Journal of Marine Systems最新文献

Time-series are fundamental for enhancing our comprehension of plankton community dynamics and forecasting future changes that could significantly affect entire marine food chains and ecosystems. In this study, we investigated spatial and temporal variations in occurrence, abundance and body size of marine branchiopods in the Belgian Part of the North Sea (BPNS), using both traditional microscopy, as well as digital imaging (ZooSCAN). We studied the population dynamics of branchiopods collected between 2014 and 2021 in the BPNS and compared these results with a previously collected (2009–2010) dataset for the same area. The time series showed no significant changes in abundance (Podon spp., Evadne nordmanni) over the years, but we did observe a pronounced seasonal pattern, with both species completely absent in the winter months. Abundance and biomass were positively correlated with water temperature but negatively correlated with nutrient concentrations and turbidity. Additionally, Podon spp. abundance was negatively correlated with anthropogenic chemicals (i.e., polycyclic aromatic hydrocarbons). We employed generalized additive models to quantify the relative contribution of temperature, salinity, turbidity, chlorophyll a concentration and pollutant levels to the dynamics of the studied taxa. Turbidity and chlorophyll a concentrations were revealed to be the predictor with the highest importance in all models predicting the abundances/body size of the selected species. Anthropogenic chemicals were not informative in explaining branchiopod abundance or body size. The findings of this study establish a baseline for future studies, which is essential for our understanding of the zooplankton dynamics in the North Sea, particularly in the context of climate change and changing water quality.

Carbon monoxide (CO) concentrations in the atmosphere and ocean are mainly influenced by anthropogenic inputs, abiotic photoproduction, biogenic sources, and bacterial consumption. This study, for the first time, investigated the distributions, sea-to-air fluxes, and microbial consumption rates of CO in the Bohai Sea (BS) and the Yellow Sea (YS) in winter to identify the main factors controlling CO distributions in both the atmosphere and seawater in colder temperature. Atmospheric CO mixing ratios ([CO]_atm) and the concentrations of CO in surface seawater ([CO]_surf) ranged from 176.8 to 1245.8 ppbv (mean value: 551.4 ± 214 ppbv) and from 0.49 to 3.1 nmol L⁻¹ (mean value: 0.98 ± 0.55 nmol L⁻¹), respectively. In addition, the spatial distribution of [CO]_atm and [CO]_surf showed that anthropogenic sources dominated the distribution of [CO]_atm, but abiotic photoproduction processes were the main influencers of the distribution of [CO]_surf. The surface water at most sampling stations was supersaturated with CO, with a mean saturation factor of 1.9, and the sea-to-air fluxes of CO were estimated to range from −13.88 to 123.88 nmol m⁻² h⁻¹ (12.59 ± 21.32 nmol m⁻² h⁻¹), suggesting that the BS and the YS were the source of atmospheric CO,  and were estimated to contribute 0.009% to 1.4% to the global ocean emission. Microbial consumption experiments indicated that the microbial CO consumption rate constants (K_bio) ranged from 0.15 to 2.14 h⁻¹, and showed that CO concentrations decreased exponentially with incubation time, suggesting that anaerobic CO consumption would limit CO accumulation in winter, thereby affecting the flux of [CO]_surf to [CO]_atm.

A rare event known as Fujiwhara effect occurred in the southeastern tropical Indian Ocean when tropical cyclones (TCs) Seroja and Odette were co-existed, interacted each other, and merged into one TC in April 2021. Here, remotely sensed data (surface winds, sea surface temperature, chlorophyll-a concentration, and surface currents) were analyzed to determine the impact of Fujiwhara effect on the ocean biophysical variables in the region. Ekman pumping velocity were computed to determine the upwelling/downwelling process. During the entire development of the TCs to the merging, the TCs induced sea surface temperature (SST) cooling and raising sea surface chlorophyll-a. Ekman pumping and inertial pumping may serve as the primary driving force for the observed negative SST anomaly and positive anomaly in chl-a concentration associated with TCs. This rare event adds the complexity of ocean and climate dynamics of the region as an exit gate of the Indonesian throughflow to the Indian Ocean and may have implications to circulation and climate in the Indian Ocean and beyond. The present research likely represents the first scientific documentation of oceanic responses to a Fujiwhara effect in the region.

Harmful algal blooms (HABs) frequently threaten the health of marine environments and ecosystems in the adjacent waters of the Yangtze River Estuary (YRE) in summer. To better understand the spatiotemporal distribution, variation characteristics, and major influencing factors of algal bloom-prone zones in the adjacent waters of the YRE in summer, the present study used Geostationary Ocean Color Imager (GOCI) chlorophyll-a (Chl-a) data from 2011 to 2020. The Chl-a concentration threshold for summer algal blooms in the adjacent waters of the YRE was determined to be 16 mg/m³, based on which the monthly and interannual distribution characteristics of algal blooms were further clarified, and the influence of runoff and sea surface temperature (SST) on algal blooms was analyzed. The results showed that the area of the algal bloom-prone zones was the largest in July, at 1337 km², which was approximately 2.8-fold greater than that in June (474 km²) and 1.3-fold greater than that in August (1028 km²); the algal bloom-prone zones were mainly distributed in the eastern sea area of the YRE, and the spatial distribution of the algal blooms showed significant interannual variation. In 2020, the distribution range of the algal bloom-prone zones was the largest, and the maximum probability was >20%. Runoff had a significant positive effect on the algal bloom index (BI) (r = 0.89, p < 0.05), the correlation between BI and SST was weak (r = 0.50, p = 0.14), and the algal bloom probability had a significant negative correlation with SST (r = −0.71, p < 0.05), implying that above a certain range of temperatures, algal growth rates may decrease with increasing temperature. The research results can provide a scientific basis for the early prevention, control, and emergency response of disasters, which is conducive to the sustainable and healthy development of marine resources and has significant scientific and management significance.

The dynamics of dissolved oxygen in the ocean are of crucial importance for understanding marine ecosystems, with influences ranging from exchange with the atmosphere to biological processes and ocean circulation. In this study, we focus on the southern Adriatic Sea, an essential component of the Eastern Mediterranean “conveyor belt”, to investigate long-term oxygen dynamics and its driving factors. We use cross-platform datasets from 2013 to 2020, including remote sensing data, model reanalysis and in-situ observations from Argo floats, ocean gliders and ship-based measurements. Our analysis investigate the interplay of physical, biological and atmospheric forcing that drive oxygen variability. The distribution of dissolved oxygen in the southern Adriatic Sea is influenced by vertical mixing, advection of water masses and ecosystem dynamics. In the surface layer, the variability of dissolved oxygen is triggered by annual primary production and deep convection events. The dynamics in the intermediate and the deep layers are instead primarily influenced by physical processes, such as the vertical mixing and the water masses inflow from the adjacent sub-basins, which is driven by the periodic reversals of northern Ionian Gyre circulation. In particular our study reveals that the water masses advective dynamics driving the increase and decrease of dissolved oxygen have drastically changed in recent years. The highest dissolved oxygen concentrations are currently observed during the northern Ionian Gyre anticyclonic phase, while they have been previously documented during the cyclonic phase. This change appears to be connected with the significant increase in salinity observed in the southern Adriatic Sea in the same period and contributes to a better understanding of the processes that determine oxygen distribution in the Eastern Mediterranean basin.

In the present study, we addressed the spatial characterization and species assemblages of the planktonic cnidarian community (Siphonophorae, Hydromedusae, and Scyphomedusae) in winter, a period that has been the subject of few studies in the NW Mediterranean. Data were obtained on two oceanographic cruises, in February 2017 and 2018. In 2017, the early onset of spring conditions and the subsequent phytoplankton bloom favored a mixture of winter and spring species, resulting in a higher species richness but a lower abundance of cnidarians. However, the typical winter oceanographic conditions in 2018 allowed winter species populations to develop, leading to a higher abundance of cnidarians that year. The most abundant species in both winters were Lensia subtilis, Muggiaea kochii, Chelophyes appendiculata, Abylopsis tetragona (eudoxid), Aglaura hemistoma, and Velella velella rataria larvae, while Obelia spp. was particularly numerous in 2017. In both years, the cluster and redundancy analyses showed a coastal-offshore ordination in species assemblages resulting from the effect of environmental variables (particularly bathymetry) and oceanographic structures (water masses and the shelf-slope density front). The presence of submarine canyons, in which great depths are reached close to the coast, modified the circulation patterns, resulting in a mixture of coastal and offshore species in these areas. In the current scenario of global warming, our results will help to provide a baseline for identifying future changes in the structure of the planktonic cnidarian community.

Hypoxia is a global concern, affecting marine ecosystems. In this study, we investigated the effect of low Oxygen concentration on the egg hatching rate of Acartia erythraea in Gamak Bay, where hypoxia frequently occurs in summer. Three in situ experiments were conducted in June and August 2013 and July 2014. Environmental parameters, including the water temperature, salinity, dissolved Oxygen (DO) concentration, and pH, were measured during the experiments. Hypoxic conditions had a significant negative impact on the hatching rate of A. erythraea eggs; hatching rate was positively correlated with the DO concentration (r = 0.843, p < 0.01) and pH (r = 0.600, p < 0.01). These findings suggest that hypoxia has significant negative impacts on recruitment of planktonic A. erythraea, with potential implications for overall plankton and nekton dynamics.

Over the past decade, there has been a significant increase in low oxygen conditions within marine coastal areas, profoundly impacting ecosystem processes and living coastal resources. Coastal bays in highly productive upwelling regions, where hypoxia occurs naturally, are special areas affected by both local and adjacent shelf-related processes. Paracas Bay (13.8°S) is a traditional shellfish fishing and intense farming area highly influenced by one of the most active upwelling centers of the Peruvian coast. Despite the small dimensions of the bay (35 km²), a key feature is its complex physical dynamics and high environmental variability. Recently, important efforts have been made in the study of both the spatial and temporal oxygen concentration variability, nevertheless, information regarding the ecological and biological impact of hypoxic events is still lacking. In this study, the spatial and temporal distribution of hypoxic events was analyzed across Paracas bay at different depths by means of high-frequency hourly dissolved oxygen records collected by data-loggers deployed across the bay during the periods September 2012 – February 2013 and March 2015 – February 2017. To study the ecological impact of hypoxic events, we developed a hypoxia intensity index, while the biological impact was studied through the development of a hypoxia biological effect index using as model species the Peruvian scallop (Argopecten purpuratus). Our results showed that hypoxic events have an intrinsic variability across the bay. The deeper areas of the bay, towards the northwest and center, were characterized by long, intense, and lethal events, while the southeast and southwest, shallower areas, were characterized by shorter events of low intensity and either sublethal or innocuous. We propose that the observed variability is not only related to the large-scale environmental context in which the events occurred, but also to small-scale variability linked to local circulation, biological activity, and sediment biogeochemistry. We expect that our research will be useful not only for scientific purposes, but also for coastal resource management and aquaculture, underlining the importance of developing high-resolution oxygen monitoring systems in coastal bays.

We present unique data of abundance, spatial diversity, and bathymetric patterns of the Peracarida communities of the economic and ecological important scarce studied area of the southern Gulf of Mexico. Peracarida macrofauna was collected from 63 sites in a large geographical area (92.67°– 96.70° W, 18.74°–23.04° N) with a wide bathymetric gradient (185–3740 m depth) of the deep-sea southwestern Gulf of Mexico. The samples were obtained onboard the R/V Justo Sierra (Universidad Nacional Autónoma de México, UNAM) using a Reineck-type box corer during four oceanographic cruises (SOGOM 1–4; 2015–2018). We examined the bathymetric and spatial patterns of standardized abundance (ind. m^-2) and taxonomic diversity (Hill numbers, q = 0, 1, and 2). Abundance patterns were related to environmental parameters (organic matter, aromatic and aliphatic hydrocarbons, bottom water temperature, dissolved oxygen and grain composition). We collected 684 specimens belonging to 53 Peracarida families of 4 orders (Amphipoda, 19; Isopoda, 17; Tanaidacea, 13; and Cumacea, 4). The most abundant orders were Amphipoda and Tanaidacea, representing 36.4% and 35.8% of the total abundance, respectively, followed by Isopoda (25.1%). Cumacea was the least abundant order (2.7%). The top ten abundant families in order were Apseudidae, Phoxocephalidae, Caprellidae, Desmosomatidae, Nototanaidae, Nannoniscidae, Tanaellidae, Ischnomesidae, Podoceridae, and Agathotanaidae, accounting for 66% of the total relative abundance. The abundance decreased with increasing depth. Highest values were recorded in the northwestern region of the study area and in the Campeche Bay salt domes zone, whereas the lowest abundance values were registered at the abyssal locations and in some sites located in the Coatzacoalcos and Campeche Canyons. The composition and structure of the peracarid community showed shifts related to depth. The major structural abiotic factors of the Peracarida community were: latitude, depth, temperature, and sediment aliphatic hydrocarbons. The diversity based on the three estimated Hill numbers consistently decreased with increasing depth. We recorded intermediate and low diversity values in almost the entire study area, except for the Campeche Bay salt domes zone and northwestern region, where intermediate and high diversity values were registered.

Rising Arctic temperatures are causing substantial declines in sea ice, altering ice retreat and formation in the Pacific Arctic and impacting marine communities. Despite the significant challenges facing the Pacific Arctic, there are still gaps in our understanding of the environmental impacts on pelagic communities, particularly sound scattering layers (SSLs), and their distributions in the southern Chukchi Sea (SCS), northern Chukchi Sea (NCS), and East Siberian Sea (ESS). This study utilized a wideband autonomous transceiver, net samplers, and optical instruments to explore SSLs in the Pacific Arctic, detailing their relationships with hydrographic properties. The findings indicated a greater vertical distribution of pelagic communities in the SCS than in the NCS and ESS. Significant differences in frequency spectra patterns were observed between the SCS and both the NCS and the ESS, though not between the NCS and the ESS. The correlations between the broadband acoustic and hydrographic values were generally weak to moderate. Elevated acoustic values in the SCS were linked to higher water temperature, dissolved oxygen, and chlorophyll and lower salinity. This study also revealed the behavioral properties of individual pelagic animals and identified Ctenophores and Copepods as the most abundant classes based on camera images and net samples. This research offers crucial insights into the distribution and interactions of pelagic communities with environmental factors, laying the groundwork for understanding climate change impacts. Additionally, this paper presents the first findings of frequency spectra from a broadband system in the Arctic Ocean.