Human activities significantly influence carbon sequestration and carbon stock in seagrass ecosystems; however, their impacts on small islands remain understudied. Based on this gap, this study quantified seagrass carbon stocks across Indonesian islands, examining spatial variability and anthropogenic pressures. Carbon stocks were measured using the Loss on Ignition (LOI) method. Results showed relatively high values, with biomass ranging from 0.65 to 11.25 tC ha−1 (4.01 ± 2.84 tC ha−1), sediment from 22.46 to 98.53 tC ha−1 (52.77 ± 17.61 tC ha−1), and total carbon from 22.70 to 98.53 tC ha−1 (56.78 ± 20.45 tC ha−1). Significant spatial differences were observed among islands and land-use categories, indicating that average or constant values cannot be reliably applied for national carbon estimates. Anthropogenic activities also had a marked effect, underscoring the need to integrate human impacts into management and conservation strategies. These findings provide essential baseline data for national carbon accounting while highlighting the ecological and climate importance of small-island seagrass ecosystems. Protecting and restoring seagrass meadows should be prioritized as a dual strategy for climate adaptation and biodiversity conservation.
{"title":"Carbon stocks on the intertidal seagrass meadow of the Indonesian Islands: Spatial and anthropogenic activities variability","authors":"Fery Kurniawan , Agustin Rustam , Robba Fahrisy Darus , Fauziyah , Almira Nadia Kusuma , Muhammad Noval Alghifari , Luky Adrianto , Yonvitner","doi":"10.1016/j.csr.2025.105604","DOIUrl":"10.1016/j.csr.2025.105604","url":null,"abstract":"<div><div>Human activities significantly influence carbon sequestration and carbon stock in seagrass ecosystems; however, their impacts on small islands remain understudied. Based on this gap, this study quantified seagrass carbon stocks across Indonesian islands, examining spatial variability and anthropogenic pressures. Carbon stocks were measured using the Loss on Ignition (LOI) method. Results showed relatively high values, with biomass ranging from 0.65 to 11.25 tC ha<sup>−1</sup> (4.01 ± 2.84 tC ha<sup>−1</sup>), sediment from 22.46 to 98.53 tC ha<sup>−1</sup> (52.77 ± 17.61 tC ha<sup>−1</sup>), and total carbon from 22.70 to 98.53 tC ha<sup>−1</sup> (56.78 ± 20.45 tC ha<sup>−1</sup>). Significant spatial differences were observed among islands and land-use categories, indicating that average or constant values cannot be reliably applied for national carbon estimates. Anthropogenic activities also had a marked effect, underscoring the need to integrate human impacts into management and conservation strategies. These findings provide essential baseline data for national carbon accounting while highlighting the ecological and climate importance of small-island seagrass ecosystems. Protecting and restoring seagrass meadows should be prioritized as a dual strategy for climate adaptation and biodiversity conservation.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105604"},"PeriodicalIF":2.2,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520170","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 : 2025-11-03DOI: 10.1016/j.csr.2025.105603
Claire T. Shellem , Karin R. Bryan , Conrad A. Pilditch , Chris D. Cornelisen , Joanne I. Ellis
Climate change is causing shifts to thermal regimes in coastal marine environments often expressed as alarming marine heat waves; however, such changes are not well understood or observed in fjord environments. Ongoing exposure to intensifying marine heatwaves is becoming increasingly likely and could cause significant and even catastrophic outcomes on the unusual and sensitive ecosystems that characterize fjords. Here we identify spatial and temporal changes in temperature and salinity in the surface waters (0.5–19 m) of a temperate fjord, Doubtful Sound, New Zealand, utilising high resolution data. Data were collected between 2005 and 2023 and recorded at 15-min intervals at three sites, an outer-, mid- and inner-fjord site. IIncreasing temperature anomalies, including two marine heatwave events, were superimposed on seasonal and interannual temperature and salinity patterns. We detect both increasing temperatures through time, from the surface to 19 m and a notable freshening of the near surface low salinity layer. Annual mean temperatures increased at a rate of 0.39–0.67 °C per decade, with the deeper waters (11–19 m) warming faster than shallow waters (<2 m). This is one of the first studies to document the temporal oceanic progression of a heatwave into a fjord, taking several hours for the most intense temperatures to travel from the outermost site to the innermost site, about 30 km. The documented heatwaves in this temperate fjord caused increases of 2–3 °C above mean summer temperatures. Marine heatwaves are emerging as a pervasive threat to marine communities; hence the ecological implications of these findings are considered.
{"title":"Warming temperatures and prevalence of marine heatwaves in a temperate fjord","authors":"Claire T. Shellem , Karin R. Bryan , Conrad A. Pilditch , Chris D. Cornelisen , Joanne I. Ellis","doi":"10.1016/j.csr.2025.105603","DOIUrl":"10.1016/j.csr.2025.105603","url":null,"abstract":"<div><div>Climate change is causing shifts to thermal regimes in coastal marine environments often expressed as alarming marine heat waves; however, such changes are not well understood or observed in fjord environments. Ongoing exposure to intensifying marine heatwaves is becoming increasingly likely and could cause significant and even catastrophic outcomes on the unusual and sensitive ecosystems that characterize fjords. Here we identify spatial and temporal changes in temperature and salinity in the surface waters (0.5–19 m) of a temperate fjord, Doubtful Sound, New Zealand, utilising high resolution data. Data were collected between 2005 and 2023 and recorded at 15-min intervals at three sites, an outer-, mid- and inner-fjord site. IIncreasing temperature anomalies, including two marine heatwave events, were superimposed on seasonal and interannual temperature and salinity patterns. We detect both increasing temperatures through time, from the surface to 19 m and a notable freshening of the near surface low salinity layer. Annual mean temperatures increased at a rate of 0.39–0.67 °C per decade, with the deeper waters (11–19 m) warming faster than shallow waters (<2 m). This is one of the first studies to document the temporal oceanic progression of a heatwave into a fjord, taking several hours for the most intense temperatures to travel from the outermost site to the innermost site, about 30 km. The documented heatwaves in this temperate fjord caused increases of 2–3 °C above mean summer temperatures. Marine heatwaves are emerging as a pervasive threat to marine communities; hence the ecological implications of these findings are considered.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105603"},"PeriodicalIF":2.2,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467315","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 : 2025-11-01DOI: 10.1016/j.csr.2025.105601
Tobias Kukulka , Robert J. Chant
<div><div>This study investigates theoretically the impact of the Coriolis force on the gravitationally driven estuarine circulation based on the tidally averaged coupled nonlinear momentum and salinity budget equations. Without Coriolis force, it was previously shown that the governing non-dimensional equations for the estuarine circulation depend on two non-dimensional numbers which control the effects of lateral advection and mixing. With Coriolis force, the estuarine circulation is controlled by one additional parameter, a non-dimensional Coriolis parameter, <span><math><mrow><mi>ϕ</mi><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>=</mo><mi>f</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow></msub><msubsup><mrow><mi>u</mi></mrow><mrow><mi>S</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, where <span><math><mi>f</mi></math></span>, <span><math><msub><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>S</mi></mrow></msub></math></span>, and <span><math><mi>δ</mi></math></span> symbolize, respectively, the Coriolis parameter, maximum depth, classic estuarine circulation velocity scale, and depth to width aspect ratio. For sufficiently strong vertical mixing, the scaling with Coriolis force predicts qualitatively the dominant budget terms, straightforwardly extending previous scaling results. For this extended scaling, the lateral velocity scale is obtained assuming a balance between vertical friction and pressure gradient forces. For sufficiently rapid rotation and weak vertical mixing, however, the along-channel velocity approaches a geostrophic thermal wind balance violating the straightforward extended scaling. For rapidly rotating estuaries, the equations are alternatively rescaled assuming a geostrophic balance for the along-channel velocity. This rapid rotation scaling reveals the Ekman number Ek<span><math><mrow><mo>=</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>Z</mi></mrow></msub><mo>/</mo><mrow><mo>(</mo><mi>f</mi><msubsup><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>)</mo></mrow></mrow></math></span> as a key non-dimensional number consistent with earlier work (<span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>Z</mi></mrow></msub></math></span> is a vertical mixing coefficient). The rapid rotation scaling applies for sufficiently small Ek and predicts a geostrophic balance for the cross-channel direction and, with greater <span><math><mrow><mi>ϕ</mi><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, a mixed geostrophic-Ekman balance in the along-channel direction so that the along-channel velocity approaches a coastal current structure. Furthermore, for rapidly rotating estuaries, the dynamics is nonlinear due to nonlinear coupling of momentum with salinity. The
{"title":"Coriolis force effects on the density driven estuarine circulation: Inception of a coastal current","authors":"Tobias Kukulka , Robert J. Chant","doi":"10.1016/j.csr.2025.105601","DOIUrl":"10.1016/j.csr.2025.105601","url":null,"abstract":"<div><div>This study investigates theoretically the impact of the Coriolis force on the gravitationally driven estuarine circulation based on the tidally averaged coupled nonlinear momentum and salinity budget equations. Without Coriolis force, it was previously shown that the governing non-dimensional equations for the estuarine circulation depend on two non-dimensional numbers which control the effects of lateral advection and mixing. With Coriolis force, the estuarine circulation is controlled by one additional parameter, a non-dimensional Coriolis parameter, <span><math><mrow><mi>ϕ</mi><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>=</mo><mi>f</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow></msub><msubsup><mrow><mi>u</mi></mrow><mrow><mi>S</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msubsup><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, where <span><math><mi>f</mi></math></span>, <span><math><msub><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>S</mi></mrow></msub></math></span>, and <span><math><mi>δ</mi></math></span> symbolize, respectively, the Coriolis parameter, maximum depth, classic estuarine circulation velocity scale, and depth to width aspect ratio. For sufficiently strong vertical mixing, the scaling with Coriolis force predicts qualitatively the dominant budget terms, straightforwardly extending previous scaling results. For this extended scaling, the lateral velocity scale is obtained assuming a balance between vertical friction and pressure gradient forces. For sufficiently rapid rotation and weak vertical mixing, however, the along-channel velocity approaches a geostrophic thermal wind balance violating the straightforward extended scaling. For rapidly rotating estuaries, the equations are alternatively rescaled assuming a geostrophic balance for the along-channel velocity. This rapid rotation scaling reveals the Ekman number Ek<span><math><mrow><mo>=</mo><msub><mrow><mi>K</mi></mrow><mrow><mi>Z</mi></mrow></msub><mo>/</mo><mrow><mo>(</mo><mi>f</mi><msubsup><mrow><mi>h</mi></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>)</mo></mrow></mrow></math></span> as a key non-dimensional number consistent with earlier work (<span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>Z</mi></mrow></msub></math></span> is a vertical mixing coefficient). The rapid rotation scaling applies for sufficiently small Ek and predicts a geostrophic balance for the cross-channel direction and, with greater <span><math><mrow><mi>ϕ</mi><msup><mrow><mi>δ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, a mixed geostrophic-Ekman balance in the along-channel direction so that the along-channel velocity approaches a coastal current structure. Furthermore, for rapidly rotating estuaries, the dynamics is nonlinear due to nonlinear coupling of momentum with salinity. The","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105601"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520753","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 : 2025-11-01DOI: 10.1016/j.csr.2025.105602
Jeancarlo M. Fajardo-Urbina , Ulf Gräwe , Herman J.H. Clercx , Theo Gerkema , Matias Duran-Matute
This study identifies and quantifies the distinct contributions of wind and tides to the variability of Lagrangian residual transport in the Dutch Wadden Sea (DWS), a mesotidal system of interconnected tidal basins of high ecological relevance. A three-dimensional hydrodynamic model and offline particle tracking were used to simulate the transport of particle patches over individual tidal periods of the record 1980-2015 using depth-averaged currents. This transport was decomposed into the net displacement of their center of mass (advection) and the tidally averaged rate of change of dispersion from their center of mass (the dispersion coefficient). The results reveal that advection is predominantly wind-driven on the temporal scale of events. Strong winds from the North Sea aligned with the topographical orientation of the system trigger advection comparable to the width of the basins. Although the role of tides in advection is secondary, they induce residual circulation cells near the inlets, particularly evident during weak wind conditions. In contrast, dispersion is controlled by the tides and exhibits filamentous structures with large values around all the DWS inlets. The strength of these structures has a linear correlation with the tidal amplitude, which is mainly modulated by the spring-neap cycle. However, the location of these structures changes predominantly from shallow areas surrounding the channels when particles are released at high tide to within the channels when released at low tide. These findings underscore the distinct separable roles of wind and tides in Lagrangian residual transport within event-driven, multi-inlet coastal systems such as the DWS.
{"title":"Tidal and wind-driven spatiotemporal variability in the residual displacement and dispersion of Lagrangian particles in a system of intertidal basins","authors":"Jeancarlo M. Fajardo-Urbina , Ulf Gräwe , Herman J.H. Clercx , Theo Gerkema , Matias Duran-Matute","doi":"10.1016/j.csr.2025.105602","DOIUrl":"10.1016/j.csr.2025.105602","url":null,"abstract":"<div><div>This study identifies and quantifies the distinct contributions of wind and tides to the variability of Lagrangian residual transport in the Dutch Wadden Sea (DWS), a mesotidal system of interconnected tidal basins of high ecological relevance. A three-dimensional hydrodynamic model and offline particle tracking were used to simulate the transport of particle patches over individual tidal periods of the record 1980-2015 using depth-averaged currents. This transport was decomposed into the net displacement of their center of mass (advection) and the tidally averaged rate of change of dispersion from their center of mass (the dispersion coefficient). The results reveal that advection is predominantly wind-driven on the temporal scale of events. Strong winds from the North Sea aligned with the topographical orientation of the system trigger advection comparable to the width of the basins. Although the role of tides in advection is secondary, they induce residual circulation cells near the inlets, particularly evident during weak wind conditions. In contrast, dispersion is controlled by the tides and exhibits filamentous structures with large values around all the DWS inlets. The strength of these structures has a linear correlation with the tidal amplitude, which is mainly modulated by the spring-neap cycle. However, the location of these structures changes predominantly from shallow areas surrounding the channels when particles are released at high tide to within the channels when released at low tide. These findings underscore the distinct separable roles of wind and tides in Lagrangian residual transport within event-driven, multi-inlet coastal systems such as the DWS.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105602"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520172","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 : 2025-10-29DOI: 10.1016/j.csr.2025.105593
Seerangan Manokaran , Thadickal V. Joydas , Paravanparambil Rajakumar Jayachandran , Jayanath Gopi , Omer Reshi , Karuppasamy P. Manikandan , Mohamed A. Qurban
The ecosystem functions of macrobenthic invertebrates were studied in the Red Sea. In total, 193 taxa were recorded. The functional traits of biomass (B) and density (D), such as infauna with internal irrigation (B - 53.4 %), blind-ended burrows, no burrow systems (D - 44.5 %), surface filter (B - 41.5 %), and surface deposit feeders (D - 50.8 %) were dominant attributes with significant regional and depth differences. However, irrigation depth 0 to 2 – 5 cm (B - 50 %, D - 45 %); movements through the sediment matrix mobility pattern (B - 68.3 %, D - 47.2 %), and reworking superficial modifiers (B - 54.2 %, D - 45.2 %) also significantly dominated. The functional individuals, biomass, richness, density, and diversity were 11 ± 1 (Mean ± SE) species m−2, 1.25 ± 0.26 g m−2, 1.70 ± 0.13 Fd’, 361 ± 57 ind. m−2, and 2.76 ± 0.11FH' (log2). These indices decreased with increased depth and were higher in the north compared to the central region. The composition of bioturbation potential community index (BPc) and bio-irrigation potential community index (IPc) values was significantly (P < 0.05) higher in the north (29.46 ± 5.48, and 42.12 ± 10.33) and shallower (55.32 ± 12.79, and 83.76 ± 26.93) depth zones. The taxa Aglaophamus dibranchis, holothuria, sand dollar, and Glycinde sp.1 were responsible for higher BPc, and the taxa sand dollar, Spionidae indet. Notomastus latericeus, Glycinde sp.1, and Prionospio spp. contributed higher to IPc. The environmental variables MGS, silt/clay, depth, latitude (region), As, and Fe influenced functional density (P = 0.191) and biomass (P = 0.182), and MGS, depth, latitude, As, Mn, and Pb also influenced bioturbation (P = 0.224) and bio-irrigation (P = 0.218) of the macrobenthic community. Generally, the functional attributes influence deep-sea nutrient cycling by enhancing benthic and pelagic coupling processes on the Red Sea coast, particularly in relation to coastal developmental activities.
{"title":"Ecosystem function: Trait diversity, bioturbation, and bio-irrigation potentials of macrobenthic invertebrate communities in the Red Sea","authors":"Seerangan Manokaran , Thadickal V. Joydas , Paravanparambil Rajakumar Jayachandran , Jayanath Gopi , Omer Reshi , Karuppasamy P. Manikandan , Mohamed A. Qurban","doi":"10.1016/j.csr.2025.105593","DOIUrl":"10.1016/j.csr.2025.105593","url":null,"abstract":"<div><div>The ecosystem functions of macrobenthic invertebrates were studied in the Red Sea. In total, 193 taxa were recorded. The functional traits of biomass (B) and density (D), such as infauna with internal irrigation (B - 53.4 %), blind-ended burrows, no burrow systems (D - 44.5 %), surface filter (B - 41.5 %), and surface deposit feeders (D - 50.8 %) were dominant attributes with significant regional and depth differences. However, irrigation depth 0 to 2 – 5 cm (B - 50 %, D - 45 %); movements through the sediment matrix mobility pattern (B - 68.3 %, D - 47.2 %), and reworking superficial modifiers (B - 54.2 %, D - 45.2 %) also significantly dominated. The functional individuals, biomass, richness, density, and diversity were 11 ± 1 (Mean ± SE) species m<sup>−2</sup>, 1.25 ± 0.26 g m<sup>−2</sup>, 1.70 ± 0.13 Fd’, 361 ± 57 ind. m<sup>−2</sup>, and 2.76 ± 0.11FH' (log<sup>2</sup>). These indices decreased with increased depth and were higher in the north compared to the central region. The composition of bioturbation potential community index (BPc) and bio-irrigation potential community index (IPc) values was significantly <em>(P < 0.05)</em> higher in the north (29.46 ± 5.48, and 42.12 ± 10.33) and shallower (55.32 ± 12.79, and 83.76 ± 26.93) depth zones. The taxa <em>Aglaophamus dibranchis,</em> holothuria, sand dollar, and <em>Glycinde</em> sp.1 were responsible for higher BPc, and the taxa sand dollar, Spionidae indet. <em>Notomastus latericeus</em>, <em>Glycinde</em> sp.1, and <em>Prionospio</em> spp. contributed higher to IPc. The environmental variables MGS, silt/clay, depth, latitude (region), As, and Fe influenced functional density (<em>P = 0.191</em>) and biomass (<em>P = 0.182</em>), and MGS, depth, latitude, As, Mn, and Pb also influenced bioturbation (<em>P = 0.224</em>) and bio-irrigation (<em>P = 0.218</em>) of the macrobenthic community. Generally, the functional attributes influence deep-sea nutrient cycling by enhancing benthic and pelagic coupling processes on the Red Sea coast, particularly in relation to coastal developmental activities.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105593"},"PeriodicalIF":2.2,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467271","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 : 2025-10-27DOI: 10.1016/j.csr.2025.105594
Katarína Holcová , Martina Havelcová , Sanah Shaikh , Markéta Chroustová , Katarína Šarinová , Filip Scheiner , Petr Kraft , Ivana Sýkorová , Rastislav Milovský
This study investigates fossil seagrass accumulations in the Pliocene–Pleistocene Kritika Formation on Rhodes Island using geochemical, organic petrology and palaeobiological proxies. The studied section can be correlated with the lower Calabrian (1.7–1.6 Ma). Inorganic geochemistry revealed fluctuations between freshwater and marine environments, suggesting a dynamic estuarine environment, as supported by the analysed δ13Corg values, which varied from −25.0 to −23.5 ‰. High concentrations of terrestrial organic matter indicate significant riverine input to the coastal area under warm and humid climatic conditions. Further, elevated Ni (720–1100 ppm) and Co (41–60 ppm) concentrations in the sediments indicate a basic/ultrabasic (ophiolitic) sediment source in the catchment area. The absence of marine organisms in these accumulations and reduced estuarine salinity suggest that Posidonia leaves were transported within the estuary rather than deposited in situ. Organic geochemical analyses revealed minor peaks of submerged plant-specific n-alkanes (C21, C23, C25) similar to modern dead Posidonia accumulations. Abundant short even n-alkanes (C16, C18) associated with heterotrophic bacteria and fungi are also present, indicating microbial decomposition. Identical geochemical signatures in samples without Posidonia body fossils confirmed the presence of amorphous organic matter of seagrass origin, further demonstrating that organic geochemical proxies can identify ancient seagrass meadows even in the absence of body fossils.
{"title":"Early Pleistocene fossil seagrass assemblages on Rhodes Island – a proof of allochthonous origin","authors":"Katarína Holcová , Martina Havelcová , Sanah Shaikh , Markéta Chroustová , Katarína Šarinová , Filip Scheiner , Petr Kraft , Ivana Sýkorová , Rastislav Milovský","doi":"10.1016/j.csr.2025.105594","DOIUrl":"10.1016/j.csr.2025.105594","url":null,"abstract":"<div><div>This study investigates fossil seagrass accumulations in the Pliocene–Pleistocene Kritika Formation on Rhodes Island using geochemical, organic petrology and palaeobiological proxies. The studied section can be correlated with the lower Calabrian (1.7–1.6 Ma). Inorganic geochemistry revealed fluctuations between freshwater and marine environments, suggesting a dynamic estuarine environment, as supported by the analysed δ<sup>13</sup>C<sub>org</sub> values, which varied from −25.0 to −23.5 ‰. High concentrations of terrestrial organic matter indicate significant riverine input to the coastal area under warm and humid climatic conditions. Further, elevated Ni (720–1100 ppm) and Co (41–60 ppm) concentrations in the sediments indicate a basic/ultrabasic (ophiolitic) sediment source in the catchment area. The absence of marine organisms in these accumulations and reduced estuarine salinity suggest that <em>Posidonia</em> leaves were transported within the estuary rather than deposited <em>in situ</em>. Organic geochemical analyses revealed minor peaks of submerged plant-specific <em>n</em>-alkanes (C<sub>21</sub>, C<sub>23</sub>, C<sub>25</sub>) similar to modern dead <em>Posidonia</em> accumulations. Abundant short even <em>n</em>-alkanes (C<sub>16</sub>, C<sub>18</sub>) associated with heterotrophic bacteria and fungi are also present, indicating microbial decomposition. Identical geochemical signatures in samples without <em>Posidonia</em> body fossils confirmed the presence of amorphous organic matter of seagrass origin, further demonstrating that organic geochemical proxies can identify ancient seagrass meadows even in the absence of body fossils.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105594"},"PeriodicalIF":2.2,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418562","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 : 2025-10-25DOI: 10.1016/j.csr.2025.105600
Erick D. Ruvalcaba-Aroche , Emilio Beier , Laura Sánchez-Velasco
The tropical branch of the California Current (TBCC) converges with tropical waters in the Pacific off Mexico, generating thermal fronts whose hydrographic structure and ecological implications remain poorly understood. Using satellite-derived sea surface temperature (SST) data (2003–2021) and in situ measurements from four oceanographic cruises, this study examines the spatiotemporal variability of thermal fronts and their relationship with chlorophyll-a (CHL) as a proxy for productivity. Fronts were persistent along the peninsular coast, driven by coastal upwelling, with seasonal shifts in distribution: spring showed the highest frontal prevalence south of 24 °N, while summer activity shifted northward (26–28 °N). Autumn and winter exhibited minimal frontal activity. Seasonal variability explained 20–50 % of frontal occurrence in coastal zones and the oceanic zone south of 23 °N but was negligible offshore. The cold phase of ENSO (La Niña) correlated with enhanced frontal activity and elevated CHL, particularly south of 24 °N. A significant positive correlation between frontal probability and mesoscale CHL anomalies highlighted two key oceanic regions where fronts likely boost productivity: near Punta Eugenia (25–29 °N) and Cabo San Lucas (20–24 °N), especially in spring and summer. In situ data revealed that spring fronts featured steep thermocline slopes and coincided with CHL gradients, whereas autumn fronts lacked vertical structure and ecological influence. These findings underscore the role of thermal fronts in modulating productivity in the TBCC, particularly during spring and summer, while emphasizing the limited ecological impact of density-compensated fronts in autumn.
加利福尼亚流（TBCC）的热带分支在墨西哥附近的太平洋与热带水域汇合，产生热锋，其水文结构和生态影响仍然知之甚少。利用2003-2021年卫星海表温度（SST）数据和4次海洋巡航的现场测量数据，研究了热锋的时空变化及其与叶绿素-a （CHL）的关系，并以此作为生产力的代表。在海岸上升流的驱动下，锋面沿半岛海岸持续存在，其分布具有季节变化特征：春季锋面盛行度在24°N以南最高，夏季锋面活动向北移动（26-28°N）。秋季和冬季的锋面活动最小。季节变化解释了沿海带和23°N以南海域锋面发生的20 - 50%，但近海可以忽略不计。ENSO的冷期（La Niña）与锋面活动增强和CHL升高相关，特别是在24°N以南。锋面概率与中尺度CHL异常之间的显著正相关突出了锋面可能提高生产力的两个关键海洋区域：Punta Eugenia（25-29°N）和Cabo San Lucas（20-24°N）附近，特别是在春季和夏季。原位资料显示春季锋面具有陡峭的温跃层坡度，与CHL梯度一致，而秋季锋面缺乏垂直结构和生态影响。这些发现强调了热锋在调节TBCC生产力方面的作用，特别是在春季和夏季，同时强调了秋季密度补偿锋的生态影响有限。
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Pub Date : 2025-10-24DOI: 10.1016/j.csr.2025.105568
Carlos Alberto da Silva Junior , Guilherme Burg Mayer , Áthila Andrade Bertoncini , Rafael de Lima , Renato Hajenius Aché de Freitas
{"title":"Corrigendum to “A three-year survey of hatched elasmobranch egg capsules on Santa Catarina Island, Southern Brazil” [Cont. Shelf Res. 293 (2025) 105528]","authors":"Carlos Alberto da Silva Junior , Guilherme Burg Mayer , Áthila Andrade Bertoncini , Rafael de Lima , Renato Hajenius Aché de Freitas","doi":"10.1016/j.csr.2025.105568","DOIUrl":"10.1016/j.csr.2025.105568","url":null,"abstract":"","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105568"},"PeriodicalIF":2.2,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617807","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 : 2025-10-22DOI: 10.1016/j.csr.2025.105596
Ramsey R. Harcourt, John B. Mickett, K. Ravi Prakash
A widespread prevalence of subsurface acoustic ducts impacting mid-frequency sound propagation was observed over the outer shelf and the continental slope during a field experiment in July–August 2022 in the Pacific Northwest coastal ocean of North America. Simulations of the coastal shelf ocean using LiveOcean, a tidally driven operational model (MacCready et al., 2021), based upon a widely used variant of the Regional Ocean Modeling System (ROMS), were compared with observations of the thermohaline stratification layers responsible for the ducts, and found to have a nearly complete absence of these acoustic features due to excessive parametrized mixing. After implementing additional realistic constraints in the ‘k-ε’ second moment closure (SMC) to control instabilities in the turbulence mixing model with low background mixing, the source of instabilities was identified in a coding error for the default, third-order upstream advection of the turbulence parameters for TKE k and its dissipation ε, a longstanding and significant bug impacting mixing parametrization, and one also found in the older SMC ‘Mellor-Yamada 2.5’ mixing parametrization option in ROMS. With code improvements, LiveOcean was able to successfully simulate the production of observed subsurface acoustic ducts. The primary process for generating the ducts along the outer shelf involves the southward transport of low sound speed water during upwelling, combined with the cross-shelf displacement of higher sound speed water from offshore beneath this layer in bottom-driven Ekman transport.
{"title":"Taming turbulence closure in tidally driven simulations of coastal oceans and estuaries","authors":"Ramsey R. Harcourt, John B. Mickett, K. Ravi Prakash","doi":"10.1016/j.csr.2025.105596","DOIUrl":"10.1016/j.csr.2025.105596","url":null,"abstract":"<div><div>A widespread prevalence of subsurface acoustic ducts impacting mid-frequency sound propagation was observed over the outer shelf and the continental slope during a field experiment in July–August 2022 in the Pacific Northwest coastal ocean of North America. Simulations of the coastal shelf ocean using LiveOcean, a tidally driven operational model (MacCready et al., 2021), based upon a widely used variant of the Regional Ocean Modeling System (ROMS), were compared with observations of the thermohaline stratification layers responsible for the ducts, and found to have a nearly complete absence of these acoustic features due to excessive parametrized mixing. After implementing additional realistic constraints in the ‘k-ε’ second moment closure (SMC) to control instabilities in the turbulence mixing model with low background mixing, the source of instabilities was identified in a coding error for the default, third-order upstream advection of the turbulence parameters for TKE k and its dissipation ε, a longstanding and significant bug impacting mixing parametrization, and one also found in the older SMC ‘Mellor-Yamada 2.5’ mixing parametrization option in ROMS. With code improvements, LiveOcean was able to successfully simulate the production of observed subsurface acoustic ducts. The primary process for generating the ducts along the outer shelf involves the southward transport of low sound speed water during upwelling, combined with the cross-shelf displacement of higher sound speed water from offshore beneath this layer in bottom-driven Ekman transport.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105596"},"PeriodicalIF":2.2,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418565","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 : 2025-10-22DOI: 10.1016/j.csr.2025.105597
John A. Goff
The shoreface is a highly dynamic sedimentary environment, and also a challenging one to obtain stratigraphic data due to shallow depths and surf zone condition. A pole-mounted chirp subbottom profiler survey was conducted in May 2021 along the shoreface of Shell Island, Florida. These data are investigated with the aim characterizing sediment dynamics of an underwater unexploded ordinance test bed location. The Shell Island shoreface consists of three principal sedimentary units in the shallow subsurface. The substrate consists of the MAFLA marine sand sheet, which is organized into oblique-to-shore sand ridges, and which merges with the barrier island sands of Shell Island. Along the lower shoreface/inner shelf, this substrate is overlain by an ebb-tidal delta unit associated with sands exiting through St. Andrews Pass, the 1930's-era ship channel constructed by the US-Amy Corps of Engineers for access to Saint Andrews Bay, and transported to the SE. The ebb-tidal delta is prograding alongshore to the SE, as evidenced by the internal dipping reflectors, and consistent with the measured sediment transport direction. I calculate that the ebb-tidal delta has grown by ∼0.92x106 m3/yr since the opening of the Pass. Along the upper shoreface, the substrate is overlain by the nearshore sandbar, organized into crescentic morphology of alternating highs and lows with a spacing of ∼750 m alongshore. The sand bars are underlain by a strong seaward-dipping reflector, inferred to be the basal surface for mobile sands. The sand bars overlie the ebb-tidal delta unit, indicating a prograding shoreline.
{"title":"Ebb-tidal delta and sand bar construction offshore Shell Island, Florida","authors":"John A. Goff","doi":"10.1016/j.csr.2025.105597","DOIUrl":"10.1016/j.csr.2025.105597","url":null,"abstract":"<div><div>The shoreface is a highly dynamic sedimentary environment, and also a challenging one to obtain stratigraphic data due to shallow depths and surf zone condition. A pole-mounted chirp subbottom profiler survey was conducted in May 2021 along the shoreface of Shell Island, Florida. These data are investigated with the aim characterizing sediment dynamics of an underwater unexploded ordinance test bed location. The Shell Island shoreface consists of three principal sedimentary units in the shallow subsurface. The substrate consists of the MAFLA marine sand sheet, which is organized into oblique-to-shore sand ridges, and which merges with the barrier island sands of Shell Island. Along the lower shoreface/inner shelf, this substrate is overlain by an ebb-tidal delta unit associated with sands exiting through St. Andrews Pass, the 1930's-era ship channel constructed by the US-Amy Corps of Engineers for access to Saint Andrews Bay, and transported to the SE. The ebb-tidal delta is prograding alongshore to the SE, as evidenced by the internal dipping reflectors, and consistent with the measured sediment transport direction. I calculate that the ebb-tidal delta has grown by ∼0.92x10<sup>6</sup> m<sup>3</sup>/yr since the opening of the Pass. Along the upper shoreface, the substrate is overlain by the nearshore sandbar, organized into crescentic morphology of alternating highs and lows with a spacing of ∼750 m alongshore. The sand bars are underlain by a strong seaward-dipping reflector, inferred to be the basal surface for mobile sands. The sand bars overlie the ebb-tidal delta unit, indicating a prograding shoreline.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"296 ","pages":"Article 105597"},"PeriodicalIF":2.2,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364468","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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