Cadmium (Cd) pollution has become a global issue due to industrial and agricultural developments. However, the molecular mechanism of Cd-induced detrimental effects and relevant signal transduction/metabolic networks are largely unknown in marine fishes. Here, greenfin horse-faced filefish (Thamnaconus septentrionalis) were exposed to 5.0 mg/L Cd up to 7 days. We applied both biochemical methods and multi-omics techniques to investigate how the gills respond to Cd exposure. Our findings revealed that Cd exposure caused the formation of reactive oxygen species (ROS), which in turn activated the MAPK and apoptotic pathways to alleviate oxidative stress and cell damage. Glycolysis, protein degradation, as well as fatty acid metabolism might assist to meet the requirements of nutrition and energy under Cd stress. We also found that long-term (7 days, “long-term” means compared to 12 and 48 h) Cd exposure caused the accumulation of succinate, which would in turn trigger an inflammatory response and start an immunological process. Moreover, ferroptosis might induce inflammation. Overall, Cd exposure caused oxidative stress, energy metabolism disturbance, and immune response in greenfin horse-faced filefish. Our conclusions can be used as references for safety risk assessment of Cd to marine economic fishes.

To address the issue of harsh marine background noise impacting the monitoring signal of fiber-optic hydrophones, we propose a low-noise fiber Bragg grating (FBG) hydroacoustic monitoring system with a reference sensor based on genetic algorithm backpropagation (GA-BP). Through theoretical analysis, we deduce the noise suppression steps of the GA-BP algorithm based on the reference sensor and construct train and test sets based on the data from the reference sensor and monitoring sensor at different times, optimizing the GA-BP algorithm to find the best fitting results and thereby obtaining the low-noise monitoring signal. Experimental results from the anechoic tank show that the proposed method can suppress background noise interference on effective signals and that the suppression effect improves as the background noise increases. The sound pressure sensitivity ranges from −173.76 dB to −171.33 dB at frequencies of 8 kHz to 12 kHz, with a response flatness of less than 2.43 dB. The noise suppression effect is obvious under the condition of poor signal-to-noise ratio (SNR), which can reach more than 18.3 dB. The advantages of the proposed algorithm in array signal processing are further demonstrated by the directivity experiment, which proves that the algorithm has a great potential for engineering applications in harsh marine environment.

The Bohai Sea is a semi-enclosed shallow water that is influenced by both natural and anthropogenic stressors. However, the microeukaryotic communities and environmental factors that affect them in different regions remain largely unclear. We investigated microeukaryotic communities in surface sediments from five geographic regions using high-throughput sequencing of the 18S rDNA gene. The Miaodao Archipelago, Yellow River Estuary, and Central Bohai Sea had the highest Shannon and Simpson indices of the eukaryotic communities, while the Yellow River Estuary exhibited the highest Chao1 index. The microeukaryotic communities in surface sediments were mainly composed of Dinoflagellata, Bacillariophyta, Ciliophora, Cercozoa, and Protalveolata. Thalassiosira has a relatively high abundance at the Liaodong Bay and Central Bohai Sea, possessing the proportion of 41.70% and 38.10%, respectively, while Gonyaulax was the most abundant taxa in the Bohai Bay, occupying a proportion of 57.77%. Moreover, a negative correlation between diatoms and dinoflagellates was observed. Phosphorus, nitrogen, salinity, temperature, and silicate were major environmental determinants of microeukaryotic composition. Microeukaryotic communities in the surface sediments, especially for the composition and ratio of diatoms to dinoflagellates, reflected the environmental quality of marine ecosystems. Overall, these microeukaryotic community compositions provide a reliable indicator for monitoring the level of marine eutrophication in the Bohai Sea.

With increasing global demand for deep-sea resources, polymetallic nodule mining has become a potential approach for accessing critical minerals. To identify potential areas of ecological concern associated with future deep-sea mining activities, this study predicted the suitable habitat distribution of Balaenoptera species in the Pacific polymetallic nodule areas using the Maximum Entropy Model (MaxEnt). The results showed that environmental variables, such as temperature, salinity, and chlorophyll-a concentration, were the major contributors to Balaenoptera habitat suitability, with their combined contribution exceeding 70% across four species. Temperature showed the highest contribution to habitat suitability predictions for B. acutorostrata, B. edeni, and B. physalus, with contribution values of 38.2%, 46.4%, and 45.4%, respectively. In contrast, salinity contributed the highest (38.4%) to the habitat suitability of B. musculus. Moreover, future climate scenarios posed different changes in the predicted suitable habitats for different Balaenoptera species. Under the current climate scenario, a large proportion of suitable habitat (PSH) were affected in the eastern Pacific mining areas, including 8.52% for B. acutorostrata, 54.94% for B. edeni, 53.73% for B. musculus, and 20.74% for B. physalus. Under future climate scenarios, the PSH of B. acutorostrata and B. musculus showed an increasing trend, which was especially pronounced under the SSP1-2.6 climate scenario (3.96% and 17.27% respectively); while B. edeni showed opposite trends, with a decrease (−6.14%) under SSP1-2.6 and an increase (4.91%) under SSP5-8.5 scenario. The PSH of B. physalus showed a slight decrease (−0.43% and −0.32%) under both scenarios. These findings may support future environmental management and impact assessment for deep-sea polymetallic nodule exploitation.