Crédit : Ian Probert

Phytoplankton is active in the water column

Ice algae don’t need much light to photosynthesize and grow.

It’s spring in Qikiqtarjuaq. During my three week stay here, one of the most obvious changes in the environment is rapid snow and ice melt. This change is important for flowering in biota (and thus in all ecosystems) because the sunlight becomes more available for organisms at the base of the ecosystem which harvest it.

Spring bloom in the Arctic Ocean begins with flowering of the ice algae that grow in the bottom of the ice. While much less light is available compared to lower latitudes, low-light adapted/acclimated ice algae flourish here (Figure 1).

The results of this year show a slight decrease in chlorophyll a contents compared to those of last year,  but there is an increase in biomass.

While chlorophyll a (chl a) concentrations this year tend to be lower than those in 2015 so far, our recent observations showed that the color of the bottom ice is getting darker, implying the rapid increase in ice algae biomass of ice algae. Meanwhile, the amount of light in the water column has gradually, but certainly, increased over last two weeks (Figure 2).

Phytoplankton activity  was measured at depth between 1.5 m and 5 m

Despite the very low light in the water column, we have observed clear peaks of optical properties that are related to phytoplankton activity at depth between 1.5 m and 5 m (Figure 3).

Although it’s too early to conclude what’s happening in the water column, these peaks imply that phytoplankton is active in the water column, suggesting that the bloom of the ice algae and phytoplankton might be coming soon.

Atsushi Matsuoka

Contributors: Anita Lebaron, Guislain Bécu, Laurent Oziel, Marie-Hélène Forget, Annick Bricaud, and Marcel Babin


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