The ecology of the invasive cyanobacteriumCylindrospermopsis raciborskii(Nostocales, Cyanophyta) in two hypereutrophic lakes dominated byPlanktothrix agardhii(Oscillatoriales, Cyanophyta)

Abstract

Biological invasions have attracted particular attention since they often result in serious consequences for natural ecosystems. One planktonic invasive species is Cylindrospermopsis raciborskii, a cyanobacterium originally reported to occur exclusively in the tropics. Over the last few decades its range has extended to temperate regions and it occupies shallow highly eutrophic lakes previously dominated by other cyanobacteria. The purpose of this study was to examine the ecology of C. raciborskii during Planktothrix agardhii blooms in two shallow lakes in western Poland and to determine whether these species have different environmental preferences. Multiple linear regression showed that the biomass of P. agardhii was significantly negatively related to Secchi depth in Lake Bnin´skie. In Lake Bytyn´skie, P. agardhii was significantly positively related to concentrations of PO 3À 4 , chlorophyll a and total phosphorus and negatively related to Secchi depth, NO À 3 , and total nitrogen. Cylindrospermopsis raciborskii was significantly positively related only to concentrations of NH þ 4 . There was a negative correlation between the biomass of P. agardhii and C. raciborskii perhaps showing different responses to environmental variables. Moreover, the biomass of P. agardhii was negatively correlated with Shannon-Wiener diversity of the phytoplankton assemblages. Our results support the concept that these cyanobacterial species have different environmental preferences and their niches differ from each other. These results suggest that light is an important driver of phytoplankton community structure resulting in shifts from a community dominated by P. agardhii in very turbid waters to more diverse communities perhaps including the invasive C. raciborskii in clearer waters.

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

“…Our results showed that under N-source starvation, monocultures of P. agardhii were unable to grow when NH 4 + or NO 3 x was depleted (i.e., m max = 0), whereas the growth of C. raciborskii seemed unaffected under NH 4 + and/or NO 3 x depletion and low concentration. The growth curves (IVF) recorded here, tend to suggest that C. raciborskii had a higher affinity for NH 4 + , as previously reported in Saker and Neilan (2001) and Kokocinski et al (2010) and other studies, who found that C. raciborskii grew faster when N was supplied in the form of ammonia, followed by nitrate, and then urea. In contrast, P. agardhii exhibited a clear preference for NO 3…”

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).…”

“…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). P. agardhii and C. raciborskii can also co-occur in the same water bodies (Kokociński et al, 2010;Bonilla et al, 2012) and, therefore, they are excellent model species for use in tests of C. raciborskii's growth capacity. This capacity may be evaluated using experimental studies that assess its response to changing environmental factors in combination with other similar species.…”

“…We designed short-term interaction experiments in which C. raciborskii was added as an inoculum to another cyanobacteria culture (Planktothrix agardhii). This species was selected for the interaction experiments because it co-occurs in nature with C. raciborskii (Kokociński et al, 2010) and the two taxa have overlapping environmental preferences (i.e., turbidity and mixing tolerance, growth in a wide range of temperatures) (Briand et al, 2002;Kokociński et al, 2010;Bonilla et al, 2012). The interaction experiments allow us to test the combined influence of temperature and light intensity on the growth capacity of C. raciborskii.…”

On the occurrence and toxicity of Cylindrospermopsis raciborskii in Poland

“…Moreover, its numerous occurrence is limited to the warmest summer months, although single filaments have also been observed during colder temperatures in late September and October (Brygider and Kokociński 2016). The long term phytoplankton analysis in Poland revealed the ability of C. raciborskii to outcompete a native bloom forming cyanobacterial species Planktothrix agardhii (Kokociński et al 2010). It was also experimentally evidenced that the Polish strain of C. raciborskii can outcompete Microcystis aeruginosa even at relatively low initial biomass .…”