Are We Underestimating Benthic Cyanotoxins? Extensive Sampling Results from Spain

Abstract

Microcystins (MCs) are potent hepatotoxins, and their presence in water bodies poses a threat to wildlife and human populations. Most of the available information refers to plankton, and much less is known about microcystins in other habitats. To broaden our understanding of the presence and environmental distribution of this group of toxins, we conducted extensive sampling throughout Spain, under a range of conditions and in distinct aquatic and terrestrial habitats. More than half of the tested strains were toxic; concentrations of the hepatotoxin were low compared with planktic communities, and the number of toxic variants identified in each sample of the Spanish strains ranged from 1–3. The presence of microcystins LF and LY (MC-LF and MC-LY) in the tested samples was significant, and ranged from 21.4% to 100% of the total microcystins per strain. These strains were only detected in cyanobacteria Oscillatoriales and Nostocales. We can report, for the first time, seven new species of microcystin producers in high mountain rivers and chasmoendolithic communities. This is the first report of these species in Geitlerinema and the confirmation of Anatoxin-a in Phormidium uncinatum. Our findings show that microcystins are widespread in all habitat types, including both aerophytic and endolithic peat bogs and that it is necessary to identify all the variants of microcystins in aquatic bodies as the commonest toxins sometimes represent a very low proportion of the total.

Co-Occurrence of Microcystins and Taste-and-Odor Compounds in Drinking Water Source and Their Removal in a Full-Scale Drinking Water Treatment Plant

“…Compared to the cyanobacterial density or biovolume, chlorophyll- a concentrations were easier to detect and more suitable to be used as the indicated index especially for the water sources suffering with different algal species and many variants of cyanotoxins [ 1 , 28 ]. This method to establish chlorophyll- a thresholds in different seasons is not only based on MCs but also on T&O compounds to guide the management of the water source and the DWTP and to guarantee the safety of drinking water involved in multiple contaminants.…”

Spatial and Temporal Variability in the Development and Potential Toxicity of Phormidium Biofilms in the Tarn River, France

“…Only the ks2 gene fragment, involved in the biosynthesis of ATX, was detected by PCR, while negative signals were observed for gene fragments involved in microcystin and saxitoxin biosynthesis. These latter gene fragments (associated with microcystin and saxitoxin synthesis) were screened because other cyanobacterial species (e.g., Dolichospermum ), that are known to produce these toxins, can be found in association with Phormidium in biofilms, and because microcystins [ 5 , 29 , 30 , 31 ] and saxitoxins [ 29 ] have been previously detected in Phormidium extracts.…”

Extracts from benthic anatoxin‐producing Phormidium are toxic to 3 macroinvertebrate taxa at environmentally relevant concentrations

“…Over the last decade there has been a marked increase in the distribution and intensity of benthic mat‐forming cyanobacteria in rivers and streams globally (Quiblier et al ). Some of these taxa also produce cyanotoxins (Quiblier et al ), which have been increasingly monitored in New Zealand (McAllister et al ), Europe (Echenique‐Subiabre et al ; Cantoral et al ), and the United States (e.g., California; California Water Boards ). Recently, Fetscher et al () reported that one‐third of the samples from streams in a large sample‐set from California contained one or more cyanotoxins of benthic origin.…”