Jenny Greenleaf was happy that it was lastly heat sufficient to go barefoot when she and her husband took their common stroll alongside York seaside in Southern Maine this week.
But after they returned to their seaside chairs and commenced to brush the sand off their ft, they observed their usually pale soles have been a deep black.
“I’ve never seen anything like this,” Ms. Greenleaf, a e-book designer and artist, mentioned. “It was almost like I walked through charcoal.”
At residence they showered and scrubbed their ft, however the smudge, which was neither slick nor greasy, would solely partly come off.
Along Maine’s southern coast, in addition to in neighboring New Hampshire, many others have been additionally struggling to take away darkish stains from their ft.
“I still can’t get it off,” mentioned Kyra O’Donnell, who has had black ft since she visited Great Island Common seaside in New Hampshire, about 14 miles south of York seaside, on Sunday.
Robin Cogger, the director of Parks & Recreation within the city of York, mentioned she had fielded about 100 calls and emails about stained ft this week. Similar experiences on social media got here from as far south as Gloucester, Mass., and as far north as Wells, Maine, a span of greater than 70 miles.
Theories abounded. Algae and oil have been frequent ones. “In Hawaii, the sand can turn black from volcanic gas, but no volcanoes in Maine so it’s probably something gross,” one man wrote in a neighborhood Facebook group.
Ms. Greenleaf had a fringe idea, which even her personal husband scoffed at, that concerned a submarine she had seen within the space.
“Maybe that submarine belched out a cloud of nastiness,” she mentioned.
On Wednesday, Jim Britt, a spokesman for Maine’s Department of Agriculture, Conservation and Forestry, supplied the doubtless reply: Millions of tiny black kelp flies that feed off decaying seaweed appeared to have died on one stretch of seaside.
“It’s not known why,” he mentioned. “Nature does crazy stuff. This might be one of those instances.”
The insect carcasses, which appeared to have washed ashore, include a naturally occurring pigment, he mentioned.
Efforts have been underway to determine the actual type of kelp fly, which also needs to assist reply the place they got here from. Regardless, stepping on them doesn’t pose any well being points, Mr. Britt mentioned.
He couldn’t reply whether or not it could be dangerous for canine to eat them, a query that some have been asking on social media.
Linda Stathoplos, a retired National Oceanic and Atmospheric Administration oceanographer, did her personal casual examination of the sand on Wells Beach in Southern Maine on Tuesday, accumulating a pattern and it below a microscope.
“There were tons and tons of little bugs, about the size of a tip of a pin,” she mentioned. Some had two wings. Others had 4. “They were definitely all dead.”
She couldn’t bear in mind ever listening to a couple of comparable mass “mortality event” of flies.
Neither may Joseph Kelley, a marine geologist on the University of Maine. “I have worked on the geology of beaches for 40 years on the Maine coast and never seen anything like this (or heard about it elsewhere),” he mentioned in an e mail.
On Facebook, seaside vacationers with tainted ft listed all of the methods that they had tried to get the stain off. Neither dish cleaning soap nor child wipes have been notably profitable.
Ms. Greenleaf inadvertently found a foot-cleaning resolution throughout a subsequent stroll. She and her husband had returned to the seaside after a rain to search for clues. Although the search was fruitless, by the tip of their stroll the sand and stones had buffed the stains away.
“Our feet were spotless,” she mentioned.