About This Project

In this research project, we will use controlled biofouling experiments to quantify the progressive colonization of microplastics by microorganisms and the subsequent implications on their density, buoyancy, and aggregation with biogenic particles. Concurrently, we will use laboratory experiments on phytoplankton-zooplankton species pairs to investigate the consequences of aggregation of microplastics with phytoplankton on the uptake of microplastics by zooplankton.

Ask the Scientists

What is the context of this research?

Plastic particles are found in all marine and freshwater environments, including the polar regions and deep sea [1, 2]. It is estimated that over 20 million metric tons of plastics enter rivers, lakes, and oceans each year, a figure projected to reach 53 million metric tons by 2030 [3]. While all plastic particles pose a threat to the health of seawater and freshwater ecosystems, microplastics (< 5mm particles) are of particular concern [4] as they can easily interact with organisms and enter the food chain [5]. To understand the rate of uptake of microplastics (MPs) into the aquatic food web, we need to know (i) the abundance of MPs in seawater and freshwater, (ii) probability of encounter of MPs and aquatic organisms, and (iii) the impact of consumption of MPs by organisms.

What is the significance of this project?

Mitigating the impact of microplastics (MPs) on marine species relies essentially on the understanding of their large-scale transport, and their interaction with aquatic organisms at small scales. Aggregation of biofouled microplastics with phytoplankton and zooplankton (biogenic particles) creates a pathway for buoyant MPs to sink to deeper layers, and in some cases sequestration in sediments on the ocean floor. In addition, aggregation of MPs with biogenic particles can make them more bioavailable to microorganisms. This project is aimed at understanding the small-scale aggregation and consumption rates of MPs and will be integrated into our research program on understanding the fate of MPs in natural environments.

What are the goals of the project?

The first goal of this project is to quantify the impact of biofouling on the rate of aggregation of microplastics (MPs) with biogenic particles (BPs). The experiments will utilize multi-step milling process to produce MPs of desired shapes and sizes, followed by precise measurements of particle and aggregate sizes and surface charges. A high frame rate camera coupled with a laser enables rapid imaging of the evolution of particle aggregates. The second goal is to understand how zooplankton are directly affected by MPs when particles are ingested or egested or indirectly affected by MPs via their effects on phytoplankton. We will expose zooplankton to microplastics and aggregates similar to the ones used in the first part of the project.