Journal of Sea Research最新文献

In order to better understand Mimachlamys varia (Linneaus, 1758) response to nutritional stress, a controlled-condition experiment was conducted. Two scallop batches (i.e. juveniles and adults) were completely food-deprived for 3 months. Changes in mass and energy content of tissues (adductor muscle, digestive gland, rest of the soft tissues), as well as stable carbon and nitrogen isotope ratios of the adductor muscle were monitored weekly. Both batches exhibited a 3-phase response to starvation. For adults, phase 1, was characterized by a fast loss in mass, an δ¹⁵N-enrichment, a stable calorific power, and a low mortality, corresponding to a transitional stage associated with protein-storage consumption. Phase 2 (day 28–42) exhibited a stabilization of mass and δ¹⁵N values, coinciding with a digestive gland calorific power drop and an acceleration in mortality. This corresponds to a “protein sparing” stage where highly energetic fuel such as lipids, which are stored especially in the digestive gland in pectinids, are consumed in priority. Juveniles exhibited a distinct response characterized by a significant mass loss and an increase in calorific power during the first phase (day 0–28). This body weight decrease may involve the remobilization of low-caloric biochemical compounds (e.g. proteins) using the structure as internal fuel, thus limiting somatic maintenance costs. During the second month, body mass and calorific power stabilized, indicating a “protein sparing” stage. In a third phase for both age classes, mass decreased again together with a sharp increase in mortality: essential structure was ultimately remobilized. The survival rate of juveniles was higher than that of adults during the first two months of the experiment (97% and 64%, respectively). Although the time required for starvation to deplete of half the cohort is higher for juveniles than for mature individuals, increase in mortality rate after reaching the “Point of No Return”, (e.g. the beginning of the last phase) was higher in juveniles than in adults. These results highlight the potential impacts of starvation at the population level, beyond the direct impact on individual survival. For instance, individuals may not effectively contribute to reproduction during the spawning period if exposed to a prolonged winter starvation episode. In particular, since highly energetic compounds stored in the digestive gland are often used as fuel to initiate gametogenesis in pectinids. Similarly, decrease in somatic weight in juveniles may delay their sexual maturity and hence their ability to contribute to population reproductive potential.

Ballast water management is an effective measure to ensure that organisms and bacteria do not migrate with the ballast water to other areas. The International Maritime Organization adopted the International Convention on the Control and Management of Ballast Water and Ship Sediments, in 2004 which regulates issues of ballast water management. Many technologies have been researched and developed; in particular, using UV rays is the method that is evaluated with many advantages and meets the requirements of the Convention. The UV reactor in the ballast water treatment system has a very large capacity, so in the ballast water treatment system, it is often necessary to use many high-power UV lamps in one UV reactor. These high-power UV lamps consume a lot of electrical energy and are very expensive. Research on the control of UV radiation in the process of disinfecting water appropriately and effectively is necessary in order to improve the life of UV lamps, consume less electricity, and ensuring anti-bacterial duty is well conducted. This paper presents the development of a controller for a UV reactor and ballast water flow in the ballast water treatment system installed on ships. Experimental results on ships indicate the efficiency achieved by the developed UV controller.

Mangrove is one of the most carbon-rich ecosystems in the world. Nevertheless, the understanding of organic carbon partitioning between dissolution and particle in the processes of mangrove outwelling is rather limited, flood–ebb samplings were conducted in January 2021 with 8 sampling sites covering the upper tidal boundary to the mouth in the Zhangjiang Estuary. Water samples were collected to analyze physicochemical properties, dissolved organic carbon (DOC) and particulate organic carbon (POC) contents, and their phase portioning were investigated to analyze the spatial variation between the two phases (dissolve and particle), and their influencing factors. The results showed: (1) DOC was the dominant content with the wide range of 0.48–3.29 mg·L⁻¹, accounting for 77.6% on average; while POC contents were 0.17–1.86 mg·L⁻¹, accounting for 22.4% on average. (2) Silt was dominant component in estuarine suspended sediment, accounting for 68.0% on average; clay accounted for 17.5% of the suspend sediment, and was mainly located in mangrove forest area; sand proportion was the lowest. (3) Both the closed Beijiang sluice and ponds effluents could significantly increase the water organic carbon content, but only ponds effluents changed the phase distribution of organic carbon. In natural processes, a significant positive correlation between particulate and dissolved organic carbon and dissolved oxygen (DO) in the upper estuary (r > 0.9), and a significant negative correlation between particulate and dissolved organic carbon and salinity in the lower estuary (r < −0.7) were observed. The study indicated that DOC was the dominant content, the phase partition coefficients were significantly increased due to the DOC content from pond effluents. In the natural processes, the autotrophic activities by microalgae in the upper estuary and the seawater mixed dilution followed with heterotrophic activities are the important influencing factors.

The edible sea urchin (Paracentrotus lividus) is of significant economic importance due to high demand for its consumption in various Mediterranean countries. This echinoderm plays a crucial ecological role by regulating the dynamics of seaweed and seagrass through its grazing behaviour. The abundance of sea urchin is variable in time and space, but it is currently potentially declining in the Mediterranean Sea, and likely to be negatively affected by global change. Therefore, gaining a more comprehensive understanding of sea urchin larval dispersal patterns over an extended period could contribute to our understanding of how their dynamics relate to population connectivity. To investigate the trajectories of larval dispersal of this sea urchin in the Northwestern Mediterranean Sea, we combined a Lagrangian model (Ichthyop) with a hydrodynamic model (MARS3D). This study covered the years 2010–2018 and aimed to quantify the connectivity between the preferred habitats of the sea urchin (seagrasses and rocky substrates). The present study explores seasonal variations in dispersal routes and habitat connectivity relationships for two spawning scenarios identified in the literature (spring and autumn). The results enable us to identify dispersal routes, and their regularity over time. They highlight a consistent connection between Sardinia, Corsica, and the coastlines of the Ligurian and Tyrrhenian Seas, indicating a lack of genetic structuring within the edible sea urchin population in this area, particularly in Corsica. The connectivity matrices confirm the observed dispersal trajectories and highlight certain areas of significant and enduring local retention over time. The results also reveal minimal seasonal variability. Conversely, interannual variability appears pronounced, particularly in relation with trends in the warming of surface waters in the Mediterranean, which seem to impact the dispersal routes taken by P. lividus larvae. Lastly, a connectivity map was created to explore spatial resource management perspectives, aiming to identify frequent connections over an extended time period and assign varying levels of intensity to them. This approach can provide guidance with regard to resource management issues for different coastal areas that can be connected by larvae.

This study aims to investigate the inherent correlation between economic growth and marine conservation in the coastal regions of China, specifically the shifting relationship between high and low economic growth periods and marine pollution. A nonlinear model is employed to determine the dynamic relationship based on historical data, with the inclusion of a nonlinear zone system transfer factor to achieve this dynamic relationship. The study's data was sourced from a statistical database of 11 Chinese coastal provinces, containing details on economic growth rates and emissions of industrial waste. In the study, significant differences in the mean, variance and smoothing probability of the different provinces were observed in the different systems. Notably, Shandong recorded the highest mean μ2 in both systems, 0.7261* and 0.7261**, while the correlation coefficient between the two systems in the high growth area was −0.3543. Significant differences exist in the intrinsic links between economic growth and marine environmental protection within provinces and cities. Therefore, targeted strategies must be developed for specific regions when formulating economic and environmental policies.

Recently, much work has been put into improving species distribution models, especially for systematic conservation planning for important ecosystems. Understanding fish spawning sites requires a thorough examination of ichthyoplankton. These examinations usually produce sparse counts contaminated by inaccurate detection, making it impossible to directly infer the abundance or occurrence from observational data, which could lead to inaccurate model predictions. A flexible modeling framework for estimating and inference about the abundance of eggs with ensemble models that include the presence/absence and abundance components is described in this study. The generalized linear model, generalized additive model, integrated nested Laplace approximations, and random forest habitat modeling approaches were compared within this framework to those currently being used for fish conservation planning at regional scales. Additionally, the distribution of suitable habitats for small yellow croaker (Larimichthys polyactis) spawning stocks were mapped based on the ensemble model. Furthermore, the promotion ability of ensemble models with different weighting methods was evaluated. The outcomes demonstrated that machine learning algorithms performed better than statistical models, and the geometric weighted ensemble model further increased prediction accuracy. However, there was no significant difference compared to the optimal individual model (p > 0.05). The predicted distributions of the four models can be divided into two groups. The central sea of Jiangsu was recognized as the most suitable area by the GAM with a fixed effect for each year and INLA models, while the GLM was similar to the RF with spatial effect (RF-LL) and demonstrated Haizhou Bay as the most suitable area. The ensemble model discovered several areas of highly suitable habitat that dominated areas in the two groups of models and revealed many finer-scale patterns in the egg distribution. According to the ensemble model, although 5.37% of the area could be suitable habitat, only 0.12% was highly suitable. It is suggested that examining small yellow croaker spawning aggregation areas would benefit from using an ensemble modeling approach to identify and prioritize conservation areas.

Both tropical and extratropical cyclones can affect the East China Sea (ECS) shelf in summer. Based on a current mooring deployed in 2014, near-inertial waves (NIWs) triggered by both extratropical and tropical cyclones were examined. During the observation period, three tropical cyclones (i.e., NEOGURI, MATMO, and NAKRI) passed by the mooring site. MATMO and NAKRI led to obvious near-inertial responses. The weakest tropical cyclone (MATMO) caused the strongest NIWs due to its large translation speed and favorable position relative to the mooring site. Mode 1 dominates the vertical structure of the NIWs caused by tropical cyclones. Due to the modulation of the background vorticity, the NIWs show a significant blueshift. However, the NIWs caused by extratropical cyclones are mainly concentrated near the surface layer with a higher proportion of mode-2 NIWs. The highest value of the near-inertial kinetic energy generated by extratropical cyclones is about half of that generated by tropical cyclones. In addition, both two kinds of cyclones can lead to an enhancement of sub-inertial current in the ECS shelf. The nonlinear interactions between NIWs and semidiurnal internal tides (D₂) are also evidenced, with the NIWs being a potential trigger for D₂-f waves. This study highlights the important role of NIW on the nonlinear interactions and energy transfer within the internal wave spectral continuum in the continental shelf region.

Green tide disasters have been occurring along the Qinhuangdao coastal area for several years since 2015. This study investigated the interannual changes of green tides in Qinhuangdao from 2018 to 2020 and found that the green algae biomass was significantly reduced in 2020. The peak biomass of the green tide in July was only 151.5 g m⁻³, which is significantly lower than 7789.4 g m⁻³ in July 2018 and 5873.9 g m⁻³ in July 2019. Further comparative analysis showed that the decrease in nutrients, reduction in the density of Ulva microscopic propagules, and low biomass of attached macroalgae on the seaweed beds along the Jinmenghaiwan bath coastal area were the main causes for the decrease in the scale of green tides in Qinhuangdao in 2020. This paper also summarizes the factors of green tide formation in Qinhuangdao and proposes relevant prevention and control suggestions for the local governments based on the previous research.

For the last half century, studies based on an increasing, diverse data set, have focused on passive continental margin evolution, as a result of a sequence of tectonic processes that occur in crustal scale and in the geological time. Where extensive subsurface data exists, two distinct endmembers of continental margin architectures were first described along specific margins of the North Atlantic: 1) wide continent-ocean transitions or hyper-extended; 2) narrow continent-ocean transitions or hypo-extended. The lateral transition between these endmember margins, which can occur laterally in short distances, is still not fully understood. The same two endmember margin types are observed across passive margins around the world and notably along the South Atlantic margin. In an area known for controversial interpretations about the crustal nature and the limits of thinned continental crust, this investigation integrates crustal thickness, seismic interpretation, and facies analyses across ∼150,000 km of seismic data along the Brazilian southeastern margin. This study has implications for those investigating the crustal geometry variations for basin analysis and results impact hydrocarbon assessments for the southeastern margin of Brazil. We resume continental margin analyses, in a critical moment as hydrocarbon exploration advances from the continental slope to ultra-deep waters. Results indicate a marked change from a narrow, hypo-extended, sub-aerial, Iceland-like, plume-related volcanic crust in the Pelotas Basin, to a hyper-extended, Iberia-like, magma-rich crust in the Santos Basin, which is separated by a pronounced oceanic transform-fault zone. Dextral movement along this NW-oriented fault zone accommodated differential extensional rates between the hypo- and the hyper-extended margins. Lateral variations in magmatic content within these margin types are interpreted as result from the interaction with mantellic plumes. Margin architecture can locally be affected by pre-existing fault zones and be later modified by oceanic transform faults. The interactions between crustal extensional rates, crustal rheology, mantle underplating, and volcanic material exhumed through mantle-derived plumes, are the key controls for the evolution of continental margins. Tectonic framework classification proposed in this study presents an alternative, original model for continental passive margins evolution.

This study explored the anthropogenic stressors of a coral habitat and predicted the role of a proposed MPA around coral habitat on biodiversity conservation. The study was conducted in the Saint Martin's Island which is located in the south east coastal area of Bangladesh. Data on anthropogenic stressors were collected through intensive stakeholder survey and the role of MPA in biodiversity conservation was explored by utilizing Allometric Trophic Network model. This study identified about 16 anthropogenic stressors for the coral reef ecosystem. Increasing fishing pressure significantly reduced the species biomass while reduced fishing pressure increased the biomass of species. Biomass of the species in the system with no fishing area increased significantly (3–6%) while compared with the species biomass of an area without fishing restriction. Our simulations found that imposing fishing restriction in an exploited system significantly improve the species standing stock. Our model outputs suggest that declaration of MPA is beneficial for conservation of biodiversity. However, for sustainable implementation of conservation initiatives a proper management framework is necessary integrating diverse stakeholders.