Bohinj 2008 field work
Part of my training for a biologist consists of field work. The last comprehensive camp was last week at lake Bohinj. Bohinj is located at the north-western part of Slovenia in a valley in Julian Alps (east part of the Alps you keep hearing about). I didn’t have time to take a lot of photos (or I didn’t take the time, because the camera wasn’t as handy as I would want it to be), but I did take a few. Here is one of Savica brook just before it spills into the lake. The brook is very cold (around 5˚C) and it creates a thermocline in its delta - a sharp transition from its temperature to that of the surface temperature of the lake, which is about 20˚C in this time of year. The cold water runs at the bottom of the lake and doesn’t mix with the upper layers of the lake as one might imagine. The lake is meromictic, meaning it gets mixed by winds two times a year (spring and autumn). The east part is the deepest, about 45 meters. River flowing out of the lake is called Jezernica.
I was sampling with Ekman’s corer (also dubbed Bodengriefer, švaba) at about 40 meters. As luck would have it, I hit a spot with a lot of subterranean amphipod crustaceans, which indicates there is an underwater spring thereabout. Hopefully this will be of any value to the scientists at http://niphargus.info/. Sampling was done on one day, sorting the samples the other and identifying on the third. Identifying was interesting. Most animals were Diptera larvae, but oligochaetes were common as well. As already mentioned, one sample contained a lot of amphipods. Deep parts of lakes are usually poor in animal diversity (and zero in plant diversity, because there is usually no light below a certain compensation point defined by many factors) because of extreme environmental conditions. Animals have to be adapted to low temperatures and often low oxygen levels. Some animals (like the amphipods I already mentioned twice) avoid low oxygen levels by moving through the ground into subterranean streams.
Cool! I ID’ed some Niphargus ictus from caves in Northern Italy for a microbial ecologist working in the cave. Their front claws were really oddly shaped, almost looked liked they were for trimming. Coincidentally, the sulfur-oxidizing bacteria in the caves are filamentous. I proposed to her that they were eating the bacteria, perhaps even farming it. Hopefully they will exam the gut contents and stable isotopes of the amphipods.
Comment by kevin z — 6 July, 2008 @ 12:47
I’ve heard of those caves that have a bucket load of bacteria hanging from everywhere. I’ve actually heard this at a lecture by a visiting scientist at our Uni a few years ago. I mentioned Francesco Canganella here.
Comment by romunov — 6 July, 2008 @ 13:14