“Microplastic Pollution: Impact on the SF Bay Delta and Remediation Strategies” Symposium with Delta Stewardship Council and Coastal Marine Sciences Institute

By Miranda Bell-Tilcock

In May, I had the privilege of attending the Microplastic Pollution: Impact on the SF Bay Delta and Remediation Strategies symposium hosted by the Coastal Marine Sciences Institute (CMSI) and the Delta Stewardship Council (DSC). Microplastics are all over the news and have been found almost everywhere. They are defined as being plastic pollution that are generally smaller than 5mm a piece. When found in the environment, they are often incorporated into the foodwebs, either through filtration or consumption which can cause various issues for those animals that consume microplastics. 

This symposium was filled with a great series of talks that covered a wide range of the current issues in microplastics being researched. Talks described monitoring programs in different habitats, looked at specific ways that microplastics act as toxins and spread pathogens, and discussed frameworks for monitoring and managing the risks around this emerging issue. 

Below, I discuss a few of the studies that were presented about the effects of microplastics in the environment.

We kicked off the day with an incredible keynote presentation by Dr. Susanne Brander, Associate Professor at Oregon State University, co-lead of the Pacific Northwest Consortium on Plastics, and co-chair of the California Ocean Protection Council Science Advisory Team on Microplastics, and graduate of the UC Davis Toxicology graduate program. Her keynote talk was titled Everything Everywhere All at Once; and this pretty much sums up microplastics. She gave an overview of the field of microplastics research and how, initially, researchers thought it was just plastics from things like  bottles ending up inside of fish – but it is now realized to be so much more than that. Scientists are now realizing that there is evidence of small particles, from things like microfibers in our laundry, or from our tires and brake pads,  inside aquatic organisms. Most particles ingested by marine organisms tend to be microfibers (e.g., from our clothing) and not what we tend to think of when we think of microplastics (e.g., waterbottles, plastic beads,etc). Dr. Brander also discussed research gaps, such as how 95% of microplastics end up in soils and how more needs to be studied in the terrestrial environment in general, since most studies have been done in aquatic environments. Dr. Brander’s talk covered many more important elements that it’s impossible to cover in a single paragraph. Do make sure to check the recording linked at the end of this blog post to see more!

Another talk by Jenessa Gjeltema, UC Davis, discussed research that took place in Lake Tahoe, historically one of the most pristine bodies of water in California, but where there are growing concerns about plastics being found along the shoreline and throughout the lake. The main goal for this project is to provide baseline data for microplastics, evaluate seasonal trends, characterize the potential risks, and inform future research directions. The majority of the particles sampled were found on the surface of the water and in higher concentrations during the spring and summer seasons, during peak tourist season for lake activities. Future work will continue to study microplastic concentrations and the impacts on food webs. 

Another interesting talk was by Karen Shapiro, UC Davis, which focused on how plastic pollution can interact with pathogens and influence disease transmission. Dr. Shapiro described a laboratory experiment that focused on 3 pathogens: Cryptosporidium, Giardia, and Toxoplasma gondii that can be found in seafood and marine life. In this experiment, they looked at these pathogens in oysters and found that concentrations of the pathogens increased with coexposure to microplastics in the water. More concerning, there was evidence that the oysters might retain pathogens for longer periods of time when co-exposed to plastics in the water. These results were shared with caution as they were done in a controlled lab study and have not been tested in the field as of yet. Dr. Shapiro’s are currently working on getting funding to do this work in the field. 

Favorite fact of the day: while collecting samples for microplastics, samplers will wear hot pink. Since this is a color that is not a common microplastic color, it’s a way to check for sample contamination by identifying the hot pink fabric fibers that came from those who took the sample.

There was also a series of lightning-talks that covered various topics, titled:

“The toxicity of 6PPD-quinone, a tire-derived contaminant, to aquatic species of conservation concern” – Jackie Lang

“Determining the extent of microplastics infiltration into a protected marine environment” – Zeke Spooner (This is where the pink shirt photos came from!)

Accumulation of Microplastics in the Littoral-Shoreline: Analysis of Rock Rings, Shoreline Surface Water and Macrophytes” – Ashlyn Nance

All of this and more before lunch! All the talks were recorded and can be found on the CMSI website to see all the research not covered in this blog post. Information regarding events with CMSI can be found on the Events page of their website here. 

Further Reading

Ula Chrobak, 2024, The Problem with Microplastics, UC Davis Magazine

Katie Senft and Heather Segale, 2021, Big Problem in Tiny Pieces, TERC Microplastics Storymap

About the Author

Miranda Bell-Tilcock is the Deputy Director of the Center for Watershed Sciences (CWS). Prior to this position change, her research at CWS focused mainly on fish eye lenses and isotopes, such as Chinook Salmon eyes, to reconstruct their life history. Her work on fish eyes and isotopes was featured on National Public Radio’s Science Friday. Miranda enjoys hanging out with her three children when she’s not working, as well as baking bread and other tasty treats.