Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species
Global climate change models indicate that a rise in temperature and reduction in rainfall in the Western Cape Province of South Africa is inevitable and unavoidable. Within the Western Cape lies the Cape Floristic Region (CFR); a biodiversity hotspot with high levels of endemism. This includes its...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Biological Sciences
2017
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613200505110528 |
|---|---|
| access_status_str | Open Access |
| author | Reizenberg, Jody-Lee |
| author2 | Dallas, Helen Fiona |
| author_browse | Dallas, Helen Fiona Reizenberg, Jody-Lee |
| author_facet | Dallas, Helen Fiona Reizenberg, Jody-Lee |
| author_sort | Reizenberg, Jody-Lee |
| collection | Thesis |
| description | Global climate change models indicate that a rise in temperature and reduction in rainfall in the Western Cape Province of South Africa is inevitable and unavoidable. Within the Western Cape lies the Cape Floristic Region (CFR); a biodiversity hotspot with high levels of endemism. This includes its freshwater fish assemblage. Whereas the current greatest threats to native fish biodiversity are habitat degradation and invasion by non-native species, predicted climate change is likely to further impact fish communities negatively. As a master abiotic variable in aquatic ecosystems; temperature influences the fitness, behaviour, and life-histories of aquatic biota. Thermal alteration may therefore affect sensitive fish species. The upper thermal limit, determined via the critical thermal method, has been validated as a measure of thermal sensitivity. To better understand the impacts of climate change on the native fish of the CFR, upper thermal limits (critical thermal maxima/CTmax) were determined for seven native species of freshwater fish. Thermal preferences were also determined for five of these species using the acute gradient tank approach to elucidate thermal habitat preferences. Species that were identified by the IUCN as vulnerable, endangered, or critically endangered were selected from the four main families of native fish in the CFR (Anabantidae, Austroglanidae, Cyprinidae, and Galaxiidae), from four Rivers. Overall, Cape galaxias (Galaxias zebratus), Breede River redfin (Pseudobarbus burchelli), Berg River redfin (Pseudobarbus burgi), Clanwilliam redfin (Pseudobarbus calidus), and fiery redfin (Pseudobarbus phlegethon) were found to be most sensitive to increased temperature (CTmax= 29.8-32.7⁰C). Clanwilliam rock-catfish (Austroglanis gilli) and Cape kurper (Sandelia capensis) were found to be moderately sensitive (CTmax= 33.0-35.3⁰C). Similar trends were found using the thermal preference approach as CTmax and thermal preference were found to correlate well. The results were related to in-situ water temperature, which influenced both parameters. Thermal tolerances and preferences of all the native species exceed that of invasive salmonids (Onchorynchus mykiss and Salmo trutta). However, non-native centrarchids (Micropterus spp.) are more thermally tolerant, indicating an increase in threat by warm adapted non-natives. These data suggest that species interactions and distributions are likely to undergo substantial changes in response to elevated water temperature. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/25537 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:21.936Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/25537 The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species Reizenberg, Jody-Lee Dallas, Helen Fiona Shelton, Jeremy Mark Reed, Cecile C Freshwater Research Climate Change Global climate change models indicate that a rise in temperature and reduction in rainfall in the Western Cape Province of South Africa is inevitable and unavoidable. Within the Western Cape lies the Cape Floristic Region (CFR); a biodiversity hotspot with high levels of endemism. This includes its freshwater fish assemblage. Whereas the current greatest threats to native fish biodiversity are habitat degradation and invasion by non-native species, predicted climate change is likely to further impact fish communities negatively. As a master abiotic variable in aquatic ecosystems; temperature influences the fitness, behaviour, and life-histories of aquatic biota. Thermal alteration may therefore affect sensitive fish species. The upper thermal limit, determined via the critical thermal method, has been validated as a measure of thermal sensitivity. To better understand the impacts of climate change on the native fish of the CFR, upper thermal limits (critical thermal maxima/CTmax) were determined for seven native species of freshwater fish. Thermal preferences were also determined for five of these species using the acute gradient tank approach to elucidate thermal habitat preferences. Species that were identified by the IUCN as vulnerable, endangered, or critically endangered were selected from the four main families of native fish in the CFR (Anabantidae, Austroglanidae, Cyprinidae, and Galaxiidae), from four Rivers. Overall, Cape galaxias (Galaxias zebratus), Breede River redfin (Pseudobarbus burchelli), Berg River redfin (Pseudobarbus burgi), Clanwilliam redfin (Pseudobarbus calidus), and fiery redfin (Pseudobarbus phlegethon) were found to be most sensitive to increased temperature (CTmax= 29.8-32.7⁰C). Clanwilliam rock-catfish (Austroglanis gilli) and Cape kurper (Sandelia capensis) were found to be moderately sensitive (CTmax= 33.0-35.3⁰C). Similar trends were found using the thermal preference approach as CTmax and thermal preference were found to correlate well. The results were related to in-situ water temperature, which influenced both parameters. Thermal tolerances and preferences of all the native species exceed that of invasive salmonids (Onchorynchus mykiss and Salmo trutta). However, non-native centrarchids (Micropterus spp.) are more thermally tolerant, indicating an increase in threat by warm adapted non-natives. These data suggest that species interactions and distributions are likely to undergo substantial changes in response to elevated water temperature. 2017-10-04T14:30:51Z 2017-10-04T14:30:51Z 2017 Master Thesis Masters MSc http://hdl.handle.net/11427/25537 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Freshwater Research Climate Change Reizenberg, Jody-Lee The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| thesis_degree_str | Master's |
| title | The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| title_full | The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| title_fullStr | The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| title_full_unstemmed | The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| title_short | The thermal tolerances and preferences of native fishes in the Cape Floristic Region: towards understanding the effect of climate change on native fish species |
| title_sort | thermal tolerances and preferences of native fishes in the cape floristic region towards understanding the effect of climate change on native fish species |
| topic | Freshwater Research Climate Change |
| url | http://hdl.handle.net/11427/25537 |
| work_keys_str_mv | AT reizenbergjodylee thethermaltolerancesandpreferencesofnativefishesinthecapefloristicregiontowardsunderstandingtheeffectofclimatechangeonnativefishspecies AT reizenbergjodylee thermaltolerancesandpreferencesofnativefishesinthecapefloristicregiontowardsunderstandingtheeffectofclimatechangeonnativefishspecies |