Research recently published in the journal Environmental Pollution sheds new light on the effects of microplastics (MPs) on freshwater microalgae, specifically Chlorella, throughout its entire life history. The detailed study by Leng Panchuan and colleagues from the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection at Chengdu University of Technology examines not only the immediate impact but also the potential long-term environmental risks posed by polystyrene (PS) microplastics of varying concentrations and sizes.
DOI: 10.1016/j.envpol.2024.123349
In this 2500-word article, we explore the groundbreaking findings of the study, their implications for aquatic ecosystems, and the critical need for a deeper understanding of microplastic pollution.
Microplastics have been recognized as one of the most pervasive and persistent pollutants in aquatic ecosystems. With particle sizes less than 5mm, these plastic fragments originate from a variety of sources including cosmetic products, clothing fibers, and the degradation of larger plastic waste. Once released into the environment, they pose challenges in remediation and are known to affect numerous aquatic organisms.
“For years we have known that microplastics can have negative effects on marine and freshwater species, but we have often lacked comprehensive research on the full scale of their impact, particularly on foundational organisms like microalgae,” explains Jing Liu, corresponding author of the study.
Chlorella, a genus of single-celled green algae, is an essential component of freshwater ecosystems. As a primary producer, it forms the base of many food chains and its health is indicative of the overall wellbeing of aquatic habitats.
The study performed by Panchuan’s team entailed exposing Chlorella to three different concentrations of polystyrene microplastics – 10, 50, and 100 mg/L – and three particle sizes – 0.1, 0.5, and 1 μm. By doing so, the researchers could observe the algae’s responses at various stages of its life history, from growth to reproduction, and the photosynthetic activity measured through chlorophyll fluorescence.
The study found that the smallest polystyrene particles (0.1 μm) inhibited the growth of Chlorella, suggesting toxic effects that could disrupt the algae’s ability to reproduce and survive. Conversely, the larger particles (0.5 and 1 μm) showed a promotional effect, enhancing the growth of Chlorella under certain concentrations.
“This is a fascinating outcome that raises more questions about the interaction between microplastics and algae,” says Yu Hao, one of the study’s authors. “Are larger particles less toxic, or could they be providing some kind of shelter or substrate for the algae to grow on?”
While the implications for Chlorella are concerning on their own, the study’s broader environmental significance cannot be overlooked. The responses observed in Chlorella could have cascading effects throughout the food web. Changes in primary producer populations and health can lead to shifts in species diversity and abundance, altering ecosystem functions.
“In scenarios where Chlorella growth is inhibited, organisms that rely on it for food could suffer, and this could lead to decreased biodiversity,” notes Wang Xin, another researcher involved in the study. “If larger particle sizes are promoting growth, it could lead to algal blooms, which have their own set of ecological consequences.”
The study by Leng Panchuan et al. highlights the complex nature of microplastic pollution and the need for comprehensive risk assessments that consider multiple pollutants’ physical characteristics and concentrations. These should also factor in the valence of impact — whether inhibitory or stimulatory — and the potential for acute and chronic effects.
“As policymakers and environmental managers look to address microplastic pollution, studies like ours provide necessary data to inform effective strategies,” says Li Dan, part of the research team. “We need to understand not just that microplastics are a problem, but how and why they are a problem across different ecological contexts.”
The research from Chengdu University of Technology offers crucial insights into the potentially dichotomous effects of microplastic pollution on aquatic primary producers like Chlorella. As microplastic research progresses, it’s clear that studies examining the full life history of affected species are vital to capturing the complexity of ecological interactions and assisting in the formulation of nuanced environmental protections.
While this study has brought us a step closer to understanding the enigmatic impacts of microplastics, it also underscores the urgency for further investigation and action to mitigate this invisible threat to freshwater systems globally.
The study referenced in this article is titled “Effects of different concentrations and particle sizes of microplastics on the full life history of freshwater Chlorella,” published in the Environmental Pollution journal. The DOI for this study is: 10.1016/j.envpol.2024.123349.
References
1. Leng Panchuan, et al. (2024). Effects of different concentrations and particle sizes of microplastics on the full life history of freshwater Chlorella. Environmental Pollution, 344, 123349.
2. Wright, S. L., & Kelly, F. J. (2017). Plastic and Human Health: A Micro Issue? Environmental Science & Technology, 51(12), 6634-6647.
3. Wang, J., et al. (2019). Microplastics in freshwater river sediments in Shanghai, China: A case study of risk assessment in mega-cities. Environmental Pollution, 250, 312-322.
4. Cole, M., et al. (2011). Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin, 62(12), 2588-2597.
5. Eerkes-Medrano, D., Thompson, R. C., & Aldridge, D. C. (2015). Microplastics in freshwater systems: A review of the emerging threats, identification of knowledge gaps and prioritisation of research needs. Water Research, 75, 63-82.
Keywords
1. Microplastics impact
2. Chlorella growth
3. Polystyrene microplastics
4. Aquatic ecosystem pollution
5. Freshwater microalgae study