It has been a few months since my last blog post here. Honestly I was super busy with prepping everything for the new field season going to conferences. And now here we are!
This year we wanted to start our measurements earlier than last year in Vobster Quay. There were two main questions we needed to answer first:
Winter has come and the field season is now ended...
At the end of October we pulled up the Thermistors chain we deployed at the beginning of June. The T chain (see image below) is just a simple rope with small electronic devices that measure continuously the water temperature at different depths. The string has an anchor on the bottom and a buoy on the surface to keep the rope straight and the thermistors at the same depths.
Temperature chain sketch
Today I'm going to explain how we measure the turbulence in the lake. But first of all, what is the turbulence? When I say "turbulence", most of you will think to the motion you experience while flying on an aircraft which is the result of the interaction of the plane with air jet streams in the atmosphere.
Daphnia. Source: wikipedia.org
Coepods. Source: http://www.britannica.com/animal/copepod
Following the previous post about how to collect the zoo samples, we measured the zooplankton concentration during the day to verify that Daphnia is actually hiding during the day from predators (fishes). To do that, we collected samples during June more precisely on 25/06 @ 2.40pm and 5.30pm and on 30/06 @ 2.30pm.
ADCP with its frame on our boat
Last week we put down on the bottom of Vobster Quay the device shown in the figure above. The device is called ADCP and is an acoustic device that uses the same principles of a sonar or a fish-finder but it is actually much more advanced. It was firmly fastened to the aluminium frame and lowered with the three blue ropes from our boat.
Vobster Quay from the jetty
5 days ago (12th May - yes my 28th birthday!), my supervisor and I went to Vobster Quay to do some preliminary measurments and check if that lake was suitable for my research.
Vobster is a natural lake 40 minutes from Bath (https://goo.gl/maps/EaqO8) with a maximum depth of 40 meters, very deep if compared to other nearby lakes. Vobster is a diving centre opened 7 days a week (yes, also during winter) and if you like diving there are nice and cool attractions to see! (more…)