September 16, 2016

Microplastics

Microplastics

Approximately 275 million metric tons of plastic waste was generated by 192 coastal countries and 4.8 to 12.7 million tons entering the ocean in 2010 (Jambeck et al., 2015).  Perhaps the best-known source of plastic accumulation is the “Great Pacific Garbage Patch” that has often been featured in popular press accounts.  (Jambeck et al., 2015).  Reports of the “the worlds largest rubbish dump” in between California and Hawaii (Jambeck et al., 2015) are common.   Even though the media paints the picture of a giant landfill on the water, the reality is that most of it is below the surface, and mostly broken down into smaller pieces of plastic such as fishing line, styrofoam and wrappers from food waste (Jambeck et. al 2015). This swirling area is within the North Pacific subtropical gyre, one of many ocean gyres (Kaiser 2010).  Researchers have found plastics in our ocean, on our coral reefs and on our sandy beaches in varying sizes ranging from meters to micrometers (Barnes et. al 2009). These plastics break down into smaller pieces becoming microplastics, defined as pieces < 5mm (NOAA: 2008).

More than 50% of plastics are associated with hazardous monomers, additives and chemical byproducts (Lithner 2011). The main ingredient in PVC is carcinogenic and is what we use to transport our drinking water (Roachman 2014).  PBTs are found on plastic debris globally, bioaccumulate in food webs, and are linked with several adverse effects including endocrine disruption, decreased fish populations, and reduced species evenness and richness (Roachman 2014).

- Dorothy Horn, 2016

Student Research Highlights

Alumni Dorothy Horn

Dorothy Horn:

Pervasive Plastics: A New Challenge for Crabs and our Sandy Beach Ecosystem

Abstract:

Marine debris is an emerging global issue. Millions of tons of debris are added to marine and coastal systems annually with plastics a major component and of particular concern given their potential inherent toxicity, propensity to attract other pollutants, and tendency to degrade into more easily-ingestible microplastics (particles or fibers <5mm). Sandy beaches accumulate debris, exposing their abundant detritivorous and planktivorous infauna to a high microplastic ingestion risk. To assess this risk, we sampled sand from 51 beaches spanning >900 km of the California coast (northern San Francisco, to San Diego, including the California Channel Islands) and found microplastics (microfibers, micro beads, or plastic particles) present at every beach. We also sampled and dissected beach-dwelling Pacific sand crabs (Emerita analoga) from the same geographical area. Microplastics were present within the bodies of adult sand crabs from every sampled beach. In aggregate, 35% of all crabs examined had ingested microplastics with prevalence of ingested plastics at individual beaches ranging from 10-80%. Given these levels, microplastic ingestion may well lead to measurable sub-lethal effects on predator avoidance behavior, reproductive output, or other such crabs toxicity. Particulate feeders like these crabs provide a clear exposure pathway for plastic and daughter compounds to enter marine and coastal food webs.

Alumni Alex Ceja

Abstract:

The Southern California Bight is greatly diverse in number of species, variety of habitat, anthropogenic land use and levels of urbanization. Although there are strict environmental regulations in California, the coastal zone remains at risk from a number of environmental hazards. The effect that microplastic pollution has on the ecosystem is proving to be a force to be reckoned with (Van et al, 2011). Research shows that plankton are consuming plastic inadvertently (Cole et al, 2014). Recent findings suggest that a measurable portion of the Emerita analoga (Sand Crab) population is consuming plastic in Southern California. Considering that E. analoga  represents 90% of Amphistichus argenteus’ (Barred Surf Perch) diet, the purpose of this project is to analyze a sample of the A. argenteus population for microplastic in their gastrointestinal system (Carlisle et al, 1960). The primary focus of this project is to attempt to track plastic between trophic levels. The driving question for this project: Is A. argenteus ingesting plastic unintentionally due to its presence in their prey?

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