What drives the distribution of the bloom-forming cyanobacteria Planktothrix agardhii and Cylindrospermopsis raciborskii?

Abstract

The cyanobacteria Planktothrix agardhii and Cylindrospermopsis raciborskii are bloom-forming species common in eutrophic freshwaters. These filamentous species share certain physiological traits which imply that they might flourish under similar environmental conditions. We compared the distribution of the two species in a large database (940 samples) covering different climatic regions and the Northern and Southern hemispheres, and carried out laboratory experiments to compare their morphological and physiological responses. The environmental ranges of the two species overlapped with respect to temperature, light and total phosphorus (TP); however, they responded differently to environmental gradients; C. raciborskii biovolume changed gradually while P. agardhii shifted sharply from being highly dominated to a rare component of the phytoplankton. As expected, P. agardhii dominates the phytoplankton with high TP and low light availability conditions. Contrary to predictions, C. raciborskii succeeded in all climates and at temperatures as low as 11 °C. Cylindrospermopsis raciborskii had higher phenotypic plasticity than P. agardhii in terms of pigments, individual size and growth rates. We conclude that the phenotypic plasticity of C. raciborskii could explain its ongoing expansion to temperate latitudes and suggest its future predominance under predicted climate-change scenarios.

The success of the cyanobacterium Cylindrospermopsis raciborskii in freshwaters is enhanced by the combined effects of light intensity and temperature

“…In these environments other cyanobacteria may also commonly alternate in dominance with C. raciborskii, including the colonial Microcystis aeruginosa (Marinho and Huszar, 2002;Soares et al, 2009) and the filamentous Planktothrix agardhii and Aphanizomenon sp. (Kokociński et al, 2010;Bonilla et al, 2012). Planktothrix agardhii is a filamentous cyanobacterium that can grow forming resilient, dense blooms in shallow eutrophic ecosystems at different latitudes (Scheffer et al, 1997;Bonilla et al, 2012).…”

Initial growth phases of two bloom-forming cyanobacteria (Cylindrospermopsis raciborskiiandPlanktothrix agardhii) in monocultures and mixed cultures depending on light and nutrient conditions

“…Further investigations need to be extended to several strains to confirm their growth capacity, as the both species (especially C. raciborski) have a great phenotypic plasticity, enabling them to cope with environmental changes and thrive under new conditions (Bonilla et al, 2012;Sinha et al, 2012). Likewise, as our investigation involved a short-time period, it would be useful to extend the time-scale up to 21 days, in order to determine more precisely the interactions, such as competition and/or interference that may occur between these two bloom-forming species when they are both present.…”

“…The short time-scale involved (6-days) was expected to provide data on the rapid growth of C. raciborskii that makes it such a competitor, and show whether there were any interactive effects when the two species were exposed together to the same conditions. Although many investigations have referred to the ecological requirements and preferences of species in their natural habitats, very few have included "in vitro" experimental assays using physiological data about the species and their relationships to various environmental factors (Bonilla et al, 2012). Fewer still have looked at the interactions and growing performances of two species in mixed cultures.…”

On the occurrence and toxicity of Cylindrospermopsis raciborskii in Poland

“…Over the years, numerous experimental and in-field studies on C. raciborskii have been conducted by Australian, Asian, North and South American and European research teams (for reviews see Bonilla et al 2012;Antunes et al 2015;Burford et al 2016). Investigations in Poland have contributed to a general understanding of C. raciborskii in the temperate zone although a number of unknowns remain that require further attention.…”

“…see Acs et al 2013;Smutná et al 2016;Rzymski et al 2017); (iv) the geographical diversification of toxin production raising questions as to the evolutionary/environmental reasons behind this phenomenon (Gugger et al 2005;Cirés et al 2014;; (v) no scientific consensus as regards the ecological role of produced metabolites, although some hypotheses, e.g. use in allelopathic interactions have been put forward (Holland and Kinnear 2013;; (vi) phenotypic plasticity in response to key environmental factors such as temperature, light, nutrient availability (Bonilla et al 2012); (vii) the occurrence of ecotypes differing in environmental tolerance (Chonudomkul et al 2004;Bonilla et al 2016); (viii) the potential for future expansion to new environments and an invasive nature owing to reasons given in the three previous points (Padisák and Reynolds 1998;Sinha et al 2012;Engström-Öst et al 2015).…”