< Previous | Contents | Next >
Challenging the Antarctic krill and other zooplankton with plastic beads that are about 20 microns or so in size has demonstrated that these microparticulates are readily ingested by these organisms. They appear to ingest the particles unselectively, and the ingestion rates depend on the concentration of particles in the environment.
Plastics are bio-inert and are not expected to be toxic to the animal in the conventional sense. While physical obstruction or indirect interference with physiology is always possible (as with sea birds showing satiation on ingesting plastics) the material will pass through the animal virtually unchanged.
The concern, however, is that plastics exposed to sea water tends to concentrate toxic and non-toxic organic compounds present in the sea water at low concentrations. These, including PCBs, DDT, and nonylphenols, have very high partition coefficients and are very efficiently concentrated in the plastic material.
Plastic-related distress to over 250 species has been documented worldwide. The focus has very much been on larger species in surface waters or beaches, despite the fact that 99 percent of marine species live in the benthos. The impact of negatively buoyant plastic waste (such as nylon net fragments) on benthic species has remained virtually unaddressed.
Despite years of interest on the topic little research has been carried out by the government agencies or the plastics industry to address the key issues relating to plastics in the marine environment.