Journal of Marine Systems最新文献

A group of self-developed surface drifters were released near the Pearl River Estuary (PRE) from November to December 2021, and it is found that most of the drifters were finally stranded off the coast around Hainan Island after 10–30 days. This result makes us want to find out whether the surface floating objects around the PRE are converging on Hainan Island and what factors dominate this process. The velocity of the drifters not only displays prominent characteristics of tidal currents but is also highly correlated to winds associated with winter monsoon. A particle tracking model is employed to investigate the fate of the drifters and detailed process. Model simulation results show that the most important factor is winds, which affect the movement of floating objects through the direct way (direct wind drag) and indirect ways (wind-driven currents and the wave-induced Stokes drift). The influence of non-wind-driven flows (e.g., geostrophic currents, density-driven currents) is relatively limited. Tidal currents can significantly influence trajectory details within a tidal cycle. Extended model experiments with a large number of surface floaters released in October and January 2021 show that ∼34% of the surface floaters are stranded near the PRE, ∼30% are stranded to the east of Hainan Island, and ∼ 25% move to the west of Hainan Island. Our results indicate that a high proportion of the surface floaters from the PRE would converge around Hainan Island in the autumn and winter, of which the environmental impact warrants further investigation.

Here we used data from six BGC-floats deployed in the southeast Pacific and southwest Atlantic Oceans, within the Southern Ocean's Subtropical Zone, to assess the seasonality of particulate organic carbon production from phytoplankton (POC_phyto) and estimate POC transfer efficiencies at 100 m below the euphotic zone (T_100). While small particles <100 μM dominated the mixed layer, large particles >100 μM comprised a significant fraction of POC_phyto below the mixed layer in both areas, possibly due to a “shade flora” composed by large diatoms. POC_phyto was highly seasonal with highest biomass accumulation in the Atlantic side for both small and large particles. In the Pacific, the seasonal change in small particle production ΔPOC_phyto was ∼66 mg m⁻² versus ∼54 mg m⁻² from large particles. In the Atlantic, ΔPOC_phyto was ∼852 mg m⁻² for small particles versus ΔPOC_phyto ∼ 262 mg m⁻² for large particles. Monthly T_100s in the Pacific ranged from 76% to 92% with maximum efficiencies during the deepening of the mixed layer depth. In the Atlantic, T_100s ranged from 43% to 76% with two periods of high T_100s: the first coinciding with the decline of large particles from the “shade flora”, and the second coinciding with the deepening of the mixed layer during elevated small particle production.

This special issue merges results obtained during a scientific expedition along the eastern Beagle Channel (BC) with previously available relevant data from the area. The expedition was conducted from 9 to 19 November 2019 on board the BIPO “Victor Angelescu”, a research vessel belonging to the National Institute for Fisheries Research and Development (INIDEP-Argentina). The cruise was the result of collaborative bi-national (Chile-Argentina) diplomatic (Argentinian and Chilean Ministries of Foreign Affairs) and scientific efforts, led by the Austral Center for Scientific Research (CADIC-Argentina) and the Research Center: Dynamics of High Latitude Marine Ecosystems (IDEAL-Chile). In addition, this special issue is enriched with historical data from several research initiatives developed by both countries in the BC area and from other international collaborations, thereby providing a wider and comprehensive vision of the biological, chemical, and physical characteristics of the BC. From a historical point of view, both countries, which share the third longest international border of5,300 km, almost engaged in war in 1979 due to a border conflict in the southeastern BC. This war was averted and subsequently there have been decades of tight and close collaborations and friendly diplomatic, scientific, and social relationships. This special issue reflects these efforts.

Seasonal-scale local forcings sharply reduce the coastal pH and aragonite saturation state (Ω_aragonite). However, habitat-specific seasonality and control change signatures under increasing atmospheric CO₂ are still poorly characterized. Here, we investigated carbonate system parameter dynamics over a Dongshan coral habitat that is greatly influenced by seasonal current patterns on the western Taiwan Strait coast. Specifically, relatively low pH and Ω_aragonite were observed in the trial zone throughout the seasons. Using a first-order Taylor decomposition considering biological carbon metabolism, we suggest that the higher net aerobic respiration related to intense local human activities produced worse ocean acidity in the trial zone. Seasonally, a decreasing Ω_aragonite trend was observed from the transition to the northeast monsoon seasons, mainly controlled by dissolved inorganic carbon (DIC) divergence among seasons. The pH/hydrogen ion concentration ([H⁺]) seasonal cycle was determined by both DIC and temperature components, revealing the lowest/highest value in the southwest monsoon season. Based on ocean acidification scenario modeling forced with a business-as-usual emissions scenario, the Ω_aragonite seasonal amplitude attenuation was projected to exceed 30% during the 21st century. However, [H⁺] seasonal amplitude was amplified over 170%. The attenuation in the Ω_aragonite seasonal amplitude mainly resulted from an increase in anthropogenic CO₂ seasonal divergence. The increase in [H⁺] seasonal amplitude mostly followed from an increase in the [H⁺] sensitivities to DIC and temperature changes.

We demonstrate how the wind-driven Ekman transport enhances the advection and mixing of cells from the colder waters of the Surface Antarctic Waters from the south to the warmer waters of the northern Polar Front (PF) belt. This mechanism provides cells a mean ambient temperature near optimum levels for specific species and, ultimately, for community growth rates high enough to develop blooms under non-light limiting macronutrients and iron conditions. A Lagrangian trajectory model was constructed for tracking plankton cells as tracers forced by winds and surface currents. Depending on the region along the circumpolar front, increased winds can enhance this process across temperature gradients, and further accelerate such temperature-controlled growth. These results indicate that favorable temperature may enhance the growth rate even further when iron is sufficiently available, and thus have far-reaching implications for increased productivity in a future warming climate.

Spiny icefish (Chaenodraco wilsoni), a common high-Antarctic ichthyofauna icefish, exhibits variable feeding habits in regions around the Southern Ocean. In the Bransfield Strait (BS), C. wilsoni has received considerable attention as it preys predominantly on krill. Antarctic krill (Euphausia superba), the keystone species in the Southern Ocean, has a versatile feeding strategy, particularly in a highly dynamic environment. The central basin of the BS is a highly dynamic environment, providing an ideal place to explore the application of biochemical tracers in a specialist predator to reveal the diet of its prey. In this study, fatty acid and stable isotopic data demonstrated that the trophic niche of C. wilsoni expanded from late austral summer to early fall, which was primarily reflected in variability in the food availability of krill, i.e., herbivorous features were weakened, benthic-feeding features were strengthened, and omnivorous features showed no significant difference. A highly dynamic hydrography, coupled with an unusual diatom bloom in the BS during 2016, may have resulted in krill's prolonged filtering on diatoms in the water column, which was further reflected in the difference in biochemical tracers of C. wilsoni from late austral summer to early fall. The study demonstrated that biochemical tracers can be used to reflect the variability in the diet of prey, particularly in a highly dynamic environment.

The object of research - the Vistula Lagoon is one of the two lagoons on the Polish coast, which is of great importance not only from an economic point of view, but also an environmental one. The purpose of the paper is to provide calculations on the current water balance for the Vistula Lagoon, before and after construction of a canal through the Vistula Spit. This is important because the construction of a new connection between the Vistula Lagoon and the Baltic Sea can result in changes in the lagoon's water balance, which in turn cause changes in the Vistula Lagoon biotic and abiotic environment. In addition, we wish to update the estimate of the water exchange between the Vistula Lagoon and the Baltic Sea through the Strait of Baltiysk and to estimate the exchange through the Vistula Spit canal after it is fully open. The main works consisted of researching source materials from various state institutions, which allowed to calculate the water balance of the Vistula Lagoon and perform mathematical modeling. These data include the amount of precipitation and evaporation, the amount of inflow from the catchment, the amount of inflow from polders, underground supply, the amount of inflow and outflow through the Strait of Baltiysk. The largest portion of the water received by a coastal lagoon comes from the adjacent ocean. In this case, it is about 75%. In addition, an array of catchment sources yields 20% of the studied lagoon's water. The Strait of Baltiysk constitutes the main outflow pathway for water exiting the Vistula Lagoon – close to 98% of outflow. Simulations have shown that the construction of the Nowy Swiat ship canal will not alter the water balance in the Vistula Lagoon to a meaningful extent. The problems that may emerge include those related to changes in the local biotic and abiotic environment due at the construction stage or in the period that follows resulting from the disturbance of highly polluted lagoon floor deposits. Thus it may be argued that the new canal is desirable from an economic or flood control point of view, but not from an environmental point of view.

The São Francisco River is the fourth largest river in Latin America, and particularly important since it crosses the Brazilian semi-arid region. During the 1960s–90s, a series of dams for hydropower were built in cascade, changing drastically the flow regime. To evaluate the influence of changes in the flow on hydrodynamic processes and saline intrusion in the estuary, a three-dimensional hydrodynamic model was applied to the system. The model was calibrated and validated from hydrodynamic data collected in the estuary. The simulated scenarios of river discharges were Q_min, Q₁₀, Q₈₀ and Q_max (corresponding to 600, 5000, 1200, and 12,000 m³.s⁻¹, respectively), determined from historical river discharge observations. There was an increase in the mixing and a decrease in the river contribution after the installation of dams. The average salinity in the estuarine domain ranged from 0.7 g.kg⁻¹ for intermediate pre-dam discharge to 15.6 g.kg⁻¹ in the lowest discharges after the dam installations. The results of the simulations were used to establish an exponential relationship between fluvial discharge and saline intrusion, which can be used by management agencies to optimize the water quality in catchments for human consumption.

In November 2019, a first joint Chilean–Argentinian research cruise was conducted along the eastern section of the Beagle Channel (BC). Here we present the results of the microbial plankton (2–200 μm cell size) abundance and composition analyses in relation to water masses and environmental variables, along a longitudinal transect characterized by contrasting hydrology. Plankton samples were analyzed within the photic zone along the channel and at two fixed stations during two short time series (a first one of 30 and a second one of 42 h). Results revealed a spatial zonation in the composition and structure of the plankton assemblages, related to bathymetry, water temperature and nutrient availability but also, a small-scale temporal variability due mainly to a rise in air and water temperature. The inner (westernmost) and outer sectors of the sampled area, west and east of Mackinlay Strait, respectively, were characterized by low plankton abundances, mostly dominated by nanoflagellates and some large diatoms. In contrast, the easternmost sector of BC, showed the highest total cell abundances, displaying a high diversity of small and large diatoms. Notably, in the inner BC (fixed station F1), chlorophyll-a (chl-a) concentrations almost doubled in 24 h, along with an increase in total plankton abundance and the dominance of small diatoms and nanoflagellates. Rapid changes in plankton relative abundance were also observed east to Mackinlay Strait. This highlights the large spatial (km) and temporal (hours to days) plankton heterogeneity along the eastern section of the BC, scales which should be considered for further sampling strategies.