Boreal Baltic Inlets (fjords)

Compiled by: Mats Lindegarth, Sweden

1. European Unions Natural Marine Habitat types definitions:
    1650 Boreal Baltic narrow inlets

PAL.CLASS.: 12.51 (1997 version)

1.1. Definition of the habitat

Long and narrow bays in the Boreal Baltic sea area, which are partly separated from the open sea by a submerged sill. These inlets consist usually of soft mud. The salinity varies depending on the freshwater contribution or the salinity value of the Baltic Sea. The low tidal range and low salinity of the Baltic Sea creates an ecology that is different from that of the North Atlantic coasts. River discharge to the innermost end of the bay is common, resulting in a density stratification of the water column. Narrow inlets unaffected or almost unaffected by man are very rare.

1.2. Characteristic species

Plants: Ceratophyllum demersum, Hippuris vulgaris, Myriophyllum spicatum, Phragmites australis, Potamogeton perfoliatus, Sagittaria sagittifolia, Schoenoplectus lacustris, Schoenoplectus tabernaemontani. Algae: Cladophora aegagropila, Nitellopsis obtusa.

Animals: Birds: Anas crecca, Anas platyrhynchos, Circus aeruginosus, Cygnus olor, Podiceps cristatus. Insects: Chironomus plumosus coll. Crustaceans: Monoporeia affinis. Mollucs: Macoma baltica, Nucula tenuis, Syndosmya nitida, Thyasira flexuosa. Polychaeta: Maldane sarsi. Sponges: Axinella rugosa, Phakellia spp., Mycale lingua, Polymastica spp., Vosmeria spp.

1.3. References

European Commission (2007). Guidelines for the establishment of the Natura 2000 network in the marine environment. Application of the Habitats and Birds Directives. Appendix I: Marine Habitat types definitions. Update of “Interpretation Manual of European Union Habitats” (EU interpretation manual)

Lindholm, T. (1991). Från havsvik till insjö. Miljöförlaget. Åbo, 160 pp.

Luther, H. (1951). Verbreitung und ökologie der höheren Wasserpflanzen im Brackwasser der Ekenäs-Gegend in Süd-Finnland. I. Allgemeiner Teil. Acta Bot. Fennici, 49:1-232. & II. Specieller Teil. Acta Bot. Fennici, 50:1-370.

Mathiessen, H. & Mathiessen, L. (1992). Floristic aspects of one coastal inlet inre Verkviken, northern Åland. Acta Phytogeogr. Suecic., 78: 101-110.

Niemi, Å. (1978). Ecology of phytoplankton in the Tvärminne area, SW coast of Finland. III. Environmental conditions and primary production in Pojoviken in the 1970s. Acta Bot. Fennici, 106:1-28.

 

2. Additional HELCOM information

2.1. Description of the habitat

This natural habitat type represents a complex consisting of narrow, elongated bays surrounded mostly by rocky shores. They are often characterized by a more or less pronounced salinity and nutrient gradient caused by riverine water. The presence of a shallow (sill) at the mouth of a fjord limits the exchange of water and causes large fluctuations in salinity.

2.2. Distribution (past and present)

Such fjords are present in Swedish and Finnish coastal areas of the Bothnian Sea, the Gulf of Finland and the Baltic Proper. Their present and past distribution is in areas of crystalline bedrock.

2.3. Importance (sub-regional, Baltic-wide, global)

Flora and fauna in shallow areas are characterized by dense stands of common reed, pondweed and a large variety and abundance of birds and fish. The benthic fauna consists mainly of soft-sediment invertebrates, such as polychaetes, crustaceans, bivalves and insect larvae. Fjords are of Baltic-wide importance.

2.4. Status of threat/decline

The overall assessment of this habitat complex is that it is endangered (HELCOM, 1998). This is mainly due to its sensitivity to decreased quality, rather than loss of area. Regeneration is considered difficult.

2.5. Threat/decline factors

This habitat type is threatened by physical modification due to construction of roads and bridges as well as eutrophication and pollution (mainly from agriculture and forestry). Particularly eutrophication causes risks for oxygen deficiency in bottom water.

2.6. Options for improvement

In a long-term perspective anoxia and other impacts of eutrophication can be alleviated by reduced input of nutrients to the sea (by e.g. introduction of ecologically sound farming and forestry methods). Protection and possibly even recovery of this habitat type can be achieved by restricting coastal constructions, dredging and dumping of dredged material.

As for all natural habitat types an inventory and a monitoring and assessment programme (also for human activities) is obligatory for EU Member States. They are further obliged to take all appropriate steps to avoid further deterioration. This includes the obligation to protect this natural habitat type within the Natura 2000 network, and thus to designate as many SACs as necessary to guarantee its favourable conservation status. Member States have to follow Article 6 (3) of the Habitats Directive: Plans and projects which are not directly connected with or necessary to the management of a Natura 2000 site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications.

2.7. References

HELCOM (1998). Red List of Marine and Coastal Biotopes and Biotope Complexes of the Baltic Sea, Belt Sea and Kattegat - Including a comprehensive description and classification system for all Baltic Marine and Coastal Biotopes. HELCOM-Baltic Sea Environment Proceedings 75, Helsinki Commission. 115 pp.

Nordiska Ministerrådet (2001).  Kustbiotoper i Norden: hotade och representativa biotoper.  TemaNord 2001:536.  ISBN 92-893-0626-2.  pp.  345. (in Swedish).