Inuit observations of a Tunicata bloom unusual for the Amundsen Gulf, western Canadian Arctic
Climate change impacts are taking place in the Arctic faster than anywhere else in the world and there are increasing reports from Inuit of unusual observations in coastal marine ecosystems.
For Inuit Elders to have witnessed something novel in the natural environment is not trivial, given their tight bond to the surrounding environment and extensive Traditional Knowledge passed down through generations.
Documenting these observations is critical for monitoring potential climate impacts and maintaining sustainable resource use. For Inuit that depend on subsistence harvest, ecosystem changes have direct implications for their livelihoods.
In the summer of 2019 near the community of Ulukhaktok, Northwest Territories, western Canadian Arctic, Inuit Elders observed dense clouds of white translucent organisms in the water stretching for several kilometres along the marine coast.
Read this open access paper on the Arctic Science website.
These observations at the waters’ surface — backed by sample collection and identification, and underwater video footage — was, to our knowledge, a first-time account of a pelagic tunicate bloom near the community. Pelagic tunicates are small gelatinous zooplankton, similar to small jellyfish.
Blooms of these small animals have a unique and important role in ocean ecosystems due to the structures they make to filter the water of very small plant-like particles (nanoplankton and picoplankton).
Called “houses”, they cycle through and discard several of these translucent structures in a day as they become clogged. This biomass falls through the ocean depths and is fed on by many other marine animals, adding to the “biological pump” of nutrients between ocean depths and providing a link from very small plankton to large growing animals.
These blooms, however, also clog fishing nets and large life stages could compete with some other more conventional Arctic species, such as copepods, which are more energy rich than pelagic tunicates as food source. They could also attract greater numbers of large jellyfish and other sub-Arctic animals that regularly feed on them.
The Inuit Elders’ observations and description of events highlighted some of the potential impacts of the bloom on marine mammals, such as ringed seals limiting their diving to avoid the bloom and the suggestion that these stinging organisms in high densities could affect their eyes.
There is very little research on the interaction between marine mammals and these organisms and these insights and concerns highlight the gap in knowledge for the region and Arctic in general.
These organisms could have been brought to the area via the Bering Sea, as Pacific water gets pushed along the Mackenzie shelf and into the Amundsen Gulf. Earlier ice breakup and longer open water seasons provides more opportunity for plankton growth in surface waters for the organisms to feed on.
It is unusual for these tunicates to be in such high numbers close to the surface and the coast. They could have been brought close to Ulukhaktok via strong west winds supported by nutrient plumes coming out of the Mackenzie Delta.
Read the paper — Inuit observations of a Tunicata bloom unusual for the Amundsen Gulf, western Canadian Arctic by Harri Pettitt-Wade, Tristan Pearce, David Kuptana, Colin P. Gallagher, Kevin Scharffenberg, Ellen V. Lea, Nigel E. Hussey, and Lisa L. Loseto.
