Journal of Sea Research最新文献

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.

Understanding the amino acid (AA) composition of phytoplankton-derived particulate organic matter (POM) is crucial for unraveling phytoplankton physiology and assessing food quality. This study investigated AA compositions and food quality of POM associated with two phytoplankton groups in the Ross Sea polynya. The Phaeocystis antarctica (P. antarctica)-predominant group, with P. antarctica overwhelmingly contributing to its composition, demonstrated a fresh state and heightened physiological activity. In contrast, the P. antarctica and diatoms-mixed group exhibited superior essential amino acids (EAAs) contributions and a higher EAA index (EAAI), indicating enhanced food quality. Dissimilarity Index values provided nuanced insights into degradation stages not captured by other indices. Despite lower physiological activity, diatoms in the mixed group stood out as crucial sources of high-quality nutrition for higher trophic levels in the Ross Sea polynya. The observed variations in AA compositions not only reflected the phytoplankton community structure but also provided insights into their physiological conditions. Given the ongoing climate-induced environmental changes potentially influencing phytoplankton communities, this study underscores the potential impacts on the intricate food web dynamics in the Ross Sea polynya. The assessment of AA composition emerged as a valuable tool for understanding the ecological implications for higher trophic levels in this polar region.

The scour protection layer (SPL) is a layer of large stones placed around man-made structures in the marine environment, preventing sediment scouring while also providing new hard substrate and potentially increasing the structural complexity of the original environment. This fosters development of diverse benthic communities, supporting high abundance of organisms. Future SPLs are therefore a potential tool for the ecological enhancement of degrading marine habitats following the principles of nature-inclusive design. Yet, factors that shape the benthic communities on SPLs are poorly understood. Here, we analysed existing data from SPLs from offshore wind farms and a gas platform in the southern North Sea to determine how SPL characteristics affect the biofouling community structure. We combined this analysis with an in-situ experiment testing for the effects of habitat complexity on SPL communities. Our results demonstrate that abundant and diverse communities are present on all SPLs. On a regional scale, communities are mainly affected by depth and location. Increasing habitat complexity has significant and positive effects on species richness yet was non-significant for biomass and abundance of the biofouling community. If applied thoughtfully, nature-inclusive design of the SPL habitat, including manipulation of the physical complexity of the structure, can effectively promote biodiversity.

The mechanical properties of glass fiber composite structures prepared by vacuum forming manufacturing process are influenced by various factors and have a certain degree of dispersion, resulting in unclear durability characteristics when applied in corrosive seawater engineering. Firstly, a variety of resin materials for underwater protective structures are tested for seawater degradation, and excellent resins that can still ensure the structural load-bearing capacity and stability after immersion are selected. Secondly, based on relevant standards and specifications, the article conducted seawater immersion aging tests at room temperature and accelerated seawater immersion aging tests at 60°C on glass fiber specimens of 430 epoxy bisphenol vinyl resin and 1967 polycyclic pentadiene resin. Finally, the degradation characteristics of strength, modulus, and impact toughness of the specimens were obtained through a series of mechanical property tests, such as bending, compression, shear and impact, under different aging time periods in room temperature and 60°C seawaters, respectively. The article summarizes the differences in the durability and mechanical properties degradation of large glass fiber protective structures with different resins during seawater immersion.

Typhoons and extratropical cyclones both occurred frequently on the Shandong Peninsula and have induced severe dynamic marine disasters. In this study, the typhoons and extratropical cyclones that occurred from 1979 to 2018 were counted and classified according to their tracks. We simulated the storm surge and disastrous waves using a coupled ocean-wave model and assessed the hazard distribution under different types of typhoons and extratropical cyclones. Through comparison, it was found that the southern Yellow Sea steering type typhoons and Yangtze-Huai cyclones occurred most frequently and were most likely to cause disasters. Regarding the hazard posed by the storm surge, there was a clear demarcation between the northern and southern coasts of the peninsula, as well as between the eastern and western coasts. The western coast of the peninsula was more exposed to storm surges induced by typhoons, while the northern coast of the peninsula was more exposed to storm surges induced by extratropical cyclones. The hazard posed by waves exhibited a localized characteristic. The wave hazard was the greatest near the peninsula cape and the lowest surrounding the Laizhou Bay, which was contrary to the distribution of the storm surge hazard. The identification of key management areas for disasters provides basic data and a technical reference for coastal development planning and can play a positive role in disaster prevention.

The snow crab (Chionoecetes opilio) fishery has great economic importance for Nova Scotia, contributing $263 million to fisheries and more than one-fifth of Canadian snow crab revenues in 2021. Being a stenothermic species, snow crabs can only live within a narrow range of temperatures between −1 to 6 °C. The Scotian Shelf holds the southernmost populations of snow crab in the Atlantic and snow crab catch-per-unit-area (CPUA) in the Scotian Shelf. Trawl survey data from Ocean, because these cold-temperature requirements are a limiting factor for its distribution. This study investigates the relationship between bottom ocean temperature Fisheries and Oceans Canada from 2012 to 2021 were used. Through nonlinear modelling, CPUA (mt/km²) was regressed with respect to bottom ocean temperature along Northwest Atlantic Fisheries Organization divisions N-ENS, CFA 23, CFA 24, and CFA. The temperature-vs-CPUA relationship was unimodal for all studied years. The best-fit models explained a limited amount of variation, but CPUA consistently decreased to zero towards the highest recorded temperatures. Due to the ongoing global warming, bottom ocean temperatures across the Scotian Shelf will likely continue to increase, which thus might harm the Scotian Shelf snow crab fishery. In conclusion, this study underscores the potential impact of global warming on the economically significant snow crab fishery in the Scotian Shelf. The findings serve as a critical alert to the possible consequences of rising ocean temperatures, thereby contributing to our understanding and preparation for the future of marine ecosystems and industries.

Pinna nobilis Linnaeus, 1758 is a Mediterranean endemic bivalve critically endangered due to a severe epidemic caused mainly by the parasite Haplosporidium pinnae. Presently, live populations in Spanish waters are restricted to the Ebro Delta (Catalonia) and the Mar Menor (Murcia). The coastal lagoon of the Mar Menor has faced several eutrophication crises since 2016, which pose a threat to the survival of P. nobilis. Since 2016, >95% of the specimens of this species have died due to recurrent episodes of eutrophication in the lagoon. An analysis of the mortality within the relict population of P. nobilis in the Mar Menor lagoon after the last population survey in 2019 has been carried out, together with a characterisation of some microscale factors that describe its current habitat in the lagoon. For this purpose, three sampling localities were selected along the east coast of the lagoon, where a study of both live and dead individuals was conducted. Additionally, a characterisation of the macrophyte beds and the sediment conditions surrounding these individuals was carried out, comparing the sediment near the recently dead and live individuals. All studied localities exhibit similar mixed macrophyte beds of Cymodocea nodosa (Ucria) Asch., 1870 and Caulerpa prolifera (Forsskål) J.V. Lamouroux, 1809. At the location where significantly less C. nodosa cover was observed, the mortality of P. nobilis individuals was higher, and the sediment near the dead individuals was also more disturbed (with a more negative Eh and higher percentage of organic matter). These results contribute to a better understanding of the dynamics of microscale factors following P. nobilis mortality events, facilitating the identification of potential survival areas.

Under the effect of global climate change, the enhanced wave condition leads to lateral erosion at the mangrove vegetation edge, threatening the survival of mangrove habitat and the safety of coastal defense. By means of investigations on soil physicochemical properties and wave flume experiments, we quantify the lateral erosion rates of mangrove soils under waves and bridge the edge stability and vegetation with soil properties. It is found that different mangrove species and stand ages significantly alter the physiochemical properties of soils, and consequently affect the erosion resistance. Lateral erosion rate is positively correlated with organic matter content and negatively correlated with saturated density, which serve as two main factors that affect soil resistance to wave forcing. Experimental datasets suggest that the soil lateral erosion rate of Kandelia obovata reaches several times larger than that of Sonneratia apetala among different stand ages, indicating that the erosion resistance has significant differences between mangrove species. Among different Sonneratia apetala sites, the erosion resistance is enhanced with increasing mangrove stand age. This study sheds light on the feedbacks between geo-morphodynamics and intertidal vegetation, which provides a promising experimental approach to evaluate the ecological functions of mangrove forests with respect of resistance to external disturbance. Insights gained from this study is useful in guiding the nature-based solutions for coastal defense through proper spatial-temporal configuration of suitable saplings with higher potential in resilience.

Global Sea Surface Temperature (SST) trends have garnered significant attention in several ocean-related domains, including global warming, marine biodiversity, and environmental protection. This involves having an accurate and efficient forecast of future SST to ensure early detection and response in time to these events. Deep learning algorithms have become popular in SST prediction recently, although directly obtaining optimal prediction results from historical observation data is not simple. In this paper, we propose STA-SST, a new deep learning approach for forecasting SST, by combining the temporal dependencies of SST using the Bidirectional Long Short-Term Memory (BiLSTM) model, spatial features extracted from the convolution layer, and relevant information from the attention mechanism. To assess how well the Attention-BiLSTM with convolution layer predicts SST, we conducted a case study in the Moroccan Sea, concentrating on five different areas. The proposed model was compared against alternative forecasting models, including LSTM, XGBoost, Support Vector Regression (SVR), and Random Forest (RF). The experimental results show that STA-STT produces noticeably the best prediction results and is a solid choice for field implementation.