Recent Advances in the Ecology of Bloom-Forming Raphidiopsis (Cylindrospermopsis) raciborskii: Expansion in China, Intraspecific Heterogeneity and Critical Factors for Invasion.

ABSTRACT

Water blooms caused by the invasive cyanobacterium Raphidiopsis raciborskii occur in many reservoirs in the tropical and subtropical regions of China. In recent decades, this species has spread rapidly to temperate regions. Phenotypic plasticity and climate warming are thought to promote the worldwide dispersion of R. raciborskii. However, investigations into the genetic and phenotypic diversities of this species have revealed significant intraspecific heterogeneity. In particular, competition between R. raciborskii and Microcystis aeruginosa was highly strain dependent. Although the concept of an ecotype was proposed to explain the heterogeneity of R. raciborskii strains with different geographic origins, microevolution is more reasonable for understanding the coexistence of different phenotypes and genotypes in the same environment. It has been suggested that intraspecific heterogeneity derived from microevolution is a strong driving force for the expansion of R. raciborskii. Additionally, temperature, nutrient fluctuations, and grazer disturbance are critical environmental factors that affect the population establishment of R. raciborskii in new environments. The present review provides new insights into the ecological mechanisms underlying the invasion of R. raciborskii in Chinese freshwater ecosystems.