| Autor: |
Erratt KJ; School of Environment & Sustainability, University of Saskatchewan, Collaborative Science Research Building, 112 Science Place, Saskatoon, SaskatchewanS7N 5E2, Canada., Creed IF; School of Environment & Sustainability, University of Saskatchewan, Collaborative Science Research Building, 112 Science Place, Saskatoon, SaskatchewanS7N 5E2, Canada.; Department of Physical & Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto, OntarioM1C 1A4, Canada., Freeman EC; Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, CambridgeCB2 1TN, U.K., Trick CG; Department of Health & Society, University of Toronto, 1265 Military Trail, Toronto, OntarioM1C 1A4, Canada., Westrick J; Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, Michigan48202, United States., Birbeck JA; Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, Michigan48202, United States., Watson LC; Environment and Climate Change Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, OntarioL7S1A1, Canada., Zastepa A; Environment and Climate Change Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, OntarioL7S1A1, Canada. |
| Abstrakt: |
The risk of human exposure to cyanotoxins is partially influenced by the location of toxin-producing cyanobacteria in waterbodies. Cyanotoxin production can occur throughout the water column, with deep water production representing a potential public health concern, specifically for drinking water supplies. Deep cyanobacteria layers are often unreported, and it remains to be seen if lower incident rates reflect an uncommon phenomenon or a monitoring bias. Here, we examine Sunfish Lake, Ontario, Canada as a case study lake with a known deep cyanobacteria layer. Cyanotoxin and other bioactive metabolite screening revealed that the deep cyanobacteria layer was toxigenic [0.03 μg L -1 microcystins (max) and 2.5 μg L -1 anabaenopeptins (max)]. The deep layer was predominantly composed of Planktothrix isothrix (exhibiting a lower cyanotoxin cell quota), with Planktothrix rubescens (exhibiting a higher cyanotoxin cell quota) found at background levels. The co-occurrence of multiple toxigenic Planktothrix species underscores the importance of routine surveillance for prompt identification leading to early intervention. For instance, microcystin concentrations in Sunfish Lake are currently below national drinking water thresholds, but shifting environmental conditions (e.g., in response to climate change or nutrient modification) could fashion an environment favoring P. rubescens , creating a scenario of greater cyanotoxin production. Future work should monitor the entire water column to help build predictive capacities for identifying waterbodies at elevated risk of developing deep cyanobacteria layers to safeguard drinking water supplies. |
