Bayden Russell1, Alison Freeman1, Rhian Evans1, Juan Diego Gaitan-Espitia1
1The University of Hong Kong, China
We are in the midst of a global biodiversity crisis, with global heating and extreme events reshaping entire communities. Key amongst our concerns is the loss of habitats which support biodiversity and enhance ecosystem function. In many coastal marine systems, seaweeds are not only the major primary producers but also form extensive habitats. Yet, data on the effects of ocean heating and marine heatwaves on these algal assemblages is restricted to a few well-studied regions. Here, we have assembled a database of algal species records from the temperate-tropical climatic transition zone along the southern coast of China spanning 170 years. We found that up to 150 species of algae have potentially been lost from the waters of Hong Kong, possibly representing poleward range shifts of a large percentage (>60% of recorded species) of the algal community. We then used in situ physiological measurements and laboratory warming experiments to demonstrate that warming winter (not summer) water temperatures over the past 3 decades have shortened the winter growth season for forest-forming Sargassum spp. Based on our projections, these once extensive seaweed forests may be absent from Hong Kong’s waters within the next 50 years, which would signify the local extirpation of a once highly productive and biodiverse ecosystem.
Biography
Bayden RUSSELL is an Associate Professor at the Swire Institute of Marine Science at The University of Hong Kong. Prof. Russell is an ecophysiologist whose research focuses on the impact of climate change on ecosystem function, the biology of key species, and how to manage ecosystems in this context. He also investigates the human relationship with, and dependence on, marine ecosystems and how these can be made sustainable through nature-based solutions, especially oyster reef restoration.