Giant Pacific garbage patch provides a deep-ocean home for coastal species

2023-04-18 08:49:39

A study of plastic debris collected in the North Pacific Subtropical Gyre, also known as the Great Pacific Garbage Patch, has revealed that litter provides a home to species not otherwise found in the depths of the ocean. More than two-thirds of the litter examined is home to coastal marine species, many of which are clearly breeding in what would otherwise be alien habitat. The findings suggest that, as far as coastal species were concerned, there was nothing inhospitable about the open ocean other than the lack of anything solid to hold on to. […]

Plastics, especially things like buoys, floats and nets, are often designed to withstand the harsh marine environment and could provide a stable home at the top of the water column. To find out if that was happening, the researchers collected more than 100 items of plastic debris from the North Pacific Subtropical Gyre in late 2018 or early 2019.

While some items could be assigned to Asian or North American origins, most were pretty generic. such as ropes and fishing nets. There was a wide variety of other items present, including bottles, boxes, buckets, and household items. Some had clearly eroded significantly since they were made, suggesting they had been in the ocean for years. Critically, almost all of them had creatures living on them.

Ninety-eight percent of the items found had some type of invertebrate living on them. In almost all cases, that included species found in the open ocean (just 95 percent of the plastic). But a handful had nothing but inshore species present. And more than two-thirds of the items had a mixed population of inshore and offshore species. Although open ocean species were found in more features, the researchers tended to find the same species repeatedly. In total, coastal species accounted for 80 percent of the 46 taxonomic richness represented by identified organisms. Significantly, the coastal species were reproducing. In several cases, the researchers were able to identify females carrying eggs; in others it was clear that the individuals present had a wide range of sizes, suggesting that they were at different stages of maturity.

“Something that caught the attention of the researchers was that the list of species present in the plastic of the North Pacific Subtropical Gyre was different from that found in the tsunami debris,” the report added. “Part of that may be because some items carried across the ocean by the tsunami, such as docks and ships, had already established coastal communities when they were lost at sea.”