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

Abstract

<p>Toxic cyanobacterial blooms in freshwaters are thought to be a consequence of the combined effects of anthropogenic eutrophication and climate change. It is expected that climate change will affect water mixing regimes that alter the water transparency and ultimately the light environment for phytoplankton. Blooms of the potentially toxic cyanobacterium <em>Cylindrospermopsis raciborskii</em> are expanding from tropical towards temperate regions. Several hypotheses have been proposed to explain this expansion, including an increase in water temperature due to climate change and the high phenotypic plasticity of the species that allows it to exploit different light environments. We performed an analysis based on eight lakes in tropical, subtropical and temperate regions to examine the distribution and abundance of <em>C. raciborskii</em> in relation to water temperature and transparency. We then conducted a series of short-term factorial experiments that combined three temperatures and two light intensity levels using <em>C. raciborskii</em> cultures alone and in interaction with another cyanobacterium to identify its growth capacity. Our results from the field, in contrast to predictions, showed no differences in dominance (>40% to the total biovolume) of <em>C. raciborskii</em> between climate regions. <em>C. raciborskii</em> was able to dominate the phytoplankton in a wide range of light environments (euphotic zone = 1.5 to 5 m, euphotic zone/mixing zone ratio <0.5 to >1.5). Moreover, <em>C. raciborskii </em>was capable of dominating the phytoplankton at low temperatures (<15°C). Our experimental results showed that <em>C. raciborskii</em> growing in interaction was enhanced by the increase of the temperature and light intensity. <em>C. raciborskii </em>growth in high light intensities and at a wide range of temperatures, suggests that any advantage that this species may derive from climate change that favors its dominance in the phytoplankton is likely due to changes in the light environment rather than changes in temperature. Predictive models that consider only temperature as a drive factor can therefore fail in predicting the expansion of this potentially toxic cyanobacterium.<em></em></p>

Regulation of phosphate uptake reveals cyanobacterial bloom resilience to shifting N:P ratios

“…Filamentous cyanobacterial blooms are common in well‐mixed waters with different light intensity conditions (Aguilera et al., ; Havens, James, East, & Smith, ; Paerl et al., ). For instance, while some species such as Cylindrospermopsis raciborskii , a species phylogenetically related to R. mediterranea (Aguilera, Berrendero, Kaštovský, Echenique, & Salerno, in press; Moustaka‐Gouni, Kormas, Vardaka, Katsiapi, & Gkelis, ), succeed under high‐ Z eu / Z mix conditions (values ≥1) (Bonilla et al., ), P. agardhii blooms in highly turbid water columns ( Z eu / Z mix < 1; Bonilla et al., ) (Scheffer et al., ). Variable conditions in the Z eu / Z mix ratio during our study (range 0.37–1.42) may have favoured both cyanobacteria species in combination with changing nutrient conditions.…”

Different Gene Expression Response of Polish and Australian Raphidiopsis raciborskii Strains to the Chill/Light Stress

“…For example, its high affinity for phosphorus uptake and strain variation in phosphorus storage [23] has allowed its dominance in habitats with phosphate deficiency [24]. Growth under a broad range of temperature and light conditions is also an important capability for successful invasion [18,[25][26][27]. The dual roles of light and temperature in the dominance of certain species is not fully understood, and field and laboratory studies have shown contrasting results [7,28,29].…”

Temperature elevation reduces the sensitivity of invasive cladoceran Daphnia lumholtzi to filamentous cyanobacterium Raphidiopsis raciborskii

“…Stage‐specific population growth rate ( r ) and somatic growth rate (SGR) were used as measures of fitness. Raphidiopsis raciborskii was used as a food stressor because of its tropical origin (Padisák, ), high thermal and light tolerance (Bonilla et al, ; Recknagel et al, ), high invasiveness, wide (especially in Europe), and still‐expanding distribution (Wilk‐Woźniak et al, ; Kokociński et al, ; Rzymski et al, ).…”