Benzophenone-4 (BP-4), a widely utilized organic ultraviolet (UV) filter, is recognized as a pseudo-persistent contaminant in aquatic environments. To elucidate the effects and mechanisms of BP-4 on marine diatoms, an investigation was conducted on the growth rate, photosynthetic pigment content, photosynthetic parameters, antioxidant enzyme activity, malondialdehyde (MDA) levels, cellular structure, and transcriptome profile of the model species, Phaeodactylum tricornutum. The results showed a pronounced inhibition of algal growth upon exposure to BP-4, with a 144 h-EC₅₀ value of 201 mg·L^-1. In addition, BP-4 exposure resulted in a significant reduction in biomass, disruption of cell membrane integrity, and increased MDA accumulation, with levels escalating 3.57-fold at 125 mg·L^-1 of BP-4. In the BP-4-treated samples, 1556 differentially expressed genes (DEGs) were identified, of which 985 were upregulated and 571 were downregulated. Gene ontology and KEGG pathway enrichment analysis revealed that the carbon fixation and carbon metabolism processes in P. tricornatum were disrupted in response to BP-4 exposure, along with excessive reactive oxygen species (ROS) production. The upregulation of genes associated with photosynthetic pigment (chlorophyll and carotenoids) synthesis, phospholipid synthesis, ribosome biogenesis, and translation-related pathways may be regarded as a component of P. tricornatum's tolerance mechanism towards BP-4. These results provide preliminary insights into the toxicity and tolerance mechanisms of BP-4 on P. tricornatum. They will contribute to a better understanding of the ecotoxicological impacts of BP-4 on the marine ecosystem and provide valuable information for elimination of BP-4 in aquatic environment by bioremediation.

In recent years, with the scale and standardization of Stichopus japonicus mariculture, artificial reefs are increasingly used in S. japonicus farming to promote the development of the S. japonicus aquaculture industry. To provide shelter and improve the habitat environment for S. japonicus, three types of artificial reefs (box-shaped reef, triangular-shaped reef, and trapezoidal-shaped reef) were designed according to the ecological habitats of S. japonicus and the marine environment of Haizhou Bay (China) in the present study. After comprehensively comparing the three reef structures, we found that the trapezoidal-shaped reef has good permeability, a larger attachment area, and excellent anti-slip and anti-overturning properties. Further, the flow field characteristics surrounding a trapezoidal-shaped reef at different angles and flow velocities are investigated by three-dimensional numerical simulations. Then, the impact of the placement distance on the flow field surrounding the artificial reef combination was investigated. At the head-on angle θ = 0°, the upwelling volume increases as the flow velocity increases and then decreases, and the back eddy volume remains relatively constant. At the longitudinal spacing D = 4 L, the large slow-flow area surrounding the reef under this condition is more suitable for the S. japonicus habitat. In this study, the trapezoidal-shaped reef design is suitable and beneficial for S. japonicus aquaculture. Moreover, this study will contribute theoretical references to the design and arrangement of artificial reefs in coastal areas.

Given the unstable input of electricity generated by offshore renewable energy in connection to the power grid at present, one solution is energy storage technology. In recent years, the new marine gravitational energy storage technology has received wide attention in China and worldwide. To apply this new energy storage technology for use in the ocean, in view of the structural characteristics of the new offshore gravitational energy storage system, a support structure based on the foundation of a wind-powered pipe frame is proposed. In order to verify the feasibility of the support structure, a finite element model is established using SACS to analyze whether it meets the requirements. The construction of this structure in a specific sea is simulated through finite element simulation. Then, in accordance with the hydrogeological conditions of the sea area, the wind turbine data, and the dimensional parameters of the energy storage system’s structure, a finite element model is established with SACS for static analysis, modal analysis, random wave response analysis, and wave spectrum fatigue analysis, thereby determining whether the structure meets the requirements for strength, deformation, and fatigue. The research results show that the UC value of the static strength of the support structure of the new offshore gravitational energy storage system is less than 1. In the modal analysis, the natural frequencies of the first- and second-order modes are not within the danger range. In the corresponding random wave analysis, it is found that the natural frequencies of the first four orders are the greatest contributors to the dynamic response during the normal operation of the turbine. In fatigue analysis, it is concluded that the structure meets all the requirements of DNV specifications. The research results provide a reference for the engineering application of the support structure of the new gravitational energy storage system in the ocean.