Journal of Sea Research最新文献

The La Niña event not only affected global ocean dynamics but also marine productivity. Due to its importance to the life of organisms and ecosystems, the biophysical aspects should be analyzed. One of the important regions in the eastern region of the Indian Ocean is located in the upwelling system and central marine biodiversity. The study aims to investigate several parameters, including SSTs, dissolved oxygen levels, nitrate distribution, and Chlor-a concentration, which are combined with ocean currents. These parameters are then analyzed in the period 2020 to 2022, which is La Niña condition. Based on the results, significant changes occur in SST during the first transitional season of 2022, where the increase reaches 1–4 °C. There was an increase in La Niña during this period. For marine productivity parameters, the recorded DO is in the range of 197 to 218 mmol/m³, nitrate with a value range of 0 to 0,02 mmol/m³, nanoplankton with a value range of 0 to 0.03 mg/m³, and Chlor-a with a value range of 0 to 4 mg/m³. We also found that changes in ENSO events affect the productivity of the Eastern Region of the Indian Ocean, especially in the Chlor-a parameter, where the occurrence of La Niña extreme is the most important parameter.

This study investigates the temporal variability of mesoscale eddies in the Bay of Bengal (BoB) over a 29-year period (1993–2021) using satellite altimeters. High-resolution daily sea level anomaly data are considered to identify the mesoscale eddies in the BoB utilizing py-eddy-tracker, an automated eddy detection and tracking method. Wavelet coherence analysis was conducted to find a statistically significant relation between eddy properties and climate indices. The findings indicate that anti-cyclonic eddies are more susceptible to the consequence of the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) than cyclonic eddies. Additionally, the joined impact of ENSO and IOD conceivably alters eddy activities across the BoB, as the second downwelling coastal Kelvin wave (dCKW) were absent. The mesoscale eddies exhibit correlations with climate indicators, suggesting that eddies get stronger during La Niña and negative IOD years and get weaker during El Niño and positive IOD years. This is because La Niña and negative IOD events intensify the second dCKW, while it weakens or becomes completely absent during El Niño and positive IOD years. Random Forest model was used to compare the influence of ENSO and IOD on the forecasting performance of the eddy properties. It was demonstrated that a unique positive IOD (+IOD) negatively affects the forecasting of eddy properties when using Sea Surface Temperature (SST) and SST anomalies. The findings bear importance in verifying and confirming the interactions between the ocean and climate.

The analysis of ocean eddies in the marginal ice zone via remote sensing and modeling data is a challenging task. However, it is of crucial importance for various scientific applications and anthropogenic activities in the Arctic. Models often struggle to accurately represent eddies near the MIZ due to the intricate nature of sea ice-ocean interactions, unresolved small-scale processes, and coarse resolution. Nevertheless, combining the information provided from both SAR and model data offers promising results that can potentially improve eddy detection accuracy near the MIZ. Furthermore, accurate characterization of the spatial and temporal variability of eddies near the MIZ demands a holistic approach that incorporates multi-platform observations, including numerical models and remote sensing data. This study demonstrates a specific test case on the intercomparison of the eddy signatures located in the MIZ in the Fram Strait based on remote sensing SAR scenes and Lagrangian modeling data from the two global oceanographic reanalysis GOFS 3.1 and GLORYS 12 V1. The study specifically displays the strong agreement in the eddy polarity and synchronism with reality, as well as differences in spatial scales and location of eddy centers. Overall, the obtained results support the further use of the presented approach for studying the eddies in the MIZ regions in the Arctic.

The North Frisian Wadden Sea (NFWS), an open tidal basin within the UNESCO World Heritage Wadden Sea, is characterized by its barrier systems, tidal inlets, intertidal flats, and estuaries. Unlike its East Frisian and Dutch counterparts, the NFWS is underexplored in terms of residual sediment and flow transport pathways—knowledge crucial for coastal conservation and nature-based protection. These pathways are a product of complex interplay between tides, winds and waves that together shape the morphology of the NFWS. This study investigates these interactions using a high-resolution process-based model to perform a representative period simulation derived through a novel unfiltered-reduction technique. Our results reveal an anticlockwise residual flow circulation in the back-barrier region, which was not discernible in the residual sediment pathways. Waves primarily dictated sediment transport over intertidal flats, showing high variability in transport direction under energetic conditions. The coastline orientation and fetch size favored southward wavedriven sediment transport, opposing the northward residual flow transport driven by tidal propagation. A dynamic residual divergence pattern in the nearshore region of the barrier islands is also revealed for both sediment and flow, which moves alongshore during energetic events. The discussion compares these patterns and their implications with earlier local measurements, conceptual pathways, and different systems globally to provide a comprehensive overview of the transport dynamics in the NFWS.

To enhance storm surge forecasting and establish open boundary conditions for sophistical numerical simulation of tides and tidal currents in the Bohai Sea, Yellow Sea, and East China Sea, this study evaluated the accuracy of eight global and regional tide models (EOT20, FES2014, NAO.99Jb, TPXO9, DTU16, HAMTIDE12, OSU12, and GOT4.10c) based on 41 tide gauges in the region. The differences between tide models and 8 offshore tide gauges were notable, with the root mean square (RMS) values ranging from 12.67 to 25.97 cm for M₂, 6.09–13.73 cm for S₂, 2.96–6.56 cm for K₁, and 2.50–4.20 cm for O₁. For the offshore stations, the NAO.99Jb model demonstrated superior performance with the root square sum (RSS) value of 12.63 cm among the eight tide models. For the island and coastal stations, the EOT20 model performed the best for M₂ (RMS 13.03 cm), the FES2014 model for S₂ (RMS 6.26 cm), and the DTU16 model for K₁ and O₁ (RMS 2.73 cm and 2.26 cm, respectively). Overall, the EOT20 model also exhibited the lowest RSS value (15.22 cm) among the eight models for 24 island and coastal stations. The EOT20 model slightly outperformed others with the RSS of 14.88 cm across all 32 tide gauges. Regarding the Sa tidal component, great discrepancies were found between TIDAL CONSTANTS (TICON) harmonic constant data and tide gauges. The reason for this is that the Doodson number for the Sa tidal component derived from tide gauge data, which is influenced by meteorological factors, should be (0,0,1,0,0,0), while the TICON harmonic constant data employed the Doodson number of (0,0,1,0,0,−1) corresponding to the basic astronomical variables. A correction method was proposed to adjust tidal constants from inconsistent Doodson numbers. Comparing with the harmonic constants of the Sa tidal component at 28 coastal tide stations revealed large errors in the NAO.99b, FES2014, and EOT20 models, with RMS values of 19.03, 22.08, and 13.61 cm, respectively. Consequently, caution should be taken when using the Sa results from these ocean tide models.

The greatest purpose of this study is to analyze the importance of surface waves on the hindcasting of the oil spill through the Symphony wheel accident in the Qingdao coastal waters. During the accident period, a total of four synthetic aperture radar (SAR) images by Gaofen-3 (GF-3) were acquired from 2 to 19 May 2021. The hindcasting of two sea surface dynamics, namely currents and waves, is carried out using a coupled marine numeric model. This model, known as the finite-volume community ocean model-simulating waves nearshore (FVCOM-SWAVE), employs a triangular grid. Simulated significant wave height (SWH) is validated against remotely sensed product by the Haiyang-2B (HY-2B) altimeter on April 2021 yields a root mean square error (RMSE) of 0.38, a correlation coefficient (COR) of 0.78, and a scatter index (SI) of 0.34. Subsequently, Stokes drift estimated by waves are included to hindcasting oil spills using the oil particle-tracing method. The bias of the spatial coverage (SAR minus simulations) of an algorithm called the constant false alarm rate (CFAR) is −73.92 km² with Stokes drift, which is significantly less than the 55.45 km² coverage without Stokes drift. Moreover, compared with model-simulated oil spills, the bias of the geographic location at the center point with Stokes drift is 8.18 km, which is less than the 12.95 km bias without Stokes drift. These results demonstrate that Stokes drift needs to be included in the prediction of oil spills.

Teredinid bivalves (shipworms) are the main wood degraders in marine environments. However, little is known about the biological interactions between these marine wood borers and wood-associated biofouling species. Filter-feeding species and seaweeds are frequent biofoulers on the submerged wood. Using the marine xylophagous bivalve Bankia martensi (Stempell, 1899) as a model, we hypothesized that increasing the abundance of biofouling species on wood will decrease the recruitment and subsequent growth of the shipworm B. martensi. During the springs of 2020 and 2021, experiments manipulating biofouling cover were carried out using pine panels in Bahía Metri, southern Chile. Three experimental levels of biofouling cover were established (low: 0%–10%, intermediate: 40%–50%, and high: 90%–100%). After five months, the number of B. martensi perforations (as proxy as larval settlement density) and specimen sizes (length, width and volume) in the panels were measured. An inverse relationship between the perforation densities of B. martensi and biofouling cover on the wooden panels was observed. The most frequent biofouling species were mussels and seaweeds which tended to settle on the upper and lateral surfaces, while acorn barnacles and bryozoans were more frequent on the lower surface. Bankia martensi perforations were reduced with increasing biofouling cover. The number of perforations varied according to the panel surface, higher density on the upper and lateral surfaces and lower on the underside. Bankia martensi specimens were larger, both in length and in volume, in panels with low biofouling compared to intermediate and high biofouling cover, while width did not vary with treatment. Our results suggest that the biofouling cover decreases B. martensi recruitment and growth rates, which in turn reduces the wood degradation rate caused by this teredinid. Future manipulative experiments with selected biofouling species (filter-feeders, such as mussels and barnacles), as well as incorporating measurements of reproductive traits of shipworms could help in understanding the biological interactions between these marine communities of wood-boring and biofouling species.

Eddies have been observed at all depths and in all regions of the Arctic Ocean. However, given the complex geographic conditions and dynamic environments of this ocean, the synchronized observations of temperature, salinity, and currents, and the detailed analysis of individual eddies are still lacking in the Northwind Basin. Our study aims to address these research gaps. We observed an eddy from a mooring in the Northwind Basin in late October 2017. It is a large anticyclonic cold eddy within the Arctic halocline, with a maximum azimuthal velocity reaching 52.63 cm/s and a horizontal scale (~56 km) that significantly exceeds the first local baroclinic Rossby radius of deformation, i.e., it is in mesoscale. Its azimuthal velocity and scale are larger compared with those of nearby eddies, suggesting a relatively young state. This eddy possibly originated from the northern Chukchi Sea shelf, converging near Hanna Shoal with the Chukchi Slope Current before being advected northward into the Northwind Basin. Our study outlines detailed steps for extracting and analyzing eddies from mooring data and contributes to improving the understanding of the characteristics of Arctic Ocean eddies, providing a typical case for the investigation of eddies in the Northwind Basin.

Bioturbation in estuarine environments describes all sediment reworking processes implied in sediment transport. However, modelling at large spatial and temporal scales remains a challenge because of the need to consider the fauna at the community level, and because animal behaviour is highly seasonal with non-linear effects of macrofauna functional trait interactions. Bioturbation processes can be linked to the activity of organisms, based on the principle of energy ecology, linking the metabolic rate to the erodibility of a sediment colonised by benthic fauna. This study investigates this postulate by evaluating the erodibility parameters of a sediment subjected to: i) the bioturbation under seasonal temperature variations; ii) the synergistic bioturbation of different species. The experimental design consisted of: i) three temperature levels (winter, spring and summer), ii) three types of species duos (Cerastoderma edule and Macoma balthica; Scrobicularia plana and Hediste diversicolor; Corophium volutator and Peringia ulvae) at 4 different relative densities. Two successive experiments were carried out on the same individuals: measurement of oxygen consumption of fauna then measurement of the erodibility of the colonised sediment in a flume. The oxygen consumption confirmed that the metabolic rate is a good model of the fauna respiration, regardless of species. The erosion results indicated that the metabolic rate in the case of the fluff layer resuspension is an interesting descriptor for 1) the assessment of the bioturbation under variable temperatures and 2) the integration of the two different bioturbator species that could co-occur in the same habitat. In contrast, the effect of bioturbation on the mass sediment erosion threshold cannot be easily modelled by using the metabolic rate and the classification in functional groups is required. Bioturbation models of the fluff layer using metabolic rate is a promising tool for modelling the effects of faunal communities on sediment transport at the scale of an estuary and over the long term, even projected in the context of global warming.

Since 2018, severe and recurrent copepod depletions have been observed in Belgian coastal waters. These depletions have been described as temperature-induced mass mortality events. This paper confirms the relation of copepod abundance anomalies with periods of high temperature based on new data. Although severe, the effects, consequences and implications of this depletion remain unknown. Our study suggests that the absence of zooplanktonic predators in autumn, together with the availability of nutrients discharged via the Scheldt estuary, allowed a bloom of the diatom Bellerochea, in a season otherwise characterised by low phytoplanktonic activity. Although the bloom reaches high abundances, its effects on the marine environment are not yet visible. The enormous abundances are likely to induce small-scale oxygen depletions which might further translate to the environment. Communities of Calanoida, Canuelloida and Cyclopoida tend to recover from the annual autumn depletion, although the typical autumn peak is entirely missing in the years subject to severe heat waves and associated high water temperatures. As a result, copepod dynamics have drastically changed since the first observed depletion and associated bloom of Bellerochea in 2018.