IW11 Threatened inland water species

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Status

According to the Red List of Finnish Species published in 2010, the proportion of inland water species of all threatened species was 5.9%. This equals the proportion of inland water species of all well known Finnish species. Inland water species are thus not under- nor overpresented among threatened species. In total, there are 132 threatened inland water species.

Almost a third of threatened inland water species are found primarily in lakes. Rivers and brooks both host a fifth of them. Despite their small area, small spring complexes are  especially important habitats for inland water species. They host 24% of all threatened inland water species.   

Approximately half of the threatened vertebrates in lakes and ponds are bidrs. Majority of the invertebrates are beetles. Rivers host plenty of threatened fishes and dragonflies. The threatened fresh water mosses are mainly found in brooks and small spring complexes.

Development

A quarter of the changes in inland water species' conservation statuses were positive and three quatrers negative between years 2000 and 2010.

Two of the positive status changes concern birds. Eurasian Marsh Harrier and Great Bittern have been completely removed from the red list due to growth of their populations. Also the conservation status of two fishes has been lowered for the same reason. The populations of the Baltic Sea Salmon and river spawning Asp have recovered during the last decade.

Most of the negative changes concern birds. The red-list status of seven bird species has tightened. Six of them are hunted duck species. In addition, among the declined fresh water species there are five moss species and four beetles.

Threats

Construction and regulation of water bodies is the main threat for inland water species. It is the primary reason for the threatened status of 53 species (36 %). Construction and regulation includes, besides direct digging and damming, also large scale land-use changes in drainage basins that affect the quality and behaviour of water. The scale of construction and regulation ranges from damming large rivers and building reservoirs to minor water intake structures in small stream complexes.

The chemical changes in water quality, mainly eutrophication and harmful substaces, are quite seldom primary threats for fresh water species (15% of species). Even random factors are more common as primary threats. The importance of adverse chemical impacts however grows when the secondary threats are considered. Adverse chemical impacts cause a threat to 67 inland water species.

Measures of agriculture, forestry, drainage of forests or mires and peat production have an effect on inland waters as they change flow directions and volumes and increase the discharge of nutrients and organic matter.
This indicator will be completely updated as the new list of threatened species is completed in 2020. Small revisions and additions may be made before that.

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