Effects of stream restoration on the macroinvertebrate community in the River Esrom, Denmark

✍ Scribed by Per Gørtz

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 258 KB
• Volume: 8
• Category: Article
• ISSN: 1052-7613
• DOI: 10.1002/(sici)1099-0755(199801/02)8:1<115::aid-aqc263>3.0.co;2-l

✦ Synopsis

1. The macroinvertebrate fauna of three restored and two reference sections in the River Esrom was compared 4 years after completion of a restoration project using gravel, boulders and stream concentrators on a 3.2-km reach in order to enhance the physical structure and natural trout spawning.

2. Sampling was performed by standard methods (stone-, core-and kick-sampling). The faunal communities were compared by Bray-Curtis similarity, diversity (H), saprobic index (SI) and Danish fauna index (DFI) methods.

3. Restoration with stream concentrators resulted in a deeper and narrower stream with a higher flow velocity near the bottom and a coarser substrate compared with the reference section. The fauna showed higher similarity to the fauna found on the stony bottom sections due to immigration of taxa preferring stony substrate (e.g. Lepidostoma hirtum, Theodoxus flu6iatilis) and SI and DFI generally improved from II to/towards I -II. Clean-water species such as Agapetus ochripes and Limnius 6olckmari, were found in significantly higher numbers in the restored sections compared with the reference section.

4. Five times as many trout spawning redds occurred in the restored sections than in the non-restored. However, electro-fishing revealed few young-of-the-year trout and did not reflect spawning success.

5. It was concluded that attempts to improve the physical structure and spawning environment altered invertebrate composition, but did not enhance trout production.