In a recent article published in the journal Scientific Reports, researchers have developed an innovative sensor integrated with a bioreactor for ultra-sensitive detection of hazardous contaminants, particularly those released from antifouling (AF) paints. The research aims to assess the impact of these contaminants on the photosynthetic activity of green microalgae, specifically Chlamydomonas reinhardtii, using advanced monitoring techniques.
The figure illustrates the advanced algae online monitoring system (Photon Systems Instruments, Drásov, Czech Republic). At its core is the modified measuring head, integrated with a flow-through cuvette, a peristaltic pump, and a fluorometer control unit. This configuration is shown connected to the photobioreactor, demonstrating the continuous and automated transfer of the algae culture to the measuring head. Image Credit: https://www.nature.com/articles/s41598-024-63631-6
Background
Studying the impact of hazardous contaminants from AF coatings on microalgae is crucial due to the escalating environmental concerns associated with these coatings. AF coatings, commonly used in marine applications to prevent biofouling on submerged structures, often contain toxic compounds like copper and zinc that can leach into aquatic ecosystems, posing risks to marine life and biodiversity.
Microalgae, such as C. reinhardtii, serve as fundamental components of aquatic food chains and ecosystem health indicators. However, the presence of hazardous contaminants, such as those found in AF paints, can significantly affect algae's physiological processes. Understanding algae's stress response to these contaminants is essential for sustainable aquaculture practices.
The Current Study
In this study, C. reinhardtii cultures were acclimated under controlled laboratory conditions prior to experimentation. The algae were grown in a standard culture medium supplemented with appropriate nutrients and maintained at optimal temperature and light conditions to ensure healthy growth and physiological activity.
Four different types of AF coatings, designated AF1, AF2, AF3, and AF4, were selected for the study. These coatings contained copper oxide and zineb as primary biocides. Algal cultures were exposed to the AF coatings in separate experimental setups to assess the impact of hazardous contaminants on photosynthetic activity.
Non-invasive chlorophyll fluorescence measurements were conducted using an advanced monitoring system equipped with an ultra-sensitive sensor. The system allowed for real-time monitoring of fluorescence dynamics in response to AF coatings. Flash-induced chlorophyll fluorescence was utilized to evaluate the photosynthetic activity of C. reinhardtii under varying concentrations of biocides.
The toxicity of hazardous contaminants released from the AF coatings was determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). This analytical technique enabled the quantification of copper, zinc, and iron concentrations in algal cells exposed to the AF coatings, providing insights into bioaccumulation and potential toxic effects.
Statistical analysis of the data was performed using Origin Professional software, with the Fisher test employed to determine significant differences in fluorescence decay kinetics between algal cultures exposed to different AF coatings. This rigorous statistical approach ensured the reliability and validity of the experimental results.
Data on fluorescence dynamics, element bioaccumulation, and photosynthetic activity were collected at regular intervals throughout the experimental period. The obtained data was analyzed using appropriate statistical methods and compared to control samples to assess the impact of AF coatings on algal physiology.
Results and Discussion
Non-invasive chlorophyll fluorescence measurements showed significant changes in the photosynthetic activity of C. reinhardtii following exposure to different antifouling (AF) coatings. Within the first hour post-exposure, a marked decrease in photosynthetic efficiency was noted, as evidenced by the reduced maximum quantum yield of primary photochemistry (FV/FM).
This rapid decline suggests that the biocides in the AF coatings directly affect the photosynthetic machinery of the algae. Although a partial recovery in FV/FM values was later observed, they remained significantly lower than those in the control samples. These results highlight the algae's sensitivity to the toxic effects of AF coatings and illustrate the dynamic nature of photosynthetic responses to environmental stressors.
ICP-OES analysis further confirmed the bioaccumulation of copper, zinc, and iron in the algal cells exposed to the AF coatings. The levels of copper and zinc varied among the coatings, with AF1 showing higher concentrations than AF4. Iron also showed signs of bioaccumulation, though its levels were consistent across different coatings. These findings suggest that the algae absorb and accumulate toxic elements from the AF coatings, which could lead to physiological disruptions and stress responses at the cellular level.
The noted inhibitory effects on photosynthesis and the bioaccumulation of hazardous elements have significant implications for aquatic ecology and sustainable aquaculture practices.
Understanding how microalgae respond to environmental contaminants like those in AF coatings is vital for reducing their adverse effects on aquatic ecosystems. This study provides crucial insights into the toxic mechanisms of AF coatings on algae and emphasizes the need to refine these formulations to minimize ecological damage.
Conclusion
The use of ultra-sensitive sensors and fluorescence decay analysis in advanced monitoring techniques has offered valuable insights into how hazardous contaminants affect microalgae photosynthesis.
This study highlights the need to refine antifouling (AF) coating formulations to reduce their ecological impacts and support sustainable aquaculture. Further research is necessary to improve bioreactor scalability and deepen our understanding of how algae respond to environmental stressors.
Journal Reference
Orzechowska, A., Czaderna-Lekka, A., Trtílek, M. et al. (2024). Novel technique for the ultra-sensitive detection of hazardous contaminants using an innovative sensor integrated with a bioreactor. Scientific Reports 14, 12836. https://doi.org/10.1038/s41598-024-63631-6, https://www.nature.com/articles/s41598-024-63631-6