The incidence and effects of ingested plastic in seabirds

This thesis comprises two major sections: an assessment of the incidence of plastic particles at sea and in seabirds {Chapters 1-3), and an investigation of the postulated effects of plastic ingestion on seabirds (Chapters 4-7). The incidence of plastic at sea was recorded from neuston trawls performed monthly at 120 sampling stations off the southwestern Cape, South Africa, during 1977-78. The types of plastic particles collected are described, and the temporal and spatial distribution patterns of plastic pollution are discussed. Ingested plastic was recorded from 36 of 60 seabird species sampled. The effect of different sampling techniques on the incidence of plastic is discussed. The frequencies of occurrence of plastic colour-types in birds are compared with those of particles collected at sea in neuston trawls. Pale particles were under-represented in all species, but the disparity was less for small than for large species, which may account for the higher incidence of ingested plastic in small than in large species