Endangered species

Most of the existing populations of the threatened species of macrophytes in the Baltic Sea can be found in the SEAmBOTH area. There are a lot of populations from before 1995 in the southern Finland, Sweden, and south of the Baltic Sea which have now vanished. Whether this is due to lack of recent knowledge or that the populations have really disappeared, is not clear in every case, but most of the time it’s the sad fact that these populations are no longer there. This is most probably due to heavier human pressures and more altered or overgrown habitats in the south.

A map of Baltic Sea where most green and blue dots are found in the Bothnian Bay, orange dots in south Finland and Sweden.
HELCOM map of endangered macrophyte species in the Baltic Sea. Orange dots tell us where these species have occurred before 1995, green dots represent the ones present after 1995 and blue dots before and after 1995. You want to concentrate on green and blue dots to get a picture of where the endangered species can be found right now.

The SEAmBOTH area seems to be a haven for threatened and endangered macrophytes. Of the Species and Habitats directive Annex IV, we have Alisma wahlenbergii growing as wide underwater meadows both in Finland and Sweden and Hippuris tetraphylla forming meadows at the water’s edge in Finland. The beetle Macroplea pubipennis is not a macrophyte but it is also an Annex IV species and can be found in both countries in the SEAmBOTH area, it was also found in Sweden for the first time during the project!

A woman is holding a plant and a cutting board with the data sheet taped to it.
Hippuris tetraphylla was found in Kempeleenlahti, Finland, and Suvi is writing down information of the metapopulation. Later the handwritten data is moved to a species database. Photo Jalmari Laurila, Metsähallitus.

Why Sweden doesn’t have Hippuris tetraphylla in the SEAmBOTH area beats us. The models tell us that the species could or should easily be found in the project area, but it just doesn’t exist there, only in one confirmed place south of Umeå. In the Finnish SEAmBOTH area, it’s sometimes found as thousands or tens of thousands of individuals forming large meadows in the mudflats of Hailuoto and Krunnit islands.

Narrow leaved plant with a few branches under water
Potamogeton friesii is considered nearly threatened in the SEAmBOTH area and has attracted special attention from the HELCOM because it is more threatened in the scope of the whole of the Baltic Sea compared to the Bothnian Bay. Modelling this species’ distribution is difficult because it likes both the muddy soft bottom puddles with almost black water and the outer archipelago gravely shores with lots of wave action and clear water, as well as brown watered rivers. Photo Ville Savilampi, Metsähallitus.

Another mystery species is the Charophyte Chara braunii. In Sweden it forms underwater meadows but in Finland, despite really searching for it, we can only find individuals here and there. On the other hand, the SEAmBOTH inventories more than doubled the known number of Chara braunii findings in the national species database in Finland.

Green plants with darker and orange colored dots of reproductive organs under water
Chara braunii is a rare Charophyte in the SEAmBOTH area, but easily identified from all other Charophytes. In the Finnish SEAmBOTH area, it has just started to be found in larger numbers during the past two or three years. Photo Länsstyrelsen.

Some of the species are a bit baffling – for example, in Finland Crassula aquatica is considered as vulnerable (VU) and in Sweden “only” near threatened or NT. A shore macrophyte Primula nutans seems to be endangered (EN) in Finland and not the least bit endangered or “least concerned” (LC) in Sweden.

A broad leaved plant in shallow water in a lush macrophyte meadow
Persicaria foliosa is considered endangered (EN) in Finland but only nearly threatened (NT) in Sweden. It can be found in the river estuaries. Photo Niina Kurikka, Metsähallitus.

In the biological field inventories during the SEAmBOTH project we especially concentrated on very shallow coastal waters and river estuaries. This is one of the reasons why we did many hundreds of sightings of various threatened macrophytes, more than half of the findings being new to each country. Somehow for a marine biologist like me, who is working in her dream job in practical marine nature conservation, it is always uplifting to find a new population of endangered species. Even though it inevitably leads to a long bureaucratic trail of papers to be filled (read a blog about that in Finnish here).  And every now and then you can see the fruits of your labour when a new status for each macrophyte is decided every ten years and some of the species might go “down the list” from a more threatened status to a less threatened status (read a blog about that in Finnish here and here). Then it’s time for celebration and you know that you’ve done something right – even if you wouldn’t have been able to make the Baltic Sea a better place for the species, at least you’ve done enough research to prove that the species is doing better than expected and can be lowered to a less threatened category.

Essi Keskinen


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