Mr Jackson Wai Ting Lau1, Dr Tin Yan Hui1, Prof Gray A. Williams1
1The Swire Institute of Marine Science and the Area of Ecology & Biodiversity, The School of Biological Sciences, The University of Hong Kong, Hong Kong SAR,
Understanding the drivers regulating ecological assemblages is important in predicting and conserving ecological function of systems. These drivers, however, interact both synergistically and antagonistically and, consequently, identifying key drivers is challenging. In the strongly seasonal monsoon system in Hong Kong, previous work suggests top-down (grazing) and bottom-up biological processes are important in maintaining mid to low rocky shore assemblages, while harsh physical conditions (hot rock temperatures) is an important driver in the mid to high shore, causing physiological stress and high mortalities, particularly in the summer. To identify the relative roles of biological processes or physiological stress in driving the temporal dynamics of rocky shore assemblages, rock surface temperatures, food availability and species distributions and abundance were surveyed monthly over two years at three rocky shores and analysed with nonlinear time-series modelling. Over the study period, the density and the impact of predators (dogwhelks) remained low, but mass mortality events of grazers occurred in early summer when rock temperatures increased. The density of grazers, however, recovered when juveniles recruited in late summer. The temporal dynamics of algal coverage was also temperature-dependent, but the responses varied spatially between sites (with different algal assemblages). This series of temperature-driven events repeated between the winter and summer seasons over the two-year period, highlights the importance of thermal stress as a controlling force in regulating tropical rocky shore assemblages. Algal and grazer assemblages, however, exhibit rapid recovery after summer which appears to be typical of the fast turnover rates of populations on seasonal, tropical shores.
Presentation Slides – Jackson Wai Ting Lau
Biography:
Jackson Lau is a PhD student in the Tropical IntertiDal Ecology (TIDE) in the Swire Institute of Marine Science, HKU. His research focuses on physical and biological processes influencing rocky intertidal species assemblages. He is also interested in the taxonomy of gastropods and algae.
