A new study suggests sharks will need to adapt, move or die as climate change could soon render their nurseries uninhabitable.<\/p>\n
Baby sharks rely on coastal nursery-like spaces such as shallow lagoons and mangroves for food as well as protection from predators. But they also need to be robust enough to cope with the challenging conditions these environments throw at them\u2014conditions that may soon become unbearable in a warming world.<\/p>\n
\u201cIn shallow coastal habitats, baby sharks already have to tolerate the strain of high temperatures,\u201d said the study\u2019s lead author Dr Ian Bouyoucos, from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU).<\/p>\n
\u201cThe temperatures can also fluctuate dramatically on a daily basis. It\u2019s the constant change that makes these environments \u2018extreme\u2019.\u201d<\/p>\n
Dr Bouyoucos said nursery areas are important for sustaining the local shark populations by serving as \u2018safe havens\u2019 for newborns and juveniles to learn critical survival and foraging skills. But the impacts of climate change are increasingly becoming a problem for their survival.<\/p>\n
\u201cWe don\u2019t know if sharks can adapt and can continue to use these important habitats early in life, or whether they will be able to find new nurseries, or whether populations will die off\u201d he said.<\/p>\n
Co-author Associate Professor Jodie Rummer, also from Coral CoE at JCU, says this is a case of adapt, move or die.<\/p>\n
\u201cHeatwaves due to climate change are becoming more frequent and severe, and lasting longer with climate change,\u201d Dr Rummer said.<\/p>\n
She said more work is needed to find current tolerance limits for newborn sharks to survive and thrive in shallow, warm nursery habitats.<\/p>\n
\u201cThe temperature thresholds that limit their performance today can help us predict how future populations might fare as the waters continue to warm with climate change,\u201d she said.<\/p>\n
\u201cBut adaptation\u2014changes in DNA over generations to accommodate new conditions\u2014may not be possible. This is because sharks are slow to reach sexual maturity compared to most other fishes and do not reproduce as often or have as many babies. Therefore, not enough generations can go by fast enough to keep pace with the rate at which we\u2014humans\u2014are changing their habitats.\u201d<\/p>\n
Dr Rummer said there was a possibility newborn sharks could move to new nursery-like areas that are not as warm.<\/p>\n
\u201cOr, we might just see these shark populations disappear,\u201d she said.<\/p>\n
\u201cThis is a real risk. We know sharks are tolerating a lot already. The oceans, their habitats, are getting warmer, lower in oxygen, and lower in pH with climate change.\u201d<\/p>\n
As predators, sharks are essential for healthy ocean ecosystems. Without predators, whole ecosystems can collapse.<\/p>\n
\u201cWe need to keep studying and protecting sharks,\u201d Dr Bouyoucos said.<\/p>\n
\u201cOur sharks, ecosystems, and our futures all depend on us urgently cutting greenhouse gas emissions to curb climate change.\u201d<\/p>\n
PAPER<\/strong><\/p>\n Bouyoucos I, Simpfendorfer C, Planes S, Schwieterman G, Weideli O, Rummer J. 2022. \u2018Thermally insensitive physiological performance allows neonatal sharks to use coastal habitats as nursery areas<\/strong>\u2019. Marine Ecology Progress Series<\/em>. DOI: 10.3354\/meps13941<\/a><\/p>\n IMAGES<\/strong><\/p>\n A selection of images<\/a> can be used for media stories with credit to the photographer as stated in the file name. Please note these are for single use with this story only, not for any other story. No archival permissions are granted.<\/p>\n CONTACT<\/strong><\/p>\n Ian Bouyoucos<\/strong>\u00a0(Manitoba, CST)
\nE: ian.bouyoucos@umanitoba.ca<\/a><\/p>\n