FINMARINET New information on the underwater nature of the Baltic Sea Layman’s report

1 Why FINMARINET?

The fractured and fragmented Finnish coastline and Nevertheless, it is still unknown as to what extent this archipelagos mould the seabed into many diverse established network may guarantee the preservation of habitats. These unique and highly variable landscapes the biological diversity along the Finnish coast. both above and below the waterline are composed of The use of sea areas is increasing constantly, yet islands and islets, reefs, sand banks, glacial esker islands, the lack in knowledge of underwater nature makes it as well as elevated shores and lagoons formed by post- difficult to site, e.g. fairways, dredging and wind energy glacial rebound. Underwater marine and brackish-water production areas, in an environmentally sustainable species live in parallel with freshwater species and form manner. The coordination of marine uses and natural a unique ecosystem specific to the Baltic Sea. However, values, better known as marine spatial planning, is due to the unfavourable conditions of the Finnish marine therefore needed to protect marine nature. Such planning areas, the number of species is relatively low. Various flora is, however, impossible to promote without first gaining and fauna, including kelp, aquatic plants and mussels, reliable information about marine biodiversity. form the key species of their communities upon which For centuries, information has been gathered on land to other organisms are dependent. produce detailed terrestrial maps. By contrast, in marine The Natura 2000 network of protected areas was areas, practically the only information on maps and charts established in order to conserve both aquatic biodiversity, has related to depth. Therefore, specific research methods as well as habitats that are becoming increasingly rare. are required to obtain more underwater information. Petra Pohjola, Metsähallitus Julia Nyström, Metsähallitus Lari Järvinen, Metsähallitus Taking a look underwater can yield surprises: although the outer islets in the Gulf of Finland are often barren in appearance on the surface, the sea bottom can be rich in plants and animals.

2 FINMARINET – Transferring knowledge from the sea to maps Harri Kutvonen, GTK • During the project, data from seabed was collected • The acquired data were used in modelling to predict the using various methods. occurrence of habitats best suited for a number of species • Collected field data were analysed and transformed in and the locations of valuable habitat types, such as reefs numerical format. and sand banks. • Data sets on environmental parameters, such as water • The information produced through the models is present- salinity and nutrient content, were produced for each ed on maps. Lari Järvinen, Metsähallitus target area. • The new knowledge about under-water nature helps in identifying valuable areas in terms of biodiversity.

3 1 2 Sand forms the dominant bottom type of the Bay of Bothnia. The The Quark Archipelago is shallow and rocky. Post-glacial land uplift, which vegetation is sparse and patchy due to strong wave action and scouring by measures 8-9 mm per year, results in the continuous erosion of the seabed ice, with some areas being devoid of plant life entirely. The flora and fauna in many areas. Photo: Ulrika Björkman, Metsähallitus. consists mainly of freshwater species. In the Gulf of Bothnia, meadows of charophytes on the shallow sandy bottoms provide good spawning grounds for fish. Photo: Essi Keskinen, Metsähallitus.

3 4

An outer rocky reef covered with bladder wrack in the Bothnian Sea. The bottom topography of Archipelago Sea is particularly variable. Many other species are dependent on this kelp species, which forms Although the salinity in this area is the highest in Finnish waters, fresh water their living habitat. Photo: Anu Riihimäki, Metsähallitus. species also occur. Such varied and fragmented environments result in a highly diverse flora and fauna. Photo: Heidi Arponen, Metsähallitus.

4 Across the entire spectrum The project’s six research areas extend from the Gulf of Bothnia in the north to the easternmost part of the Gulf of Finland. These were selected to cover a range of different regions of the Finnish maritime, and from almost fresh- water areas to the outer reaches of the archipelago, which borders on the Baltic Proper.

Target area Territorial waters EEZ 5 Near Tammisaari, located in the western part of the Gulf of Finland, are 1 situated the densest blue mussel populations on the Finnish coast, with up to 150 000 individuals or more occurring in one square metre. Photo: Mats Westerbom, Metsähallitus.

2

3 6 5 4 6

Almost all bottom types are found in the eastern Gulf of Finland. Most of the sandy bottoms are associated with esker islands, e.g. Kaunissaari Island. Such sandy bottoms are dominated by plant species, which include pondweeds and 0 50 10 0 200 SYKE water milfoils. Kuva Juho Lappalainen, Metsähallitus. Kilometriä

5 Reefs

The map shows the general location of vegetation -covered reefs in the Bothnian Sea. Reefs are depicted according to depth class. Those reefs deeper than 30 metres have been omitted. Map courtesy of Åbo Akademi University & SYKE.

Depth of reef, m 15,0 - 30,0 10,0 -15,0 5,0 -10,0 0,5 - 5,0 Reefs reaching surface Bothnian Bay national park Natura 2000

0 2.5 5 10 ¯ Kilometres

6 Underwater marine nature: A more accurate description

FINMARINET has provided new information on The large amount of field data produced in the species and their constituent communities in the FINMARINET project has allowed the development Finnish sea areas. The project has collected data on of reliable models. These models have been produced animal and plant species from more than 22 000 for a broader range of marine benthic species than ever sampling points from six study areas. In addition, the before in Finland. geological data acquired has involved scanning nearly From models based on the natural diversity data, 800 km2 of the seabed. maps of valuable habitats and organisms have been The project increases our understanding of prepared, which are freely available in an internet- biodiversity and focuses on the location and extent of based map service: http://paikkatieto.ymparisto.fi/ important habitats such as reefs, sand banks, lagoons, velmu/map.htm (in Finnish). large shallow bays and estuaries. In particular, we now The FINMARINET project has also reached literally know much more about habitat types and species from thousands of people by sharing information about the offshore areas. This information is being provided underwater wildlife and biodiversity in a variety of to the authorities to assess the adequacy of networks of public events and media. Finland’s first underwater protected areas and to guide possible further actions. press conference was held in Vaasa in 2009.

Applications of underwater nature information: • Management and planning of marine Natura 2000 sites • Assessment of the adequacy of existing protected areas/ assessment of potential new conservation needs and allocation • Zoning, spatial planning at sea Location guidance of wind power, fish

• SYKE Kostamo, Kirsi farming, dumping of dredged materials and sea lanes in sea areas.

7 Four-leaf mare’s tail (Hippuris tetraphylla) grows in low salinity brackish water on soft bottoms. Although it has been found rarely on almost the entire Finnish coast, today it is mainly found only in the Bothnian Bay. This sharp decline is thought to be caused by the eutrophication of the Baltic Sea, as well as the demise of shore grazing practices. Photo: Lari Järvinen, Metsähallitus.

A community of Rough stonewort (Chara aspera) in the Bay of Bothnia. Photo: Pekka Lehtonen, Metsähallitus.

Water plantain (Alisma wahlenbergii) grows in shallow brackish water in mostly sheltered beaches with soft bottoms. It is a native species of the Baltic Sea region and is mainly a resident of the eastern shore of the Gulf of Bothnia. Its range has shrunk considerably. Threats to this species include, dredging, and, above all, the decline of grazing practices of shoreline meadows. As a result, and in conjunction with eutrophication, it is replaced by the increasing spread of reed beds. Photo: Manuel Deinhardt, Metsähallitus.

8 Bay of Bothnia

Although the underwater conditions of the Bay of knowledge on the distribution of these moss species. The Bothnia are quite peculiar to this region, compared information produced by the surveys may even change with other Finnish coastal areas, it is thus far the least their endangered classification. known. The surveys showed the presence of endangered In addition, stoneworts brought a positive surprise in water moss species, such as Feather- and Phoenix that they were found to be more extensive than previously mosses. In some places, these mosses form extensive expected. The surveys also gave additional information underwater meadows, which provide shelter and food for on the distribution of two other endangered aquatic benthic animals. Until now, there has been only limited plants, i.e. the four-leaf mare’s tail and the water plantain.

Fontinalis sp

Phoenix moss (Fissidens fontanus). Photo: Essi Keskinen, Metsähallitus.

0 5 10 20 Kilometres ¯

Observations Probability of occurrence Model reliability 0 - 0.4 0.8 -1.0 AUC=0.80 Model TSS=0.68 0.4 - 0.6 unreliable 0.6 - 0.8 Natura 2000 The map gives an overview of the most suitable habitats for Fontinalis moss in the Gulf of Bothnia. Mosses which grow on hard and rocky bottoms are often mixed with other vegetation. Map courtesy of Åbo Akademi University & SYKE.

9 10 The Quark

The specific nature of the geology of the Quark region forms a threshold between the Bothnian Sea and the Bay of Bothnia and also creates particular conditions for this area’s underwater ecosystems. The northern and southern parts are markedly different due to differences in salinity. In addition, the harsh conditions vary widely, from exposed outer islands to protected shallow bays and lagoons. Due to the continuous land uplift, the sea floor is increasingly exposed, thereby reducing and finally cutting off its lagoons to form gloe lakes. The particularly large number of rocky reefs and shallows throughout the Quark area give rise to a diverse and extensive algal growth. In the southern part of the Quark are found marine species, such as kelp, i.e. Fucus vesiculosus and F. radicans. In particular, the presence of the latter species has provided a wealth of new information. The Quark coastline is dotted with lagoons. In areas of shallow, sheltered and soft bottoms, stonewort meadows may occur. Stonewort (charophyte) communities have an important ecological role. Their particularly dense growth is responsible for binding nutrients, as well as providing protection for both invertebrates and fish juveniles.

A diver writing down observations on a data form. Kelp (Fucus vesiculosus)

Stonewort (Chara sp.) meadow.

Stonewort meadow in the Quark. Photo: Ulrika Björkman, Metsähallitus. Photos: Ulrika Björkman, Metsähallitus.

11 12 The Bothnian Sea

The underwater environment of the outer areas of the The FINMARINET surveys have provided important Rauma archipelago is dominated by moraine and rock information about the new Bothnian Sea national park ridges formed by the reefs, as well as extensive areas of in relation to its underwater wildlife and conservation clay, which are usually covered with sand and gravel. needs. The survey results have shown that virtually the Relatively rare De Geer moraines were found for the whole of the outer islands and the open sea near Rauma first time in the coastal area of Rauma. There is very is an area of erosion, where strong currents prevent little area covered only by soft deposits. the deposition of sediments. In practice, this would Bedrock or rocky reefs are extensively covered mean that dredged material could not be dumped by kelp (bladder wrack) meadows, which may be without it and its potentially harmful sediment- homogenous and range in depth down to eight or nine bound contaminants being spread by the strong water metres. Within and below these meadows are found red currents. In such a case, valuable and species diverse algae, such as clawed forkweed (Furcellaria lumbricalis) reef formations would be endangered. and black siphonweed (Polysiphonia fucoides).

Sonar image displaying De Geer moraines located near Rauma. These moraines, here running in a north to south-westerly direction, are formed in parallel with the retreating edge of the ice sheet. These formations are named after the Swedish Geologist, Gerard De Geer, who first described them in the 1800s. Map courtesy of GTK. Algae. Photo: Heidi Arponen, Metsähallitus.

13 14 The Archipelago Sea

The southern limit of the Archipelago Sea is bounded reefs as resting places between feeding periods. by the Baltic Proper, forming the most “marine” Surveys were also carried out on observations environment for aquatic organisms living on the Finnish of regionally threatened red algal species, such coastline. Here, the archipelago sinks below the surface as Aglaothamnion roseum. In general, red algae and forms a zone of spectacular underwater reefs. have adapted to survive in low light conditions According to the FINMARINET results, these reefs and are capable of growing deeper than other algal maintain abundant ecosystems of benthic organisms. species. However, this means that even the smallest They also provide seals and sea birds excellent feeding environmental changes in the amount of light, e.g. as and resting areas. Eider ducks moult their feathers in caused by an increase in turbidity, can rapidly affect the this region during the summer, while seals use the outer distribution of red algae.

Reefs Depth of reef, m 15,0 - 30,0 10,0 -15,0 5,0 - 10,0 0,5 - 5,0 Reefs reaching surface

0 5 10 20 Kilometres ¯

Blue mussels. Photos: Heidi Arponen, Metsähallitus. An overview of the location of reefs at different depths from the Archipelago Sea. Those reefs deeper than 30 metres are omitted. Map courtesy of

Grey seal. Photo: Antti Below. Åbo Akademi University & SYKE.

15 16 The Western Gulf of Finland The western part of the Gulf of Finland is particularly Eelgrass (Zostera marina) Observations diverse and is affected by environmental factors, such as Probability of occurence salinity and turbidity, which vary widely in the area. The 0 - 0.4 FINMARINET project has provided much new insight 0.4 - 0.6 into underwater habitats in this region, in particular from 0.6 - 0.8 0.8 - 1.0 red and brown algae communities on shallow offshore Model reefs. Similarly, new information has also been collated unreliable on shallow inshore sandy habitats, as well as seagrass meadows and charophyte communities in shallow lagoons and bays. These vegetation types provide shelter, food and breeding grounds for many other species. In addition, surveys were also carried out in the Model reliability 0 2.5 5 10 AUC = 0.96 ¯ area to assess the red algae species, Aglaothamnion TSS = 0.70 Kilometres roseum and the charophyte, Nitellopsis obtusa. The A general overview of the most suitable eelgrass habitats in the western Gulf of FINMARINET project provides new information about Finland. Map courtesy of SYKE these rare aquatic plants on the Finnish coast.

Sandbanks Sandbanks Natura 2000 Military interest area

Kilometres Eelgrass anchors itself to the bottom with its well-developed root system A general overview of location and distribution of sandbanks in the western Gulf and in doing so, binds the sand and sediment in place. In some sandy areas, of Finland. Map courtesy of Åbo Akademi University & SYKE. it may form extensive meadows. Photo: Heidi Arponen, Metsähallitus. Zannichellia Julia Nyström,Metsähallitus. Photo: sp.

17 18 The Eastern Gulf of Finland

The eastwards decrease in salinity causes changes in the species. In addition, some invasive alien species, such as underwater flora and fauna and in the Gulf of Finland zebra mussels and the amphipod (Gammarus tigrinus) are we find communities which also include a number of spread widely in the Gulf of Finland. The area contains freshwater species. The FINMARINET surveys revealed almost all of the sea bed types found in Finland, e.g. esker that the outer archipelago of this area is a complex islands, reefs, sandbanks and even De Geer moraines. and highly variable environment. For example, data The results of the FINMARINET project were relating to the present distribution of benthic plant and being completed just when the Kymenlaakso regional infauna has been revised for the area. Unlike elsewhere council began preparing its commercial and maritime in the Gulf of Finland, very few red algae are present phase of regional development planning. Data from in the easternmost area. Also the density of infauna FINMARINET has been available for this maritime species such as blue mussels, amphipod crustaceans report. Based on the survey data, it has been possible to (Pontoporeia femorata) and polychaete worms (Bylgides show, for example, areas that are valuable in terms of sarsi) is extremely low. By comparison, shallow areas are both biological, as well as geological diversity. species rich, with both brackish, as well as freshwater

Underwater habitats in the eastern Gulf of Finland

An overview of the location of reefs, sandbanks, ridges and islands in the outer archipelago, including the underwater portions of islets. The eastern Gulf of Finland 0 5 10 20 is a geologically and biologically diverse Kilometres ¯ marine area, in which marine and freshwater fauna and flora co-occur. In the southern Underwater parts of esker islands Reefs Natura 2000 part of the region, those Natura 2000 areas Sandbanks Underwater parts of Boreal Baltic Military interest area which extend into Finland’s economic zone islets and small islands Exclusive economic

Zebra mussel (Dreissena polymorpha). Photo: Juho Lappalainen, Metsähallitus. encompass large sandbank formations. zone

19 The FINMARINET project – Inventory and planning for the Finnish marine NATURA 2000 network was carried out in the period 2009-2013 and received financial support from the EU LIFE+ programme. Finnish Environment Institute SYKE Additional information: Tel: +358 20 610 123 www.environment.fi/finmarinet Visiting address: Mechelininkatu 34a, Töölö, Helsinki Online map service (in Finnish): Mailing address: PL 140, FI-00251 Helsinki http://paikkatieto.ymparisto.fi/velmu/map.htm www.syke.fi/en-US Head of Unit Pasi Laihonen www.itameriportaali.fi/en_GB [email protected] i

Photos: front cover Julia Nyström, Metsähallitus, back cover photo Jussi-Tapio Roininen, Metsähallitus. Layout: Seija Aspola, SYKE. 6/2013