This is the first of a five-part series Changing Tides originally published by Carolina Public Press with support from the Pulitzer Center.
A small net dipped into a patch of grass submerged in shin-deep water near the edge of a salt marsh on the central North Carolina coast.
Retired National Oceanic and Atmospheric Administration scientist Jud Kenworthy of Beaufort lifted the net to reveal a colorfully striped juvenile pinfish, no bigger than a pinkie, among the strands of green and brown vegetation.
Pinfish are among dozens of fish species residing in estuaries for part of their lives, grazing on underwater grasses. Eventually, schools of the small fish, distinguished by a sharp dorsal fin, will spawn offshore in large groups and be hunted by predators: groupers, snappers and dolphins.
But the pinfish depends on the rich estuarine habitat that flourishes along the North Carolina coast — an ecosystem that relies heavily on a meadow of grass covered by 12 inches of salt water where land and sea merge. The threat of climate change to those seemingly mundane patches — which are seldom above water — is a threat to the entire oceanic ecosystem.
Indeed, the insidious impact of climate change on North Carolina’s coastal fisheries — the species in the water and the people who catch them, study them, sell them and eat them for dinner — may lie in murky meadows of submerged aquatic vegetation, or SAV.
The unnoticed foundation
Kenworthy anchored his small vessel in Back Sound, between Shackleford Banks and the mainland of Carteret County. The east end of the sound is framed by two barrier islands, separated by a narrow inlet, which meet at a 90-degree angle at Cape Lookout. The junction forms what looks like the apex of a tensioned slingshot, ready to blast its ammunition inland.
“North Carolina is at this unique biogeographic boundary,” said Kenworthy, a thunderhead bulging over the Atlantic Ocean behind him. “There are probably only two or three places in the world like this, where major ocean current systems overlap and collide.”
From Corolla to Calabash, a confluence of tropical water from the Gulf Stream blends with a countercurrent of chilly sea transported on the Labrador Current from the North Atlantic, nourishing the grasses.
The unique mingling of seawater yields expansive meadows of both tropical and cold-temperate marine grass species that permit a year-round supply of vegetation supporting one of the world’s most diverse ocean habitats.
Read more:: Lose the seagrass and lose the fisheries