The CTD tool is used for testing the water.

Joining students on an excursion

The sea is best studied beside the sea – and at sea.
Join thirteen students on a marine programme out in Gullmarsfjorden in Bohuslän when they go off on their first field excursion.

The thick early morning mist is about to dissolve into a somewhat thinner morning haze, but the top of the church tower in Lysekil is still hidden from view. It is just after nine o’clock on a Wednesday morning in late November. The research vessel Skagerak struggles out of Lysekil’s harbour with its sights set for Alsbäck, whose depth of 118 metres makes it the deepest point in Gullmarsfjorden.

Professor Tiselius is a Professor of Marine Ecology and is responsible for the field excursion element in the course on Marine Studies, Tools and Methods.
“Students should be able to carry out different kinds of measurements on six locations in the Fjord,” he says, and points out where the six locations lie on a map of the Fjord. “We go on this excursion once a year with the students.” Originally the focus was on oceanography, but now elements are included that involve biology and chemistry.

The thirteen students that are on board the Skagerak spend their first term doing the Bachelor programme on Marine Studies. They are divided into three different groups that take turns at carrying out work at the stations known as ‘Hydrography’, ‘Chemistry’ and ‘Plankton’, and during the day they carry out different kinds of tests on the water in the Fjord. Malin Olofsson, a doctoral student, is on the excursion and is head of the ‘Plankton’ station. With the help of two different nets she and the students catch species at depths of 20-50 metres and also in the 118 metre deep waters of Alsbäck.
“The aim is to enable the students to measure and compare the number of species at these different points,” she says. “They will obtain a measurement of the biomass; that is to say, the number of species.” Together with the tests done in other groups, they will then be able to create a complete profile of the Fjord.

The other two groups use the CTD tool for testing the water. Attached to the CTD are eight-metre long bottles that collect the water at different depths and also instruments that collect information on properties such as salinity, acidity and temperature. After that, the students sit down to work in the various lab spaces on board the Skagerak, feverishly checking the measurement results and analysing the samples of water collected.

Elenora Van Sitteren, one of the students, rounds off the day at the ‘Chemistry’ station. She thinks the day was interesting, albeit really cold, and what interested her most was the CTD element.
“There is a great difference between reading up on subjects and doing the practical elements. You get a totally different feel for the subject,” she says. “Such as when you use chemistry; you can see how oxygen is effected in the water or see how large the quantities of phosphates are.”

Shortly after 4 pm, the Skagerak reaches the final measuring points outside the entrance to Gullmarsfjorden – the area known as ‘the threshold’. Once the measurements are done, the vessel sets sail for the Lovén Centre in Kristineberg south of Gullmarsfjorden, where the students can spend the night on board the Skagerak. Lysekil can be seen to the north. The fog has not cleared from the church tower.