Low density microplastic debris is accumulating in ocean gyres
and pelagic invertebrates inhabiting these regions may be susceptible
tomicroplastic ingestion. In addition, the benthos is likely
to be a sink for high density microplastics. Some organisms may
have the capacity to egest microplastics, possibly leading to their
incorporation into marine aggregates. Benthic suspension- and
deposit- feeders are therefore likely to ingest sinking and sedimentary
microplastics. Fibres are the most commonly encountered
form of microplastics in the marine environment. Benthic
holothurians were found to selectively ingest microplastics,
showing a preference for fibrous shapes. Additionally, benthic
scavengers are susceptible to fibrous microplastic exposure, as gut
content analysis revealed nylon fibres in N. norvegicus. This implies
their habitat is a sink for fibres. Since shapemay play a role in
the toxicity of ingested microplastics e long, rod-shaped nanoparticles
are considered more toxic than spherules e these organisms
can be considered sensitive to the potential physical
toxicity of microplastics.
The presence of microplastics in myctophid fish and Hooker’s
sea lion and fur seal scats suggest microplastic transfer through
pelagic food chains: microplasticsezooplanktonemyctophid fish-
Hooker’s sea lions/fur seals. Such lower trophic organisms therefore
represent a vector for microplastic transfer and their associated
contaminants.
Microplastics may not only affect species at the organism-level;
they also have the capacity to modify population structure. Species
which were once restricted by a lack of hard substrate, such as the
marine insect H. Sericeus, are now able to proliferate. This may be
applicable to a wide range of organisms with potential impacts on
ecosystem dynamics.
The accumulation of microplastic debris has presented a new
marine habitat where biological interactions are taking place. This
habitat and its environmental impacts are still emerging areas of
research. It is hoped that future work on this growing issue (see
Table 3) will contribute to the development of better methods for
controlling marine litter.