Breakthrough day!

Today was awesome! It began for me before sunrise. I walked to the lab about 6 am and as I walked a glimmer of gold caught my eye. I moved closer to investigate thinking I may have suddenly become rich. Upon closer examination. I learned I had not found gold. Instead I found either a land snail with a shell or a slug with a snail's shell. I decided that because it moved rather slowly that I would pick it up and move it off the bike path. So I guess I'm no richer, but my new acquaintance is safe.

At 7 am the good crew of Jean-Christophe (Crew leader), Guillaume (Lover of outside work), Tristan  (Our young and enthusiastic worker) & I (your faithful story teller) set sail for a day's work on Leman. It was absolutely gorgeous today with little to no wind and a sunny blue sky.  We observed with the echo sounder an absence of scattering from the surface (minus some noise that is always present in the first 1-2 m depth) to a depth of about 4 m. I assumed this meant that during sunny days that the copepods in Lake Leman were moving down into the water column to avoid the high light levels. It is common for zooplankton to avoid light because when you are small yet can be seen, you can be eaten. It is called negative phototaxis I think. The phenomenon was most evident in the 420 & 208 kHz acoustic data (see below).

I had the good crew collect zooplankton tows from both 25 m to the surface & 4 m to the surface to validate the echosounde data. We collected data with 2 meshes (63 & 200 micron) or 4 samples in total (see picture below). Note that the two samples from 4 m to the surface were largely void of zooplankton and the water was crystal clear. So the acoustic data makes great sense!

Today we caught a 21 mm larval coregonid. Tristan & I agreed it was a monster!