Professor Sun’s research has centred on marine biology, with particular emphasis on polar marine ecosystems, jellyfish biology and blooms, and marine food-web dynamics. Through national research programmes and participation in Antarctic and Arctic scientific expeditions, he has contributed to research on polar marine biodiversity, the ecological responses of ocean ecosystems to environmental and climate change, and the population dynamics and ecological roles of gelatinous zooplankton. His work has been published in peer-reviewed journals and monographs and has contributed to the development of marine biological research and polar science in China. Through sustained research, leadership of national marine research institutions, and international scientific collaboration, Professor Sun has contributed to connecting fundamental marine ecological research with practical questions concerning polar observation and research, marine ecosystem conservation, and sustainable use of ocean resources across the Eurasian region and beyond.