Though the seas cover the majority of our planet's surface, far less is known about the biodiversity of marine environments then that of terrestrial systems (Ormond et al., 1997). Irish and Norse (1996) examined all 742 papers published in the journal Conservation Biology and found that only 5% focused on marine ecosystems and species, compared with 67% on terrestrial and 6% on freshwater. As a result of this disparity, marine conservation biology severely lags behind the terrestrial counterpart (Murphy and Duffus, 1996), and this gap of knowledge poses major problems for conservation of marine biodiversity and must be addressed.
This study shows that there is overwhelming evidence that plastic pollution is a threat to marine biodiversity, already at risk from overfishing, climate change and other forms of anthropogenic disturbance. So far however, that evidence is basically anecdotal. There is a need for more research (especially long term monitoring) to assess the actual threat posed by plastic debris to marine species. The research information would provide input for conservation management, strengthen the basis for educational campaigns, and also provide marine scientists with better evidence that could be used to demand from the authorities more effort to mitigate the problem. Due to the long life of plastics on marine ecosystems, it is imperative that severe measures are taken to address the problem at both international and national levels, since even if the production and disposal of plastics suddenly stopped, the existing debris would continue to harm marine life for many decades.