Quantifying the impacts of abrasion and bacterial transfer when fish are exposed to sand during a catch-and-release event:
- Foster, Ryan M, Childs, Amber-Robyn, Brooks, Margot, Farthing, Matthew W, Butler, Edward C, Potts, Warren M
- Authors: Foster, Ryan M , Childs, Amber-Robyn , Brooks, Margot , Farthing, Matthew W , Butler, Edward C , Potts, Warren M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160427 , vital:40445 , https://doi.org/10.2989/1814232X.2020.1792982
- Description: Best-practice guidelines to improve recreational fishers’ handling during catch-and-release (CandR) events are critical to improve the conservation and management of fish stocks worldwide. While best-practice research is growing, there are knowledge gaps, with the effects of sand exposure on fish mucous membranes understudied. This study aimed to determine the effects of exposing a fish to sand during a CandR event. A total of 360 juvenile (48–137 mm TL) Cape stumpnose Rhabdosargus holubi were subjected to a simulated CandR event during which they were either held: (i) with wet hands, or (ii) dry hands; or with wet hands and then placed on either (iii) wet sterilised sand, (iv) dry sterilised sand, (v) wet unsterilised sand, or (vi) dry unsterilised sand. Fish were maintained in a recirculating system for two weeks, euthanised and subjected to an examination of their mucous layer (bacterial counts, abrasion counts and percentage of abrasion area) and an internal biological assessment. Bacteria fro m fish mucous layers were cultivated on agar plates to count bacterial colonies.
- Full Text:
- Date Issued: 2020
- Authors: Foster, Ryan M , Childs, Amber-Robyn , Brooks, Margot , Farthing, Matthew W , Butler, Edward C , Potts, Warren M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160427 , vital:40445 , https://doi.org/10.2989/1814232X.2020.1792982
- Description: Best-practice guidelines to improve recreational fishers’ handling during catch-and-release (CandR) events are critical to improve the conservation and management of fish stocks worldwide. While best-practice research is growing, there are knowledge gaps, with the effects of sand exposure on fish mucous membranes understudied. This study aimed to determine the effects of exposing a fish to sand during a CandR event. A total of 360 juvenile (48–137 mm TL) Cape stumpnose Rhabdosargus holubi were subjected to a simulated CandR event during which they were either held: (i) with wet hands, or (ii) dry hands; or with wet hands and then placed on either (iii) wet sterilised sand, (iv) dry sterilised sand, (v) wet unsterilised sand, or (vi) dry unsterilised sand. Fish were maintained in a recirculating system for two weeks, euthanised and subjected to an examination of their mucous layer (bacterial counts, abrasion counts and percentage of abrasion area) and an internal biological assessment. Bacteria fro m fish mucous layers were cultivated on agar plates to count bacterial colonies.
- Full Text:
- Date Issued: 2020
Metabolic activity throughout early development of dusky kob Argyrosomus japonicus (Sciaenidae)
- Edworthy, Carla, James, Nicola C, Erasmus, B, Kemp, Justin O G, Kaiser, Horst, Potts, Warren M
- Authors: Edworthy, Carla , James, Nicola C , Erasmus, B , Kemp, Justin O G , Kaiser, Horst , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125159 , vital:35737 , https://doi.10.2989/1814232x.2018.1441907
- Description: Metabolism quantifies the energy-consuming activities of an organism (Nelson 2016) and is used as an indication of how organisms partition energy resources to activities that allow them to survive, grow and reproduce (Post and Lee 1996). The metabolic profile, which is a composition of the various metabolic rates of an individual, therefore gives an indication of the efficiency of energy transformation and allocation (Fry 1971; Brown et al. 2004). McKenzie et al. (2016) suggested that an organism’s physiology contributes towards its ability to survive under specific environmental conditions. As a result, physiological condition can be a reflection of the performance and fitness of an organism (Pörtner 2010). When combined with information on changing environmental conditions, physiological information can provide insight into species- and community-level responses (Pörtner and Farrell 2008). These kinds of data have served numerous ecological applications, including resource management, conservation (McKenzie et al. 2016) and climate-change assessments (Pörtner and Farrell 2008).
- Full Text:
- Date Issued: 2018
- Authors: Edworthy, Carla , James, Nicola C , Erasmus, B , Kemp, Justin O G , Kaiser, Horst , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125159 , vital:35737 , https://doi.10.2989/1814232x.2018.1441907
- Description: Metabolism quantifies the energy-consuming activities of an organism (Nelson 2016) and is used as an indication of how organisms partition energy resources to activities that allow them to survive, grow and reproduce (Post and Lee 1996). The metabolic profile, which is a composition of the various metabolic rates of an individual, therefore gives an indication of the efficiency of energy transformation and allocation (Fry 1971; Brown et al. 2004). McKenzie et al. (2016) suggested that an organism’s physiology contributes towards its ability to survive under specific environmental conditions. As a result, physiological condition can be a reflection of the performance and fitness of an organism (Pörtner 2010). When combined with information on changing environmental conditions, physiological information can provide insight into species- and community-level responses (Pörtner and Farrell 2008). These kinds of data have served numerous ecological applications, including resource management, conservation (McKenzie et al. 2016) and climate-change assessments (Pörtner and Farrell 2008).
- Full Text:
- Date Issued: 2018
Ontogenetic and seasonal shifts in the diet of Diplodus cervinus hottentotus (Pisces: Sparidae) in southern Angola
- Winkler, Alexander C, Santos, Carmen V D, Potts, Warren M
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125452 , vital:35784 , https://doi.10.2989/1814232X.2014.951392
- Description: Fishes of the family Sparidae occupy a diverse range of trophic niches, from herbivores to generalist omnivores and specialist predators (Hanel and Tsigenopoulos 2011). Feeding specialisation in this family is facilitated by diversity in tooth type and anterior jaw arrangement (Vandewalle et al. 1995). Other fish families, such as Cyprinidae and Labridae, have developed crushing pharyngeal teeth to process their food. Sparids, however, have retained a simple pharyngeal tooth arrangement and instead have developed molariform teeth to process hard-shelled molluscs and invertebrate prey. Hanel and Tsigenopoulos (2011) suggested that this alternate strategy is a major factor facilitating the trophic diversity in sparid fishes.
- Full Text:
- Date Issued: 2014
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125452 , vital:35784 , https://doi.10.2989/1814232X.2014.951392
- Description: Fishes of the family Sparidae occupy a diverse range of trophic niches, from herbivores to generalist omnivores and specialist predators (Hanel and Tsigenopoulos 2011). Feeding specialisation in this family is facilitated by diversity in tooth type and anterior jaw arrangement (Vandewalle et al. 1995). Other fish families, such as Cyprinidae and Labridae, have developed crushing pharyngeal teeth to process their food. Sparids, however, have retained a simple pharyngeal tooth arrangement and instead have developed molariform teeth to process hard-shelled molluscs and invertebrate prey. Hanel and Tsigenopoulos (2011) suggested that this alternate strategy is a major factor facilitating the trophic diversity in sparid fishes.
- Full Text:
- Date Issued: 2014
Does reservoir trophic status influence the feeding and growth of the sharptooth catfish, Clarias gariepinus (Teleostei: Clariidae)?
- Potts, Warren M, Hecht, Thomas, Andrew, Timothy G
- Authors: Potts, Warren M , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124309 , vital:35591 , https://doi.org/10.2989/A JAS.2008.33.2.6.503
- Description: The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.
- Full Text:
- Date Issued: 2010
- Authors: Potts, Warren M , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124309 , vital:35591 , https://doi.org/10.2989/A JAS.2008.33.2.6.503
- Description: The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.
- Full Text:
- Date Issued: 2010
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