Marine environmental research最新文献

Changes in the ocean temperature, seawater acidity, and oxygen level are parts of global change that may indirectly impact the biogeochemical cycles of trace metals in the marine system, particularly for the particulate phase. The different factors influencing the level of particulate trace metals are interesting topics for investigation. Following up on marine research in the estuary and coastal areas, we specifically review the distribution of particulate trace metals. This review aims to provide an overview of the progress of studies on particulate metals in the marine environment and to understand the factors that influence the level of particulate metals. Spatially, the distribution of particulate trace metals decreases towards the sea due to the influence of salinity, while the temporal distribution portrays the unique feature of each location that differences in metal sources and phytoplankton bloom periods might cause.

Microbial community coalescence describes the mixing of microbial communities and their integration with the surrounding environment, which is common in natural ecosystems and has potential impacts on ecological processes. However, few studies have focused on microbial community coalescence between different habitats in estuarine regions. In this study, we comprehensively investigated the environmental characteristics and bacterial community changes of different habitats (water body (Water), subtidal sediments (SS) and intertidal salt marsh sediments (SM)) in Luanhe estuary during flood and normal flow periods. The results showed that flood event significantly reduced the salinity of the estuarine habitats, changed the nutrient structure and intensified the eutrophication of estuarine water. By calculating the proportion of overlapping groups and applying the ‘FEAST’ algorithm, we revealed that flood event facilitated the migration of bacterial communities along alternative pathways across habitats, markedly enhanced the cross-habitat mobility of bacterial communities, which underscores the pivotal role of flood event in driving bacterial community coalescence. Flood-induced community coalescence not only increased the α-diversity of bacterial communities within habitats, but also increased the proportion of overlapped species between habitats, ultimately leading to homogenization between habitats. Canonical correlation analysis combined co-occurrence network analysis revealed that flood event attenuated the role of environmental filtration in microbial assembly, while increased the impact of dispersal processes and intensified interspecific competition among microorganisms, led to the change of keystone species and reduced the complexity and stability of bacterial communities. In conclusion, this study demonstrates the complex effects of flood events on estuarine microbial communities from the perspective of multi-habitat interactions in the estuary, and emphasizes the key role of river hydrodynamic conditions in facilitating the coalescence of estuarine microbial communities. We look forward to further attention and research on estuarine microbial coalescence, which will provide new insights into assessing the stability and resilience of estuarine ecosystems under flood challenges and the sustainable management of estuarine wetlands.

Spatial differences in the isotope values of widely distributed marine apex consumers may reflect geographical differences in the isotopic composition of basal resources (e.g., phytoplankton) fueling food webs (bottom-up effects) or spatial differences in the trophic ecology of the taxon of interest (top-down effects). We examined spatial variation in δ¹³C and δ¹⁵N values from 264 South American sea lions (SASL, Otaria flavescens) of different age classes (adults, subadults and juveniles), their putative prey consisting of pelagic and benthic coastal fishes, and particulate organic matter (POM) measured from locations situated across >2300 km of the Chilean coast (between 18°42′ and 39°17′ S). We used generalized least squares (GLS) models to compare the form of the relationship between δ¹³C and δ¹⁵N and latitude between the three functional groups. Our results show that SASL from northern, central, and southern areas were isotopically distinct, with individuals from the north having lower δ¹³C and higher δ¹⁵N values in comparison to individuals from the south. When the relationship for each functional group was modelled individually using GLS, results indicated that for each degree of increasing latitude δ¹⁵N decreased on average by 0.12‰ (POM), 0.15‰ (prey), and 0.14‰ (SASL), while δ¹³C increased by 0.06‰ (POM) and 0.05‰ in both prey and SASL. We suggest that the latitudinal differences observed in SASL δ¹³C and δ¹⁵N values reflect baseline isotopic variation rather than marked differences in trophic ecology of these widely distributed consumers.

Growing trend of interests for contributions of cultivation of kelp to carbon sequestration have been driven globally. Saccharina japonica is an important cultivated seaweed, with erosion phenomenon usually occurs at the distal part of the frond in S. japonica throughout the growth cycle. However, the dynamics of dissolved organic carbon (DOC) release induced by erosion of S. japonica are not well understood. This study revealed that erosion induced a substantial increase in DOC release, with a 14% increase under low light (LL) conditions and a 54% increase under high light (HL) conditions. A 10 cm of long slit cut into the distal part of S. japonica increased the rate of DOC release by 56% under LL conditions, and by 13% under HL conditions. Additionally, the epibiotic microorganisms facilitate the release of DOC, and the effects were even more pronounced in erosive S. japonica. Conversely, the proximal part of S. japonica exhibited a higher photosynthetic carbon fixation capacity, with a carbon-to-nitrogen (C/N) ratio approximately 1.76 times higher than that in distal part. During the growth of S. japonica, excess photosynthetic products were often transported from the proximal part into distal part, further facilitating DOC release. In summary, DOC released induced by erosion of S. japonica could make contributions to oceanic carbon sequestration.

The use of pyrethroids in aquaculture has been an important component of achieving a thriving salmon farming industry in Chile. While the residual presence of such substances is known to depend on environmental conditions, most ecotoxicological studies to date have not considered environmental context. Here, we conducted oceanographic monitoring combined with experiments aiming to estimate the effects of two pyrethroids on the feeding rates of larvae of farmed mussels, Mytilus chilensis. In additional experiments, mussel spats were exposed to both pyrethroids, but under contrasting temperature/pH so as to mimic winter and summer conditions. Experiments mimicking spring conditions revealed that both pyrethroid substances affected the feeding of mussel larvae as a function of concentration. Conversely, significant impact of pyrethroids on adults were not observed with regard to temperature and pH, but a significant impact of low temperature/low pH condition on ingestion rates was confirmed. Given the current status of increasing ocean acidification, the results of this study are expected to provide useful information with regard to achieving sustainable mussel aquaculture, especially considering both activities occur in similar geographic areas, and the expansion of salmon farming areas is ongoing in Chile.

Acoustic communication is linked to fitness traits in many animals, but under the current scenario of global warming, sound signals can be affected by rising temperatures, particularly in ectothermic organisms such as fishes. This study examines the effect of water temperature in acoustic communication in the two-spotted goby, Pomatoschistus flavescens. To address this, we looked at the effect of different temperatures on the acoustic features of drums produced by males during territorial defence and related it with their auditory sensitivity. We also analysed the differences in acoustic features between male agonistic drums and previously reported male courtship sounds, to better understand how acoustic communication may be affected by different temperature conditions. We recorded two-spotted goby males during territorial intrusions for 10 min at 16 °C, 19 °C, and 21 °C in the laboratory. We found that agonistic drums were shorter, had fewer pulses and shorter pulse periods at higher temperature, in contrast with the peak frequency that remained unaffected. Male agonistic and mating drums (recorded in a previous study) at 16 °C only differed in pulse period, which was higher in mating drums. Hearing thresholds obtained with Auditory Evoked Potentials at 16 °C, revealed higher sensitivity below 400 Hz, matching the main energy of agonistic and mating sounds. Our findings suggest that increasing temperature could potentially affect acoustic communication in this species by reducing the duration of agonistic drums, which might hinder effective communication. Nevertheless, the impact may not be significant as there was a good match between the best hearing sensitivity and the peak frequency range of their calls, which was not influenced by temperature. As fish and other organisms are increasingly threatened by multiple anthropogenic stressors, including warming, future research should address how changes in water temperature impact acoustic communication within a more realistic multi-stressor scenario.

Evidence of local and regional declines in the canopy-forming alga Ericaria amentacea, a foundation species of diverse marine forest communities on exposed Mediterranean coasts, have spurred restoration efforts focused on sustainable ex-situ techniques. The need to balance the costs of culture maintenance and the susceptibility of early life stages to stressors in the native habitat, including rapid, often extreme shifts in temperature, hydrodynamics and nutrient availability, have driven current efforts to create a culture environment that primes seedlings for outplant, increasing their resilience rather than maximizing growth. We tested the effects of 1) higher culture temperature (25 °C) combined with wave simulation and 2) reduced nutrient loads (10% of standard protocol) with wave simulation on post-culture and post-outplant outcomes relative to optimal growth conditions in established protocols (20 °C, no waves, high-nutrient culture medium). While increased temperature and water motion negatively affected seedling growth in culture, and higher nutrients caused oxidative stress likely associated with enhanced epiphyte overgrowth, these effects were not clearly translated into patterns of long-term growth in the field. Instead, survival in the initial days post-outplant appeared to be the bottleneck for restoration potential, where substrates with persisting seedlings at one month were generally found with flourishing juveniles at four months. Larger clumps of seedlings, in turn, were strongly associated with both initial survival and future growth. These results underscore the importance of the zygote settlement phase to establish high seedling densities, which may be optimized by phenological monitoring of the donor population. They also suggest that less-controlled, more environmentally-realistic culture conditions involving the introduction of mild stress may enhance the survival of early life stages of E. amentacea during the transition to the native environment, providing a means to simultaneously reduce human resource costs in culture and move toward scaling up.

During the operational phase of offshore wind farms, the generation of low-frequency underwater noise has received widespread attention due to its potential adverse impact on fish health. This study conducted a field survey of underwater noise at offshore wind farms located in Shandong province, China. Subsequently, a small-scale experiment was conducted to study the stress on black rockfish (Sebastes schlegelii). The fish were exposed to noise with dominant frequency of 80 Hz, 125 Hz and 250 Hz. These frequencies are same with the frequencies from wind power noise (wpn) at the actual site. After a 40-day experimental period, transcriptome sequencing was conducted on brain, liver, and kidney tissues of black rockfish to elucidate the underlying molecular mechanisms involved in the response to noise stress originating from offshore wind farms. The results revealed that the 125 Hz group exhibited the highest number of differentially expressed genes (DEGs) between the noise-exposed and control check group (CK group), with a total of 797 in the brain, 1076 in the liver, and 2468 in the kidney. Gene Ontology (GO) analysis showed that DEGs were significantly enriched in entries related to cellular processes, membrane components, binding, and metabolism. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were enriched mainly in metabolism, immunity, apoptosis, signal transduction, and diseases. The findings indicate that prolonged exposure to underwater noise from offshore wind farms may induce metabolic imbalance, immune dysfunction, and an increased risk of myocardial diseases in black rockfish.

The Yellow Sea Warm Current (YSWC) constitutes a significant hydrological feature in the Yellow Sea, particularly prominent during winter, facilitating the transport of warm, saline waters and warm-water species from the open sea to the Bohai and Yellow Seas. The YSWC induces alterations in the community structure and function of zooplankton. However, the effects of the YSWC on the functional trait compositions and functional groups of zooplankton remain unclear. This study aimed to elucidate the influence of the YSWC on the community structure, functional trait composition, and functional groups of zooplankton during winter of 2016. The YSWC significantly impacted the zooplankton assemblage in the central Yellow Sea (CYSA), resulting in notable distinctions from the Shandong coastal assemblage (SCA) and Jiangsu coastal assemblage (JCA). Compared to the SCA and JCA (comprising 45 and 34 taxa, with abundances of 119.4 ± 114.6 ind·m⁻³ and 82.8 ± 62.1 ind·m⁻³, respectively), the CYSA exhibited higher species richness and abundance (with 51 taxa and 144.4 ± 103.4 ind·m⁻³, respectively). This study documented a total of 11 warm-water species, showing a decreasing trend in both species richness and abundance from south to north. The CYSA was characterized by the predominance of medium‒sized, current‒feeding, omnivorous‒herbivorous broadcast spawners, whereas the SCA and the JCA were predominantly dominated by giant‒sized, ambush‒feeding carnivores. The Qingdao-Shidao anticyclonic eddy in the southern of Shandong Province led to a significant increase in the abundance of zooplankton, potentially impacting Yellow Sea fishery resource. This research contributed to a deeper understanding of how YSWC influence the zooplankton community and offered fresh insights into the effects of YSWC on zooplankton function traits and functional groups.

Over the past 18 years, green tides have persistently occurred in the Yellow Sea. Micropropagules of these algae are key to bloom formation, yet their species composition and succession during dissipation remain underexplored. During the dissipation process of accumulated green tide algae, a large number of micropropagules are released. This study monitored the dissipation of green tide algae at a coastal site, tracking micropropagules in water and sediment using an internal transcribed spacer (ITS) and 5S rDNA primers. Results showed that the dissipation lasted about one month, with significant micropropagule release. Initially, micropropagules matched 5S-II Ulva prolifera, but later species like Ulva torta, Ulva simplex, Ulva flexuosa, and Ulva meridionalis emerged. Ulva meridionalis dominated sediment in July and August, while U. torta was prevalent in water, and U. flexuosa was dominant in other months. Accumulated U. prolifera in the intertidal zone may not contribute to the seeding of the next year's bloom. This study sheds light on the dissipation process and succession patterns of micropropagules in coastal environments.