The paper presents a conceptual model of the route of macroplastic debris (5 > mm) through a fluvial system, which can support future works on the overlooked processes of macroplastic storage and remobilization in rivers. We divided the macroplastic route into (1) input, (2) transport, (3) storage, (4) remobilization and (5) output phases. Phase 1 is mainly controlled by humans, phases 2–4 by fluvial processes, and phase 5 by both types of controls. We hypothesize that natural characteristics of fluvial systems and their modification by dam reservoirs and flood embankments construction are key controls on macroplastic storage and remobilization in rivers. The zone of macroplastic storage can be defined as a river floodplain inundated since the beginning of widespread disposal of plastic waste to the environment in the 1960s and remobilization zone as a part of the storage zone influenced by floodwaters and bank erosion. The amount of macroplastic in both zones can be estimated using data on the abundance of surface- and subsurface-stored macroplastic and the lateral and vertical extent of the zones. Our model creates the framework for estimation of how much plastic has accumulated in rivers and will be present in future riverscapes.

The diet and feeding behavior of South Polar Skuas (Stercorarius maccormicki) are well studied within the species' breeding range, but are poorly understood on the Haswell Islands. Goal: to establish how South Polar Skuas used the abundance of living resources of the Haswell Archipelago (66°31' S, 93°01' E, Davis Sea, Southern Ocean) under conditions of prolonged human activity. Methods: direct observations, study of pellets, spontaneous regurgitation and stomach contents of feathered birds. South Polar Skuas fed primarily on terrestrial resources. The dominant prey of skuas were vertebrates. Emperor Penguins (Aptenodytes forsteri) and Adélie Penguins (Pygoscelis adeliae) make up the bulk of the skuas’ diet in the pre-breeding and breeding periods. Surface feeding at sea was observed in the post-breeding period, when the availability of land-based food resources was reduced. Throughout history, kitchen waste supported the skuas population. Scavenging is the dominant strategy for obtaining food. Predation (primarily on Adélie Penguin eggs and chicks) is of minor importance. South Polar Skuas do not affect the breeding success of Emperor Penguins if they feed on frozen chicks and eggs in their colony. Skua predation influences breeding success of Adélie Penguins and fulmarine petrels, but the extent of the impact is unknown.