Ocean Acidification Masks The Smell Of Death

Posted on 23. Nov, 2009 by Ross in Climate Change, Oceania

Ocean acidification is the silent, unfashionable side-effect of climate change. With the world’s media focused on the prospect of more powerful storms, droughts, sea level rises and other meteorological phenomena, as well as the impact on humanity from lower quality of life through to climate refugees, what happens beneath the churning surface of the stormy seas seems of relatively little consequence.

However, the projected effects of ocean acidification upon the oceans and the animal populations within it are becoming increasingly bleak, with more and more research opening up new ways in which ocean acidification will decimate aquatic ecosystems and destroy the fish stocks upon which a huge percentage of the world rely on as a food source. The latest bad news: ocean acidification will destroy fish larvae’s ability to smell predators.

Ocean acidification is a result of carbon dioxide dissolving into the world’s oceans. All gases are soluble in water to greater or lesser extents, but when carbon dioxide dissolves it forms weak carbonic acid, lowering the pH of the water.

As the concentration of carbon dioxide increases in the atmosphere - a currently unstoppable trend as the world continues to use fossil fuels as the feedstock for its escalating industrialisation - the amount of carbon dioxide dissolved in the oceans also increases, resulting in further acidification.

According to the latest research published in Nature, the amount of anthropogenic (industrial) carbon dioxide acidifying the world’s oceans currently stands at around 150 billions tonnes - a third more than during the mid-1990’s. The good news for the oceans and bad news for the atmosphere is that the ability of the oceans to continue to soak up carbon dioxide may already be slowing, according to the same study.

Most of the established studies on the effects of ocean acidification have focused on coral reefs and zooplankton which form shells from calcium carbonate. Ocean acidification increases the solubility of carbonates, destroying existing coral reefs through a process known as ‘bleaching’ and preventing the formation of new corals as well.

The effects of ocean acidification are especially pronounced in the Southern Ocean, where the vast majority of anthropogenic carbon dioxide enters the world’s oceans. Entire ecosystems are expected to be destroyed by ocean acidification: Australian scientists declared last week that the Great Barrier Reef has only a 50% chance of survival if global carbon dioxide emissions weren’t reduced by at least 25% over the next decade.

Wake Up And Smell The Predators

However, the latest research from Danielle Dixson at James Cook University widens the net of aquatic ecosystem chaos across the whole world. According to her team’s latest publication in Ecology Letters, fish larvae lose the ability to smell predators when growing up in acidified water. The research, which involved testing the response of clown fish larvae to streams of water from predator fish and neutral fish populations, clearly displayed an inability of fish larvae raised in acidic water to detect predators by smell.

Such smell responses are the key survival behaviour of young fish, and the destruction of their ability to smell danger by growing up in an acidified ocean could potentially have cataclysmic effects upon fish stocks across the world. The North Atlantic is particularly at risk from such fish stock collapses from ocean acidification, since the greatest level of acidification has happened in those waters.

Other researchers have pointed out that Atlantic fish stocks are moving towards the poles as the waters begin to warm under climate change. This will force populations in the North Atlantic into more acidic waters, especially along the North America’s east coast where the ocean becomes more acidic the further north along the coast.

With populations all over the world dependant upon fish stocks as a vital part of their diet, this latest development in ocean acidification research threatens to massively increase the likelihood of climate change famines in the future if drastic steps aren’t taken now to reduce carbon dioxide emissions.

Image of a clown fish by wohnai @ Flickr