Biodiversity and Biocomplexity of the Protists and an Overview of Their Significant Roles in Maintenance of Our Biosphere

Summary. The ubiquitous and very numerous protists, eukaryotic organisms mostly unicellular in structure and small in size, play numerous roles of importance that are often neglected or overlooked in biodiversity, biocomplexity, and conservation considerations of life on planet Earth. The present review article reminds readers, who hopefully include general biologists and other scientists as well as persons engaged directly in research activities that primarily involve solely protists (e.g. diverse studies on species belonging mainly to many individual groups of algae or protozoa), of such roles whether they be in areas directly or indirectly beneficial to human comfort and survival or in ones deleterious to our health and welfare. Matters become complex when multiple interactions are part of the overall picture (e.g. in food webs or in symbiotic relationships). Clearly, our far from complete knowledge of protistan taxonomic and phylogenetic interrelationships, as well as of their ecology, physiology, biochemistry, and molecular and evolutionary biology, hinders rapid progress in better understanding of their multiple roles in sustaining todayis biosphere.