Marine Bacteria Colonization Rates on Microplastics in the North Pacific Subtropical Gyre

Abstract

Plastic pollution is a growing concern in the microecology of the oceans. Studying bacteria colonization rates on plastic provides one way of understanding of how toxic debris can move through the food chain through ingestion. This process of toxins moving through the food chain is called biomagnification and can eventually reach humans. To evaluate bacterial colonization rates, seawater was collected in coastal waters of Hawaii and near the Pacific garbage patch (GPGP). Seawater was intermixed with 5 different kinds of clean plastics then timed to determine how long it took bacteria to colonize the plastic surfaces. Bacteria on the plastic were counted under an epifluorescence microscope then divided by the time of colonization to determine the rate. Alongside the colonization rate, surface microplastics were collected with a manta net; then sized and classified with a dissection microscope. Seawater was collected from a Niskin bottle attached to a CTD rosette to calculate bacterial abundance with the use of a Guava flow cytometer. The findings of the research displayed little to no correlation between surface bacterial abundance and plastic density, with an R2 value of 0.1072. Bacteria were found to colonize plastics at 48 and 96 hours in the waters near the Pacific garbage patch with a rate of 7.4E+04 cells/mm. The colonization rates and plastic abundance support evidence of plastics being integrated into the ocean ecology.