Continental Shelf Research最新文献

{"title":"Assessing the conservation status of Mediterranean coastal ponds: Checklist, ecological and functional diversity of diatom communities","authors":"Davide Taurozzi ,&nbsp;Massimiliano Scalici","doi":"10.1016/j.csr.2024.105359","DOIUrl":"10.1016/j.csr.2024.105359","url":null,"abstract":"<div><div>Coastal ponds are peculiar and threatened habitats, considered biodiversity hotspots. In many ecosystems ponds can be a valuable resource for the conservation of freshwater biodiversity. The Castelporziano Presidential Estate is a Mediterranean protected area hosting numerous ponds which are suffering severe droughts and a general decline in number and hydroperiod length. Hydroperiod changes can be particularly relevant for biodiversity inhabiting ponds, in particular diatom communities. Here, for the first time, we evaluate the conservation status of Mediterranean ponds inside the Castelporziano Reserve. The aims of this research are to i) investigate the influence of environmental variables on diatom communities of ponds; (ii) analyse diatom community structure in function of species richness and competitive interactions; (iii) highlight the potential and effectiveness of diatom ecological guilds in supporting the interpretation of the ecological status of threatened small waterbodies. Overall, 122 diatom taxa in the 29 ponds were described. <em>Nitzschia</em> (18 species) was the most species-rich genus, followed by <em>Gomphonema</em> (14) and <em>Navicula</em> (13). 17 species were included in the Red List of endangered species. Intra-pond distance and anthropogenic impacts didn't influence diatom assemblages. On the contrary, diatom communities were influenced by altitude and the distance from the sea. Furthermore, temporary ponds showed the lowest values for Shannon, evenness and Simpson indexes Considering Beta-diversity, both Bray-Curtis and Jaccard dissimilarity matrices highlighted a large dissimilarity between sampling sites. Inter-variability between sites and intra-variability within the sites resulted both very low. Our results highlight that diatom species are not influenced by hydroperiod length. Moreover, a structured diatom community emerged, where segregation processes predominating over aggregation ones. Finally, the average water quality of the ponds, calculated using the EPI-D index, was described as “good”. This study represents the most complete checklist of diatom communities inside coastal ponds of Castelporziano, providing valuable insights into the effects of natural and anthropogenic influences on ponds conservation and management activities. However, spatial-temporal changes and anthropogenic impacts should be deeply investigated.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"283 ","pages":"Article 105359"},"PeriodicalIF":2.1,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664177","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 century of tidal evolution around the Panama Canal","authors":"Haidong Pan ,&nbsp;Min Gan ,&nbsp;Tengfei Xu ,&nbsp;Zexun Wei","doi":"10.1016/j.csr.2024.105357","DOIUrl":"10.1016/j.csr.2024.105357","url":null,"abstract":"<div><div>As one of the most vital passageways worldwide, the Panama Canal plays essential roles in global trade and maritime logistics. Sea levels around the Panama Canal are dominated by ocean tides but local tidal evolution is still unexplored to date, which motivates present study. Two secular tide gauges longer than 110 years (Cristobal and Balboa) around the Panama Canal are analyzed to explore multi-time scale tidal variability. It is found that observed nodal modulations of major constituents are generally consistent with the equilibrium tidal theory. M₄ and Mf nodal modulations notably deviate from the theory possibly due to non-linear processes. Long-term trends exist in main semi-diurnal tides, while main diurnal tides do not have significant secular trends. It is worth mentioning that M₄ and MS₄ amplitudes at Cristobal have halved in the past century. Moreover, tidal parameters of major constituents at Cristobal and Balboa show abnormal mutations in 1908, 1990–1998, and 2013–2018. As a result of changing tides, tidal asymmetries at Cristobal are significantly weakened while the number of high tides per year is notably decreased. Tides at Balboa are almost symmetric. Tidal regimes at Cristobal can periodically shift between mixed diurnal tides and mixed semi-diurnal tides following the 18.61-year nodal cycle. However, such regime shift has disappeared since 1997 due to secular negative trends in M₂ amplitudes. In general, the findings of this study can be helpful for ships navigating in the Panama Canal.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"283 ","pages":"Article 105357"},"PeriodicalIF":2.1,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664260","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":"Flow characterization and turbulence in the eastern section of the Strait of Magellan, Southern Chile","authors":"Leandro Suarez ,&nbsp;Maricarmen Guerra ,&nbsp;Megan E. Williams ,&nbsp;Cristián Escauriaza ,&nbsp;Iossif Lozovatsky ,&nbsp;Ronald Coppersmith ,&nbsp;Harindra Joseph S. Fernando","doi":"10.1016/j.csr.2024.105344","DOIUrl":"10.1016/j.csr.2024.105344","url":null,"abstract":"<div><div>The Strait of Magellan connects the Pacific and Atlantic oceans in South America’s southern region, and it has been recognized for centuries as an important transoceanic navigation route as well as a unique marine environment with a rich ecological diversity. Evaluations of the impact of human activities in the channel and multiple potential future developments require a better understanding of the physical environment to design sustainable strategies aimed at preserving these characteristics. In this investigation, we study the flow near the Atlantic inlet of the Strait where the dynamics is characterized by the interactions of the tide propagation within two narrows, which are the predominant features of the channel morphology. Tides amplified by the Patagonian shelf generate strong currents through these narrows and control the exchange between the Atlantic and central regions of the Strait. We employ bottom-mounted and vessel-mounted Acoustic Doppler Current Profilers (ADCPs) with tide gauges to analyze the mean flow, tidal propagation, and turbulence, complementing the data with previous available measurements. The analysis reveals residual flows directed toward ebb flow at the channel center and flood near the edges, showing a significant spring-neap variation. Turbulence statistics in the second narrows exhibit a significant variability between ebb and flood, with a balance between production and dissipation observed only during ebb phases.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"283 ","pages":"Article 105344"},"PeriodicalIF":2.1,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664259","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":"Machine learning reveals biological activities as the dominant factor in controlling deoxygenation in the South Yellow Sea","authors":"Qingyi Liu ,&nbsp;Chunli Liu ,&nbsp;Qicheng Meng ,&nbsp;Bei Su ,&nbsp;Haijun Ye ,&nbsp;Bingzhang Chen ,&nbsp;Wei Li ,&nbsp;Xinyu Cao ,&nbsp;Wenlong Nie ,&nbsp;Nina Ma","doi":"10.1016/j.csr.2024.105348","DOIUrl":"10.1016/j.csr.2024.105348","url":null,"abstract":"<div><div>Dissolved oxygen (DO) is a crucial element for both biotic and abiotic processes in marine ecosystems, but has declined globally in recent decades. Therefore, there is an urgent need for solid large-scale and continuous estimation of DO concentration in vital ecosystems, such as coastal areas. A random forest (RF) model for DO in South Yellow Sea (SYS) was developed by integrating satellite data and simulation data during 2011–2019. The root mean squared error (RMSE) for the training and test sets were 0.514 mg/L and 0.732 mg/L, respectively. Spatiotemporal distributions of DO of multiple layers in the study area during 2011–2019 were very well reproduced by the RF model and showed a slight decline trend in most SYS areas, while more intense decline occurred in the deep central SYS. The analysis of the mechanisms of DO decline in the South Yellow Sea cold water mass (SYSCWM), located in the deep central SYS, indicates that the deoxygenation here is largely due to biological activities. This finding may have implications for studies on drivers of deoxygenation in coastal areas. Furthermore, integrating satellite data with machine learning models can offer a powerful approach to capturing the continuous spatiotemporal characteristics of ocean parameters over large spatial scales.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"283 ","pages":"Article 105348"},"PeriodicalIF":2.1,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664258","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":"Echoes of a Cold War","authors":"Valeriy Y. Rusakov ,&nbsp;Ruslan A. Lukmanov ,&nbsp;Bulat R. Soktoev ,&nbsp;Andrey Y. Mishan'kin","doi":"10.1016/j.csr.2024.105347","DOIUrl":"10.1016/j.csr.2024.105347","url":null,"abstract":"<div><div>The Kara Sea was an area of radionuclide contamination as a result of nuclear weapons testing, since it is located in close proximity to the nuclear test site on the Novaya Zemlya archipelago. The vertical distribution of ¹³⁷Cs and ²¹⁰Pb in 15 sediment cores from the sea made it possible to reconstruct the chronology of ¹³⁷Cs entry into marine sediments. The reconstruction was based on the age-depth model RUS2023 (Rusakov et al., 2024) for ²¹⁰Pb_ex, taking into account the grain-size composition and sorption capacity of sediments. Our study showed that higher ¹³⁷Cs concentrations in sediments of the Novaya Zemlya Trough correspond to the time of active nuclear weapons testing in 1961–63 (about 9.0 ± 1.6 Bq kg^‒1), as well as in estuarine sediments of the Yenisei Bay in 1986 (85.2 ± 3.2 Bq kg^‒1). The abnormally high flux in 1980s represents the superposition of ¹³⁷Cs fluxes as a result of global fallout (Chernobyl trace) and as a result of the release of radionuclide from regional source located in the Yenisei River catchment. Both of these events are associated with increased the sedimentation and mass accumulation rates of marine sediments. In 1961‒63, this was a consequence of the release of sediment into the atmosphere due to nuclear explosions, and in the 1980s, as a result of an increase in sediment supply with river runoff. Currently, against the backdrop of a decrease in sediment fluxes into the sea, Novaya Zemlya and Yenisei River remain the main sources of ¹³⁷Cs supply to marine sediments. Background values for recent sediments in the Kara Sea are &lt;2.0 Bq kg^‒1.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"283 ","pages":"Article 105347"},"PeriodicalIF":2.1,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664257","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":"Storms can increase beach resilience on a low-energy coast in the proximity of a harbor","authors":"Gabriela Medellín ,&nbsp;Gemma L. Franklin ,&nbsp;Alec Torres-Freyermuth","doi":"10.1016/j.csr.2024.105343","DOIUrl":"10.1016/j.csr.2024.105343","url":null,"abstract":"<div><div>Storms drive energetic waves and induce high water levels on the nearshore. Hence, they are commonly associated with negative effects on the coast (i.e., beach erosion and coastal flooding). Beach resilience, the capability to resist and recover from storms, relies on the beach width and elevation. This study investigates the subaerial beach morphological response to storms on a micro-tidal, low-energy tropical beach located in the proximity of a harbor. The study area, situated on a barrier island on the northwestern coast of the Yucatan Peninsula, is prone to winter, tropical, and local storms. Beach surveys were carried out over the 2015–2023 period, with a high spatial and temporal resolution, along a 4-km stretch of coast, comprising beach transects located downstream (erosive beach) and upstream (accretive and stable beach) of the harbor jetties. Moreover, offshore wave conditions and water levels were measured to identify storm events. Pre- and post-storm beach surveys are employed to estimate beach geoindicators to assess the impact of 66 storms. Consistent with prior studies, field observations suggest that the beach response (accretive or erosive) is dependent on the water level and pre-storm beach morphology. Furthermore, a net subaerial sediment volume gain, correlated with seasonal changes on the dimensionless fall velocity parameter and water level, occurs during the winter storm season on the prograding/stable beach section. On the other hand, storms induced subaerial sand volume losses on the receding beach section exposed to the same forcing conditions. Thus, our observations suggest that moderate winter and tropical storms can contribute to increasing beach resilience in this region.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"282 ","pages":"Article 105343"},"PeriodicalIF":2.1,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578654","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":"The Dnipro-Buh plume: A tale of high-volume freshwater discharge in a non-tidal sea","authors":"Alexander E. Yankovsky ,&nbsp;Yuriy P. Ilyin","doi":"10.1016/j.csr.2024.105345","DOIUrl":"10.1016/j.csr.2024.105345","url":null,"abstract":"<div><div>The Dnipro River has the second-largest annually-averaged discharge among European rivers and together with the Pivdennyi Buh River runs off on the Black Sea northwestern shelf, forming the Dnipro-Buh coastal buoyant plume. This study presents shipboard observations of the Dnipro-Buh plume in May of 1992 and 1994, when the freshwater discharge was lower and higher, respectively, than its climatological value for May, while the wind forcing was light and variable. In-situ data are complemented with satellite images obtained under similar forcing conditions at later times. Weak mixing in the Dnipro-Buh estuary leads to the formation of a thin, 1.5–3 m deep surface-advected plume. The estuarine outflow runs off parallel with the coastline, but with downstream distance it rapidly expands offshore over multiple baroclinic Rossby radii. On synoptic to monthly time scales, the Dnipro-Buh plume spreads in bimodal fashion, both upstream and downstream from the estuarine mouth. The downstream geostrophic transport of freshwater in the plume is a small fraction of the freshwater discharge feeding the plume. Also, as salinity anomaly decreases offshore, the freshwater content remains near-constant or even increases. This implies that the freshwater spreading is sustained by cross-frontal “diffusion” to a greater extent than through the advection by geostrophic circulation associated with the plume. Meso- and submesoscale instabilities are likely to play a major role in mixing and offshore spreading of the Dnipro-Buh plume.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"282 ","pages":"Article 105345"},"PeriodicalIF":2.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142537505","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":"Sedimentation characteristics of surficial sediments in Baiyun Canyon area, Northern South China Sea","authors":"Qingjie Zhou ,&nbsp;Youkou Dong ,&nbsp;Lejun Liu ,&nbsp;Xishuang Li","doi":"10.1016/j.csr.2024.105342","DOIUrl":"10.1016/j.csr.2024.105342","url":null,"abstract":"<div><div>The Baiyun Canyon area on the Northern Slope of the South China Sea is a potential hotspot for oil and gas resource development, but the sediment characteristics and sedimentary environment in this region present challenges for offshore engineering. This study comprehensively analyzed the physical, and mechanical properties of sediments in the area using geophysical exploration, engineering geological investigation, fixed-point sampling and hydrological observation. The engineering geological characteristics and sedimentary environment of surface sediments in the Baiyun Canyon area were studied, and the relationship between physical and mechanical properties and sedimentary environment was explored. The study revealed that the sediments in this area consist mainly of organic soft clay with high water content, low density, high pore ratio, high liquid limit, high plasticity and low strength. The physical and mechanical properties of the sediments vary, with the mechanical properties exhibiting higher variability than the physical properties. The research findings offer a scientific basis for understanding the seabed soil properties for designing submarine engineering structures in the deep waters of the northern South China Sea. This study holds significant theoretical and practical implications for oil and gas exploration and offshore engineering construction.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"282 ","pages":"Article 105342"},"PeriodicalIF":2.1,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528861","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":"Analysis of the annual number of tropical cyclones over Japan using the extreme value theory","authors":"Fumio Maruyama","doi":"10.1016/j.csr.2024.105341","DOIUrl":"10.1016/j.csr.2024.105341","url":null,"abstract":"<div><div>We predicted the extreme value of the annual number of typhoons, tropical cyclones over the western North Pacific, approaching typhoons, and landing typhoons for 1951–2019 over Japan and the minimum central pressure for 1987–2020 using the extreme value theory. The generalized extreme value (GEV) distribution was used to fit the extreme indices. Various diagnostic plots for assessing the accuracy of the GEV model fitted to the annual number of typhoons, approaching typhoons, and landing typhoons are shown, and all four diagnostic plots support the fitted GEV model. The shape parameter ξ for the annual number of typhoons and approaching typhoons is negative, and the number of typhoons has a finite upper limit. The calculated upper limits were 44.5 and 23.2 for the annual number of typhoons and approaching typhoons, respectively. However, ξ in the number of landing typhoons was zero; therefore, the number of landing typhoons did not have a finite upper limit, and there was a possibility that a significant risk would occur. The number of typhoons increased for 1951–2019. The minimum central pressure of typhoons estimated using geostationary satellite images decreased for 1987–2020, and the number of strong typhoons increased. The annual number of violent typhoons (<span><math><mrow><mo>≥</mo></mrow></math></span> 54 m/s) increased in the 2010s. The calculated limit of the minimum central pressure of the typhoon is 877 hPa. When the Pacific Decadal Oscillation (PDO) index is positive, more violent typhoons tend to occur.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"282 ","pages":"Article 105341"},"PeriodicalIF":2.1,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528860","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":"Phosphorus fractions and their vertical distribution in seabed sediments of the eastern Baltic Sea","authors":"Markus Ausmeel ,&nbsp;Martin Liira ,&nbsp;Päärn Paiste ,&nbsp;Aivo Lepland ,&nbsp;Sten Suuroja","doi":"10.1016/j.csr.2024.105340","DOIUrl":"10.1016/j.csr.2024.105340","url":null,"abstract":"<div><div>Phosphorus fractions and their vertical distribution in seabed sediments were studied in short cores from four coastal sites of western Estonia (Western Gulf of Finland, Väinameri Sea, Suur Strait, and Gulf of Riga) representing accumulation and erosion/transport settings. As a result of recent large-scale discharges of nutrients into the marine environment, abundant phosphorus has accumulated in the seabed sediments, from where it can, under the expansion of hypoxic or anoxic conditions, be remobilized and released back into the water column. A sequential extraction method with a neutral, a reducing, a basis, and an acidic solution was used to evaluate the distribution of phosphorous in pools of five different carrier fractions. Potentially mobile phosphorus is mostly associated with redox-sensitive iron- and manganese oxyhydroxides, and this fraction is significant in the Western Gulf of Finland and the Gulf of Riga. As oxygen conditions gradually deteriorate, the remobilization of a considerable amount of potentially mobile phosphorus from sediments can affect the entire Baltic Sea ecosystem.</div></div>","PeriodicalId":50618,"journal":{"name":"Continental Shelf Research","volume":"282 ","pages":"Article 105340"},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440965","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}