First record of toxins associated with cyanobacterial blooms in oligotrophic North Patagonian lakes of Chile—a genomic approach

Abstract

Blooms of cyanobacteria have negative effects on aquatic organisms and even on human health, since many species can synthesize dangerous toxins. Studies on cyanobacteria and their potential toxicity have been very scarce in Chile and have been limited to lakes of the central zone. Recently, North-Patagonian lakes, although characterized by their low nutrient concentration and low productivity, revealed also the presence of blooms of cyanobacteria, mainly constituted by Microcystis and Dolichospermum species (former Anabaena sp.). To identify potential toxicological risk associated to these blooms, six North Patagonian lakes (Lakes Caburgua, Villarrica, Calafquen, Panguipulli, Ranco, and Puyehue) were sampled during the summer period and screened for the presence of cyanobacteria and different toxins. Our results revealed for the first time the presence of microcystins in all studied lakes, whereas other toxins such as cylindrospermopsin, saxitoxin, and anatoxin were negative for all sites. By applying a genomic approach, Cylindrospermopsis raciborskii was found in one lake (Lake Ranco) constituting the first report of this cyanobacterium in a Chilean lake. This study highlights the effectiveness of molecular methods as a first approach to describe cyanobacteria and their potential cyanotoxins in Chilean North-Patagonian lakes.

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

“…From a management point of view, understanding what drives low toxin quota during high cyanobacterial biomass or high toxin quota during low cyanobacterial biomass versus simply looking at the overall toxin concentrations would be helpful to better understand variation in toxin concentrations and the risks they pose for use of the water systems [ 58 ]. Even in oligotrophic lakes that typically have low cell densities, the cyanobacterial biomass may accumulate at surface and form scums at leeward shores [ 59 ], potentially leading to highly localized toxin concentrations, especially when cells possess considerable toxin quota. In contrast, the influence of environmental factors on strain composition is hardly understood.…”

Mitigating eutrophication nuisance: in-lake measures are becoming inevitable in eutrophic waters in the Netherlands

“…Watson et al, 1997;Rabalais, 2002). However, cyanobacterial blooms and surface scums may also occur in oligotrophic waters, such as North-Patagonian lakes (Nimptsch et al, 2016) and, thus, are not always the result of eutrophication. Taking nutrient-directed measures is of little use in those lakes.…”

Factors associated with blooms of cyanobacteria in a large shallow lake, China

“…Because of their unique characteristics, such as adapting low or high light, in the presence of excess nutrients, cyanobacteria have competitive advantages of many other species of plankton. Several cyanobacteria, such as Microcystis spp., Dolichospermum flos - aquae , and Oscillatoria tenuis , can produce toxins [ 24 , 25 ], such as microcystins (MCs) [ 26 ], microcystins, especially microcystin-LR (MC-LR; L for leucine and R for arginine), are widely distributed across eutrophic freshwater ecosystems and have been shown to be toxic to a wide range of aquatic organisms and humans [ 27 – 31 ]. However, the impacts of MC-LR on structure and diversity of aquatic communities specifically phytoplankton communities have been rarely reported in natural waters [ 5 , 32 ].…”