Effects of Ocean Acidification on Fish

Ocean acidification is becoming a growing concern. Ocean acidification is caused by the uptake of CO2 from the atmosphere, decreasing the overall pH of the water. It is predicted that the acidity of the oceans could be about 150 times more acidic by the end of the century, showing a rate much faster than any rate seen in the last 20 million years. Clearly, this could be problematic on a number of levels, and even now the slight decline in pH has revealed changes in fish behavior as a result.

Scientists performed a study at naturally occurring CO2 seeps, where underwater volcanoes were releasing abnormally high amounts into the ocean. This scenario they hypothesized would be similar to the situation that may occur at the end of this century. In this area, the behavior of the fish was significantly impaired in a way that makes them more susceptible to predation. Fish in these areas were overall riskier and bolder; more attracted to scents they would usually avoid, and more prone to swimming out into the open. A promising observation was that the fish were not at all physically impaired and perfectly capable swimmers.

It will be interesting to see if over time the fish are able to adapt to these conditions. The fish studied were young and had lived on the reefs for months but still showed no signs of being able to adapt to these conditions psychologically. At first it was thought that fish would be able to deal with the increased acidity because when exposed to more acid they typically absorb it and produce more bicarbonate, a base, to counteract. Unfortunately increasing the bicarbonate is what is believed to be interfering with the neurological pathways.  It may take much longer than a lifetime for any sort of adaptation to occur. Time will tell if the fish will be able to adapt fast enough to cope with the increasing ocean acidity and what other effects ocean acidification will have on the underwater environment. 

Posted by: Morgan Matuszko (11)