Bontle Mataboge

MSc Candidate
Bontle Mataboge


 

Comparing activity levels of exploited & unexploited fish populations under stressful physiological conditions.


The upper ocean is changing rapidly due to anthropogenic global climate change. Fish populations in southern Africa are and will be subjected to increasing frequency and intensity of upwelling events. Variation in water temperature impacts the metabolic rate of fishes, affecting their activity patterns. The metabolic scope of fishes is maximised at a specific temperature range to promote fitness related traits, such as growth and reproduction. When temperatures fall outside of this optimal temperature range, the capacity of fishes to perform aerobically declines. As such, it is expected that increasing frequency and intensity of upwelling may place fish under significant physiological stress, impacting on their resilience to temperature change. Their resilience is largely dependent on their physiological attributes, such as metabolic rate. Theoretically, fish with broader metabolic scope will be more tolerant to the impacts of climate change as they have energy available for adaptation. Recent research has suggested that fish species, normally targeted by line fisheries, from inside marine protected areas (MPAs) have broader metabolic scope, compared to those found outside of MPAs. Thus, it is possible that fish populations protected within well-established MPAs may be more resilient to physiological stresses caused by upwelling. Baited remote underwater stereo-video systems (stereo-BRUVs) can detect local changes in fish assemblage structure resulting from short-term changes in water temperature. These changes typically manifest in reduced diversity, abundance and greater levels of lethargy in the fish that are seen. Using indicators of activity levels which correlate with metabolic rate, this project aims to quantify the impacts of temperature change on fish behaviour from stereo-BRUVs videos. By repeating these observations inside and outside of the Tsitsikamma and Goukamma MPAs, we will be able to determine if MPAs support fish populations that are more resilient to physiological stress and better able to cope with climate change.

Registered:  Rhodes University (Department of Ichthyology and Fisheries Science)
Supervisor: Bernard A, James NC,  Potts WM