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Gooseneck barnacles are hermaphrodites that reproduce in warmer waters by internal fertilisation. Free-swimming larvae are released into the ocean and these larvae seek out a surface to attach to. Due to our planet now having so much ocean litter, this is frequently where they latch and end up on our shores. (Photo: Ann Haigh)

World - WILDLIFE: Nature’s hitch-hikers highlight growing coastal litter problems

UP until a few years ago I hadn’t heard of gooseneck barnacles (Lepas anatifera) but recently we’ve been seeing so many of these crustaceans on our local beaches that they are hard to miss.

Gooseneck barnacles are curious looking creatures. They have a white shell up to 5cm long, made up of five smooth plates and they attach to solid surfaces by a fleshy stalk. The stalk can be up to 80cm long, but is usually closer to 4-10 cm, it reminds me of cola bottle gummy sweets. This may seem a strange association but the stalk is soft, yet tough, and is semi-translucent with brown coloration. The gooseneck barnacle is a pelagic (open ocean) species, most often found in tropical and subtropical waters. They feed by extending feather-like structures from their shell which filter the sea water and are efficient at trapping prey such as plankton.

How they hitch a ride

So how do they move from the open ocean to our beaches? They are hermaphrodites that reproduce in warmer waters by internal fertilisation. Free-swimming larvae are released into the ocean and these larvae seek out a surface to attach to. Due to our planet now having so much ocean litter, this is frequently where they latch. Westerly gales and the current of the North Atlantic Drift then bring ocean debris with the barnacles on to our shores. Once they wash up, they are initially alive and their stalks can be seen retracting and extending.

Ocean litter

Ocean litter is an ongoing and major environmental issue. According to the IUCN (International Union for Conservation of Nature) an estimated 10m tonnes of litter enter the world’s oceans each year and plastic makes up 80% of this. Consequences include wildlife entrapment and entanglement, damage to habitats, transport of non-native or invasive species from one area to another (hitching lifts) and ingestion by marine wildlife. Many of us have seen the horrifying post-mortem photographs of whales, with their opened stomachs shown to be packed full of plastic. Even a study on gooseneck barnacles found that 33.5% of them had ingested plastic in their digestive system. The effects of eating plastic for marine creatures may include blockage of the digestive system, reduced feeding, altered hormone levels and reduced ability to reproduce. What we see on our coastline is only part of the problem. It’s estimated that 70% of marine litter is on the seabed, 15% is floating in the water column and 15% is what we can find and pick up from our beaches.

Pollution solutions

If we don’t act there will be more plastic in the ocean than fish by 2050. This is a horrifying prospect. Even though, as members of the public, we only have access to a relatively small percentage of the total ocean litter, by working together we can make a huge difference to the damaging plastic and litter on our coastlines. It’s been studied that for the first five years, 77% of land originated litter stays by the coast line. So, if you’re looking for something good to do in 2023, visiting your local beach to remove litter and prevent deeper ocean pollution is up there on the good deed list.

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