Project Results

Dear Funders,

 I am so thrilled to let you know that three years (almost to the day) after I finished my graduate program, I have a publication to share with you!  It took some grit, lots of perseverance, and a great deal of others coaching me through the process, but it was so important that I see this through, giving up was not an option. This being my first publication, there was a steep learning curve, and perhaps even more so because I was working outside of my field during the process. On that note, I am excited to also share that I am now working for a non-profit organization in Blue Hill, ME that studies marine environmental biology and the impact on human health, including microplastics. Both of these lovely life events occurred–as they tend to do– just when I thought they never would. 

Feel free to read the paper if you wish. As I mentioned, the learning curve was steep, and even now wish to high heaven I could still edit parts of it. But at worst, it is a little reminder of how we always continue to learn and grow. 

Thanks for being on this journey with me.

Sincerely,

Heather Richard

About This Project

I want to know how ocean bacteria and algae that live on plastic debris influence the toxins plastic picks up.

Plastic debris picks up chemical pollution like heavy metals, pesticides and flame retardants from the water. These are toxins which then could be transferred to marine life, and possibly the seafood we eat.

Plastic is colonized by bacteria and algae the minute it gets into the water, and these cells form a mucus film, similar to plaque on our teeth, called a biofilm. We know biofilms alter the way chemicals stick to sediment particles, but exactly how these organisms alter the way plastic debris attracts and accumulates chemical pollutants remains a mystery. We need to find out so we can make more informed estimates about plastic as a potential source of toxins for marine life.

Ask the Scientists

What is the context of this research?

The scientific literature on plastic marine debris is extensive, and can be classified into three categories; abundance and distribution, chemical interactions, and biologic interactions.

Two papers independently have suggested that there is over 250,000 tons of plastic in the world's oceans broken up into 5 trillion pieces.

We know this plastic collects persistent toxins like flame retardants, pesticides and heavy metals. Experiments have shown that these toxins can cause stress for marine organisms when ingested along with plastic particles.

Marine life readily colonizes and fouls plastic debris.

Almost nothing is known, however, about how biologic interactions such as colonization by bacteria and algae influence the behavior of chemicals attracted to and collected by plastic marine debris.

What is the significance of this project?

Understanding how fouling affects the toxins attracted to plastic will give us a better understanding about the significance of plastic as a vector for bringing toxins into the food web.

Colonization of plastic debris by microorganisms alters the affinity some chemicals have for plastic's surface. Fouling may make plastic a better place for heavy metals to collect because it decreases the surface hydrophobicity. Therefore, anything eating fouled plastic may get larger doses of lead and copper than uncolonized plastic.

However, most surfaces underwater are colonized by microbes, and experiments are needed to understand whether plastic is a significant source of these heavy metals, or if any surface prone to colonization by microbes will accumulate similar loads of heavy metals from the water.

What are the goals of the project?

The experiments I will perform have two aims, both of which will quantify metals and biofilms on beads less than 5mm in diameter.

First I want to know how natural biofilms change the way dissolved metals in seawater collect onto plastic debris. I have already performed bottle experiments using low density polyethylene (LDPE) in seawater with high and low field-relevant metal concentrations.

Second, I will deploy three different materials (glass, LDPE and biodegradable plastic) in two different locations of a metal contaminated bay to see how these patterns hold up over space and time. This second aim will act as a way to ground-truth bottle and laboratory experiments performed to clarify the driving mechanism behind the sorption of metals onto plastic debris.