The violet snail seen in the picture is also called raft snail because it stays on the water surface with an air cushion. This consists of a chitin membrane under which the snail collects air bubbles from the water surface. This “tire” of air above her makes her virtually invisible. Along with other passively swimming sea creatures (neustones) such as jellyfish, barnacles and crustaceans, the small snail relies on ocean currents for its transport. The animals are brought together by the whirlpool. So they can hunt, eat and mate.
A research team led by Fiona Chong from the University of Hull in Great Britain has now investigated the connection between the occurrence of such neuston organisms at the sea surface and the location of the growing garbage patch in the North Pacific. They followed the North Pacific Subtropical Gyre (NPSG) along a computer-calculated route to areas with high levels of litter. During the 80-day sailing expedition, researchers collected samples of plastic waste and animals.
The North Pacific Garbage Patch (NPGP) is the largest and most notorious of all marine garbage patches. Plastic waste from various regions of the Pacific collects in it. The researchers found out that this area is also a neglected convergence zone of neustones. These sea creatures also congregate in this complex habitat shaped by human waste. For example: The Janthina snail species need direct physical contact with their prey or their reproductive partners. Because of the bubbles that enable them to move, they are particularly dependent on sufficient space on the water surface. But this is denied them in the North Pacific garbage patch by the floating garbage.
“The ‘garbage patch’ is more than just a dump. It’s an ecosystem, not because of the plastic, but despite the plastic,” says co-author Rebecca Helm of Georgetown University in Washington DC. The scientists now aim to learn more about the temporal cycles and food webs of the neustones. The study also underscores the need to consider the ecosystem at sea’s surface when considering offshore industries and measures to reduce the garbage patch.