The Examination of Microplastic Consumption by Zooplankton Collected in an Urban Estuary and a Pristine Antarctic Coastal System: Approaches, Challenges, and Outcomes

Microplastics, observed frequently in seawater, are emerging contaminants in the marine environment with the potential to enter the food chain. Smaller diameter plastics are of concern given the bioavailability to zooplankton that play a key role in potential transport of microplastics up to higher trophic levels. However, to determine potential plastic consumption by zooplankton in situ, a digestion procedure must be conducted to remove biological material to isolate the ingested microplastics. To date, there are only a few previously tested digestion protocols and this presentation will highlight the effectiveness and the challenges encountered using these approaches on different zooplankton collected from highly variable environments. Zooplankton samples of primarily copepods (Acartia tonsa)were recently collected inside and outside of frontal systems during both a low-flow and high-flow event in a highly urbanized estuary (Raritan Bay, NJ/NY, 2018-2019). Additionally, crystal krill (Euphausia crystallorophias) were collected during an austral summer 2018 cruise in the Ross Sea, Antarctica. The organisms were chemically digested using two methods, one with nitric acid and one using the enzymatic Proteinase-K technique. Methodological challenges include incomplete digestion that complicated both FTIR and Raman Spectroscopy analyses. However, we will present troubleshooting techniques employed that improved analyses and microplastic detection and put into context the potential ecological impacts of these findings.