Thanks to the phytoplankton Iceland is attractive for whales

November 20, 2020

If you have been on one of our whale watching tours from Reykjavík, on board of Andrea you know that we emphasize on education during the tour. There is for example a small onboard museum in the bow. This is where we sometimes display our plankton sample. We take the sample, with our plankton net, while we sail out in the direction of the whales feeding grounds, in Faxa bay.

What is this magic plankton and why is it important for us, you may ask?

Plankton describes a diverse collection of organisms that are driven by the current. In this blog, we emphasize on phyto- and zooplankton. At the beginning of the marine food chain stands the phytoplankton, single cellular microscopic algae. They are found almost everywhere in the surface layer of the ocean. It is imitated by sunlight and nutrients such as Iron, Nitrogen and Silicate. The nutrients are mainly found in the depth while the photosynthetic active light only penetrates the uppermost layer of the ocean. And that makes our bay, Faxaflói, so productive, it is very shallow. In the winter when the level of sunlight is low there is an intensive mixing going on bringing the nutrients up. Diatoms typically dominate the phytoplankton spring bloom over the Icelandic shelf and afterwards Dinoflagellates increase in abundance. If the conditions are favourable other groups such as coccolithophores multiply rapidly and colour the ocean such as Emiliania huxleyi does every year – that can be seen from space!

In our petri dish on board, we display the zooplankton, in Icelandic water dominated by the copepod Calanus finmarchicus. The biomass in the upper layer is on average 2-4 g dry weight m-2. If you want to read more about the connection of whales and plankton have a look into this blog article.

The trace nutrient Iron is limiting the phytoplankton bloom by 30% in the world’s ocean so called high nitrate low chlorophyll regions (HNLC). In the year 2010 this was for once no limiting factor in Iceland.  

On the 14th of April, the volcano Eyjafjallajökull erupted, in the south of Iceland, causing ash to deposited across up to 570,000 km2 of the North Atlantic Ocean. This input of dissolved Iron increased the algae bloom by about 20%.