Response of stream fish to improved water quality: a comparison between the 1960s and 1990s

• Published in: Freshwater biology 1998-12, Vol.40 (4), p.771-782
• Main Authors: Eklöv, A. G., Greenberg, L. A., Brönmark, C., Larsson, P., Berglund, O.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Barbatula barbatula; Biological and medical sciences; Conservation, protection and management of environment and wildlife; Environmental degradation: ecosystems survey and restoration; fish assemblage; Freshwater; Fundamental and applied biological sciences. Psychology; hypoxia; Pisces; pollutant; Pungitus pungitus; recolonization; Salmo trutta
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1046/j.1365-2427.1998.00370.x

Summary 1. The effect of improved water quality on fish assemblages in streams in southern Sweden was assessed by comparing species composition at 161 sites and water quality at twenty‐nine sites in the 1960s and the 1990s. 2. Water quality had improved and there was an increase in the number of sites or catchments with brown trout (Salmo trutta), stone loach (Barbatula barbatula) and eel (Anguilla anguilla). The response was greatest for brown trout and was best explained by increased oxygen concentrations. 3. The number of sites with nine‐spined stickleback (Pungitius pungitius), ide (Leuciscus idus) and brook lamprey (Lampetra planeri) decreased between the 1960s and 1990s. The decrease was greatest for nine‐spined stickleback and was related to the increase in sites with trout, suggesting that nine‐spined stickleback may be sensitive to predation or competition. 4. Improved water quality has led to recolonization by brown trout, probably enabling biotic interactions to play a larger role in structuring fish assemblages. Improving water quality was an effective method for rehabilitating fish populations in streams where natural colonization was possible.