Mr Callum Hudson1,2, Dr Sylvain Agostini3, Dr Shigeki Wada3, Professor Jason Hall-Spencer2,3, Professor Sean Connell4, Dr Ben Harvey3
1Okinawa Institute of Science and Technology Graduate University, Tancha, Japan, 2Marine Biology and Ecology Research Centre, University of Plymouth, Plymouth, UK, 3Shimoda Marine Research Center, University of Tsukuba, Shimoda, Japan, 4Southern Seas Ecology Laboratories, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
Environmental change can alter the structure and function of biological communities to drive abrupt and marked regime shifts. Ocean acidification can simplify algal systems, switching community dominance to groups with reduced biodiversity and ecological complexity. Our understanding of the mechanisms that stabilise against such switches or lock communities into altered states is limited, yet critical to anticipating future states and the challenge of reversing unwanted state change. In this study, using a CO₂ gradient at a shallow-water volcanic seep, we examined how the resistance and recovery of algal communities at three levels of ocean acidification (equivalent to means of contemporary ~350 and future ~500 and 900 μatm pCO₂) determine their stability in the face of disturbance by typhoons. Consistent with most temperate CO₂ seeps around the world, sites exposed to acidification were increasingly monopolised by low-complexity algae and were clearly different to high-complexity macrophyte-dominated reference sites. Over three years of cyclical typhoons, we found these contrasting states were stabilised by resistance and recovery mechanisms. A near total ecosystem reset of low complexity states by typhoons (i.e. negligible resistance), rapidly recovered to the same low-complexity state (i.e. high recovery), whereas reference sites were resistant to typhoon damage. Thus, low-complexity states might increase in prevalence due to ocean acidification, and typhoons can ‘lock-in’ this degraded state (of low value to humanity) by hysteresis.
Presentation Slides – Callum Hudson
Biography:
Callum completed his Bachelor’s degree in Biological Sciences at the University of Oxford, before graduating from the University of Plymouth with an MRes degree in Marine Biology. During his Master’s, Callum researched the impacts of ocean acidification on the structure and stability of marine communities following typhoon disturbance, utilising underwater CO2 seeps as natural analogues for future ocean conditions. Callum has now started his PhD at OIST in Japan, supervised by Professor Tim Ravasi and external co-supervisor Dr. Ben Harvey, where he will continue to study the responses of marine communities to changing environments.
