Pub Date : 2026-02-01DOI: 10.1016/j.pocean.2026.103681
Xinxin Li , Yifan Qi , Ziyan Wang , Wenpeng Li , Hongwei Chen , Xin Zhao
Circadian POC-diurnal and nocturnal cycling of particulate organic carbon (POC)- could influence their seasonal and interannual biogeochemical patterns. In order to understand circadian POC in oligotrophic northern South China Sea, this study conducted a continuous 24 h time-series sampling across four depths (5 m, chlorophyll maximum depth, 200 m, and 662 m) of one site on the continental slope and analyzed optical properties of suspended particulate matter (SPM), POC properties, microbial community abundance and respiration rate (MCR) of size-fractionated microorganisms, and their dark carbon fixation rates (DCF). The results suggested varying degrees of coupling among SPM, POC, MCR, microbial abundance, and light intensity, associated with different primary production and diel vertical migration patterns. Size-fractionated analysis revealed three distinct metabolic patterns but no significant differences in their contribution to total MCR: synchronized variations between abundance of small phytoplankton and bacterioplankton organisms (0.2–0.8 μm) followed a “fast carbon cycling mode”; medium organisms (0.8–3.0 μm) showed significant correlations between bacterial abundance, POC, and MCR, functioning as primary POC decomposers; and large organisms (>3.0 μm) displayed decoupled metabolic patterns, potentially utilizing non-primary productivity carbon sources. Dark carbon fixation (56.9 ± 9.2 mg C m−2 d-1) was an important POC supply besides export production and lateral transport in the deep ocean. The study emphasized the critical importance of considering the science of circadian POC when assessing biological carbon pump efficiency in oligotrophic marginal seas.
{"title":"Circadian particulate organic carbon driven by size-fractionated microbial communities in northern South China Sea","authors":"Xinxin Li , Yifan Qi , Ziyan Wang , Wenpeng Li , Hongwei Chen , Xin Zhao","doi":"10.1016/j.pocean.2026.103681","DOIUrl":"10.1016/j.pocean.2026.103681","url":null,"abstract":"<div><div>Circadian POC-diurnal and nocturnal cycling of particulate organic carbon (POC)- could influence their seasonal and interannual biogeochemical patterns. In order to understand circadian POC in oligotrophic northern South China Sea, this study conducted a continuous 24 h time-series sampling across four depths (5 m, chlorophyll maximum depth, 200 m, and 662 m) of one site on the continental slope and analyzed optical properties of suspended particulate matter (SPM), POC properties, microbial community abundance and respiration rate (MCR) of size-fractionated microorganisms, and their dark carbon fixation rates (DCF). The results suggested varying degrees of coupling among SPM, POC, MCR, microbial abundance, and light intensity, associated with different primary production and diel vertical migration patterns. Size-fractionated analysis revealed three distinct metabolic patterns but no significant differences in their contribution to total MCR: synchronized variations between abundance of small phytoplankton and bacterioplankton organisms (0.2–0.8 μm) followed a “fast carbon cycling mode”; medium organisms (0.8–3.0 μm) showed significant correlations between bacterial abundance, POC, and MCR, functioning as primary POC decomposers; and large organisms (>3.0 μm) displayed decoupled metabolic patterns, potentially utilizing non-primary productivity carbon sources. Dark carbon fixation (56.9 ± 9.2 mg C m<sup>−2</sup> d<sup>-1</sup>) was an important POC supply besides export production and lateral transport in the deep ocean. The study emphasized the critical importance of considering the science of circadian POC when assessing biological carbon pump efficiency in oligotrophic marginal seas.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103681"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001419","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}
Pub Date : 2026-02-01DOI: 10.1016/j.pocean.2026.103680
Garima Chaudhari , Smita Mitbavkar , Pranoy Paul , Jagadish S. Patil , Samir Damare
Picophytoplankton are globally ubiquitous and play essential roles in marine food webs and biogeochemical cycles, yet the Eastern Indian Ocean remains comparatively understudied. To address this gap, we investigated picophytoplankton biogeography, community structure, and carbon biomass across the Bay of Bengal (BoB), Equatorial Indian Ocean (EqIO), and South Tropical Indian Ocean (STIO), spanning the 90°E Ridge (20°N − 30°S) during the spring inter-monsoon of 2021. The EqIO exhibited the warmest waters, followed by the BoB and STIO, while salinity increased progressively from the BoB to the STIO. Flow-cytometric analyses revealed a decreasing trend in picophytoplankton abundance and carbon biomass from the BoB to the STIO. Synechococcus populations were highest above the subsurface chlorophyll maxima layer (SCML), whereas Prochlorococcus and picoeukaryotes dominated within the SCML. Depth-integrated abundances and biomass of Synechococcus and Prochlorococcus were highest in the BoB, followed by the STIO and EqIO, while picoeukaryotes, though contributing the least, aligned with Synechococcus in the STIO. The presence of Synechococcus and Prochlorococcus in the BoB Oxygen Minimum Zone (130 m) suggests potential heterotrophic or mixotrophic capabilities. Picophytoplankton abundance and carbon biomass were elevated in the westward-flowing, nutrient-rich, stratified South Equatorial Current (Indonesian Throughflow), and lower in the reverse-flowing, deeply-mixed waters of the Equatorial Under Current. The Generalized Additive Model revealed a non-linear predictor-response relationship across the study region. The RCbray analyses showed that the picophytoplankton community assembly across all regions was overwhelmingly governed by stochastic processes, with the majority of samples falling within the ecological drift range. The insights gained from this study provide valuable inputs for improving predictive models of microbial responses to environmental variability and for refining biomass estimations in the Eastern Indian Ocean.
{"title":"Picophytoplankton biogeography, community structure, and carbon biomass in the Eastern Indian Ocean during the spring inter-monsoon season","authors":"Garima Chaudhari , Smita Mitbavkar , Pranoy Paul , Jagadish S. Patil , Samir Damare","doi":"10.1016/j.pocean.2026.103680","DOIUrl":"10.1016/j.pocean.2026.103680","url":null,"abstract":"<div><div>Picophytoplankton are globally ubiquitous and play essential roles in marine food webs and biogeochemical cycles, yet the Eastern Indian Ocean remains comparatively understudied. To address this gap, we investigated picophytoplankton biogeography, community structure, and carbon biomass across the Bay of Bengal (BoB), Equatorial Indian Ocean (EqIO), and South Tropical Indian Ocean (STIO), spanning the 90°E Ridge (20°N − 30°S) during the spring inter-monsoon of 2021. The EqIO exhibited the warmest waters, followed by the BoB and STIO, while salinity increased progressively from the BoB to the STIO. Flow-cytometric analyses revealed a decreasing trend in picophytoplankton abundance and carbon biomass from the BoB to the STIO. <em>Synechococcus</em> populations were highest above the subsurface chlorophyll maxima layer (SCML), whereas <em>Prochlorococcus</em> and picoeukaryotes dominated within the SCML. Depth-integrated abundances and biomass of <em>Synechococcus</em> and <em>Prochlorococcus</em> were highest in the BoB, followed by the STIO and EqIO, while picoeukaryotes, though contributing the least, aligned with <em>Synechococcus</em> in the STIO. The presence of <em>Synechococcus</em> and <em>Prochlorococcus</em> in the BoB Oxygen Minimum Zone (130 m) suggests potential heterotrophic or mixotrophic capabilities. Picophytoplankton abundance and carbon biomass were elevated in the westward-flowing, nutrient-rich, stratified South Equatorial Current (Indonesian Throughflow), and lower in the reverse-flowing, deeply-mixed waters of the Equatorial Under Current. The Generalized Additive Model revealed a non-linear predictor-response relationship across the study region. The RC<sub>bray</sub> analyses showed that the picophytoplankton community assembly across all regions was overwhelmingly governed by stochastic processes, with the majority of samples falling within the ecological drift range. The insights gained from this study provide valuable inputs for improving predictive models of microbial responses to environmental variability and for refining biomass estimations in the Eastern Indian Ocean.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103680"},"PeriodicalIF":3.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995699","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}
Pub Date : 2026-01-30DOI: 10.1016/j.pocean.2026.103687
David E. Richardson, Katrin E. Marancik, Malgorzata Adamus, Elisabeth A. Broughton, Robert K. Cowen, Trika Gerard, Christina M. Hernández, John J. Hoey, Joel K. Llopiz, Molly E. Lutcavage, Estrella Malca, Debra L. Palka, Lourdes Vásquez-Yeomans, Harvey J. Walsh, C. Michelle Willis, Glenn A. Zapfe
{"title":"A re-evaluation of Atlantic bluefin tuna (Thunnus thynnus) spawning distribution in the western Atlantic Ocean","authors":"David E. Richardson, Katrin E. Marancik, Malgorzata Adamus, Elisabeth A. Broughton, Robert K. Cowen, Trika Gerard, Christina M. Hernández, John J. Hoey, Joel K. Llopiz, Molly E. Lutcavage, Estrella Malca, Debra L. Palka, Lourdes Vásquez-Yeomans, Harvey J. Walsh, C. Michelle Willis, Glenn A. Zapfe","doi":"10.1016/j.pocean.2026.103687","DOIUrl":"https://doi.org/10.1016/j.pocean.2026.103687","url":null,"abstract":"","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"8 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072661","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}
Pub Date : 2026-01-25DOI: 10.1016/j.pocean.2026.103686
Jakiel Aleksandra, Błażewicz Magdalena
Two new deep-sea species of Pseudotanaidae are described from the North Pacific: Beksitanais seaodditys sp. nov. from the Bering Sea and Mystriocentrus bieguni sp. nov. from the Sea of Okhotsk, collected during the AleutBio and SokhoBio expeditions. Morphological examination combined with COI and 18S data reveals both congruence and conflict between datasets. The new species extend the currently known diversity of Beksitanais and Mystriocentrus and show that several characters previously regarded as diagnostic, such as the thick rod seta on the maxilliped palp and palm folds on the cheliped, are evolutionarily uninformative. Mystriocentrus bieguni lacks the thick seta on palp article-4, while B. seaodditys exhibits palm folds, indicating possible homoplasy. Phylogenetic results reveal high morphological–molecular complexity within Pseudotanaidae, providing new insights into the delimitation and evolutionary relationships of its deep-sea genera. These findings underscore the value of integrative taxonomy for advancing our understanding of tanaidacean diversity in the deep ocean.
{"title":"Integrating morphology and molecular data: Two new deep-sea species of Beksitanais and Mystriocentrus from North Pacific (Crustacea, Tanaidacea)","authors":"Jakiel Aleksandra, Błażewicz Magdalena","doi":"10.1016/j.pocean.2026.103686","DOIUrl":"https://doi.org/10.1016/j.pocean.2026.103686","url":null,"abstract":"Two new deep-sea species of Pseudotanaidae are described from the North Pacific: Beksitanais seaodditys sp. nov. from the Bering Sea and Mystriocentrus bieguni sp. nov. from the Sea of Okhotsk, collected during the AleutBio and SokhoBio expeditions. Morphological examination combined with COI and 18S data reveals both congruence and conflict between datasets. The new species extend the currently known diversity of Beksitanais and Mystriocentrus and show that several characters previously regarded as diagnostic, such as the thick rod seta on the maxilliped palp and palm folds on the cheliped, are evolutionarily uninformative. Mystriocentrus bieguni lacks the thick seta on palp article-4, while B. seaodditys exhibits palm folds, indicating possible homoplasy. Phylogenetic results reveal high morphological–molecular complexity within Pseudotanaidae, providing new insights into the delimitation and evolutionary relationships of its deep-sea genera. These findings underscore the value of integrative taxonomy for advancing our understanding of tanaidacean diversity in the deep ocean.","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"178 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048055","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}
Pub Date : 2026-01-25DOI: 10.1016/j.pocean.2026.103684
V. Venkataramana, R.K. Mishra, Melena A. Soares, P. Sabu, Alvarinho J. Luis, A. Sarkar, T. Jabir, A.Srinivas Rao, Rahul Mohan
Polar regions are particularly sensitive to even small increases in temperature. Eastern Antarctic coastal waters may therefore be especially vulnerable to warming, posing increased risk to planktonic communities. Despite this vulnerability, zooplankton studies in the coastal waters of Eastern Antarctica (Indian Ocean sector) have received comparatively less scientific attention than those in West Antarctica, particularly with respect to understanding the impacts of ongoing climate change on zooplankton. To address this information gap, we investigated zooplankton biovolume, community composition, and vertical distribution in relation to hydrographic parameters in the coastal waters of Antarctica during the sea-ice melting season (January and February) of 2017. The sea surface temperature conditions observed in the neritic zone were highly unusual and, to our knowledge, had not been reported previously. In the seasonal ice zone, freshening of surface waters likely constrained the biomass of both phytoplankton and zooplankton. Conversely, the elevated zooplankton biovolume recorded in the neritic and ice free zones was likely associated with higher chlorophyll-a concentrations compared to those in the seasonal ice zone. Calanus simillimus and Calanus australis are key taxa in the oceanic domain, whereas Stephos longipes and Paralabidocera antarctica serve as indicator species of the continental shelf region, where their occurrence is closely associated with floating sea ice. We hypothesized that the combined influence regional factors including sea surface temperature, food availability, sea ice extent, ongoing sea ice decline, and surface freshening would exert the strongest control on zooplankton abundance and species diversity in the coastal waters of East Antarctica. As a result, such environmental changes are expected to substantially affect biogeochemical process in coastal Antarctic ecosystem.
{"title":"Response of zooplankton to unusual increase in temperature and sea ice melting in a changing environment (Prydz Bay), coastal Antarctica: Climate change perspective","authors":"V. Venkataramana, R.K. Mishra, Melena A. Soares, P. Sabu, Alvarinho J. Luis, A. Sarkar, T. Jabir, A.Srinivas Rao, Rahul Mohan","doi":"10.1016/j.pocean.2026.103684","DOIUrl":"https://doi.org/10.1016/j.pocean.2026.103684","url":null,"abstract":"Polar regions are particularly sensitive to even small increases in temperature. Eastern Antarctic coastal waters may therefore be especially vulnerable to warming, posing increased risk to planktonic communities. Despite this vulnerability, zooplankton studies in the coastal waters of Eastern Antarctica (Indian Ocean sector) have received comparatively less scientific attention than those in West Antarctica, particularly with respect to understanding the impacts of ongoing climate change on zooplankton. To address this information gap, we investigated zooplankton biovolume, community composition, and vertical distribution in relation to hydrographic parameters in the coastal waters of Antarctica during the sea-ice melting season (January and February) of 2017. The sea surface temperature conditions observed in the neritic zone were highly unusual and, to our knowledge, had not been reported previously. In the seasonal ice zone, freshening of surface waters likely constrained the biomass of both phytoplankton and zooplankton. Conversely, the elevated zooplankton biovolume recorded in the neritic and ice free zones was likely associated with higher chlorophyll-a concentrations compared to those in the seasonal ice zone. <ce:italic>Calanus simillimus</ce:italic> and <ce:italic>Calanus australis</ce:italic> are key taxa in the oceanic domain, whereas <ce:italic>Stephos longipes</ce:italic> and <ce:italic>Paralabidocera antarctica</ce:italic> serve as indicator species of the continental shelf region, where their occurrence is closely associated with floating sea ice. We hypothesized that the combined influence regional factors including sea surface temperature, food availability, sea ice extent, ongoing sea ice decline, and surface freshening would exert the strongest control on zooplankton abundance and species diversity in the coastal waters of East Antarctica. As a result, such environmental changes are expected to substantially affect biogeochemical process in coastal Antarctic ecosystem.","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"1 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048045","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}
Pub Date : 2026-01-23DOI: 10.1016/j.pocean.2026.103683
Derya Akdogan, Angelika Brandt, Stefanie Kaiser
{"title":"A new species of Austroniscus Vanhöffen, 1914 (Isopoda, Asellota, Nannoniscidae Hansen, 1914) from abyssal depths of the Aleutian Trench, north-eastern Pacific","authors":"Derya Akdogan, Angelika Brandt, Stefanie Kaiser","doi":"10.1016/j.pocean.2026.103683","DOIUrl":"https://doi.org/10.1016/j.pocean.2026.103683","url":null,"abstract":"","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"46 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033593","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}
Pub Date : 2026-01-19DOI: 10.1016/j.pocean.2026.103682
Andreas Kelch, Laura Spies, Davide Di Franco, Maria A. Nilsson, Sven Rossel, Pedro Martinez Arbizu, Anja Rauh, Heiko Stuckas, Stefanie Kaiser, Angelika Brandt
{"title":"Integrative taxonomy of mesosignidae Schultz, 1969 (Crustacea, Malacostraca) from North Pacific trenches: new species description and biogeographic insights from morphology, mtDNA, and proteomics","authors":"Andreas Kelch, Laura Spies, Davide Di Franco, Maria A. Nilsson, Sven Rossel, Pedro Martinez Arbizu, Anja Rauh, Heiko Stuckas, Stefanie Kaiser, Angelika Brandt","doi":"10.1016/j.pocean.2026.103682","DOIUrl":"https://doi.org/10.1016/j.pocean.2026.103682","url":null,"abstract":"","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"123 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001427","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}
Pub Date : 2026-01-16DOI: 10.1016/j.pocean.2026.103679
Rodrigo Mogollón , Dante Espinoza-Morriberón , Oswaldo Velasquez , Guisela Yabar , Manuel Villena , Jorge Tam
The 2017 Marine Heatwave event was characterized by significant positive sea surface temperature anomalies driven by weakened and reversed wind patterns, from mid-January to mid-April. The wind reversal during the Coastal El Niño favored downwelling processes, limiting the upward transport of nutrient-rich waters and causing a rapid collapse in surface phytoplankton biomass. Additionally, reduced latent heat flux and increased shortwave radiation further exacerbated surface warming. From February to March 2017, chlorophyll-a concentrations showed strong negative anomalies (more than −3 mg m−3), with the High Productive Zone (HPZ) contracting significantly, from 300 km offshore in January to nearly 25 km from the coast during this two-months period, while the total HPZ area decreased by up to 130,000 km2 in March, demonstrating a sharp decline in surface chlorophyll-a concentration. However, as physical drivers tend to return to typical seasonal values by April, upwelling resumed, positive chlorophyll-a anomalies emerged indicating a relatively rapid recovery of phytoplankton biomass, and the HPZ re-expanded toward climatological levels. These findings emphasize the sensitivity of the northern Peruvian marine ecosystem to short-term climate variability. Given the increasing frequency of these climatic events, understanding the physical drivers of ecosystem changes is critical for predicting future impacts and informing adaptive management strategies.
{"title":"Chlorophyll response and High Productivity Zone contraction in northern Perú during the 2017 Coastal El Niño","authors":"Rodrigo Mogollón , Dante Espinoza-Morriberón , Oswaldo Velasquez , Guisela Yabar , Manuel Villena , Jorge Tam","doi":"10.1016/j.pocean.2026.103679","DOIUrl":"10.1016/j.pocean.2026.103679","url":null,"abstract":"<div><div>The 2017 Marine Heatwave event was characterized by significant positive sea surface temperature anomalies driven by weakened and reversed wind patterns, from mid-January to mid-April. The wind reversal during the Coastal El Niño favored downwelling processes, limiting the upward transport of nutrient-rich waters and causing a rapid collapse in surface phytoplankton biomass. Additionally, reduced latent heat flux and increased shortwave radiation further exacerbated surface warming. From February to March 2017, chlorophyll-a concentrations showed strong negative anomalies (more than −3 mg m<sup>−3</sup>), with the High Productive Zone (HPZ) contracting significantly, from 300 km offshore in January to nearly 25 km from the coast during this two-months period, while the total HPZ area decreased by up to 130,000 km<sup>2</sup> in March, demonstrating a sharp decline in surface chlorophyll-a concentration. However, as physical drivers tend to return to typical seasonal values by April, upwelling resumed, positive chlorophyll-a anomalies emerged indicating a relatively rapid recovery of phytoplankton biomass, and the HPZ re-expanded toward climatological levels. These findings emphasize the sensitivity of the northern Peruvian marine ecosystem to short-term climate variability. Given the increasing frequency of these climatic events, understanding the physical drivers of ecosystem changes is critical for predicting future impacts and informing adaptive management strategies.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103679"},"PeriodicalIF":3.6,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995700","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}
Pub Date : 2026-01-16DOI: 10.1016/j.pocean.2026.103678
Fany Sardenne , Carl D. van der Lingen , Marie Vagner , Yonela Geja , Eleonora Puccinelli , Margaux Mathieu-Resuge , Fabienne Le Grand , Jean-Marie Munaron , Manon Buscaglia , Sandrine Serre , Philippe Soudant , Laure Pecquerie
Small pelagic fishes (SPF) in eastern boundary upwelling systems share space and must adapt to strong seasonal and inter-annual variations in their environment. This raises questions about how these species share food resources in a changing environment and whether they compete with each other when their food resources are reduced. We approach these questions on three SPF species (sardine Sardinops sagax, anchovy Engraulis encrasicolus and round herring Etrumeus whiteheadi) living on the west and south coasts of South Africa. We combined fish muscle fatty acid profiles as a proxy for prey taxa diversity, stable isotope compositions as a proxy for habitat and trophic position, and satellite-derived chlorophyll-a and zooplankton concentrations as proxies for food availability. We found that the total fatty acid content (energy reserve) of the three species increased with chlorophyll-a concentration, suggesting that chlorophyll-a is a good proxy for food quantity. For the three SPF species, the niche width increased with the amount of chlorophyll-a. However, the niche overlap (i.e. the potential for competition) remained relatively unchanged as chlorophyll-a concentrations increased, though it varied considerably depending on local conditions (from 0 to 100 %), higher on the west coast (influenced by the Benguela upwelling) than in the south coast. The relative trophic level of the species (round herring > anchovy > sardine) was confirmed in both regions and the round herring remained on average 25 % fattier than the other two species. These results suggest that on a relatively short time scale (month) SPF species are more selective when food levels decrease but that competition for resources may or may not operate depending on local conditions. However, integrated over a larger time scale, the three species do feed on different resources (resulting in different trophic levels) and cannot be considered an ecological substitute. The recent changes in their respective biomasses could impact the amount of fat (energy) available to higher trophic levels.
{"title":"Resource partitioning among small pelagic fish remains stable regardless of food availability in a seasonally pulsed upwelling system","authors":"Fany Sardenne , Carl D. van der Lingen , Marie Vagner , Yonela Geja , Eleonora Puccinelli , Margaux Mathieu-Resuge , Fabienne Le Grand , Jean-Marie Munaron , Manon Buscaglia , Sandrine Serre , Philippe Soudant , Laure Pecquerie","doi":"10.1016/j.pocean.2026.103678","DOIUrl":"10.1016/j.pocean.2026.103678","url":null,"abstract":"<div><div>Small pelagic fishes (SPF) in eastern boundary upwelling systems share space and must adapt to strong seasonal and inter-annual variations in their environment. This raises questions about how these species share food resources in a changing environment and whether they compete with each other when their food resources are reduced. We approach these questions on three SPF species (sardine <em>Sardinops sagax</em>, anchovy <em>Engraulis encrasicolus</em> and round herring <em>Etrumeus whiteheadi</em>) living on the west and south coasts of South Africa. We combined fish muscle fatty acid profiles as a proxy for prey taxa diversity, stable isotope compositions as a proxy for habitat and trophic position, and satellite-derived chlorophyll-a and zooplankton concentrations as proxies for food availability. We found that the total fatty acid content (energy reserve) of the three species increased with chlorophyll-a concentration, suggesting that chlorophyll-a is a good proxy for food quantity. For the three SPF species, the niche width increased with the amount of chlorophyll-a. However, the niche overlap (i.e. the potential for competition) remained relatively unchanged as chlorophyll-a concentrations increased, though it varied considerably depending on local conditions (from 0 to 100 %), higher on the west coast (influenced by the Benguela upwelling) than in the south coast. The relative trophic level of the species (round herring > anchovy > sardine) was confirmed in both regions and the round herring remained on average 25 % fattier than the other two species. These results suggest that on a relatively short time scale (month) SPF species are more selective when food levels decrease but that competition for resources may or may not operate depending on local conditions. However, integrated over a larger time scale, the three species do feed on different resources (resulting in different trophic levels) and cannot be considered an ecological substitute. The recent changes in their respective biomasses could impact the amount of fat (energy) available to higher trophic levels.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"242 ","pages":"Article 103678"},"PeriodicalIF":3.6,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145995701","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}
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