Lost at sea

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1. Summary

Fish, during the course of evolution, developed a sophisticated instinct that allows them to orient themselves in the vast ocean and find the way home simply by listening to its sound. However, the effects of human-induced ocean acidification put this delicate process at risk and could ultimately leave fish lost at sea

2. Description

Most fish, long before being caught and end up on our dinner plate, hatch from a small egg and spend the first part of their life drifting in the ocean as small and vulnerable babies. These baby fish, when ready, go on an incredible journey that takes them from the open ocean to the reef; the place where grown-up fish live. Baby fish know by instinct that if they listen carefully and follow the sounds coming from the reef they can find their way even from a long distance.  Unfortunately for fish, the chemistry of the ocean is changing rapidly and this could put their survival at risk. Humans, mostly by intensively burning fossil fuels, are emitting in the atmosphere incredibly large amounts of CO2. About a third of this CO2 dissolves in the ocean, and via a series of chemical reactions, commonly referred as ocean acidification, is making the ocean more acidic. This is a problem for fish because ocean acidification can interfere with the functioning of their brain and change their behaviour in striking ways. During my PhD I discovered that baby Barramundi and Mulloway, when exposed to ocean acidification levels expected by the end of the century, get disoriented and instead of being attracted to the sound of their adulthood habitat as they should, go in the opposite direction. This means that if we continue to burn fossil fuels as usual we could put baby fish in serious trouble ultimately leaving them lost in a silent and acidified ocean. This is bad news for us too because if baby fish cannot make it to their adulthood habitats we will have no fish to catch on our coasts and an empty dinner plate. The good news is that we are still in time to limit our CO2 emissions to levels that are not too dangerous for marine animals. However, we have no time to waste and need to act now.

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For more information regarding my research please use the links below



3. Additional Details

This research was conducted as part of my PhD at University of Adelaide under the supervision of Ivan Nagelkerken and Sean Connell.

Acknowledgements: P.L. Munday, S.D. Simpson, J.C.A. Pistevos, S-A. Watson, L. Merillet

Funding provided by ARC 



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I am a marine biologist studying the effects of ocean acidification on fish behaviour, with a particular focus on sound-driven orientation. The overarching goal of my PhD is elucidating how ocean a...