Arctic ice reduction allows migration of Pacific plankton to Atlantic

It is well known that Arctic sea ice is shrinking due to warming temperature, resulting in habitat loss for animals such as polar bears. Reducing sea-ice cover also changes the habitat of diatoms, tiny microscopic plants that form a large part of the Arctic microbial community in both the plankton and within sea-ice.. Researchers at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) have discovered that, as a consequence of the reduction in sea-ice, the barrier between the Pacific and Atlantic became unblocked in 1998 allowing a Pacific diatom species called Neodenticula seminae to migrate through the unfrozen Arctic Sea to become established in the North Atlantic. The Continuous Plankton Recorder Survey run by SAHFOS, has documented the presence of this diatom,  in the Labrador Sea since the late 1990s; but it was first found in the North Atlantic in 1999, one year after the polar ice measurements were at their lowest levels. This species had been absent from the North Atlantic for at least 800,000 years and this discovery could be the first evidence of a trans-Arctic migration in modern times. Potential consequences of such a geographical shift could include changes in the biodiversity and functioning of the Arctic and North Atlantic marine ecosystems.

Diatoms and other phytoplankton species form the base of the marine food web and any alterations to their distribution may affect other marine top predators such as fish.

Read more: Reid, P.C., Johns, D.G., Edwards, M., Starr, M., Poulin, M. and Snoeijs, P., 2007. A biological consequence of reducing Arctic ice cover: arrival of the Pacific diatom Neodenticula seminae in the North Atlantic for the first time in 800,000 years. Global Change Biology, 13: 1910-1921.

Contact at SAHFOS: Philip Chris Reid

Neodenticula_Currents

Coloured dots on the map show where the  Pacific diatom, Neodenticula seminae has been found in CPR samples. Arrows indicate its the migration route through the Arctic Sea to the North Atlantic due to low sea ice levels.