The secrets of samples collected from the field are revealed in the laboratory

Many of the sea’s secrets are only discovered in the laboratory when samples collected in the field are placed under the microscope or otherwise analysed. Therefore, laboratory work is also an important part of marine research.

Laboratory work requires both precision and experience. For example, when looking down the microscope, it is not easy to recognise different plankton species. Even such monotonous work is rewarded when something surprising turns up, perhaps an unknown species in the Baltic Sea or an archaeological discovery that opens up new perspectives.

Water analysis requires devices, laboratory equipment, and precision

Water analyses are a traditional part of marine research; water samples collected from the sea have been analysed in Finland for over a century. Current methods and devices can reliably determine a wide range of variables from water samples, such as levels of harmful substances, oxygen and nutrients or for example, chlorophyll levels, which indicate the levels of phytoplankton.

Some of the collected water samples are examined on the research vessel at sea, while others are preserved and analysed later. Typically, minute concentrations of matter are measured in seawater, i.e. in grams per thousand or parts per million. In such cases, extreme care must be taken to ensure that no external material can contaminate the sample. For example, sensitive steps during analyses include adding reagents or transferring a sample to a measuring device.

The sample bottles are therefore handled very carefully in the laboratory. Cleanliness is next to godliness!

The entire biota of a sample is investigated in plankton studies

There is no shortcut for studying plankton samples. All samples collected from the field must be examined under a microscope. This work requires an experienced plankton researcher who can identify different plankton groups and species. The task is demanding, as about 2,000 phytoplankton species are known from the Baltic Sea. By contrast, the number of zooplankton varieties is smaller, with just over 200 species.

The purpose of plankton studies is to monitor changes in the abundance and composition of plankton communities. Thus, all species are identified as accurately as possible from the samples. The biomass (phytoplankton) or individual numbers (zooplankton) of each species are calculated also.

Studies pay particular attention to harmful plankton species, as well as those which act as indicators for the status of the sea. The occurrence of possible alien species is also closely monitored.

The results of plankton research are utilised both in the management of the Finnish marine area, as well as in broader scientific research. The results of such research are submitted to international databases, which, among other things, produce global maps of phytoplankton and zooplankton biomasses.

The study of benthic fauna has its own methods

Benthic faunal samples are sieved at sea immediately after sampling before they enter the laboratory. Nevertheless, apart from the benthic animals, other material may also be included in the sample, e.g. sand grains, plant remains, and other objects. In the laboratory, benthic fauna needs to be sorted from this other material and removed using fine forceps. Such work requires patience and a steady hand.

Samples of benthic animals are usually examined with a stereomicroscope. From the samples, each animal species found and the number of individuals of each species is recorded. Also, the biomass of different species, i.e. the total weight of the animals, is determined. In some species, the size may also be measured to produce a size distribution, i.e. how many individuals fall into different size classes.

The species composition of the benthic animal community varies greatly depending on the type of sediments in which the community lives. An experienced researcher can already predict at least the dominant species from the appearance of the sample. However, the whole range of species and the abundance of different species will only become clear when the samples are carefully examined, and the individual animals are distinguished.

Archaeological finds are conserved so that they remain in good condition

An important step in processing archaeological finds is their preservation. The purpose of conservation is to stabilise the conditions affecting the objects. Thus, the aim is not to restore the original appearance of the objects, but to prevent or at least slow down their destruction. In this way, they remain a resource for both researchers and museums alike.

The preservation of marine archaeological objects is essential as the objects raised to the surface come into contact with air. This speeds up the breakdown of artefacts. Drying can also be disastrous for objects, and thus they must be kept moist until they can be preserved.

Conservation is challenging for many reasons. Even though objects appear to be intact, their structure may have changed over the centuries. Heat fluctuations, light, and microbial activity may have made them very brittle. Many objects also consist of several different materials, which also makes it difficult to preserve them.

Conservation begins with cleaning the object. The artefact is then immersed in a preservative solution whose composition depends on the materials of the article. Conservation can take anywhere from a few months to several years. The progress of conservation is monitored, and more chemicals are added as needed.