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.

Harmful Cyanobacterial Blooms: Going beyond the “Green” to Monitor and Predict HCBs

“…On the other hand, during a bloom, the co-occurrence of different strains from a same species is also common, which makes it impossible to differentiate them exclusively using morphological features [88,118]. The phenotypic plasticity of some species (namely the invasive R. raciborskii and S. aphanizomenoides) can also correspond to intraspecific genetic heterogeneity even among strains from the same geographical origin [118,128], suggesting a microevolution that can provide these species an increasing expansion potential. These species-specific strains may diverse significantly in their ecological requirements and/or toxic potential [106,113,117,[129][130][131], with implications not only for the bloom development and dynamics, but also for the toxicity outcomes and health risks, depending on the ratio of non-toxic vs. toxic strains.…”

Early detection and the importance of environmental drivers for the invasive cyanobacterium Raphidiopsis raciborskii

“…As mentioned in the introduction, the invasion success of R. raciborskii in freshwaters has been attributed to its phenotypic plasticity and ability to survive under an extensive range of temperature, nutrient and light conditions, giving R. raciborskii competitive advantages over other bloomforming cyanobacteria (Zheng et al, 2023). Cyanobacterial blooms, in general, are favoured by the ratio of nitrogen to phosphorus (N:P ratio), dominating at low N:P ratio, usually below 16:1 (Huisman et al, 2018;Palus, 2015).…”