Humans are naturally curious about what washes up on the beach, from Asian tsunami debris to glass floats, shells, seaweed, and driftwood. When you delve below the surface, beach debris is plenty fascinating. Here are some things to know about flotsam and jetsam.
Log On, Log off
When we think “beach debris” we immediately think of man-made items from plastic bottles refrigerators washed up from Asia. But a lot of beach debris is natural and plays a surprisingly important role in life on the beach. For starters giant driftwood logs that fall into rivers, float out to sea, and eventually wash up on beach on a winter storm.
Big beach logs block windblown sand, which means that they help build beaches and stabilize the fronts of sand dunes. They serve as perching spots for eagles and herons, and provide housing for creatures from worms to mice, which have few other places to live on an open beach. These critters, in turn, attract other wildlife.
Wrack Me Momma Like The Wind And the Rain
Tidal wrack—the piles of kelp and seaweed that wash up with every high tide and storm—are the second category of natural beach debris. Wrack plays an equally important role, even if it stinks a fair bit when it rots on a hot day. Seaweed is incredibly nutritious, and big pile of it on the beach is a bonanza for birds, crabs, deer, and insects. The insects, like the “beach hopper” amphipods then become food for lizards, birds, and crabs. Birds and deer attract larger predators. Seaweed even nourishes land plants, by decomposing providing the soil with a rich package of nutrients. Where seaweed washes up frequently, the trees behind the beach have nearly double the rate of plant growth on land than on beaches without much tidal wrack.
Ocean currents and wind washes debris—both natural and man-made—toward certain spots while sparing a beach a few miles away. These hot spots are called “dispersion beaches”. This is a mixed blessing: lots of nutrients from wrack and driftwood, but a lot of garbage as well. The most famous dispersion beach is Kamilo Beach on Hawaii’s Big Island, where the Pacific Gyre brushes up against the Hawaiian chain. Kamilo Beach was tagged “the Dirtiest Beach in the World” by the BBC.
The same ocean currents that carry logs, seaweed, and garbage can transport invasive species. Anything that can survive a long ocean journey can become a potential invader that disrupts the ecosystem where it lands. Other invasive species, like Himalayan blackberry, Zebra Mussels, and Mitten Crabs, have gotten to North America by other ways, and with devastating effects. Concern about oceanborne invasives increased after the 2011 Japanese Tsunami. A year later, a large floating dock washed up on Agate Beach in Oregon, complete with many types of both Asian and North American life. Some unsavory characters may be hitchhiking in our direction.
One word: Plastics
Dustin Hoffman aside, plastics are one of the nastiest things we put in the ocean. Contrary to popular opinion, they don’t last forever, and that’s the problem. Floating in the ocean, a plastic drink bottle will degrade from sunlight, eventually becoming a series of very small particles that get swallowed by wildlife. 95% of Northern Fulmars, a northern subarctic arctic bird known for nesting in remote areas—had swallowed plastic, often amounting to 8.4% of their body weight. That’s the equivalent of a 200-pound human eating 17 pounds of plastic.
But even worse, plastic releases chemicals as it degrades, including nasty endocrine disruptors like Bisphenol-A and PDBEs. Once in the water column, these chemicals travel around the world, and have been found in the milk of Antarctic Orcas and the fatty tissues of polar bears, which eat seals, which eat fish, which ingest tiny bits of plastic.
Bad for Us, Too
The nasty chemicals in plastics don’t just end up in polar bears, seals, and orcas. They end up in us. People eat a lot of fish, and we tend to eat relatively large and long-lived fish, like tuna, halibut, and salmon. These large fish prey on smaller fish (which cumulatively eat a lot plastic) and during their long lives, they accumulate lots of plastic that’s absorbed into their flesh and remains in their fatty tissues. When we eat them we becomes the next step on the bioaccumulation chain.
We’ve Met the Enemy, and It Is Us
A walk on my nearby beach in Oregon gives a clue to why beach debris is such a challenge. Most of the trash didn’t wash ashore, and it’s not covered in Asian writing. It’s cigarette butts and plastic bags left by careless visitors. Like plastics, cigarettes also leach nasty chemicals as they degrade. We won’t solve the beach debris problem just by keeping the odd container from being swept off a ship somewhere out in the vast sea. It’s time to clean up our own act. Cleaner beaches ultimately start and end with you and I.