Coastal inhabitants such as crabs, mussels and barnacles seem to have found a way to survive in the open sea. According to a US study, they settle on plastic waste and, in this way, drift through the ocean. The phenomenon is regarded in marine biology as a paradigm change. Until now, the open sea was regarded as inhabitable for these organisms. A group of scientists from the Smithsonian Environmental Research Center (SERC) observed that the coastal inhabitants not only colonise the plastic waste, but many even flourish on it. How these new high-sea communities affect the eco-systems is to be the subject of further research.

 

The research team at the SERC, which has published its findings in the magazine Nature Communications, found species in the so-called Great Pacific garbage patch near Hawaii that are normally only found in coastal regions. The marine scientists suspect that the coastal inhabitants have travelled from the coast to the garbage patch via floating litter such as plastic nets, bottles or buoys. A similar development had already been observed following the earthquake and tsunami in Japan in 2011. At that time, scientists discovered that nearly 300 species from coastal regions had travelled across the Pacific on debris and, in this way, reached North America. The SERC research team under lead author Linsey Haram then made a thorough examination of the plastic components in the garbage patch off Hawaii. At that time, they were working with the Ocean Voyage Institute in Sausalito (USA), which had set itself the target of fishing some of the garbage out of the sea and recycling or disposing of it on land. A crew from the Ocean Voyage Institute collected 103 tons of litter from the garbage patch. Haram's team examined specimens from this in the laboratory and analysed which and how many creatures inhabited the plastic parts. They found that many coastal dwellers – including anemones and amphipods – survive on the marine plastic, grow on it, multiply and create colonies. The study thus shows, says Haram, that plastic litter offers coastal organisms a habitat where they also find food. How this works exactly still needs to be clarified in further studies. It was also unclear what the new symbiotic communities mean for the oceanic equilibrium. These new communities found in the middle of the ocean are described by scientists as "neopelagic" (neo = new, pelagic = relating to or living in or occurring in the open sea). When the neopelagic communities travel on the pieces of plastic like on rafts into new regions in which they settle in habitats without competition or natural predators, they could become an invasive species there and endanger the ecological balance, explains Haram. She said there were also already many indigenous species in the open ocean that settle on floating litter and would now have to compete for space and resources with the new arrivals. These interactions have also until now not been adequately researched.

 

More information: Study: „Emergence of a neopelagic community through the establishment of coastal species on the high seas““

 

Sources:

• forschung-und-wissen.de (Dec. 3, 2021)
• geo.de, spiegel.de (Dec. 12, 2021)
• Photo: © SERC Marine Invasions Lab