SUMMARY 1 1. The bullhead Cottus gobio is a small‐sized fish that occurs in stony streams and lakes in Switzerland. Its numbers have declined and its distribution has become narrower over the last 30 years, most probably due to chemical pollution and/or structural habitat deterioration, and at present it is classified as a potentially endangered species. 2 This study evaluated whether chemical parameters and/or structural habitat heterogeneity have an effect on the occurrence and density of bullhead in a river system, in order to assess the potential usefulness of this species as an indicator for these parameters. Ten sites were chosen, where chemical parameters were measured monthly over a period of 2 years. Habitat heterogeneity was assessed with respect to river width and maximum depth. Correlations were drawn between the density of bullhead, the chemical water constituents and the structural habitat diversity. The longitudinal distribution of bullhead in the whole river system was determined and all obstructions with a height of at least 10 cm were investigated. In two sites, the total population density of bullhead older than O+ was assessed using both multiple removal collecting and a mark‐recapture method. 3 Structural habitat diversity appeared not to be important for bullhead, and the only chemical parameter that correlated with the density of this species was dissolved organic carbon. 4 Obstructions with a height of 18–20 cm were impassable for upstream movement of bullhead and thus acted as migration barriers. The longitudinal connectivity of the main river was interrupted by 48 such obstructions, which were all human‐made. 5 Multiple removal collecting of bullhead resulted in small catching probabilities of 0.17 and 0.34. The total estimated population densities of bullhead were high, with 118 and 327 in 100 m2. The mark‐recapture method revealed even higher estimated densities, of 121 and 444 in 100 m2. 6 It is concluded that the bullhead is a useful indicator species for determining to what extent the longitudinal connectivity of a river is interrupted by obstructions. For restoration of rivers, it is recommended that any human‐made obstructions with a height of 20 cm or above are removed, starting at confluences with joining rivers and moving upstream.
Journal of Applied Ecology – Wiley
Published: Dec 1, 1998
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera