Abstract
Macroinvertebrates in aquatic habitats form an integral part of the diet of many freshwater fish. It is therefore important to understand the effects that weed control practices have on this community in canal fishery watercourses. The principal forms of weed control operated in the Grand and Royal Canals include mechanical cutting, using a variety of boat-mounted and land-based apparatus, and chemical treatment using dichlobenil. The community composition and relative abundance of macroinvertebrates in control, mechanically cut and dichlobenil treated canal sites was recorded on three to five occasions between 1993 and 1994. The results indicated that Asellus aquaticus was the dominant organism at all canal locations. The land-based Mowing Bucket effected the greatest reduction in macroinvertebrate numbers in the immediate aftermath of the cut. This reflects the capacity of the machine to cut vegetation to canal bed level, thereby removing any substrate for colonisation. At all eight sites examined, macroinvertebrate numbers increased relatively rapidly following treatment and no adverse effect on dependent fish life resulted. The Office of Public Works policy of removing obstructive vegetation from a central navigation channel, while preserving weeded marginal fringes, minimises the impact of weed control operations on the macroinvertebrate fauna.
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Monahan, C., Caffrey, J.M. The effect of weed control practices on macroinvertebrate communities in Irish Canals. Hydrobiologia 340, 205–211 (1996). https://doi.org/10.1007/BF00012756
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DOI: https://doi.org/10.1007/BF00012756