OCEANOGRAPHIC MEASUREMENTS (and samples)
FIELD TRIP to SVANØY 2012
25.May 2012
Oceanographers monitor marine ecosystems by measuring the ranges of each abiotic
(physical, chemical, geological) and biotic factor (distribution and abundance of organisms as
consequence of interspecific relationships). Norway has such a lush vegetation in such a high
latitude due to several degrees higher average annual sea temperature which makes a huge
difference for climate of terrestrial ecosystems – on the same latitude on Greenland there is
not one single tree. One can probably thank to some of those abiotic factors the fact that the
northernmost UWC is in Norway.
The factors we will be measuring on our way:
1. Transparency (turbidity) of water: a measure of the amount of dispersed particles
(silt, plankton etc.)
a) Secchi disc – a white disc on a rope with markings on every meter. It is dipped into
the water on the side where the boat casts a shadow (to avoid reflection). One person
slowly releases the disks deeper and deeper until it is lost from sight (watch for
uncertainties!). Then it is lifted slightly until it becomes barely visible again and the
depth is read.
b) Colorimetric measurements?
2.
On two of the sites (Dale and Open sea) the samples of the plankton will be
using the plankton net; a surface sample and a vertical sample
taken
3. Using the oceanographic probe YSI 85 we will measure the water temperature (C),
salinity (conductivity) mg/l, dissolved oxygen % saturation, at 5 different depths:
0m, 3m, 5m, 15m, 30m
It is almost impossible to have a probe positioned vertically – so we will be using a
clinometer to estimate the real depth.
The map shows the boat route from the College to Svanøy with four sites where the boat will stop so that we
can measure those physical and chemical parameters.
The students will be divided in 4 groups (9 per group) and each group take the
measurements on one of the sites. The measuring tasks will be distributed between the
members of the group - one person will be noting down all the data. The four “noters”
will exchange all the data and then the graphs can be made upon arrival to Svanøy –
or at some point later.
Results: obtain graphs of
1. Horizontal pattern of temperature, dissolved oxygen, salinity
(at least surface and 30m)
2. Vertical pattern of temperature, dissolved oxygen, salinity
3. (3D graph(s) of both????)
4. Horizontal pattern of sea water transparency
For discussion:
How can each of these patterns be explained in terms of geographical influences
and/or in terms microscopic life forms floating in sea water?