By Richard Gray
7 July 2015
(Daily Mail) – It has been found inside the digestive tracts of turtles, sea birds and whales, but it appears plastic litter in our oceans is also clogging up the insides of the tiny plankton that many larger sea creatures feed on.
For the first time copepods – tiny creatures that feed on algae in the ocean – have been filmed eating grains of plastic while they are feeding.
The video shows microscopic polystyrene beads being drawn towards the creature by its legs and eaten. The beads can be seen accumulating in the creature's body.
Normally copepods feed on certain species of algae using chemical and touch receptors to discriminate what they can eat and discard what they will not.
The video provides growing evidence that the volumes of plastic litter finding its way into the world's oceans is having a profound impact on wildlife and ecosystems.
An estimated eight million tons of plastic is dumped in the oceans every year, with fishing nets and plastic bags causing severe problems for some large species.
However, even after these have broken down – many plastic bags are designed to degrade in the environment into tiny scraps – they can still have an impact.
Dr Matthew Cole, a researcher at the Plymouth Marine Laboratory who has been researching the impact of so called 'microplastics' on marine ecosystems, said the impact of microplastics on plankton has been largely overlooked until recently.
Writing in the journal Environmental Science and Technology, he and his colleagues identified at least thirteen zooplankton creatures capable of ingesting a variety of different sized polystyrene beads.
These included the larvae of important marine animals like crabs and oysters. [more]
ABSTRACT: Small plastic detritus, termed “microplastics”, are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7–30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets laden with microplastics. We further observed microplastics adhered to the external carapace and appendages of exposed zooplankton. Exposure of the copepod Centropages typicus to natural assemblages of algae with and without microplastics showed that 7.3 μm microplastics (>4000 mL–1) significantly decreased algal feeding. Our findings imply that marine microplastic debris can negatively impact upon zooplankton function and health.