Dr Jay J Minuti1,2, Prof Maria Byrne3, Dr Deevesh A. Hemraj1,2, A/Prof. Bayden Russell1,2,4
1The Swire Institute of Marine Science and Area of Ecology & Biodiversity, School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR, China, 2Institute for Climate and Carbon Neutrality, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR, China, 3School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia, 4The Dove Marine Laboratory, School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, United Kingdom
The potential of populations to persist under extreme conditions, such as marine heatwaves (MHW), relies on individuals being able to both survive and reproduce. Fundamentally, this depends on the capacity of an organism to (1) physiologically acclimatize to, and recover from, thermal stress, and (2) pass on resistance to the next generation. To elucidate whether heat-conditioning of parents could benefit offspring development, we exposed adult sea urchins (Heliocidaris erythrogramma) to ambient summer (23°C), moderate (25°C) or strong (26°C) MHW conditions for 10 days, followed by spawning to produce larvae. Offspring were then reared along a thermal gradient (22-28°C) and development tracked. In adult urchins, greater MHW intensity drove higher metabolic rates which were not matched with an increase in food consumption, ultimately leading to latent negative physiological effects that caused mortality even when conditions returned to normal. Interestingly, progeny from the MHW conditioned adults developed through to metamorphosis faster, and were larger, than those of ambient conditioned parents. In contrast, most offspring from the control summer temperature died before metamorphosis at temperatures above 25°C (a moderate MHW). Initial survival was higher in the progeny of MHW exposed parents, even at temperatures hotter than predicted MHWs (28°C). Importantly, however, there was substantial mortality of juveniles from the strong MHW parents within two weeks. Therefore, while carryover effects of parental conditioning to MHWs resulted in faster growing, larger progeny, this benefit will only persist beyond the more sensitive juvenile stage and enhance survival if conditions return promptly to normal ambient temperatures.
Biography:
Bayden is an ecophysiologist whose research focuses on the impact of climate change and eutrophication on ecosystem function, the biology of key species, and how best to manage and conserve ecosystems in this context. He also investigates the human relationship with, and dependence on, marine ecosystems and how these can be made sustainable through habitat restoration and development of techniques to maximize the ecosystem benefits of aquaculture.
