![]() Given that numerous studies found that global warming is accelerating, and the global climate system is undergoing rapid and widespread changes for the foreseeable future ( IPCC, 2021), jellyfish populations would be expected to be affected. Research on the Strait of Messina showed that rising water temperatures can promote jellyfish outbreaks by affecting their metabolism, growth, and reproduction rates ( Rosa et al., 2013). At the Mondego Estuary, there has been an increase in jellyfish since 2005, with temperature being the main controlling factor ( Primo et al., 2012). In the North Sea, the increase in jellyfish since 1958 saw a positive correlation in the North Atlantic Oscillation (NAO) index ( Attrill et al., 2007). In the Irish Sea, climatic index could explain 68% of the variability in jellyfish abundance ( Lynam et al., 2011). As a consequence, the causes of jellyfish outbreaks have become the focus of research ( Condon et al., 2012 Fernandez-Alias et al., 2021), which was widely attributed to a number of factors such as eutrophication, fishing activities, aquaculture, marine construction, ocean shipping, and ecosystem change, especially the rise in temperature with global warming ( Mills, 2001 Purcell, 2012).Īnalysis through field investigations and long-term historical datasets found that there are strong corresponding relationships between jellyfish population dynamics and climate factors ( Mills, 2001 Purcell, 2005 Sun et al., 2012a). In the past half-century, jellyfish blooms have been reported in many regions of the world ( Mills, 2001 Purcell, 2005 Schrope, 2012), which causes serious ecological and economic problems in tourism, aquaculture, coastal facilities, marine fisheries, ecosystem health, and human life safety ( Purcell et al., 2007 Qiu, 2014). In the context of global warming, whether reproduction of polyps will eventually lead to the outbreak of jellyfish needs to be multifacetedly analyzed based on the complex situation in the field, such as the concentration and timing of jellyfish appearance, and their interactions with other species. However, these may not be only factors necessarily lead to jellyfish outbreaks in the natural environment. This experiment shows that winter and spring temperature in addition to food availability has a significant effect on the asexual reproduction of polyp. High feeding frequency helped polyps accumulate more energy and promote asexual reproduction, especially beneficial to the second strobilation. However, when warming speed was slow in spring, the polyp could conduct secondary strobilation, resulting in higher strobilation frequency and more ephyrae with a longer period. ![]() When warming speed was fast in spring, the percentage of the first strobilation was higher and ephyrae were released more intensively. Polyps had earlier strobilation, higher strobilation frequency, and more ephyra and bud production during warmer winter, but had intensive strobilation after colder winter when the temperature began to rise in spring. coerulea polyps, originally reared from planula larvae of medusae collected from Jiaozhou Bay (120.2☎, 36.1°N), were investigated at orthometric 3 overwintering temperatures (2, 5, and 8☌), 3 spring warming speeds (1☌ increment every 5 days, 7.5 days, and 10 days), and 3 feeding frequencies (once per 9 days, 6 days, and 3 days), representing the range of environment conditions in winter and spring where they exist. To understand the influence of winter and spring conditions on the reproductive process and to provide the basis for jellyfish population prediction, A. coerulea polyp predicted by local temperature could not correspond well to the field abundance of jellyfish in summer. 4Jiaozhou Bay National Marine Ecosystem Research Station, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, ChinaĪurelia coerulea, a type of scyphozoan jellyfish, has massively appeared in the coastal waters of China in recent years and caused great damage, but the asexual reproduction of A.3Laboratory of Marine Ecology and Environmental Sciences, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.2College of Marine Science, University of Chinese Academy of Sciences, Qingdao, China.1CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.Wenxiao Zang 1,2 Fang Zhang 1,2,3 Xupeng Chi 1,3 Song Sun 1,2,3,4*
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