Mini-Grant: Microplastics in Delaware Bay
Microplastics—small pieces of plastic less than five millimeters long—are an emerging marine pollution issue with implications for the health of the ocean and aquatic species.
Through funding from Delaware Sea Grant (DESG), University of Delaware master's student Julie Steinberg has been working with DESG-funded scientist Jonathan Cohen to understand the distribution and concentration of microplastics in the Delaware Bay.
The researchers collected water samples from August to December 2016 at five pre-selected stations along the Delaware Bay off Cherry Island Landfill in Wilmington, Delaware; Bombay Hook, Bowers Beach and Broadkill Beach in central and southern Delaware; and in Cape May, New Jersey.
Steinberg used a density separator to extract the microplastics from the water samples, then analyzed the materials under a microscope.
“As you work, you remove a lot of different fibers and tiny plastics; most are invisible to the naked eye,” she said.
Early results indicate a higher concentration of microplastics in industrial areas near the bay, the majority of which were filaments. The scientists found higher concentrations of smaller microplastics (0.3–1 mm) at Cherry Island and Bombay Hook, but found that microplastics at Cherry Island were three times more likely to be 1–5 mm in size versus the smaller 0.3–1 mm size.
Study results will inform project partners at the Delaware Department of Natural Resources and Environmental Control (DNREC) who are developing a strategy to investigate the extent and implications of microplastics in the Delaware Bay, as well as state water quality regulators concerned about the potential impact for fisheries, including oysters.
Marine organisms like fish that rely on zooplankton as a nutrient can mistake marine plastics for food. Zooplankton also can ingest microplastics, raising important questions about biomagnification, the idea that microplastics can work their way up the food chain when zooplankton ingest microplastics, fish feed on zooplankton and humans consume fish.
“The impacts on human health are not fully studied or known,” Steinberg said.
There are environmental consequences too. Animals can ingest or become entangled in larger scale macroplastics. Plastic particles that are not ingested can degrade as they weather, potentially releasing toxic chemicals into the marine environment. They also can concentrate contaminants, such as organic
pollutants and metals and serve as vectors for these contaminants throughout the food web.
Of particular concern are microbeads, minuscule particles from 5 micrometers (less than the width of a human hair) to 1 millimeter in size. This summer, the scientists will conduct a bay-wide survey and create
a standard protocol for the sampling and identification of microplastics (50 μm–5 mm) in water and beach sediments.
Steinberg specifically is interested in understanding the role of policy in marine debris management in places where waterways are a shared resource between states. The Delaware Estuary is a prime example, shared between Delaware, Pennsylvania and New Jersey.
Investigators: Jonathan Cohen and Julie Steinberg — University of Delaware
Mini-Grant start date: September 1, 2016
Abstract: Microplastics are an emerging marine pollution issue with implications for the health of aquatic species including those harvested from Delaware Bay for human consumption (e.g., oysters). With a new mini-grant award, researchers are developing a standard operating procedure for the sampling and identification of microplastics in water and sediments to provide the first assessment of microplastic pollution in Delaware Bay. The results will be of immediate use to project partners at the Delaware Department of Natural Resources and Environmental Control (DNREC) as they explore strategies to investigate the extent and implications of microplastics in Delaware Bay.