Jenny Greenleaf was happy that it was lastly heat sufficient to go barefoot when she and her husband took their common stroll alongside York seashore in Southern Maine this week.
However after they returned to their seashore chairs and commenced to brush the sand off their ft, they seen their usually pale soles had been a deep black.
“I’ve by no means seen something like this,” Ms. Greenleaf, a e-book designer and artist, mentioned. “It was virtually like I walked by way of charcoal.”
At residence they showered and scrubbed their ft, however the smudge, which was neither slick nor greasy, would solely partly come off.
Alongside Maine’s southern coast, in addition to in neighboring New Hampshire, many others had been additionally struggling to take away darkish stains from their ft.
“I nonetheless can’t get it off,” mentioned Kyra O’Donnell, who has had black ft since she visited Nice Island Widespread seashore in New Hampshire, about 14 miles south of York seashore, 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. Comparable studies 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 had been frequent ones. “In Hawaii, the sand can flip black from volcanic gasoline, however no volcanoes in Maine so it’s most likely one thing gross,” one man wrote in a neighborhood Fb group.
Ms. Greenleaf had a fringe idea, which even her personal husband scoffed at, that concerned a submarine she had seen within the space.
“Possibly that submarine belched out a cloud of nastiness,” she mentioned.
On Wednesday, Jim Britt, a spokesman for Maine’s Division of Agriculture, Conservation and Forestry, supplied the possible reply: Tens of millions of tiny black kelp flies that feed off decaying seaweed appeared to have died on one stretch of seashore.
“It’s not recognized why,” he mentioned. “Nature does loopy stuff. This may be a type of cases.”
The insect carcasses, which appeared to have washed ashore, include a naturally occurring pigment, he mentioned.
Efforts had been underway to determine the actual form 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 might be unhealthy for canines to eat them, a query that some had been asking on social media.
Linda Stathoplos, a retired Nationwide Oceanic and Atmospheric Administration oceanographer, did her personal casual examination of the sand on Wells Seaside in Southern Maine on Tuesday, accumulating a pattern and taking a look at it below a microscope.
“There have been tons and tons of little bugs, in regards to the measurement of a tip of a pin,” she mentioned. Some had two wings. Others had 4. “They had been undoubtedly all useless.”
She couldn’t bear in mind ever listening to a few related mass “mortality occasion” of flies.
Neither might Joseph Kelley, a marine geologist on the College of Maine. “I’ve labored on the geology of seashores for 40 years on the Maine coast and by no means seen something like this (or heard about it elsewhere),” he mentioned in an e-mail.
On Fb, seashore vacationers with tainted ft listed all of the methods they’d tried to get the stain off. Neither dish cleaning soap nor child wipes had been notably profitable.
Ms. Greenleaf inadvertently found a foot-cleaning answer throughout a subsequent stroll. She and her husband had returned to the seashore after a rain to search for clues. Though the search was fruitless, by the tip of their stroll the sand and stones had buffed the stains away.
“Our ft had been spotless,” she mentioned.