HR: 11:15h
AN: NB52B-04 INVITED     [Abstracts]
TI: Hydrological disturbance benefits native fish at the expense of exotic fish
AU: * Leprieur, F
EM: leprieur@cict.fr
AF: LADYBIO-CNRS/UPS, Universit‚ Paul Sabatier, Toulouse, France
AU: Hickey, M
EM: Matt.Hickey@orc.govt.nz
AF: Otago Regional Council, 70 Stafford Street, Dunedin, New Zealand
AU: Arbuckle, c J
EM: chris.arbuckle@orc.govt.nz
AF: Otago Regional Council, 70 Stafford Street, Dunedin, New Zealand
AU: Closs, G P
EM: gerry.closs@stonebow.otago.ac.nz
AF: Department of Zoology, University of Otago, Dunedin, New Zealand
AU: Brosse, S
EM: brosse@cict.fr
AF: LADYBIO-CNRS/UPS, Universit‚ Paul Sabatier, Toulouse, France
AU: Townsend, C R
EM: colin.townsend@stonebow.otago.ac.nz
AF: Department of Zoology, University of Otago, Dunedin, New Zealand
AB: Many of New Zealand's native fish do not coexist with introduced salmonids. Previous studies of disjunct distributions of exotic brown trout and native galaxiids in the Taieri River demonstrated native extirpation except where major waterfalls prevented trout upstream migration. In the nearby Manuherikia River, waterfalls are not significant and we predicted water abstraction for irrigation might mediate non-overlapping distributions. We used multivariate analyses to test for differences in environmental conditions (catchment and instream scales) in sympatry and allopatry, and a supervised artificial neural network to identify factors mediating non-overlapping distributions (139 sites). Brown trout are capable of reaching most locations in the Manuherikia catchment, and often occur upstream of Galaxias anomalus. In this river, their largely disjunct distributions are mediated by water abstraction for irrigation, together with pool habitat and valley slope. Brown trout are more susceptible than the natives to stresses associated with low flows and high temperatures and it seems trout are prevented from eliminating galaxiid populations from sites in low gradient streams where there is a high level of water abstraction. In contrast to many reports in the literature, hydrological disturbance associated with human activity benefits native fish at the expense of exotics in the Manuherikia River.
DE: 1842 Irrigation
DE: 1845 Limnology
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly