Tag Archives: algae

Algae as tracers for currents in Parsteiner See

Remember how I described a breeze creating a wave field on Parchsteiner See?

Well, it did not only cause a wave field, it also set up a circulation! Which I might not have noticed, had nit not also started deforming the algae patches! At first, it looked like above, and we could walk into the lake without having to wade into the green, like so.

But then a little later, there were algae everywhere, and you could see the swirls in the current traced out in green! Pretty cool passive current tracer, aren’t they?

Weird algae stripes

The other day I was waiting for my friend and her daughter and noticed a weird stripe-y pattern in the distribution of algae. As I kept watching, the pattern started to change.IMG_1787At first I thought that maybe the algae were collecting in nodes of standing waves that were reflected from the sea wall (ok, lake wall) I was sitting on, but this really does not fit with how the pattern developed later, and I have no clue what was going on.

Watch the movie and tell me what you think, please?

Seriously, though. What is going on? I don’t think the pattern is formed by advective processes – you see bubbles and the occasional leave and they don’t move a lot. I noticed that whenever the wind changed, the pattern in the algae also changed, but I didn’t notice a clear rule. And the wave theory only works for the waves coming in in parallel to the wall, I think. Any ideas?