Little is still known about the effects of microplastics on marine organisms. The Geomar team decided to use mussels for its long-time laboratory trial because they are commonly found in coastal eco-systems. These mussels would unavoidably take up microplastic particles when they filter the seawater to feed. The team, led by Thea Hamm, the lead author of the publication of the results in "Science of the Total Environment", exposed juvenile blue mussels for 42 weeks to microplastics in different concentrations. This is claimed to be the longest ever such laboratory study on mussels. The concentrations in the test tanks corresponded to those that can actually be measured in the environment. Different shapes and sizes of particles were also tested: spherical particles as are used, for example, in cosmetics, as well as irregularly shaped particles as are produced when larger plastic articles decompose.

 

During the testing period, various parameters relating to the condition of the mussels, such as growth rate, were measured. According to the authors, negative effects on mussel performance did not emerge until late in the experiment and were also fairly weak. Overall, the results indicate that microplastic particles do not represent a threat for the mussel population. This is not, however, intended to serve as an “all-clear signal”, says Thea Hamm, because other species could possibly react differently. For this, more such long-term experiments were needed.

 

From the article: "Negative impacts of realistic doses of spherical and irregular microplastics emerged late during a 42 weeks-long exposure experiment with blue mussels"

 

Sources:

• geomar.de (12.4.2021)
• Photo: © Geomar / Thea Hamm