Carbon pollution could be turning the lakes more acidic. A lack of data has left scientists with more questions than answers.
By Tiffany Chen
Imagine diving into the shallow waters off the coast of Lake Michigan. You can see bare rocks and sand as you descend. Pinky-size spottail shiners swim by, shimmering in silver. When you reach the bottom, an indigenous yellow spotted molted sculpin is lying flat on its belly, flapping its boney fins like wings.
“That was at least 20 years ago,” said Harvey Bootsma, a freshwater scientist at the University of Wisconsin-Milwaukee, who has been studying Lake Michigan for decades. “Even though [the lake] may look similar on the surface to what it did 20 or 30 years ago, underneath the surface, it has changed a lot,” he said.
Mercury pollution has eroded the health of wildlife, while invasive mussels have gobbled up phytoplankton at the base of the food chain, clearing the water. However, there may be another potential danger brewing in the lakes: water acidification. Pollution from cars, planes, factories, farms and power plants is driving up the level of heat-trapping carbon dioxide. Some of that carbon dioxide is then dissolving into oceans and lakes, turning waters more acidic. “Based on the chemistry of the Great Lakes, they should be responding to the increase in atmospheric concentration of carbon dioxide,” Bootsma said.
Scientists have focused on ocean acidification, called “climate change’s evil twin,” while overlooking the acidification of lakes and rivers, so not much is known about what carbon pollution means for the Great Lakes. Research is sorely needed to determine how it might be impacting the creatures who inhabit the lake. The little scientists understand about acidification is cause for concern.
“We don’t have any evidence that acidification is doing anything harmful to the Great Lakes, but we do know that coral reefs are being harmed in the ocean,” Bootsma said. “Sometimes that ends up with the Great Lakes being a little bit neglected.” Because there is a surfeit of data on oceans and a paucity of data on lakes, the government tends to prioritize funding for research into ocean acidification over lake acidification.
Jennifer Day, regional coordinator for a 2010 NOAA plan to study the acidification of the Great Lakes, said that her team had trouble collecting research on the topic. “So far, it’s not really a problem, so no one’s really looking at [lake acidification]” she said. The 2010 plan was never implemented. NOAA recently began work on a new plan to study the acidification of the Great Lakes, but Bootsma doubts it addresses core research needs.
“The first need is just for the use of better instruments and for more continuous records,” he said. “That’s the only way we’re really going to understand the factors that affect the pH in the Great Lakes, and whether the pH is changing over the long term.” Several factors make it challenging to study lake acidification.