Ecology of freshwater harmful euglenophytes: A review

Abstract

A diverse array of aquatic ecosystems are inhabited by the euglenophytes, a group of autotrophic and eukaryotic organisms. In inland waterbodies, the red bloom is caused by a rapid development or accumulation of euglenophytes. Recent studies have designated euglenophytes as bioindicator of organic pollution. The ecology of euglenophytes is influenced by the changes in the intensity of sunlight, temperature, nutrient cycles, and seasons. Most of the species of euglenophytes grow prolifically with the increase of water temperature. Nitrogen and phosphorus are often thought to be the main nutrients that influence the cellular growth of toxic euglenophytes. A high concentration of nutrients is required for the euglenophytes to grow and to form bloom. Heavy bloom of euglenophytes in the summer season is the characteristic of eutrophic ponds. Inland waterbodies in many countries suffer from euglenophyte blooms, which shade submerged vegetation, deplete the dissolved oxygen and disrupt the aquatic food webs. Dense bloom of euglenophytes clog the gills of fishes, cause breathing difficulties and in extreme cases results mortality. Red blooms of the deadly toxin producing Euglena sanguinea negatively affect the water quality resulting massive mortality of fishes. Consequently, aquaculture systems and fisheries are facing a serious threat from the predicted outbreak of toxic red blooms of euglenophytes worldwide. To ensure sustainability in the fisheries and aquaculture industry, it is essential to analyze the ecology of euglenophytes. Again, interesting research on euglenophycin, a Euglena-derived natural product, has shown that it can be utilized as a potential anti-cancer drug. This paper comes up with a thorough review of the latest research in this area, revealing new insights and solutions that can help mitigate the negative impact of the freshwater harmful euglenophytes. By implementing considerable management strategies, the health of the valuable aquatic ecosystems and the future of the aquaculture and fisheries can also be secured.