No surprise that, as a northerner, I have always been fascinated by snow and ice. Just right now is perfect timing to follow lakes and rivers freezing over here in the north. This morning, I was visiting some places close to the River Iijoki within some 30 km upstream from my home. And, yes, I must admit this was a combination of hobbies and work-related things again. As background information, it was a chilly morning with full sunshine, and the minimum temperature was -10oC. Can you image a better way to start doing research in a nice early-winter day?
The first location I visited was a slow-flowing reach just upstream of the crossroads of a man-made artificial channel and the original channel of the River Iijoki. This location, Raasakka, started to get ice cover in the last two days, and it was no surprise that it was almost completely covered by ice this morning.
A second location was close to Karjalankylä village. This is also a slow-flowing and quite wide part of the River Iijoki. This part was mostly covered by ice, with the exception of confluences of tributary streams, as exemplified in the photos below.
A third location where I stopped by was the confluence of the River Siuruanjoki with the mainstem of the River Iijoki. The former tributary river’s mouth is in the north in the middle of the photo. This location was still partly not covered by ice, as there are rapids in the River Siuruanjoki upstream of the confluence.
Even though not related to rivers freezing over, I cannot resist adding a photo of resident birds overwintering in icy hell, as I spotted these guys close enough to this river location. In this case, they were two males and one female of Eurasian bullfinch (Pyrrhula pyrrhula). Seeing these guys always makes me in a good mood, and this time was no exception. As it was still quite early in the morning, I had problems with enough light when taking the photo within this forest road. After this side-track to the forest’s side, I moved on to the next river location.
A fourth location was just upstream of the Kierikki hydropower dam in the mainstem of the River Iijoki. As expected, this location was also freezing over, with only some minor parts being devoid of ice. Those parts not yet completely covered by ice showed some nice patterning of water and ice.
After this account, one might wonder why and how all of this is related to my work. River ecology has been at the heart of my research for more than 20 years, yet I have not paid enough attention to how ice formation in early winter and ice break-up in the spring might affect river dynamics and river organisms. We did write a review article back in 2019 when it comes to effects of ice on river biota, but this idea kind of remained as an unfinished project outline. Now could be the time to re-visit this project outline, and that is why I needed to get new thoughts and ideas on rivers just as they are freezing over. And did I get new ideas this morning? Yes, I did, and at least I could have an excuse to spend some time outdoors close to rivers and other northern ecosystems.