The influence of active metabolites from the decomposition of camelina and barley straw on the development of phytoplankton from eutrophic freshwater ecosystem

As a result of human activities, surface waters worldwide are experiencing increasing levels of eutrophication, leading to more frequent occurrences of microalgae, including harmful algal blooms. We aimed to investigate the impact of decomposing camelina straw on mixed phytoplankton communities from eutrophic water bodies, comparing it to the effects of barley straw. The research was carried out in 15 aquaria (five of each type – containing no straw, camelina straw, and barley straw). The experiment lasted eight weeks, and the water used in the aquaria was sourced from an eutrophic reservoir. Our research revealed that the camelina straw had the most significant inhibitory effect on the growth of specific groups and species of phytoplankton (especially chrysophytes, potentially toxic cyanobacteria, and dinoflagellates). This inhibition was achieved by releasing polyphenols, primarily gallic and caffeic acids and flavonoids. Simultaneously, polyphenols promoted the growth of filamentous green algae. Our findings present novel data on the vulnerability of freshwater species and taxonomic groups of algae to the effects of camelina and barley straw exposure.