Characterization of phytoplankton by pigment analysis and the detection of toxic cyanobacteria in reservoirs with aquaculture production

Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil

“…In the Itupararanga reservoir, the positive correlations between pigment-based biomass of cyanobacteria and sxtA copy numbers demonstrated that pigment analysis may serve as a useful tool to predict the risk of occurrence of potentially toxic cyanobacteria in subtropical reservoirs. Similar results were obtained by Schlüter et al [40] in a study of Brazilian reservoirs with aquaculture production, where the presence of microcystin also correlated with pigment profiles. The authors stated that pigment analysis can provide fast and reliable data for early warning of risks of cyanobacteria and their toxins in freshwater reservoirs.…”

“…Initially, the filters were sonicated in an ice-cool sonication bath for 10 min, extracted further at 4 • C for 20 h, and then mixed using a vortex mixer for 10 s. Filters and cell debris were removed from the extracts by filtration through 0.2 µm Teflon syringe filters. Pigment analysis was carried out in a high-performance liquid chromatography system (HPLC) according to Schlüter et al [39,40] using the Van Heukelem and Thomas method [41]. The HPLC system was calibrated using 22 pigment standards from DHI Lab Products (Table S2).…”

“…The biomass of the individual phytoplankton groups, detected by the identified pigments, was calculated by CHEMTAX software v.1.95 [42] in units of chlorophyll a (µg chl a L −1 ). The initial pigment/chl a ratios used in the CHEMTAX software originated from Schlüter et al [40,43].…”

“…Furthermore, all phytoplankton cells, also including pico-sized cells that are not identifiable by standard microscopy methods, are included by the pigment method. Another advantage is that rare species with low densities can be identified by pigment profiles, but may be overlooked by microscopy [39,40,102]. Despite these advantages, the pigment analysis will only detect phytoplankton groups and thus, for the identification of genera and species, microscopic analysis may still be necessary.…”

Spatial and temporal variability of cyanobacteria in two subtropical reservoirs: community composition, molecular and cyanotoxin analyses

“…In a review of studies published on cyanobacterial toxins around the world, Merel et al (2013) observed that microcystin (MC) alone represents approximately half of the studies published while a quarter of the literature available has emphasis on saxitoxin (STX). In Brazil, the occurrence of these two cyanotoxins is well documented, with MC being the most prevalent and STX the second most studied cyanotoxin (Bittencourt-Oliveira, 2003;Anjos et al, 2006;Moschini-Carlos et al, 2009;Bittencourt-Oliveira, 2014;Borges et al, 2015;Brentano et al, 2016;Calado et al, 2017;Casali et al, 2017;Schlüter et al, 2018;Walter et al, 2018;Lorenzi et al, 2019;Oliveira et al, 2019).…”