Two new papers from our collaborative research in China: (1) Spotted seal Phoca largha underwater vocalisations in relation to ambient noise, (2) Influence of ice concentration and thickness on under-ice ambient noise levels in shallow coastal waters of Liaodong Bay, China. Dear MARMAM readers, On behalf of my co-authors, I am pleased to share our two new papers: (1) Yang, Liangliang, Xiaomei Xu, and Per Berggren. “Spotted seal Phoca largha underwater vocalisations in relation to ambient noise.” Marine Ecology Progress Series 683 (2022), 209-220. https://doi.org/10.3354/meps13951 Abstract: Animals use different strategies to adjust their vocalisations to compensate for ambient noise interference. This is true for some marine mammals, especially cetaceans, but relatively little is known about this for pinnipeds. This study recorded 4 major call types (drum, growl, knock, and sweep) of spotted seals Phoca largha in Liaodong Bay, China, to investigate if seals adjusted their vocalisation parameters in relation to broadband (50 to 4000 Hz) ambient noise recorded immediately preceding each seal vocalisation. Regression analyses showed that the received level of growls, in both broadband (50-4000 Hz) and 1/3-octave bands centred at 200 and 400 Hz, significantly increased with increasing ambient noise levels. These relationships were not observed in the other 3 call types. Further, regardless of call type, the duration, centroid frequency, and root-mean-squared bandwidth parameters showed no statistical relationship with noise levels. The noise measured in this study had relatively low broadband levels of 116 to 132 dB re 1 µPa, and no masking was predicted for any of the 4 call types at 200 and 400 Hz when applying a standard critical ratio approach. It is therefore possible that the ambient noise levels in the study area were not sufficiently loud to induce vocal compensation to avoid masking, but loud enough for the seals to adjust their growl vocalisations. This study is the first to investigate potential vocal adjustment of spotted seals in relation to ambient noise and is important in light of increasing anthropogenic noise in the marine environment. (2) Yang, Liangliang, Xiaomei Xu, and Per Berggren. “Influence of ice concentration and thickness on under-ice ambient noise levels in shallow coastal waters of Liaodong Bay, China.” Estuarine, Coastal and Shelf Science 266 (2022): 107706. https://doi.org/10.1016/j.ecss.2021.107706 Abstract: Underwater noise levels may be strongly influenced by sea ice. This study presents systematic measurements of under-ice ambient noise levels in shallow (<30 m) coastal waters using passive acoustic technology. Acoustic data were collected at 6 sites with different ice concentration (two levels: incomplete and complete ice cover) and thickness (three levels: <10 cm, 10–20 cm and >20 cm) in Liaodong Bay, China. Wind (max = 5.3 m/s) and current (max = 0.3 m/s) conditions were very weak, making minimal contributions to under-ice noise in this study. Root-mean-squared broadband (20–10,000 Hz) noise levels (BNLs) and one-third-octave-band noise levels (TOLs) at 63, 125 and 2000 Hz were measured. Median BNLs of the 6 recording sites ranged from 104.5 to 129.1 dB re 1 μPa, and median TOLs at 63, 125 and 2000 Hz were between 76.5 and 118.0 dB re 1 μPa at the 6 sites. Generalized Linear Models were used to analyze broadband and three one-third-octave-band noise levels in different ice concentration and thickness levels. The results showed that, regardless of the ice thickness, the sites with incomplete ice concentration had higher BNLs and 63, 125 and 2000 Hz TOLs than the sites with complete ice concentration, and regardless of the ice concentration, both BNLs and all three TOLs decreased with increased ice thickness. This study provides baseline characterization of under-ice noise in shallow coastal waters and indicating that both ice concentration and thickness have significant influence on the under-ice noise levels. These findings are important for future studies investigating acoustic communication and noise pollution in shallow coastal waters with sea ice. The pdf copies or any questions, please do not hesitate to email: llyang@stu.edu.cn<mailto:llyang@stu.edu.cn> (Liangliang Yang), xmxu@xmu.edu.cn<mailto:xmxu@xmu.edu.cn> (Xiaomei Xu) or per.berggren@ncl.ac.uk<mailto:per.berggren@ncl.ac.uk> (Per Berggren). Best regards, Dr Liangliang Yang Institute of Marine Sciences, Shantou University, China