Day 3 – Salinity studying in Huinay #fjordbiología #chilefoldscope #MicroToxMap

The salinity is an important parameter to consider to understand the distribution of marine planktonic communities. This parameter, quite stable in an open ocean context, is very variable in a coastal area. Depending on the quantity of fresh water reaching the sea, the salinity will change drastically. In Huinay, which is a fjord present in North of Patagonia, two components will participate to reduce the salinity by bringing fresh water, the rain and the rivers. It rains about 6-7 meters per year and the number of rivers are considerable.

With Adam we went to sample every meter from the surface down to 10 meters and we measured the salinity using an old refractometer present at the marine station.

The salinity will be given by the index of refraction of the sample
Plot of the salinity per depth

Easily, we obtained the salinity structure of the sample site. The presence of two different layers was clear on this profile, an upper layer progressively more saline and at 5 meters a stable layer quite saline, above the halocline. Silva (http://www.cona.cl/revista/english/3.1%20Hellmuth%20A.%20Sievers.pdf) had shown that the structure of the upper layer can change depending on the context :

Schematic representation of the different types of vertical salinity structures proposed for the Chilean austral channels and fjords (adapted from Silva et al., 1997, 2002).

Regarding the diversity of species present in this ecosystem, it’s interesting to observe the stratification of the species depending on the salinity.

A collage of few species observed with the foldscope in the samples we got

We clearly observed a peak of biomass at 7-8 meters which is bellow the halocline. We collected some data using other microscopes and we would like to document this distribution using the foldscope.

Thanks to Jorge’s taxonomic expertise, we’ll be able to characterize a bit better this ecological structure. Indeed, it’s very interesting to realize that marine species receive an ecological pressure from the low salinity layer when the fresh water species living on land and in the rivers are expelled into the fjord, into a higher salinity environment.

It’s also interesting to think about this at a cellular level. Such as what are the differences between membranes from a freshwater species to a marine species?

One Comment Add yours

  1. Manu Prakash says:

    Brilliant post @adam and @thibaut. Fantastic to hear that you can collect so well with recording height and salinity.

    Stunning photographs.

    Cheers
    Manu

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