The Baltic Sea is an interesting research subject

The seas are full of wonderful creatures and interesting phenomena. There are still undiscovered organisms especially in the deep, dark oceans and far out in the open seas. It is sometimes said that we know our solar system better than the seas of our own planet. Only a fraction of the world's seas have been explored, and there are many marine regions where little or nothing is known. However, luckily for us, the Baltic Sea has already been studied quite a bit!

Scientific research is constantly providing new information on the sea and its creatures. This information helps us understand how the seas function. Marine research also helps us to understand how human activities affect the marine environment. With this knowledge, we can take the seas into account in our activities and find ways to take better care of them.

The research vessel Aranda is a very important part of Finnish marine research.

Since the Baltic Sea has already been studied quite a lot, scientists are beginning to have a good understanding of the changes that human activities are causing to its ecosystem*. However, we should also remember that it is important to continue exploring the Baltic Sea. The continuing research will provide us with information about how the sea will change in the future as a result of climate change.

The sea is studied by taking samples and making models

You can do marine research using many different methods. On shallow shores and sea bays, research samples can be collected using small boats, or sometimes by scuba diving. However, samples collected far out on the high seas are usually taken in much deeper waters, making scuba diving difficult or even impossible. This requires a larger ship or vessel, and so the exploration vessel Aranda is an excellent aid for offshore exploration!

On the research ship Aranda, scuba divers do not go on dives to collect samples. Instead, samples are taken directly from the deck using modern equipment lowered on a cable into the water. Each year, Aranda visits the open sea areas of the Gulf of Finland, the Sea of Åland, and the Gulf of Bothnia. This research ship has even travelled beyond the Baltic Sea! It has also been to the Arctic Ocean and has even visited the Antarctic a few times!

Did you know that the sea can also be studied in the laboratory? For example, the conditions of the sea can be copied in different aquariums. Some of the conditions in some aquariums can be changed, like increasing the temperature or decreasing the light, so that the effect of these changes on the organisms being researched can be observed.

Baltic Sea is studied from onboard the research vessel Aranda. Left: A plant plankton net is lifted from the water. The plant plankton (phytoplankton) that are trapped in the mesh are washed into a jar at the bottom of the net. Right: The water clarity in the Baltic Sea is measured with a white disc known as a Secchi-disc. © SYKE, Jan-Erik Bruun

The sea can also be studied using computer models. This is where researchers use information collected from their samples as a basis for modelling. With the computer and the measured data they have saved, they try to find out, for example, what changes may occur in the future.

New research methods are constantly being developed. One relatively new and important close-up method involves recording the sea bottom using a waterproof video camera. Another is remote sensing, where the pictures taken by satellites are used to explore the sea from very far away!

Aerial view fo the coast, green swirls of algal bloom visible.
The state of the Baltic Sea is monitored also with remote sensing. With the aid of satellites, for example, the extent of algal blooming can be monitored.

The Baltic Sea is monitored regularly

Finland participates in the monitoring of the Baltic Sea environment together with other Baltic Sea countries. Monitoring means that there are certain spots at sea that are sampled at least once or sometimes several times per year. The information you get can be used to check if there are any differences from year to year, and how the time of year affects the samples.

What kinds of samples are there and what are scientists looking for in them? First, physical samples, e.g. water samples, are tested for their physical properties, such as clarity, salinity, temperature, and oxygen levels. Second, biological samples are studied for plant and animal plankton (tiny microscopic organisms that drift or float in the sea), benthic animals (animals living in/on the seabed), and fish. Some samples are also taken back to the laboratory for further analysis and to identify and count different species.

By regularly taking enough samples of different types, we can get a better idea of what is happening in the sea. For example, we can see that benthic animals, i.e. animals living on or in the seabed, have declined in recent years. In this case, other samples, such as the amount of oxygen in a water sample, may explain why. For example, benthic animals do not like it if the oxygen level is very low on the seabed because then they cannot breathe. Sometimes there is no oxygen in the water at all just above the seafloor and all the bottom-living animals die. Since tracking or monitoring continues over years and decades, scientists get valuable knowledge about such changes over time, including how humans affect the sea.

Exploring the Baltic Sea coastal waters. Left: A water sample taken from the sea is transferred to a bottle. Photo Ville Karvinen. Right: A benthic animal sample is taken using an Ekman-sampler and emptied into a bucket.

A phytoplankton sample is examined under a microscope. The cyanobacterium, commonly known as blue-green alga, found in this sample is called Dolichospermum cf. lemmermannii.