How we do it: Diving into human pressures

Summer of 2019 was my first experience of diving into a life of a marine biologist. My name is Eveliina and I’m studying biology in the University of Oulu. I got to spend the summer as a trainee for SEAmBOTH and also collect data for my master’s thesis in the Bothnian Bay. My thesis concentrates on how human pressures, such as boat ways, affect the underwater vegetation. Some pressures us humans put on marine ecosystems also on the Baltic Sea can be clearly seen, such as trash or old fishing equipment laying around beaches. Some are vastly known but difficult to tackle, such as eutrophication. Some are new, impossible to see but getting more and more attention, like the microplastics. All of these and more are affecting the Baltic Sea in more ways we can even think, so to know more, studies and mappings must be done.

Survived the first work dive. Photo by Suvi Saarnio, Metsähallitus.

To put it shortly, the summer was full of new and interesting experiences. Our team was wonderful, and our days on the field consisted mainly of doing wading points, drop videos and dive transects. I finished my SSI Open Water Diver (OWD) dive course in June, so I got to be part of the diving and collect data for my thesis while doing it! With having so little experience in diving, it was very thrilling to go on my first proper dives, where actual work was supposed to get done. It’s amazing, how you can really work analysing the bottom and tiny plants underwater! The dives in the Bothnian Bay are usually fairly shallow and the other divers in Metsähallitus, dive elderly (which usually means the dive partner), are extremely experienced divers, so it wasn’t like I didn’t feel safe. My concern was that I didn’t want to get in the way of them working or make it more difficult by stirring the water too much! But of course, like as always when working with professionals, everything went fine and soon I got used to being underwater. As my confidence and skills as a diver and in identifying species grew, I got to be more involved and then do my own transects as an analyser. I like to think that during the summer I evolved from a dabbling duck to some kind of frog like creature!

Taking algae samples from the transect line. Video by Suvi Saarnio, Metsähallitus.

We did 200-meter-long transect lines from the shore, to as close to a boat way as possible. Every 50 meters an area of 4 m2 got analysed (bottom sediment type, plants, sedimentation, other). Other things close to the transect line were also documented, such as fish, trash, logs… All the dives were fantastic experiences, not one like the other. Some were more exciting, like the clay canyon and some were more “ordinary”, with beautiful water mosses and algae nonetheless! Possibly the weirdest experience was to dive close to an island in Tornio, called Kuusiluoto where used to be a big sawmill (more information in Finnish of the history of this island).

Kuusiluoto, Tornio. Photo by Sjef Heijnen, Metsähallitus.
Bottom full of planks in front of the Kuusioluoto-island in Tornio. Photo by Suvi Saarnio, Metsähallitus.

The human pressures we documented during the dives this summer were mostly miscellaneous trash, boating equipment, big pieces of wood and very intriguing light mud or muck like sedimentation layer on the bottom. The latter one is something I’m very interested in, it started as a thin layer on the bottom and gradually the layer got thicker and thicker the closer we got to the boat way. Our theory is, it’s caused by the ships and boats, when the motors stir the water causing light particles to start floating and then settle to the bottom some distance away. At many places the sedimentation was so thick it would be impossible for plants to grow at the bottom. I wonder if this has any real effect on the vegetation and will it show on the data analysis of my thesis! We’ll see!

Polyps growing on an old seamark’s weight at the bottom of the Bothnian Bay. Video by Suvi Saarnio, Metsähallitus.

Now is time for the real challenge: getting my buttocks to endure all the hours of sitting in front of the computer writing away…

Written by, Eveliina Lampinen

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