Written by Anne Hay
UP Until a few years ago I had never heard of hooked barnacles (Lepas anatifera) but lately we’ve been seeing so many of these crustaceans on our local beaches that it’s hard to miss.
We’ve found it on beach trash like shoes, bottles, fish boxes, crates, buoys, and polystyrene. It seems they will attach to almost anything that floats on the sea. Before the age of plastics, they could only be found on ship hulls, ropes, driftwood, seaweed, and sometimes sea turtles. Recently, however, ocean litter has provided plenty for them to relate to.
Bowhead barnacles are strange-looking creatures. It has a white shell up to 5 cm long, consisting of five smooth plates and attached to hard surfaces by a fleshy stalk. The stalk can be up to 80 cm long, but is usually closer to 4-10 cm. It reminds me of cola gummy candies. This may seem like a strange association, but the stalk is soft, yet tough, and semi-transparent with a brown tint. The bowhead barnacle is a pelagic species, most often found in tropical and subtropical waters. It feeds by extending the feather-like structures of its shell which filters sea water and is effective at catching prey such as plankton.
How do they tie a ride
So how do they get from the open ocean to our shores? They are hermaphrodites and reproduce in warm waters by internal fertilization. Free-swimming larvae are released into the ocean and these larvae search for a surface to attach themselves to. Since our planet now contains so much ocean litter, this is often where they pick up. Then westerly storms and the North Atlantic drift current bring ocean debris with barnacles to our shores. Once washed, they are alive at first and their legs can be seen retracting and extending.
They do not survive in water for long periods, so unless they are transported back to the open ocean, they unfortunately die. When they are alive knowing what to do is always a dilemma. It’s counterintuitive to throw trash, even with barnacles, back into the sea. Chances are it will only wash up again, so unfortunately when we collect the trash if this barnacle is on something like a plastic bottle, I don’t put it back in the sea.
Ocean litter is an ongoing and significant environmental issue. According to IUCN (International Union for Conservation of Nature), an estimated 10 million tons of trash enter the world’s oceans each year and plastic makes up 80% of this. Consequences include entrapment and entanglement of wildlife, damage to habitat, transfer of non-native or invasive species from one area to another (delivery lifts) and ingestion of marine wildlife. Many of us have seen the horrifying images after whales died, with their open stomachs filled with plastic exposed. Even a study of bowhead barnacles found that 33.5% of them had ingested plastic in their digestive tracts. The effects of ingesting plastic for marine organisms may include blockage of the gastrointestinal tract, reduced feeding, altered hormone levels, and reduced ability to reproduce. What we see on our coast is only part of the problem. It is estimated that 70% of marine litter is on the sea floor, 15% is floating in the water column and 15% is what we can find and pick up from our shores.
If we don’t act, there will be more plastic in the ocean than fish by 2050. This is a terrifying prospect. Although we as members of the public have access to only a relatively small percentage of total ocean litter, by working together we can make a huge difference to the devastating plastic and litter on our coasts. It has been studied that in the first five years, 77% of the land that originated in the litter remains along the coastline. So if you’re looking for something good to do in 2023, visiting your local beach to remove trash and prevent deeper ocean pollution is on your list of good deeds. Various groups such as Clean Coasts (An Taisce), Flossie and Beach Cleaners, and the local Oceans Plastics Project run several initiatives throughout the year. It’s easy to join the 2-minute beach cleanup by Clean Coasts. You can look up these initiatives online, but if you don’t want to make things too complicated, simply removing, recycling, or safely disposing of five pieces of trash from the beach at a time will help. If more of us did this it would make a huge difference. If you don’t visit the coast often, you can also help by making sure your local river is free of litter. It is important to manage the litter in our waterways before it flows out to sea.
There are many innovative technologies and processes in development and early use that aim to reduce and remove plastic pollution from the oceans. In addition, stricter Irish government regulations apply for single-use plastic and producers of plastic packaging and fishing gear. By February 2024, a scheme for re-turning aluminum/steel packaging will be in place, details can be found at www.re-turn.ie.
It’s amazing to find these fuzzy barnacles that travel so long distances on our beaches associated with ocean litter. We can’t help but wonder how far they’ve traveled and where they’ve traveled. However, the moral of the story is that the trash they’re moving around in is a very serious problem and a sign that things need to change.
• Ann Haigh MVB MSc MRCVS Skibbereen resident, mother of two and veterinarian with a master’s degree in Wildlife Health and Conservation and passionate about biodiversity and nature