Mr Sung-Yau Chiu1, Prof. Gray A. Williams1
1The Swire Institute of Marine Science, Area of Ecology & Biodiversity, School of Biological Science, Hong Kong SAR, PR China
The relative distribution and abundance of organisms is strongly affected by local environmental fluctuations, especially in dynamic and extreme environments experienced on tropical rocky shores. Understanding the key traits of species which dominate such environments can help predict species’ success in a warming world. One such species is the rock oyster, Saccostrea cuccullata, which forms dense beds at mid-tide levels on sheltered shores throughout the Indo-Pacific where they are important ecosystem engineers. While mass mortalities occur in other bivalves during the summer in Hong Kong, oyster beds appear, in contrast, unaffected. To determine the key survival traits of oysters, behavioural and physiological responses were measured at three tidal levels at thermally different sites. Thermal performance of heart rate revealed the oyster’s thermal tolerance is below the maximum environmental temperature, and varied between sites. During low tides in summer, physiological assays showed that the oysters oxygen consumption decreases with emersion time. Monitoring shell-gaping behaviour showed that oysters do not close their valves tightly during this period which, when combined with reduced oxygen consumption, may help the oysters avoid hypoxemia. Utilizing gaping behaviour and localized physiological responses maybe key traits which allow Saccostrea to be successful in dynamic and extreme environments. These traits, however, come with costs as gonad development varied among sites and shore height, suggesting oysters modify their energy budget allocations to meet the challenges of different, local, thermal regimes. Future investigations into the oysters’ energetic and molecular physiology will shed further light on the synergies in these key traits.
Presentation Slides – Sung-Yau Chiu
Biography:
Sung-yau (Benjamin) Chiu is a PhD student under Prof. Gray A. Williams supervision. His research focuses on describing the effect of physical stress to habitat modifying bivalves, and their corresponding behavioural and physiological adaptation to mitigate environmental stresses, which contributes to their dominance and success in physically stressful environments.
