April 25, 2019 — Ocean acidification and warming may be an unhealthy combination for lobsters, say University of Maine scientists.
The heart rates of lobsters (Homarus americanus) who lived 60 days in water with predicted end-century ocean pH levels became erratic significantly sooner during an abrupt warming event than those of lobsters in ocean water with current pH levels.
The findings could be “likened to putting people on a treadmill and finding that people exposed to ocean acidification fell off the treadmill from exhaustion much sooner than those not exposed,” says Heather Hamlin, a reproductive endocrinologist and associate professor in the School of Marine Sciences.
The lobsters exposed to acidic ocean conditions also had fewer cells that fight infection in their hemolymph (similar to blood), says Amalia Harrington, a recent marine biology Ph.D. graduate.
So while lobsters in acidic ocean water may look and act normal, they experience physiological challenges when exposed to multiple stressors, says Hamlin.
She and Harrington tested adolescent female lobsters transitioning to adulthood. Effects of environmental stressors during this stage could have major impacts on the population of the species, say the researchers, who believe this is the first such study of its kind.
“We’re really trying to get at the ‘hidden’ impacts of climate change on this understudied but extremely important stage of the American lobster,” says Harrington.
“Most of the previous work exploring climate change impacts on American lobster has focused on early developmental stages (eggs and larvae). While this is helpful for understanding how environmental change might impact the number of baby lobsters that survive their time in the plankton and make it to the seafloor, it doesn’t really tell us what impact that will have on the population as a whole.”