plastic bits in fishes...
The bottom of Sydney Harbour has been contaminated by widespread microplastic pollution which could be entering the food chain, scientists say.
Professor Emma Johnston from the Sydney Institute of Marine Science said the microplastics, or fragments of plastic less than five millimetres long, represented the "emergence of new contaminants in our harbours and waterways".
In the first study of its kind, 27 sites were tested across the harbour, with researchers discovering up to 60 microplastics per 100 milligrams of sediment.
The environmental effects of the contaminants are largely unknown, but there have been moves to ban their use in products overseas.
Professor Johnston said some of the microplastic contamination was coming directly into the harbour.
There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.
Picture at top by Gus: Glebe, Sydney Harbour, Australia...