New research suggests freshwater acidification caused by human activity could stint the growth of developing pink salmon.
Pink salmon generally start out their lives in freshwater, and if this environment has high levels of carbon (which leads to acidification) the young fish tend to be smaller and less likely to survive, the University of British Columbia reported. The study highlights the risks associated with freshwater acidification, and is the first to look at how rising carbon dioxide levels caused by climate change can affect fish living in these habitats.
"Most of the work on acidification has been in the ocean, yet 40 per cent of all fish are freshwater. We need to think about how carbon dioxide is affecting freshwater species," said Colin Brauner, a professor in the Department of Zoology at UBC. "We found that freshwater acidification affects pink salmon and may impact their ability to survive and ultimately return to their freshwater spawning grounds."
The study examined how baby pink salmon responded to fresh and ocean water with carbon levels that are predicted to exist 100 years in the future. The salmon were monitored for a period of 10 weeks, from the time they hatched until they were of an age at which they would migrate to ocean water if wild.
The scientists observed the salmon exposed to the high carbon levels were smaller than average, and their ability to smell the water was reduced; this could influence their ability to find their way back to their spawning grounds and to sense danger. When the salmon reached migrating age, they were also less able to used oxygen to exercise.
"The increase in carbon dioxide in water is actually quite small from a chemistry perspective so we didn't expect to see so many effects," said Michelle Ou, a former master's student who is the lead author of the study. "The growth, physiology and behavior of these developing pink salmon are very much influenced by these small changes."
The findings were published in a recent edition of the journal Nature Climate Change.
