ECOPHYSIOLOGY OF INTERTIDAL CORALS ALONG THE KWAZULU-NATAL COASTLINE: COPING IN MARGINAL ENVIRONMENTS
Kaylee Smit and David Glassom
University of KwaZulu-Natal, School of Life Sciences

 

Abstract
Coral survival in an era of global climate change will depend largely on the ability to tolerate, acclimatise and adapt to changes in their natural environment. High-latitude intertidal corals along the east coast of South Africa withstand extreme temperature fluctuations, and endure highly marginal conditions for coral survival and growth. With focus on two intertidal species, Pocillopora verrucosa and Anomastrea irregularis, the aim was to determine the cellular, physiological and population responses in adapting to these conditions. Five sites along the KwaZulu-Natal (KZN) coastline were sampled to determine latitudinal differences, extending from Sodwana Bay to Munster, the southernmost point of the coral distribution. Interspecific and latitudinal differences between population size frequencies highlight environmental variability and the difference responses of these corals to environmental stress. These population dynamics provide insight into the life history, juvenile input and mortality of these intertidal corals.Physiological parameters such as zooxanthellae density, chlorophyll concentration and lipid content were assessed seasonally at each site for a period of one year. A clear trend in zooxanthellae density in both P. verrucosa and A. irregularis highlights the natural seasonal variation, suggesting a coping mechanism with changes in temperature and other environmental variables. Similar trends of zooxanthellae density and chlorophyll concentration suggest mechanisms by which these symbiotic algae are affected by temperature stress. Lipid depletion proposes as a means of acquiring additional energy during prolonged times of stress. Isotope analysis of coral tissue cells and zooxanthellae also highlights the possible use of heterotrophic feeding as a means of accounting for the lack of nutrition by stressed zooxanthellae. Different tissue physiological responses predict coping mechanisms that may allow these corals to adapt and survive in the extreme marginal habitats of KZN. Understanding this is important in a time of local and global environmental change.
Presentation Topic
ECOPHYSIOLOGY OF INTERTIDAL CORALS ALONG THE KWAZULU-NATAL COASTLINE: COPING IN MARGINAL ENVIRONMENTS
Contact Ms Kaylee:
Email Kaylee Smit