Editorial: Ecology of marine zooplankton and micronekton in polar and sub-polar areas

As reported by Azam et al. (2017) the polar and subpolar regions are characterized by ecosystems with high biodiversity and species richness. Hunt et al. (2016) highlighted that the variability among polar ecosystems, such as sea ice cover and thickness, population structure, abundance, diversity and food web, from phytoplankton to marine mammals, is due to the different circulation patterns of water masses between north and south. Huge environmental changes have been induced in those areas by a high climate dynamic, which has generated loss of biodiversity and consequent reduction of ecosystem services provided to the entire planet (Laffoley and Baxter, 2016). In this context, much attention was paid to the effects of these environmental changes on zooplankton structure and dynamics, and consequently on the matter and energy cycling in polar ecosystems, as also demonstrated by the results of La et al. (2019) on how climate changes can alter the zooplankton vertical migration (DVM) in the Southern Ocean. The high vulnerability of these ecosystems, in the presence of pressures such as climate change and overfishing, jeopardizes the essential ecosystem services they provide, e.g. in terms of carbon storage and suitable habitats for nursing and feeding (Azam et al., 2017; Johnston et al., 2022). The polar ecosystem presents high spatial variability in terms of the rate and direction of change in temperature and sea ice, but little is known about the mechanisms through which the spatial distribution of planktonic species is influenced (Yang et al., 2021). These changes appear to impact circumpolar food webs involving krill and other zooplankton. It follows that knowledge of the density and distribution of zooplankton is crucial to correctly estimate the energy transfer within the food web of the continental shelf and its response to climate change (Minutoli et al., 2024). In turn, ocean warming can have a significant impact on the structure and functioning of zooplankton (Fraser et al., 2023; Swadling et al., 2023).