate model simulations to predict regional SST variations, thereby suggesting a novel role for ML as an ensemble model interpolator. We propose a measure of the predictability provided by different ML implementations as well as by standard time series analysis methods. Weighting each forecast by this predictability measure computed on model data only, provides a significant improvement in forecast skill. We demonstrate the performance of this approach for regions around Australia, the Nino3.4 region (central-eastern equatorial Pacific) and in the eastern equatorial Pacific. These analyses show that SST predictability varies as a function of geographical location, area size, seasonality, proximity to the coast and model data quality.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105308"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194591","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":"Tortonian silicoflagellates from the offshore of northeast Indian Ocean","authors":"Lopamudra Roy ,&nbsp;Kevin McCartney ,&nbsp;Amit K. Ghosh ,&nbsp;Ajoy Kumar Bhaumik ,&nbsp;Sarajit Sensarma","doi":"10.1016/j.dsr2.2023.105297","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105297","url":null,"abstract":"<div><p><span>Analysis of the Tortonian sediments in the northeast Indian Ocean from NGHP–01–17A drilled at Andaman Basin shows 22 silicoflagellate taxa belonging to the genera </span><em>Bachmannocena, Dictyocha, Distephanopsis, Paramesocena</em> and <em>Stephanocha</em>. This study records the first evidence of Tortonian silicoflagellates from the offshore of northeast Indian Ocean. Two Partial Range zones namely <em>Dictyocha varia,</em> and <em>Dictyocha extensa</em> and one Subzone i.e. <em>Bachmannocena elliptica</em> have been proposed. In the present study, it has been observed that the transition of <em>D. varia</em> to <em>D. extensa</em><span> took place within the Tortonian. Fossil records of double skeletons in the silicoflagellate taxa are rare; however, we have documented double skeletons in three silicoflagellate taxa i.e. </span><span><em>Dictyocha calida, Dictyocha </em><em>fibula</em></span> subspecies <em>ausonia</em> and <em>Stephanocha speculum</em> (6-sided)<em>.</em> Ratio of <em>Dictyocha</em> and <em>Stephanocha</em> based on the combined abundance of all the taxa of the two genera reveals that there was substantial dominance of <em>Dictyocha</em> over <em>Stephanocha</em> throughout the studied sequence. The <em>Dictyocha/Stephanocha</em> palaeotemprature proxy indicated prevalence of warmer climate during the Tortonian (9.86 Ma to 7.39 Ma) with a cooling minimum in the <em>Bachmannocena elliptica</em> Subzone during 8.104 Ma – 8.088 Ma corresponding with nutrient rich condition.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105297"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194594","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":"Distinct patterns of coral lesion composition from national/quasi-national marine parks of Kerama and Yoron Islands, Ryukyu Archipelago","authors":"Dio Dirgantara,&nbsp;Mariyam Shidha Afzal,&nbsp;Takashi Nakamura","doi":"10.1016/j.dsr2.2023.105309","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105309","url":null,"abstract":"<div><p><span>A wide variety of coral communities are found in the Ryukyu Archipelago in southern Japan. Although reports of coral diseases and lesions in this region have increased since the 2000's, the variations of coral diseases among islands are somewhat limited. In this study, we conducted surveys to reveal the coral lesion assemblage and patterns in the marine national park area of Kerama Island and the quasi-national park on Yoron Island. Both sites are located 150 km away apart in the Ryukyu Archipelago. In total, 12 gross lesions were found in 30 coral genera. Corals in Yoron Island had 22% greater gross lesion abundance than Kerama Island (13.40 ± 1.36%) with an overall mean lesion abundance of 16.83 ± 1.66% (mean ± SE). Each Island shows a distinct pattern and group of coral lesion compositions. The disease lesion group of 7.21 ± 1.37% was dominated by White Syndrome (WS) and Black Band Disease (BBD), which severely infected various coral genera in Yoron Island. Corals in Kerama Island were predominantly affected by non-disease group lesion (9.76 ± 1.33%), such as </span><em>Chalinula nematifera</em> (CN) sponge overgrowing on the coral surface. Corals in the genus <em>Pachyseris</em> were highly susceptible (17.79%) to the diseases on Yoron Island, while Acroporid corals were the most susceptible (8.32%) to the diseases on Kerama Island. In addition, <span><em>Porites</em></span> were affected by disease and non-disease lesions from all sites in both Kerama and Yoron. These findings highlight the emergence of potential threats to coral communities in these national/quasi-national marine parks in Kerama and Yoron Island, which may be a factor limiting the survival and growth of key Scleractinian coral taxa. In addition, immediate consideration of environmental monitoring may be required to prevent coral disease outbreaks in the future.</p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105309"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194592","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":"Near-inertial oscillations in the deep Gulf of Mexico","authors":"Yingli Zhu,&nbsp;Xinfeng Liang","doi":"10.1016/j.dsr2.2023.105310","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105310","url":null,"abstract":"<div><p>Near-inertial oscillations (NIOs) are important for maintaining turbulent mixing that affects ocean circulation, biogeochemistry<span>, and climate. The spatial and temporal variability of NIOs in the deep part of the Gulf of Mexico<span> (GoM) has rarely been reported. In this study, a collection of moored current observations was used to examine the spatiotemporal variability of NIOs in the GoM. In the upper layer (0–800 m), a strong seasonal variability of NIOs appears in the eastern GoM with larger amplitudes in winter than in summer and is attributed to the seasonal variability of surface winds and mixed layer depth. In the bottom layer (within 400 m above the bottom), strong NIOs are found in the middle and eastern GoM and show weaker seasonal variability. While winds still matter for the seasonal variability of NIOs in the bottom layer in the eastern GoM, low-frequency flows generally play a more important role in regulating NIOs through interactions with topography, particularly on the continental slope.</span></span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"210 ","pages":"Article 105310"},"PeriodicalIF":3.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50194587","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":"Seeps and vents of the Bering Sea","authors":"Vladimir V. Mordukhovich,&nbsp;Elena M. Krylova,&nbsp;Paul R. Dando","doi":"10.1016/j.dsr2.2023.105290","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105290","url":null,"abstract":"","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105290"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174438","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":"Record-breaking 2020 summer marine heatwaves in the western North Pacific","authors":"Yulong Yao ,&nbsp;Chunzai Wang ,&nbsp;Chao Wang","doi":"10.1016/j.dsr2.2023.105288","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105288","url":null,"abstract":"<div><p><span><span>Record-breaking marine heatwaves (MHWs) occurred in the western North Pacific during the summer of 2020. These unprecedented MHWs were consistent with favorable large-scale conditions that are linked to an anomalous western North Pacific subtropical high (WNPSH), resulting mainly from sea surface temperature (SST) anomalies across the tropical oceans. In addition, a moderate La Niña-like pattern was also conducive to transporting warm seawater to the western North Pacific. Mixed-layer heat budgets suggest that surface heat flux contributed to the SST anomaly in the western subtropical Pacific. In contrast, oceanic heat </span>advection dominanted in the South China Sea and the western equatorial Pacific. Numerical model experiments indicated that the tropical Indian Ocean SST anomalies were responsible for the enhanced WNPSH. The increased zonal SST gradient across the tropical Pacific also played an important role. Inter-ocean interactions can modulate </span>climate variability<span><span> through ocean-atmospheric coupling and deserve more attention when predicting MHWs within the context of global warming. In addition, it is critical to consider MHWs as a powerful tool in detecting acute, intense thermal stress events in the </span>coral bleaching pre-warning system.</span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105288"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174423","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":"Cause and impact of Andaman Sea's salinity variability: A modeling study","authors":"Abhishek Pasula,&nbsp;Deepak N. Subramani","doi":"10.1016/j.dsr2.2023.105291","DOIUrl":"https://doi.org/10.1016/j.dsr2.2023.105291","url":null,"abstract":"<div><p>The Andaman Sea is an important and strategic region for India, both from a security and conservation viewpoint. Documenting the spatiotemporal variability of salinity<span> is fundamental to understanding this region's dynamics. We studied the Andaman Sea's seasonal and inter-annual salinity variability during the Boreal summer (JJAS) using NEMO reanalysis data (1993–2018). Analysis of river influx, precipitation, Empirical Orthogonal Functions<span> of the salinity fields, numerical particle trajectory experiments, and statistical significance tests were conducted to understand the causal factors and impact of the Andaman Sea's salinity variability. Our study shows that it is the Southwest Monsoon Current (SMC) that brings a significant influx of salinity into the Andaman Sea and governs the seasonal cycle. We also document and explain the different surface and sub-surface dynamical trends. We show that higher salinity influx to the Andaman Sea is correlated with the strength of SMC. Crucially, this study is the first-ever attempt to comprehend the salinity dynamics of the Andaman Sea utilizing both Empirical Orthogonal Function (EOF) analysis and particle trajectories. We also note the reported reduction in shark catch and qualitatively analyze its relation to the seasonal salinity cycle, motivating the need for further physical-biological combined studies of the region.</span></span></p></div>","PeriodicalId":11120,"journal":{"name":"Deep-sea Research Part Ii-topical Studies in Oceanography","volume":"209 ","pages":"Article 105291"},"PeriodicalIF":3.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50174427","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}