Natural and anthropogenic influences on benthic cyanobacteria in streams of the northeastern United States

Cyanobacterial Harmful Algal Mats (CyanoHAMs) in tropical rivers of central Mexico and their potential risks through toxin production

“…On the other hand, Cyanoplacoma sp. at the SM site was recorded minimally disturbed, showing, as in other studies, that different combinations of land uses can host toxin-producing cyanobacteria (Rider et al, 2024 ; Schulte et al, 2022 ). These results may also be related to strategies of competition for substrate with other bacteria, algae, or even as a measure to avoid herbivory (Bouma-Gregson et al, 2018 ; Graham et al, 2020 ; Kim et al, 2021 ; Reinl et al, 2021 ; Timoshkin et al, 2016 ).…”

“…Although these rivers (AB, SD, and ME) are located within subbasins that have conserved forest areas, but are subject to physical alterations of the channel for local water extraction, for example. These changes in water flow due to diversions or damming represent an important component in the proliferation of cyanobacteria and can be added synergistically to other factors such as small nutrient inputs from human activities (Robichon et al, 2023 ; Schulte et al, 2022 ). On the other hand, Cyanoplacoma sp.…”

“…One of the evolutionary strategies that allows them to compete for resources with other aquatic organisms is the synthesis of secondary metabolites called cyanotoxins, which can damage the metabolism and functioning of all kinds of living beings, including humans (Aguilera et al, 2023 ; Almuhtaram et al, 2021 ; Massey et al, 2022 ). The presence of some species of cyanobacteria, particularly when in large quantities (blooms), could imply an environmental, ecological, and human health risk (Rider et al, 2024 ; Schulte et al, 2022 ). In the scientific literature, the first mention of the term “bloom” dates back to 1953, when it was used to describe the massive growth of planktonic cyanobacteria in a lake (Sverdrup, 1953 ).…”

“…In lotic environments, these massive growths develop at the bottom of the river in a variety of continental habitats and are often not visible due to the turbidity of the water or a high concentration of suspended solids. Furthermore, they are spatially and temporally variable and the timing and magnitude of the drivers of growth in benthic productivity have been described as varied and include streamflow velocity, light, nutrients, sediment deposition, substrate composition, and watershed characteristics (Rider et al, 2024 ; Schulte et al, 2022 ). Filamentous and mucilaginous colonies are usually the dominant growth forms with a higher report of anatoxins, microcystins, and saxitoxins production in rivers (Cantoral Uriza et al, 2017 ; Legleiter & Hodges, 2022 ; Loftin et al 2016 ).…”

“…Dissolved phosphorus and nitrogen in water have been recognized as limiting nutrients that, when in excess, can drive the growth of blooms and the biosynthesis of planktonic cyanobacterial toxins (Chorus et al, 2021 ; Reinl et al, 2021 ). Although this phenomenon has also been shown to be associated with oligotrophic water bodies, these systems have been less studied, causing a limitation in our understanding of the development and maintenance of blooms (Reinl et al, 2021 ; Rider et al, 2024 ; Schulte et al, 2022 ). In the case of benthic mats, the influence of nutrients is more complex due to the diverse biosynthetic capacities of the cyanobacterial species and associated bacteria in the biofilm (Bouma-Gregson et al, 2019 ; Robichon et al, 2023 ).…”