Mr Liam Connell1, Miss Kaylee Beine1, Prof Gray Williams2, Prof Richard Greenfield1
1University of Johannesburg, Johannesburg, South Africa, 2University of Hong Kong, Hong Kong SAR, PR China
Intertidal organisms are considered vulnerable to climate change as their thermal tolerance limits are thought to be close to current environmental temperatures. Elevated temperatures have also been shown to increase toxicity of environmental pollutants such as cadmium, reducing the aerobic scope of an organism and therefore further narrowing its thermal tolerance limits. The effect of an acute exposure to a combination of two environmentally relevant concentrations of cadmium and five experimentally controlled temperature treatments on the cardiac performance (as an indicator of thermal tolerance) of Siphonaria capensis was determined from populations sampled along the warm-water southern and cold-water west coasts of South Africa. Significantly higher cardiac performance (mean heart rate) at 39 ºC (85 bpm) and lower thermal tolerance was recorded from the southern coast population. The west coast population, in contrast, showed highest cardiac performance at 29 ºC (78 bpm), after which a steady decline in cardiac performance occurred with elevated temperatures. Cardiac performance in relation to increased cadmium exposure showed a significant interaction between coasts, with the southern coast population showing elevated cardiac performance when exposed to increased cadmium concentrations, whilst a decline was observed in the west coast population. This study indicates that populations along warmer coastal regions may already be living close to their thermal tolerance limits and further increases in temperature and pollution loads may, therefore, synergistically lead to negative consequences for these populations as compared to those living in cooler, less impacted areas.
Biography:
Liam is currently enrolled at the University of Johannesburg where he is pursuing his Ph.D. in Zoology. After obtaining his MSc in Zoology, where he focused on biomarker responses in freshwater fish species in response to pollutants and poor water quality, his passion for conservation has led him into the field of intertidal ecology. His focus has shifted at looking at the effects of climate change and pollution loads on organisms along the rocky shore focusing on cardiac response and physiological adaptation.
