Journal of Marine Systems最新文献

{"title":"Climate drivers of phytoplankton production along the Chilean coast","authors":"","doi":"10.1016/j.jmarsys.2024.104013","DOIUrl":"10.1016/j.jmarsys.2024.104013","url":null,"abstract":"<div><p>The west coast of South America is known for its high primary productivity. The level of phytoplankton can be measured through satellite images that detect chlorophyll (Chl), which is dependent on several oceanographic and meteorological parameters. Climate drivers such as El Niño Southern Oscillation (ENSO) and the Southeast Pacific Subtropical Anticyclone (SPSA) affect these parameters and, consequently, the phytoplankton. The objective of this study was to identify the impact of ENSO on SPSA, climate variables, and phytoplankton patterns. Composites were created using the years selected with either strongly positive or negative ENSO to understand their influence on different parameters. To create the Chl composite, it was necessary to extend it using Canonical Correlation Analysis (CCA) based on the sea surface temperature (SST) pattern. The study concludes that ENSO has a noticeable impact on Chl, mainly in the Southern Zone during the warm season. This is driven by the expansion of SPSA to the South, which increases the sea level pressure (SLP) in that region. However, predicting the Chl concentration has a high degree of uncertainty due to its complexity.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0924796324000514/pdfft?md5=f921de2c2ad1002ce1fe9bbe33de8092&pid=1-s2.0-S0924796324000514-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244169","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":"A multidecadal study of the Malabar upwelling system influencing Indian Mackerel landings along the coasts of Karnataka and Kerala, south-east Arabian Sea","authors":"","doi":"10.1016/j.jmarsys.2024.104012","DOIUrl":"10.1016/j.jmarsys.2024.104012","url":null,"abstract":"<div><p>Indian Mackerel (<em>Rastrelliger kanagurta</em>) is an essential small pelagic fishery resource, contributing to nearly 30 % of India's total marine fish landing. However, this species' life cycle and stock status are poorly understood and data deficient. Ocean mesoscale events are also known to influence their landing, besides the environmental factors like- salinity, chlorophyll, and sea surface temperature, affecting these small pelagic fishes' availability, migration, feeding, and reproductive activity. The Malabar upwelling region (southwest coast of India) is a significant upwelling system where upwelling occurs during the monsoon months. The nutrient-rich water increases the productivity of surface water, leading to plankton abundance. This productivity sustains a fishery for several commercially important fishes, mainly small pelagics such as sardines, mackerels, and anchovies, supporting India's most significant coastal pelagic fishery. For understanding the relationship between the target fish and the oceanographic events, in the present study, Pearson's correlation has been estimated between Indian Mackerel landing, rainfall, Sea water temperature at 0, 10, 20, 30, 45, and 50 m depths, mixed layer depth (MLD), their anomalies and occurrences of potential fishing zone (PFZ) lines along the Malabar upwelling region and corresponding coasts of Karnataka and Kerala. Mackerel landing time series showed a significant autocorrelation in four-quarter lag, correlation with rainfall anomaly in one-quarter lag, with PFZ line and MLD in three-quarter lag, and with SWT@50 (Seawater temperature@50 m depth) and SST anomaly in two-quarter lag both in Karnataka and Kerala. Upwelling events, as indicated by the presence of PFZ lines, were found to significantly impact the landings of Indian mackerel along the Karnataka and Kerala coasts. Polynomial equations were used to model the relationship between mackerel landings and these environmental factors, effectively capturing the influence of these parameters on mackerel catch trends.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230454","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":"Coexistence of a native and an invasive mussel species across an environmental gradient: Do interactions matter?","authors":"","doi":"10.1016/j.jmarsys.2024.104011","DOIUrl":"10.1016/j.jmarsys.2024.104011","url":null,"abstract":"<div><p>Introductions of invasive species are increasing worldwide, potentially threatening biodiversity. Although invasive species often displace native species by outcompeting them, coexistence between native and non-native species is common in diverse communities. A field experiment investigated the interactions between the native mussel <em>Mytilus galloprovincialis</em> and the invasive black pygmy mussel <em>Xenostrobus securis</em> across an environmental salinity gradient in the Ria de Vigo (NW Spain). The salinity gradient strongly affected the physiological responses of both mussel species as well as the competitive interactions between the two species. <em>Mytilus galloprovincialis</em> had a stronger effect on the invader than vice versa. The competition with <em>M. galloprovincialis</em> and the release from predation in certain estuarine areas may in part explain the dynamics of the invader population in the Ría de Vigo. Furthermore, results suggest that the invader may contribute positively to ecosystem functioning by increasing bentho-pelagic coupling, water-column clearance, and biodeposition of organic material in the innermost parts of estuaries, where it reaches large abundances. These areas are likely to promote and maintain the supply of propagules to the outermost parts, as well as favouring secondary spread along the Galician coast.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0924796324000496/pdfft?md5=ff19c6642a1876eb7322bf0939811161&pid=1-s2.0-S0924796324000496-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172263","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":"Potential bottom-up and top-down control of large microzooplankton in response to contrasting productive scenarios in the tropical southwestern Atlantic","authors":"","doi":"10.1016/j.jmarsys.2024.104010","DOIUrl":"10.1016/j.jmarsys.2024.104010","url":null,"abstract":"<div><p>Large microzooplankton, comprising organisms generally between 64 and 200 μm, plays a significant trophic role in marine ecosystems as primary or secondary consumers. In oligotrophic systems such as the Tropical Southwestern Atlantic, where primary production is dominated by Cyanobacteria, they provide a pivotal link between the basis of food webs and higher trophic levels. In this region, seasonal variations in circulation and continental runoff and wind mixing induce heightened phytoplankton biomass during autumn when compared to a less productive scenario observed in spring, leading to increased abundances of higher trophic levels. In order to establish the connection between primary producers and these higher trophic levels, we investigated the dynamics of large microzooplankton abundance in response to variations in phytoplankton biomass across different systems in the Tropical Southwestern Atlantic. Our findings highlight the complex interactions between bottom-up and top-down control mechanisms that shape large microzooplankton assemblages in these ecosystems. The increase in primary production was accompanied by an observable increase in the abundances of large microzooplankton organisms over the continental shelf, thereby supporting the hypothesis of bottom-up control. In contrast, offshore, in the South Equatorial Current System, a lower abundance of large microzooplankton was observed in the more productive scenario. The intricate relationships between large microzooplankton and higher trophic levels, particularly planktonic cnidarians, appear to be a key driver of these contrasting patterns. The presence of voracious gelatinous predators in the offshore systems, suggests a scenario in which top-down predation may counteract the expected bottom-up response of large microzooplankton to increased phytoplankton biomass. This indicates the importance of considering the entire trophic web when analysing the responses of large microzooplankton to changes in primary production.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142039781","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":"Distribution, abundance, and reproductive stages of salps, doliolids, and chaetognaths in different water masses of the shelf and open ocean of the Southwestern Atlantic Ocean between 31° and 38° S","authors":"","doi":"10.1016/j.jmarsys.2024.104000","DOIUrl":"10.1016/j.jmarsys.2024.104000","url":null,"abstract":"<div><p>The complex distribution of gelatinous zooplankton at the shelf and open ocean of the Southwestern Atlantic Ocean (31°-38°S) was closely linked to the prevailing water masses. Species composition differed significantly between subtropical and subantarctic assemblages in both neritic and oceanic environments. Diversity was lower in neritic and Malvinas assemblages but higher to the north of the Brazil-Malvinas Confluence. The influence of the Brazil Current was evident through the dominance of warm-water species such as <em>Flaccisagitta enflata, Fl. hexaptera, Pterosagitta draco, Pseudosagitta lyra</em>, and <em>Salpa fusiformis</em>, which displayed the highest abundances and different maturity stages north of the Confluence. The cold-waters originating from subantarctic regions were indicated by the presence of <em>Ps. gazellae, Eukrhonia hamata,</em> and <em>Serratosagitta tasmanica</em>, which showed higher abundances and the co-occurrence of different maturity stages south of the Confluence. The spread of low-salinity water into oceanic stations was indicated by the presence of species such as <em>Parasagitta friderici</em> and <em>Pa. tenuis</em>, which are typically found in neritic waters with low salinity. The coexistence of typical species from both warm- and cold-waters at oceanic stations in the Confluence section reflects the complex oceanographic structure of one of the most intense open-ocean fronts in the world ocean.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141945117","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":"Variability in oceanographic conditions affecting Mesophotic Ecosystems along the South Eastern Pacific: Latitudinal trends and potential for climate refugia","authors":"Lucas de la Maza ,&nbsp;Evie A. Wieters ,&nbsp;Ricardo Beldade ,&nbsp;Mauricio F. Landaeta ,&nbsp;Alejandro Perez-Matus ,&nbsp;Sergio A. Navarrete","doi":"10.1016/j.jmarsys.2024.103999","DOIUrl":"https://doi.org/10.1016/j.jmarsys.2024.103999","url":null,"abstract":"<div><p>Oceans have been changing at the fastest pace since the beginning of the Holocene. The South Eastern Pacific (SEP), including the Humboldt Upwelling Ecosystem (HUE) is subject to changes in upwelling winds, temperature, El Niño, and the ever-increasing local anthropogenic stressors, all of which have been documented for surface coastal waters where in-situ and remote observations are readily available. Temporal and spatial changes in the adjacent deeper waters where diverse Mesophotic Ecosystems are found have been scarcely documented. These marine ecosystems have been the focus of ecological studies for less than two decades. Here we provide an overview of the thermal variability at mesophotic depths and assess their potential as climatic refugia along all SEP ecoregions. We analyzed a time series of temperature and salinity from a 19 yr reanalysis based on remote and in-situ observations (CTD, ARGO, XBTs, moorings) to quantify variability in the Tropical (0–5°S), Northern Warm Temperate (5–30°S); Southern Warm Temperate (30–39.5°S) and Magellanic subregions (39.5–45°S), at two mesophotic depth strata (50 and 100 m), and a reference surface (5 m) depth. We assessed variability in the seasonal, interannual (El Niño) and ‘long-term’ (ca. 20 yr) scales, and the relationship with wind velocities. The thermal depth gradient between surface and mesophotic depths did not change smoothly with latitude but peaked within the northern portion of the warm temperate subregion, decreasing towards lower and higher latitudes. Seasonal variation in temperature was also largest in the north and south temperate subregions and minimal in the Magellanic subregion. Depth dampening of seasonal temperature variation was also strengthened at intermediate latitudes and much reduced in the tropics, where seasonal variation at mesophotic depths was similar to that at the surface. The strong interannual El Niño events were identified at all depths in tropical and temperate subregions, with stronger standardized effects at mesophotic layers than at the surface. Long-term (ca. two decades) temperature trends were significant and changed direction from warming to cooling along the SEP but were generally patchier at mesophotic layers. Spatial temperature gradients have remained relatively stable over the past two decades and were stronger at the surface than at mesophotic depths, and stronger within the tropics than in all other subregions. Surprisingly, the velocity of climate change was patchier and generally faster at mesophotic layers than at the surface. We conclude that, judging solely by physical environmental conditions, mesophotic ecosystems may be used by species with very different temperature affinities in temperate subregions, while in the tropics, more overlap in temperature affinities of component species may be found. Importantly, while the seasonal amplitude is reduced at mesophotic depth in most subregions, except the tropics, interannual disturbances ","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141542341","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":"Mesoscale and climate environmental variability drive krill community changes in the Humboldt Current System","authors":"Macarena Díaz-Astudillo ,&nbsp;Ramiro Riquelme-Bugueño ,&nbsp;Gonzalo S. Saldías ,&nbsp;Jaime Letelier","doi":"10.1016/j.jmarsys.2024.103998","DOIUrl":"10.1016/j.jmarsys.2024.103998","url":null,"abstract":"<div><p>Euphausiids (or “krill”) play a crucial role in the food webs of eastern boundary upwelling systems. Their inter-specific predatory interactions with ecologically and commercially important species highlights the importance of understanding krill variability at different temporal and spatial scales. In the Humboldt Current System (HCS), few studies have addressed the spatio-temporal variability of krill communities and their link with climate and local environmental drivers. We studied the patterns and variability of euphausiid diversity in the coastal area off northern Chile, using zooplankton and CTD-O data, and satellite environmental data from the falls and springs of 2010–2017. The community showed low diversity and evenness, with the endemic species <em>Euphausia mucronata</em> being the most abundant. The environmental variance showed 2 main modes of variability: (1) upwelling-associated changes in the depth of the oxygen minimum zone (OMZ) and in temperature, and (2) interannual variability in salinity, associated with ENSO-driven water-mass changes. The diversity indices and community structure showed large fluctuations in the cross-shore direction, and with latitude. The general pattern showed higher diversity offshore and southward, with few species in the low temperature, shallow OMZ conditions of the coastal band. During the 2013 and 2016 marine heatwaves and the 2015-2016 El Niño, the Subtropical Water Mass was advected southward, causing an increase in salinity and temperature, and a decrease in total krill abundance. However, ENSO variability did not significantly affect the species composition. The changes in community structure were caused by fluctuations in species abundance rather than species presence, as the most abundant species dominated the community throughout the study period. These results indicate that the krill communities of the HCS are highly resilient to climate perturbations, with upwelling-associated gradients being the primary source of variability for euphausiid populations in this ecosystem.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141403269","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":"Freshwater discharge drives latitudinal changes of phytoplankton composition on the continental shelf off Chilean Patagonia","authors":"Julio Poblete-Ulloa ,&nbsp;Marcelo H. Gutiérrez ,&nbsp;Carina B. Lange ,&nbsp;Diego A. Narváez ,&nbsp;Paulina Montero ,&nbsp;Humberto E. González ,&nbsp;Camila Fernández","doi":"10.1016/j.jmarsys.2024.103993","DOIUrl":"10.1016/j.jmarsys.2024.103993","url":null,"abstract":"<div><p>A high-resolution survey of distribution, abundance and composition of phytoplankton was carried out for the first time in surface waters of the continental shelf off Chilean Patagonia (41–48°S). An Imaging FlowCytobot was used along the survey track to record phytoplankton in the size range of 10–120 μm during the austral spring of 2018. Phytoplankton community structure was complemented with continuous underway measurements of temperature and salinity, and physicochemical parameters of the water column at 35 oceanographic stations. Our results evidenced two main macrozones with distinctive phytoplankton assemblages delimited latitudinally at ~45°S. The northern macrozone was characterized by higher surface temperature and salinity, Si:N ratio &gt; 1, diatoms of the genera <em>Thalassiosira</em> and <em>Chaetoceros</em>, and dinoflagellates accounting for over 70% of the total abundance. The southern macrozone, with lower surface temperature and salinity and Si:N ratio &lt; 1, was characterized by members of the genera <em>Guinardia</em>, <em>Lauderia</em> and <em>Cerataulina</em>, representing over 60% of the total phytoplankton. These changes were attributable to the strong influence of freshwater at latitudes higher than 45°S and the enhanced discharge of meltwaters from Patagonian icefields in the area of the Taitao Peninsula and the Gulf of Penas (47–-48°S). Fresh and cold waters impacted the water column stratification and the availability of dissolved silicic acid with potential effects on phytoplankton composition and diatom cell silicification and, thus, on carbon exportation. Our estimations of phytoplankton carbon were comparable to those observed in Patagonian fjords and the highly productive upwelling ecosystem of central Chile. We suggest that the continental shelf off Patagonia can contribute significantly to strengthen the biological carbon pump through the synthesis, exportation, and sequestration of phytoplankton-based organic carbon in the southeastern Pacific Ocean.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141412059","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":"Spatiotemporal variations in the grain size distribution in the water column and sediments from the Yellow River Delta to distal areas under coastal currents","authors":"Lijian Yang ,&nbsp;Xiaochuan Ma ,&nbsp;Yiwei He ,&nbsp;Min Gao ,&nbsp;Jie Huang ,&nbsp;Jian Lu ,&nbsp;Zhendong Luan","doi":"10.1016/j.jmarsys.2024.103997","DOIUrl":"https://doi.org/10.1016/j.jmarsys.2024.103997","url":null,"abstract":"<div><p>The differentiation of sediment grain size from large river deltas to distal areas in a coastal flow system and its evolution are vital because they greatly contribute to matter transport, pollution accumulation, and carbon cycling on the inner shelf. Here, the Yellow River sedimentary system in the adjacent seas is studied, including the proximal delta of the Yellow River and the distal mud patch. The grain size distributions of the suspended particulate matter (SPM), surface sediments, and core sediments in the Shandong Peninsula Coastal Current (SPCC) system were integrated and analyzed. The results show that apparent variations in the grain size distribution exist in the SPM and sediments in the SPCC system. The grain size distribution of the SPM near the proximal delta of the Yellow River is multimodal and variable with water depth, whereas that in the distal mud area is typically unimodal. The coarse-grained endmember of suspended sediments is restricted in the proximal area by ocean fronts under fair weather conditions in both summer and winter and is only transported to the distal mud area under strengthened coastal currents in winter. In contrast, fine-grained endmembers can be transported far away under tidal currents and coastal currents year-round. The temporal grain size variation near the proximal delta is also significantly affected by historical shifts in the Yellow River mouth, while the strength of coastal currents associated with the East Asian Winter Monsoon (EAWM) controls the grain size distribution in the distal mud area. The roles of river behaviors, ocean fronts, tides, and winds are all highlighted in the control of grain size differentiation. These results potentially have significance for understanding sediment dynamics and mass transport processes in similar coastal current systems involving large rivers worldwide.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141290069","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":"Investigating Labrador Sea's persistent surface O2 anomaly using observations and biogeochemical model results","authors":"Amavi N. Silva ,&nbsp;Duncan A. Purdie ,&nbsp;Nicholas R. Bates ,&nbsp;Toby Tyrrell","doi":"10.1016/j.jmarsys.2024.103996","DOIUrl":"https://doi.org/10.1016/j.jmarsys.2024.103996","url":null,"abstract":"<div><p>Deviations of surface ocean dissolved oxygen (O₂) from equilibrium with the atmosphere should be rectified about twenty times more quickly than deviations of dissolved carbon dioxide (CO₂). Therefore, persistent O₂ disequilibria in the Labrador Sea, while CO₂ is close to equilibrium, has been a matter of interest to many previous works. Here we investigate this phenomenon by using a novel analytical technique, the ‘CORS (Carbon Dioxide and Oxygen Relative to Saturation) method’, and also by using more data than was available previously. We compare observations to results from a model we developed for the Labrador Sea which combines plankton ecology with biogeochemical cycling of oxygen, carbon and nitrogen. In contrast to earlier works which mostly considered individual factors in isolation, here we used the model, together with data, to distinguish between the varying influences of several processes potentially contributing to the long-lasting O₂ undersaturation: mixed layer depth, duration of mixed layer deepening, convection, entrainment and bottom water O₂ content. Our model experiments confirm that, for the same gas exchange rate, the effects on surface O₂ concentration differ significantly among the identified drivers. Our results suggest that prolonged surface O₂ undersaturation is not always dependent on the extreme winter mixed layer depths, but rather that even moderately deep mixed layers (e.g. 300 m), when prolonged and in conjunction with continuous entrainment of oxygen-depleted deep water, can also drive persistent surface O₂ anomalies. An implication of our results is that regions in the North Atlantic with maximum winter mixed layer depths of only a few hundred metres should also show persistent surface O₂ undersaturation. We further reveal that convection in deep water formation regions produces trendlines that do not pass through the origin of a plot of CO₂ vs. O₂ deviations which have previously been thought to indicate erroneous data.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0924796324000344/pdfft?md5=3ab28f80ed74e5e6bde616b23c18602e&pid=1-s2.0-S0924796324000344-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141303727","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}