THE EFFECTS OF MICROPLASTIC INGESTION ON MARINE ZOOPLANKTON

Microplastic pollution in the oceans is increasingly becoming a concern as plastic ingestion by marine organisms receives increased media and research attention. This two-part study analyzed concentrations of two size classes of plastic pollution in the eastern equatorial Pacific and their potential effects on the smallest and most abundant organisms in the ocean, zooplankton. Various types of zooplankton were placed in plastic sampling bags with varying concentrations of microplastic beads and incubated overnight, then examined post-mortem for plastic beads in their gut. Our results reveal that gelatinous organisms are most at risk for ingestion of microplastic pieces due to indiscriminate filter-feeding habits regardless of plastic concentration. The highest densities of macroplastics (>335 µm) were found in the gyre. Filtration counts from surface sampling between Hawaii and the equator revealed microplastic concentrations dependent on the large current patterns present in the north Pacific Ocean with the highest concentrations observed in the North Equatorial Current (NEC). Our study indicates that plastic densities in oceanographic convergence zones pose the greatest ingestion risk for gelatinous organisms. These microplastics have an adverse effect on the trophic structure of marine communities. Further study of upwelling in the western Atlantic will have implications on the food chain and possibly related fishing and shell fish industries.