Flow-related threats to rare galaxiids in the upper Waitaki River
Human activities are increasingly altering ecosystems, and are especially severe in streams where flow modification can affect environments far downstream and can interact with other pressures, such as species invasions. This has led to a disproportionately high number of threatened species in strea...
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ftdatacite:10.26021/8346 2023-05-15T17:09:26+02:00 Flow-related threats to rare galaxiids in the upper Waitaki River Howard, Simon William 2014 https://dx.doi.org/10.26021/8346 https://ir.canterbury.ac.nz/handle/10092/9976 unknown University of Canterbury. School of Biological Sciences Copyright Simon William Howard https://canterbury.libguides.com/rights/theses native fish galaxiidae flow modification Other CreativeWork Theses / Dissertations article 2014 ftdatacite https://doi.org/10.26021/8346 2021-11-05T12:55:41Z Human activities are increasingly altering ecosystems, and are especially severe in streams where flow modification can affect environments far downstream and can interact with other pressures, such as species invasions. This has led to a disproportionately high number of threatened species in streams (e.g., native galaxiid fishes in New Zealand). I investigated how threatened bignose galaxias (Galaxias macronasus) and upland longjaw galaxias (Galaxias prognathus) were affected by flow-related influences in their habitats. A survey of sub-catchments in the Mackenzie Basin showed that flow regulation played a strong role in influencing fish occurrence; native fishes dominated unregulated rivers and introduced species dominated regulated rivers. Upland longjaw galaxias (ULG) were sparsely distributed and only found in unmodified braided rivers. Targeted surveys in these rivers indicated their habitat selection was weak, and although habitat availability was high, individual habitats were only occupied for short periods because floods frequently reconfigured the river bed. Thus, disturbances played a major role in ULG populations, forcing a strategy of weak habitat selection and frequent movement. This also makes them vulnerable to large-scale flow changes making the habitat more benign and potentially increasing competition (e.g., from invasive trout). Bignose galaxias were only locally abundant in very low discharge habitats lacking other fishes, so were restricted to very small parts of the river network. An experiment manipulating flows showed bignose galaxias moved into slower habitats over the short-term, suggesting a slow-flow preference, but not excluding the competitive influences of other fish like trout. Overall, this work shows these threatened fishes are susceptible to many of the current and future global changes affecting freshwaters like habitat alteration and invaders, but the above knowledge should allow targeted management of these influences for these highly threatened endemic fish. Article in Journal/Newspaper Mackenzie Basin DataCite Metadata Store (German National Library of Science and Technology) New Zealand |
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native fish galaxiidae flow modification |
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native fish galaxiidae flow modification Howard, Simon William Flow-related threats to rare galaxiids in the upper Waitaki River |
topic_facet |
native fish galaxiidae flow modification |
description |
Human activities are increasingly altering ecosystems, and are especially severe in streams where flow modification can affect environments far downstream and can interact with other pressures, such as species invasions. This has led to a disproportionately high number of threatened species in streams (e.g., native galaxiid fishes in New Zealand). I investigated how threatened bignose galaxias (Galaxias macronasus) and upland longjaw galaxias (Galaxias prognathus) were affected by flow-related influences in their habitats. A survey of sub-catchments in the Mackenzie Basin showed that flow regulation played a strong role in influencing fish occurrence; native fishes dominated unregulated rivers and introduced species dominated regulated rivers. Upland longjaw galaxias (ULG) were sparsely distributed and only found in unmodified braided rivers. Targeted surveys in these rivers indicated their habitat selection was weak, and although habitat availability was high, individual habitats were only occupied for short periods because floods frequently reconfigured the river bed. Thus, disturbances played a major role in ULG populations, forcing a strategy of weak habitat selection and frequent movement. This also makes them vulnerable to large-scale flow changes making the habitat more benign and potentially increasing competition (e.g., from invasive trout). Bignose galaxias were only locally abundant in very low discharge habitats lacking other fishes, so were restricted to very small parts of the river network. An experiment manipulating flows showed bignose galaxias moved into slower habitats over the short-term, suggesting a slow-flow preference, but not excluding the competitive influences of other fish like trout. Overall, this work shows these threatened fishes are susceptible to many of the current and future global changes affecting freshwaters like habitat alteration and invaders, but the above knowledge should allow targeted management of these influences for these highly threatened endemic fish. |
format |
Article in Journal/Newspaper |
author |
Howard, Simon William |
author_facet |
Howard, Simon William |
author_sort |
Howard, Simon William |
title |
Flow-related threats to rare galaxiids in the upper Waitaki River |
title_short |
Flow-related threats to rare galaxiids in the upper Waitaki River |
title_full |
Flow-related threats to rare galaxiids in the upper Waitaki River |
title_fullStr |
Flow-related threats to rare galaxiids in the upper Waitaki River |
title_full_unstemmed |
Flow-related threats to rare galaxiids in the upper Waitaki River |
title_sort |
flow-related threats to rare galaxiids in the upper waitaki river |
publisher |
University of Canterbury. School of Biological Sciences |
publishDate |
2014 |
url |
https://dx.doi.org/10.26021/8346 https://ir.canterbury.ac.nz/handle/10092/9976 |
geographic |
New Zealand |
geographic_facet |
New Zealand |
genre |
Mackenzie Basin |
genre_facet |
Mackenzie Basin |
op_rights |
Copyright Simon William Howard https://canterbury.libguides.com/rights/theses |
op_doi |
https://doi.org/10.26021/8346 |
_version_ |
1766065531513733120 |