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As long as ecologists have studied temperate lakes, the winter has been their off-season. It’s difficult, even dangerous, to look under the ice, and they figured plants, animals and algae weren’t doing much in the dark and cold anyway. But an international team of 62 scientists looking at more than 100 lakes has concluded that life under the ice is vibrant, complex and surprisingly active. Their findings stand to complicate the understanding of freshwater systems just as climate change is warming lakes around the planet.

The co-authors of the research are Juta Haberman, Marina Haldna, Tiina Nõges ja Peeter Nõges from Estonian University of Life Sciences. 

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

Article: https://www.researchgate.net/publication/310479494_Ecology_under_lake_ice

Science 360 News: https://news.science360.gov/obj/story/a34f3f43-a8be-4a4e-a01b-1e077e81ab3a/study-finds-life-under-lake-ice-complex-surprisingly-active