LIFE

Debris from the sea critical to beach ecosystems

KEVIN LOLLAR

KLOLLAR@NEWS-PRESS.COM

Shells can be found in a wrack line. It also holds seagrass, algae and foliage from the area as well as seed pods from other countries.

On the beach at Estero Island's Newton Park, a dead snook lay among other beach debris — shells, seagrass, sponges, drift algae, mangrove propagules, bird feathers, drift wood, even a baseball-size lump of horse dung.

When debris accumulates on a beach to form a line, it's called a wrack line; it might be unattractive to some people, but it is environmentally important.

Pointing at the snook, Keith Laakkonen, environmental sciences coordinator for Fort Myers Beach, said:

"That's something interesting for the wrack line. It's the cycle of life. All this stuff that washes in is the basis of the beach ecosystem. It supplies nutrients, food, places for things to hide. It's a seed source for dune and beach vegetation."

Wrack lines are so important that the city of Fort Myers Beach prohibits removing them except under special circumstances, such as excessive accumulation of debris caused by red tide, drift algal blooms or storms.

Some treasures that can be found in the wrack line include feathers like this one from a roseate spoonbill found on the end of Fort Myers Beach at San Carlos Pass.

Sanibel officials also leave the wrack line alone as much as possible, said James Evans, the city's natural resources director.

"A moderate amount of algae and other species in the wrack line is healthy," he said. "It provides important foraging opportunities for birds and other species; it's habitat for crabs and things that other things feed on. So we only clean the beach in emergency situations when algae or other species impacts the ecology of the beach or if there are human health concerns."

Anybody who's been to a beach has seen a wrack line: Simply put, debris (called wrack) comes in on a rising tide and and forms a line on the beach when the tide goes out.

Shell collectors, of course, know about wrack lines — though they might not know the phrase "wrack line" — because that's where shells pile up.

While Lee County's famous shelling brings collectors to the beach, shells that don't end up in a collection are important, too, because they break down and help build the beach.

Overlooked in the wrack line by many beachcombers are sea-beans, also known as drift seeds, which are seeds and fruits, including coconuts, that wash onto beaches.

Skimmers and shorebirds including marbled godwits loaf on the shorline at the south end of Fort Myers Beach at Big Carlos Pass. The birds are just below the wrack line. The line is filled with organic debris left on the high tide line. Treasures can be found such as seed pods from other countries. It also holds food for migrating and local birds. The skimmmers won't feed on the material but godwits and sand pipers will.

At Newton Park, Laakkonen found two sea-beans, a nickerbean seed, which looked like a tiny, very hard football, and a coin vine seed, which looked kind of like a beat-up coin.

"We get sea-beans floating in from Africa and the Caribbean," Laakkonen said. "A lot of people collect them. They take it very seriously. They even put on shows."

In fact, the 19th Annual Sea-Bean Symposium will be held Oct. 17 and 18 in Cocoa Beach.

Sometimes the beach at Newton Park has an extensive wrack line, but this was what Laakkonen called a "really slow wrack day" with sporadic patches of debris and little wildlife activity.

So he drove to Carlos Point at the south end of the island, where a long continuous wrack line attracted hundreds of shorebirds, including sanderlings, semipalmated sandpipers, dowitchers, godwits and juvenile black skimmers.

Some treasures that can be found in the wrack line include feathers like this one from a roseate spoonbill on the end of Fort Myers Beach at San Carlos Pass.

"The wrack line is critical for shorebirds, especially species with very long-distance migrations," Laakkonen said. "For example, red knots fly from Tierra del Fuego at the south end of South America to the arctic to breed. When they land, they need to feed and put fuel and fat on their bodies. The wrack line is like a seafood buffet for migrating shorebirds.

In addition to natural wrack, Laakkonen found fishing gear and small strips of plastic in the wrack line at Carlos Point.

"Wrack gives us a glimpse of what's going on out in the ocean," he said. "Unfortunately, other things we find in the wrack are evidence of what we're dumping in the ocean. No matter how clean we keep the beach, there's always trash washing in from offshore."