Any child’s chemistry set will show our oceans are becoming more acidic. It comes from the ocean’s absorbing increasing amounts of carbon dioxide caused by global burning of fossil fuels for energy.
The acids prevent shells and scales from growing on marine creatures. Now scientists have found the acidity also changes fish behavior.
The normal fish, they’re used to moving between the shaded and light parts of the kelp forest, For example, looking for food, or interacting with other fish. Ocean acidification affects their neurons in a way that maybe they feel more threatened and they prefer to stay more sheltered.
Martín Tresguerres is a marine biologist at the Scripps Institute of Oceanography in California. His team studied the brains of juvenile rockfish when they live in acidic waters. Rockfish have predictable behaviors, so it’s easier to detect changes.
When placed in a tank with one dark and one white wall, a rockfish exposed to corrosive waters stayed close to the dark wall, as did a fish that had been given an anxiety-inducing drug. That might not sound like a big deal, Tresguerres says, but it is.
Depending on the species, if they normally go offshore at a certain period of time, or they might go to a certain area to spawn and reproduce, it might affect the way they interact with other fish. So the potential implications are pretty big.
The behavior changes could eventually shift the entire ecosystem as any fish species is vulnerable to the increased corrosion. Study co-author Trevor Hamilton –What could end up happening is the fish will spend less time leaving their safe environments. So there is potential for them to get caught by less nets, essentially, and get eaten by less predators. So it could have an effect all the way up the food chain as well as for general fishing for humans.
Cold waters absorb carbon dioxide more quickly, meaning fish behaviors will change faster in Alaska. While stocks won’t vanish overnight, the researchers say fishermen and managers need to be aware of the threats from corrosive oceans. On a related note: An Australian study showed that increased acidity affected the sense of smell in clownfish.
Find more fish news and links at www.alaskafishradio.com
Laine Welch, Fish Radio, 11 August 2016. Text and audio.
The terminology used in the title of this media coverage is misleading. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7″. Despite the process of ocean acidification, the oceans are alkaline (pH higher than 7) and will not become acidic in the foreseeable future. Hence, the “acid” or “acidic” should not be used when referring to seawater. Note that there are few exceptions, seawater can be acidic in the immediate vicinity of CO2 vents or in purposeful perturbation experiments. See: https://news-oceanacidification-icc.org/2015/08/26/a-plea-to-ocean-acidification-scientists/