Potential Use of Aquatic Vascular Plants to Control Cyanobacterial Blooms: A Review

Abstract

Intense “blooming” of cyanobacteria (blue-green algae) caused by eutrophication and climate change poses a serious threat to freshwater ecosystems and drinking water safety. Preventing the proliferation of cyanobacteria and reducing water nutrient load is a priority for the restoration of eutrophic water bodies. Aquatic plants play an important role in the function and structure of aquatic ecosystems, affecting the physiochemistry of the water and bottom sediments, primary production, and biotic interactions that support a balanced ecosystem. This review examines the inhibitory effect of aquatic vascular plants on harmful blooms of cyanobacteria. Aquatic plants are able to successfully inhibit the growth of cyanobacteria through various mechanisms, including by reducing nutrient and light availability, creating favorable conditions for the development of herbivorous zooplankton, and releasing allelopathic active substances (allelochemicals) with algicidal effect. Allelopathy is species-specific and therefore acts as one of the key mechanisms by which the development of cyanobacterial populations in aquatic ecosystems is regulated. However, allelopathic activity of aquatic vascular plants depends on various factors (species characteristics of aquatic plants, area, and density of overgrowth of water bodies, physiochemical properties of allelopathically active substances, hydrological and hydrochemical regimes, temperature, light intensity, etc.), which may regulate the impact of allelochemicals on algal communities. The paper also discusses some problematic aspects of using fast-growing species of aquatic vascular plants to control cyanobacterial blooms.

Interactions between Aquatic Plants and Cyanobacterial Blooms in Freshwater Reservoir Ecosystems

“…As light is one of the most important conditions for blue-green algae growth, the lack thereof can reduce or even prevent cyanobacterial blooms. The secretion of allelochemicals and increased densities of herbivorous zooplankton may also contribute to the decrease in algal abundance when floating-leaf plants and free-floating plants are dominant [15,96,97]. All the discussed interactions are good methods to fight against algal blooms, the intensity of which is also projected to increase due to climate change.…”

“…One of the known approaches to mitigate cyanobacterial blooms is biological control of such processes with the help of aquatic plants [15]. The interactions between aquatic plants and cyanobacterial blooms in freshwater ecosystems is displayed in the lowering of dissolved-nutrient concentrations, the synthesis and release of allelopathic compounds which control algal numbers.…”

“…The interest in such interactions is based on safer effect of macrophytes on other biota living in water as compared to chemical methods to control or reduce cyanobacterial blooms [16,17]. Many researchers [17][18][19][20] emphasize the importance of submerged plants in the biological control of cyanobacterial blooms and restoring water quality, while data on the role of other macrophytes, in particular floating-leaf plants and free-floating plants, in these processes are very controversial [15,19,21]. With this work, we wanted to test the hypothesis that floating-leaf plants and free-floating plants can inhibit or reduce the massive development of cyanobacteria in reservoirs regularly suffering from intense blooms of these organisms.…”

Design, Synthesis, and Mode of Action of Thioacetamide Derivatives as the Algicide Candidate Based on Active Substructure Splicing Strategy

“…These strategies primarily involve the use of physical, chemical, and biological methods. − Physical methods mainly include cyanobacteria salvage, ultrasound, and filtration, which can alleviate the occurrence of cyanobacterial blooms by controlling the number of algae in the water . Biological methods mainly include aquatic plant control, aquatic animal control, microbial control, and biological enzyme control methods, which can control the growth of algae through nutrient competition, degradation of microcystin, or guidance of algae eaters. , Although they can effectively control cyanobacterial blooms, they have the defects of high cost, long treatment time, and limited application water. , Chemical methods are widely used in the treatment of cyanobacterial blooms because of their low cost and quick effect. , However, existing chemical algicides have some limitations, such as poor selectivity, low safety, and a large amount of use. − Therefore, it is imperative to develop an efficient, safe, and specific algicide as a substitute for the current commercial algicide.…”

“…11 Biological methods mainly include aquatic plant control, aquatic animal control, microbial control, and biological enzyme control methods, which can control the growth of algae through nutrient competition, degradation of microcystin, or guidance of algae eaters. 12,13 Although they can effectively control cyanobacterial blooms, they have the defects of high cost, long treatment time, and limited application water. 14,15 Chemical methods are widely used in the treatment of cyanobacterial blooms because of their low cost and quick effect.…”