Mitigation of impacts of cattle access on stream ecosystems –
efficacy of
fencing
O’Sullivan, M.1, Ó hUallacháin, D.3,
Antunes, P. O.4., Jennings, E.4 ,
Suzanne Linnane4 , Caroline Wynne4 ,
& Kelly-Quinn, M., 1,2,
1 School of Biology and Environmental Science,
Freshwater Ecology Research Group, University College Dublin, Dublin,
Ireland, and 2UCD Earth Institute
3 Teagasc, Johnstown Castle Research Centre, Wexford,
Ireland
4 Centre for Freshwater and Environmental Studies,
Dundalk Institute of Technology, Dublin Road, Dundalk
Corresponding Author: Mary Kelly-Quinn – mary.kelly-quinn@ucd.ie
ABSTRACT
Headwater streams can constitute
up to 80% of river channel length and are vulnerable to anthropogenic
pressures due to their high connectivity to adjacent land, large
relative catchment size and low dilution capacity. In these environments
unrestricted cattle access is a potential significant cause of water
quality deterioration, resulting from increases in stream bank erosion,
riparian damage and sediment deposition among others. Several studies
have reported improvements in physico-chemical and hydromorphological
conditions of streams following elimination of cattle access; few,
however, have focussed on the ecological impacts of such management
practices. Here, such impacts are assessed. We look at the short-term
effects by comparing habitat condition, sediment deposition, and
instream macroinvertebrate communities upstream and downstream of cattle
access points prior to, and one year following exclusion via fencing.
The long-term effects are also measured by reassessing a small stream
catchment entirely fenced off from cattle access in 2008 under a
concerted management effort. In the short term, cattle exclusion led to
reduction in deposited sediment downstream of cattle access points and a
related homogenisation of macroinvertebrate community structure between
upstream and downstream sampling points. Increased abundances of
specific indicator taxa (Ancylus fluviatilis , Glossosomatidae and
Elmidae) in the fenced catchment following 9 years of exclusion
highlight the long-term ecological benefits of such mitigation
practices. These findings highlight the importance of incentivised
agri-environment schemes in reducing the negative impacts of cattle
access to these vulnerable ecosystems.