{"id":16669,"date":"2018-12-11T15:29:52","date_gmt":"2018-12-11T14:29:52","guid":{"rendered":"https:\/\/npolar.no\/projects\/havoc\/"},"modified":"2026-04-27T09:57:03","modified_gmt":"2026-04-27T07:57:03","slug":"havoc","status":"publish","type":"page","link":"https:\/\/npolar.no\/en\/projects\/havoc\/","title":{"rendered":"Ridges – Safe HAVens for ice-associated Flora and Fauna in a Seasonally ice-covered Arctic OCean (HAVOC)"},"content":{"rendered":"

HAVOC team took part in the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC)<\/a>, an expedition that drifted across the Arctic Ocean for a year in 2019 to 2020, in a similar fashion than the Fram expedition<\/a> lead by Fridtjof Nansen in 1893\u20131896.<\/p>\n<\/div><\/section>\n

The HAVOC project was funded by the Research Council of Norway<\/a> and supported by the Centre of Ice, Climate and Ecosystems at the Norwegian Polar Institute.<\/p>\n<\/div><\/section>\n

Background<\/h2>\n

While sea-ice ridges constitute a significant part of the Arctic ice pack, there is proportionally little knowledge about the exact role in the sea-ice ecosystem. However, a few earlier studies indicated that they could play a vital role in the sea-ice ecosystem, with more diverse habitats. The MOSAiC expedition also provided the unique chance to study sea ice over a full annual cycle, which especially for evolution of the ridges has not been done before.<\/p>\n<\/div><\/section>\n

Hypothesis<\/h2>\n

The overarching hypothesis of HAVOC was to examine whether: Ridges harbor key ecosystem functions in terms of habitat and food web components for sea ice, under-ice and pelagic flora and fauna in the central Arctic. Pressure ridges will become an increasingly important component of the new Arctic sea ice regime dominated by thinner first-year ice where the largest portion of the level ice melts completely in summer.<\/em><\/p>\n<\/div><\/section>\n

Key findings<\/h2>\n

From a physical point of view, it was shown that ridges, piles of ice blocks at initial formation, evolve over time, and change their physical characteristics which has also implications for their role as habitat and ecosystem function.<\/p>\n

There was new evidence provided that surface (snow) meltwater in summer can refreeze in ridge keels<\/a>, and that in winter\/spring it is even plausible that snow can enter through open leads and could possibly contribute to the rapid consolidation of ridge keels<\/a>. Ridge keels limit the spreading of meltwater layers below the ice by acting as inverted dams and reduces the melt rates of level ice<\/a>. It was also shown by repeated multibeam sonar surveys of the same ridges, that ridge keels typically melt 3-4 times faster than the level ice in summer<\/a>. Using data from an earlier expedition it was also shown that ridge keels have the potential to provide more habitable space than the level ice<\/a>, for ice associated primary producers. Overall, these different mechanisms paint a rather complex picture of how the physical characteristics of ridges evolve over time and seasons.<\/p>\n

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Schematic of seasonal aspects of the evolution of sea-ice ridges. Illustration: Frida Cnossen<\/p><\/div>\n

From a biological perspective several interesting findings came out. It was postulated that in winter, when ridges form, the submerged ice blocks warm up to the temperature of the surrounding seawater, which means the ice blocks become porous and can release material formerly trapped in the colder ice. This could be a formerly unknown energy source for the pelagic organisms in the polar night,<\/a> when there is too little light for primary production.<\/p>\n

Mapping of the biomass in sea-ice ridges showed that in summer, the ridges could potentially contain nearly 80% of all the algae biomass in sea ice<\/a>, even if their spatial coverage was only 22% and this is likely an overlooked aspect of the (Arctic) sea-ice ecosystem given there are so few observations from ridges. The consolidation, or freezing of water-filled voids, clearly impact the biological processes occurring in the ridges<\/a>. Further, the ridge keels provide diverse microhabitats, such as ice blocks surfaces and water-filled voids, that can harbor distinct but also diverse microbial communities. Also bio-optical mapping of ridges<\/a> indicated they could be biomass hotspots.<\/p>\n

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Schematic of sea-ice ridge microhabitats and the biomass in ridges versus level ice. Illustration: Frida Cnossen<\/p><\/div>\n<\/div><\/section>\n

Publications and further reading<\/h2>\n