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We are done with our field sampling!

Two days ago we finished the trawling surveys, and since then we have been submerged in assessing the diversity of the Bay of Tjärnö using a video camera method.
On one hand, we were using a sledge with an attached camera (with and without a net). Pulled for one minute, the structure stayed on the sea bottom and recorded during this minute the communities living there (called a video transect). Once in the lab, part of our group was in charge of analyzing these videos and estimating the number of species and their abundance.
A bottom full of algae and sea grass made it difficult to identify all the benthic species. Whereas, other times video footage showed clearly all the organisms attached and living on the bottom.


On the other hand, we were using our well known landing platform, that was comparable to a low-cost ROV. We used this platform for two methods! In one method, we took a picture of the sea floor in different areas of the bay. Since we knew the area caught  by the camera, we could identify how many species per m², their abundance, and estimate their densities (number of a species per area). This morning, we finished sampling with this method, and now must compare the area we covered with the area of the sledge method. 


We also used the same landing platform as a baited camera, consisting of the same technique but with the addition of a bait (we were using crushed mussels) and a 20 minutes video recording. With this method, the species were attracted by the smell and the presence of food, allowing us to record the individual's attracted to the area. Yesterday, our sampling consisted mainly in using this technique! Where part of our group went on the boat, dropping the structure, and the other half stayed in the lab working on: statistics, reading papers, analyzing videos, and waiting for the boat, with a lot of excitement for more tedious videos! Now we have many interesting results; lots of hermit crabs climbing into the bait bag, sea stars coming close to the bait, and fish swimming around! 

Now that our sampling days are over, we would like to thank our supervisor Karim Erzini! He has been another brick in our group, a very important one! He was always there to discuss about the methodologies and planning. Also, our ´’captain’ Karim who drove the boat to our many sites, lifting in and out our heavy structures, whilst keeping his good energy and passion in everything we did! Thanks a lot Karim!




Today, we will be enjoying our free afternoon! But tomorrow we will be back to work!  Now, we just have to figure out which is the most effective method to assess the diversity of the bay of Tjarno. By checking differences are between them, not just in terms of species number, but also in terms of time effort, damage caused to the habitat, and some more interesting factors to be considered.

There is between all of us a report that needs to be written, but that’s the easy part, right?

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