Introduced alien species can escape into local ecosystems and become invasive.

Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive.

Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification.

Macroplastic and microplastic debris has accumulated in marine environments.

Study of the introduction of cane toads in Australia and one other local example of the introduction of an alien species.

Discussion of the trade-off between control of the malarial parasite and DDT pollution.

Case study of the impact of marine plastic debris on Laysan albatrosses and one other named species.

Analysis of data illustrating the causes and consequences of biomagnification.

Evaluation of eradication programmes and biological control as measures to reduce the impact of alien species.