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Cyanobacterial toxins
Published in Ingrid Chorus, Martin Welker, Toxic Cyanobacteria in Water, 2021
Cylindrospermopsins are found globally as a result of the worldwide distribution of producing cyanobacteria, including Raphidiopsis raciborskii, Chrysosporum ovalisporum and Aphanizomenon sp. (Kinnear, 2010; de la Cruz et al., 2013). In Australia, R. raciborskii and C. ovalisporum are the most abundant CYN producers with a high bloom frequency, though the correlation between CYNs concentration and biovolume is generally weak. Concentrations reported often range between < 1 and 10 µg/L, occasional up to maximally 800 µg/L (Chiswell et al., 1999; Shaw et al., 1999; McGregor & Fabbro, 2000; Shaw et al., 2002). Also in the Mediterranean region and in Florida, CYN occurrence has been often, though not always, associated with C. ovalisporum. Concentrations in these regions were from below 10 µg/L up to maximally 202 µg/L (Quesada et al., 2006; Messineo et al., 2010; de la Cruz et al., 2013; Fadel et al., 2014; Moreira et al., 2017). CYN concentrations reported from more temperate regions of Northern America and Europe are often well below 10 µg/L with a maximal concentration of 9–18 µg/L (Rücker et al., 2007; Bláhová et al., 2009; Brient et al., 2009; Graham et al., 2010; Kokociński et al., 2013). The highest CYN concentrations (up to almost 3 mg/L) were reported from Brazil, although these ELISA data need to be confirmed by LC-MS/MS (Bittencourt-Oliveira et al., 2014; Metcalf et al., 2017).
Understanding the relationship between nutrient availability and freshwater cyanobacterial growth and abundance
Published in Inland Waters, 2023
Michele A. Burford, Anusuya Willis, Man Xiao, Matthew J. Prentice, David P. Hamilton
Australian strains of the toxic cyanobacterial species Raphidiopsis raciborskii (formerly Cylindrospermopsis raciborskii) are an example of a species highly adapted to low DIP availability (Burford et al. 2016). Studies in subtropical Australian reservoirs have shown that R. raciborskii typically formed blooms in summer months when dissolved inorganic P (DIP) concentrations were near the chemical detection limit (Burford and O’Donohue 2006, Burford et al. 2014). The response of R. raciborskii to low DIP availability was to increase DIP uptake rate via a physiological shift from passive to high-affinity uptake (Prentice et al. 2015, Willis et al. 2017). In the field, a threshold concentration of 4.7 µg L−1 DIP was identified as the switch from passive to high-affinity uptake during an R. raciborskii bloom (Prentice et al. 2015). The high-affinity uptake was substantiated in studies showing upregulation of the active P uptake gene, Pst (Willis et al. 2019). Below DIP availability thresholds, other studies have shown that high-affinity uptake genes, pstS and sphX, are upregulated, and the passive uptake gene, pit, is down-regulated (Orchard et al. 2009). Rapid uptake of DIP follows, the rate of which varies widely among species and strains (Xiao et al. 2022).
Quantifying the role of organic phosphorus mineralisation on phytoplankton communities in a warm-monomictic lake
Published in Inland Waters, 2019
Matthew J. Prentice, David P. Hamilton, Anusuya Willis, Katherine R. O'Brien, Michele A. Burford
Lake Wivenhoe (27°23′38″S; 152°36′28″E) is a warm-monomictic reservoir in southeast Queensland, Australia. The climate of the region is subtropical, with a mean monthly rainfall of 75 mm in summer and 34 mm in winter (Burford and O’Donohue 2006). The lake has a watershed area of 7020 km2, comprising ∼50% forested and 50% agricultural land used primarily for cattle grazing (Leigh et al. 2015). It receives input water from an upstream dam (Somerset Reservoir), the Upper Brisbane River, and via a pumpback hydroelectric power station (Splityard Creek; Gibbes et al. 2009, O'Brien et al. 2016). At full water storage capacity the lake has a volume of 1 165 000 ML, area of 107 km2, and mean depth of 10.7 m (Leigh et al. 2015). The lake stratifies during the summer wet season (austral summer, Oct–May). The phytoplankton community is generally dominated by bacillariophytes and chlorophytes during winter and by cyanobacteria, including the toxic Raphidiopsis raciborskii (previously Cylindrospermopsis raciborskii), during summer (Burford and O’Donohue 2006, Muhid et al. 2013).