A car door slammed on South Reeds Beach Road, and 300 feeding shorebirds - ruddy turnstones, sandpipers, and red knots - took wing, shrieking out over the Delaware Bay.
The commotion caught the attention of Rutgers University biologist Joanna Burger. She rose from the nearby bulkhead where she was monitoring an experiment, and started walking over.
All seemed calm on this Middle Township beach in Cape May County. And yet there is growing tension here between economics and ecology, conservationist and oyster farmer.
Oyster growers, buoyed by the state's decision last month expanding the oystering zone, are seeking to rebuild an industry that once flourished for miles along the bay's eastern shore.
But conservationists and ornithologists fear the noise and bustle of oyster aquaculture - power-washing shells at low tide, all-terrain vehicles, and hundreds of steel racks in the intertidal zone - will disrupt the threatened red knot's brief but crucial feeding time here.
"I think it would be great for the local economy if [oyster] aquaculture returns," Burger said. She is studying the movements of horseshoe crabs, whose eggs the red knot eats.
By now, the startled birds had circled around and were alighting again among the hundreds of horseshoe crabs crawling at the water's edge. "But as scientists," Burger said, "we need to understand its impact."
The tide was high this afternoon. About a third of the alighting birds were the robin-size red knots, which fly 9,300 miles each spring from the tip of South America to their summer habitat in the Arctic, returning south in the fall.
Theirs is one of the longest annual migrations of any species on earth, and the fatty eggs of the horseshoe crab they find here are, for many, their only food. Those that do not gain enough weight will die on the remainder of their journey, or arrive too weak to reproduce.
The U.S. Division of Fish and Wildlife last year declared them "threatened" and in need of protection.
Oyster aquaculturists want to study the impact of their operations as they expand them. Environmental groups want to see oyster farming scaled back while scientists study it.
"The U.S. Division of Fish and Wildlife has determined that these activities do not threaten the survival of the species," said David Bushek, director of Rutgers' Haskin Shellfish Research Laboratory in Port Norris.
"There's a bit of exaggeration about the dangers" of aquaculture, he said.
But environmentalists are incensed that the state last month added about 150 acres to the permitted zone for potential oystering - up from the current 10 - along the mudflats where the knots feed.
The "action areas" now extend north for nearly seven miles from Fishing Creek to Bidwell Creek, both in Middle Township. State officials say it could be a decade before most of it is leased.
"A lot of this [oyster aquaculture] is being pushed by the Rutgers Extension Service," said Tim Dillingham, director of the American Littoral Society, on a visit last week to Pierce's Point Beach. It's about three miles south of Reeds Beach, where Burger has created artificial reefs and replicated a small oyster farm to study their effects on horseshoe crabs' movements.
On Pierce's Point Beach, biologists, ornithologists, and two dozen volunteers were helping to tag and weigh 200 newly captured shorebirds to monitor their migratory habits.
The Littoral Society, headquartered in North Jersey, played a key role in paying to restore the red knot's ravaged habitat, through beach replenishment, after Sandy.
"But now they [proponents of oyster farming] see all this sand," Dillingham said, gesturing to the birds and crabs crowding Pierce's Point, "as a nice habitat for aquaculture."
"Nice" did not precisely capture the feel of the southwest wind shrieking Monday afternoon across the mudflats of North Norbury Beach, where it sent Gustavo Calvo's orange rain jacket flapping hard.
"We've been here three years," shouted Calvo, the Uruguayan-born owner of Sweet Amalia Oyster Farm.
Around him and his older brother Wolfgang and employee Pablo Arcier, hundreds of steel racks stood low above the sand. Most were laden with open-mesh black bags containing dozens of craggy-shelled gray oysters of varying sizes.
This is his "farm," which begins 100 yards offshore and extends west farther into the water. It comes into view for about three hours twice each day, at low tide.
"We grow about 200,000 oysters a year," said Calvo, 58, but only 75,000 survive to maturity. His patrons, he said, include the restaurants Fork and Oyster House in Philadelphia.
Far to the south, eight employees of Atlantic Capes Fisheries were working their racks. Two were moving slowly on ATVs, and two were using power washers to blast potentially suffocating mud from the encased shells.
Waves churned white in the distant west, held at bay by the flats. Onshore to the east, a few dozen sanderlings and laughing gulls picked at drying seaweed. Behind them, a vast cove of marsh grass, surrounded by barren trees, shuddered in the wind.
Conspicuously absent were the red knots and horseshoe crabs that had so densely packed Reeds Beach and Pierce's Point Beach the week before.
"They come out at high tide," said Calvo, a professional marine scientist.
He "welcomes" scientists' studying the impact of oyster farming on the red knots' feeding habits and the horseshoe crabs' movements, he said. "But I don't think we're a problem," he said, gesturing to the empty shore.
Brian Harman, aquaculturist at Atlantic Capes Fisheries, the state's largest oyster operation, also defended the farming as ecologically noninvasive.
"We don't use pesticides, fertilizers, or food," he said. Oyster farming, Harman said, "is the greenest there is."
Advocates for the red knots remain skeptical, however, and some allege that the state Department of Environmental Protection has been unduly influenced by the political and financial muscle of the burgeoning oyster industry.
"The department [DEP] has a dual role," said Lawrence Niles, a wildlife biologist who was attaching tiny radio beacons last week to captured red knots on Pierce's Point.
"They're supposed to protect endangered species like this," said Niles, gesturing to the squirming bird gripped gently in his left hand. "And at the same time they're promoting the expansion of aquaculture. So there can be a conflict of interest."
Larry Hajna, spokesman for the DEP, defended its decision to expand the area for oyster farming. The new acreage won't be leased, he said, if it appears oystering would adversely affect the shorebird habitat.
"We're trying to play Solomon," Hajna said.
Lisa Calvo, an aquaculture program coordinator at the Haskin Shellfish Research Laboratory and an oyster farmer with her husband, Gustavo, defended the DEP's expansion.
"From our perspective, it's a relatively small area," she said, scoffing at claims the oyster industry has undue political clout in Trenton.
"The Sierra Club has 60,000 members," she said. "We're eight growers."
Just about everyone agrees, however, that scientific study of oyster farming's impact on the red knot is essential. "We've worked years to save them," Burger said. "Now we need to know if there's a new threat."