Transcriptomic analysis reveals the immune response mechanisms of sea cucumber Apostichopus japonicus under noise stress from offshore wind turbine 

Highlights

• Characteristic assessment of noise at the Bodhi Island offshore wind farm
• Underwater noise suppresses protein synthesis and cellular apoptosis in sea cucumber intestines
• Underwater noise causes oxidative damage to the body cavity of sea cucumber
• Lysosomes and pancreatic secretion support sea cucumbers’ nutrient and energy needs in adverse conditions
• Sea cucumbers’ immune system responds more to low-frequency noise than high-frequency

Abstract
As an important form of renewable energy, offshore wind power can effectively reduce dependence on traditional energy sources and decrease carbon emissions. However, operation of wind turbines can generate underwater noise that may have negative impacts on marine benthic organisms in the surrounding area. Sea cucumbers are slow-moving invertebrates that inhabit the ocean, relying on their immune system to adapt to their environment. To evaluate the frequency range of characteristic noise produced by offshore wind turbines, we conducted a field survey. Additionally, we utilized sea cucumbers in simulated experiments to assess their response to the noise produced by offshore wind turbines. We established a control group, a low-frequency noise group simulating offshore wind turbine noise at 125 Hz and 250 Hz, and a high-frequency noise group at 2500 Hz, each lasting for 7 days. Results from measuring immune enzyme activity in the coelomic fluid suggest that noise can reduce the activity of superoxide dismutase enzymes, which may make sea cucumbers more susceptible to oxidative damage caused by free radicals. Exposure to low-frequency noise can have the effect of diminishing the activity of catalase, and this decrease in catalase activity could potentially increase the susceptibility of the sea cucumber’s coelom to inflammation. In order to elucidate the hypothetical mechanism of immune response, intestinal tissue was extracted for transcriptome sequencing. The results showed that under 125 Hz low-frequency noise stress, the number of differentially expressed genes was the highest, reaching 1764. Under noise stress, sea cucumber’s cell apoptosis and cell motility are reduced, interfering with lipid metabolism process and membrane synthesis. This research provides theoretical support for the environmental safety assessment of offshore wind power construction.

Xiaochen Cheng, Libin Zhang, Zhaoming Gao, Kehan Li, Jialei Xu, Weijian Liu, Xiaoshang Ru
College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao, China
CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
CAS Engineering Laboratory for Marine Ranching, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
Binzhou Ocean Development Research Institute, Binzhou, China
Zhongke Tonghe (Shandong) Ocean Technology Co., Dongying, China

Science of The Total Environment
Volume 906, 1 January 2024, 167802
doi: 10.1016/j.scitotenv.2023.167802