A new study from James Cook University has revealed the alarming impact of marine heat waves on the Spanish Flag Snapper, a popular fish found on the Great Barrier Reef. The research highlights the physiological stress these fish experience during these events and the potentially devastating consequences for their survival and the wider reef ecosystem.
Burden on Stripeys
The research, by a former JCU PhD student Dr. Another work from Victoria U. D. student Shannon McMahon deals with the Spanish Flag Snapper, a.k.a. “Stripeys.” The research found that individual fish may be sufficient to survive the initial effects of a rapid rise in water temperature, but catch-and-release fishing practices during the marine heatwaves had profound long-term impacts on their health and survival.
The researchers collected adult Stripeys from the region between Cairns and Cape Melville — one of the regions recently decimated by coral bleaching — and transported them to 12 large outdoor tanks (2,500 liters) in Townsville where they simulated marine heat wave conditions. Published in the journal Conservation Physiology, the study shows that such extreme conditions directly impose physiological stress upon adult coral reef snapper at the time of exposure with effects that can persists for at least two weeks after the event.
Increased Metabolic Stress
Dr. McMahon said “Our results show that marine heat wave conditions result in a direct physical toll on adult coral reef snapper which can persist for up to 2 weeks following these events”. “Fish experience more metabolic stress during a heat event similar to human exposure to high altitude, and it appears they try to deal with this by producing more hemoglobin,” he said.
According to the study, it can increase energy needs of this species by as much as 37% when marine heat-wave conditions occur in summer. These increases in energy demand could result into higher predation on the smaller reef inhabitants, threatening the overall health of the reef ecosystem.
Fishing and Conservation Implications
Dr. McMahon said the impacts of marine heat waves on coral reef fish, like the Stripey, were such that action was needed now. Climate change has brought enhanced frequency and magnitude of MHWs, so it is important to gain a clearer understanding of the vulnerability of organisms during and in those months after these events, Gill said.
Fishing restrictions during these marine heat waves or better catch and release / fishing on their part may be needed to limit the impact of marine heatwaves on Stripeys and related living things, the researchers argue. “Fishing or capture stresses them and they are more susceptible and sort of heat stressed, then there is a good chance that shortly after a catch and release version of the fishery that the could die despite your best efforts. ” Dr McMahon said.
The results suggest that future marine heatwaves could lead to significant losses of reef fishes, and further research on other coral reef fishes will be necessary to determine the wider impacts.
