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:
K this is just a link to another blog post explaining the importance of Daphnia for scientists but in a very nice and original way.
I really appreciated the reference to Star Wars!
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
One of my biggest problem in the past weeks was measuring the size of Daphnia we have in Vobster Quay. That's very important to understand how they can affect the mixing during the vertical migration and their life stage. Daphnia usually live for 2 months reaching the maximum body length. So different sizes means different ages.
Unfortunately the microscope I have in the Water Quality Lab @UniBath in Civil Engineering wasn't that powerful and even using my Snapzoom microscope adapter didn't help that much. The image was too blurry and I couldn't use even the ruler!
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.
After the deployment of our acoustic instrument to track the zooplankton migration Last week, we are currently collecting a lot of zooplankton samples during the day to understand the distribution of our Daphnia in Vobster Quay. And today I am going to explain how we are doing this.
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.
Daphnia from Vobster Quay samples (mid-May)
Many people reading the post title will think: What the heck is a Daphnia? A Daphnia is a tiny zooplankton - the little organisms in lakes and oceans eaten by fishes - with an average length of 1/3 mm and is a species very common in fresh water bodies. All the images in the post are taken with a microscope from one of our samples collected in Vobster Quay in mid-May and the first one precisely shows a (dead) Daphnia. Since our microscope does not have a place to insert a specific microscope camera, I used the microscope adapter Snapzooms which is cheaper and very simple to use and smartphones offer nowadays as much resolution as microscope cameras. (more…)
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…)