Ecological State of the River Tenojoki : Periphyton, Macrozoobenthos and Fish Communities

Abstract

The transboundary River Tenojoki running between Finland and Norway is a sub-arctic, oligotrophic river. The river is 382 km long and the total catchment area of the Tenojoki River Basin is 16 386 km2, of which approximately 70 % lies in Norway. The River Tenojoki is one of the biggest and the most productive Atlantic salmon rivers in the world that is still in its natural state. The brooks, tributaries and main channel of the River Tenojoki form a river reach in excess of 1 000 km long that is a suitable habitat for salmon and has potential areas for spawning.

This publication includes four articles, which describe and assess the ecological state of the River Tenojoki. The article on periphyton survey was written by Juha Miettinen (University of Joensuu) and the articles concerning macrozoobenthos, fish communities and effects of culvert restorations on juvenile Atlantic salmon were written by Heikki Erkinaro and Jaakko Erkinaro (Finnish Game and Fisheries Research Institute).

On grounds of the periphyton survey high ecological status can be assigned to the upstream parts of the River Tenojoki, and good ecological status for the downstream parts below Nuorgam. Based on the macrozoobenthos and fish community surveys all the studied areas fulfil the criteria for high ecological status defined in the Water Framework Directive (2000/60/EU).

Monitoring practices of the ecological state of the River Tenojoki water system should be targeted for possible eutrophication nearby the largest potential sources of human impact. Monitoring of acidification development would in turn be based on a representative set of comparable headwater and brook areas.