Spatial and temporal variations of a saxitoxin analogue (LWTX-1) in Lyngbya wollei (Cyanobacteria) mats in the St. Lawrence River (Québec, Canada)

C Hudon; P Gagnon; S Poirier Larabie; C Gagnon; A Lajeunesse; M Lachapelle; M A Quilliam

doi:10.1016/j.hal.2016.06.001

Spatial and temporal variations of a saxitoxin analogue (LWTX-1) in Lyngbya wollei (Cyanobacteria) mats in the St. Lawrence River (Québec, Canada)

Harmful Algae. 2016 Jul;57(Pt A):69-77. doi: 10.1016/j.hal.2016.06.001. Epub 2016 Jun 22.

Authors

C Hudon¹, P Gagnon², S Poirier Larabie², C Gagnon², A Lajeunesse², M Lachapelle², M A Quilliam³

Affiliations

¹ Aquatic Ecosystems Protection Research Division, Environment Canada, 105 McGill Street, 7th Floor, Montreal, QC, Canada H2Y 2E7. Electronic address: christiane.hudon@canada.ca.
² Aquatic Ecosystems Protection Research Division, Environment Canada, 105 McGill Street, 7th Floor, Montreal, QC, Canada H2Y 2E7.
³ Measurement Science and Standards, National Research Council of Canada, 1411 Oxford Street, Halifax, NS, Canada B3H 3Z1.

PMID: 30170723
DOI: 10.1016/j.hal.2016.06.001

Abstract

The concentration of the saxitoxin analogue LWTX-1 was quantified in samples of the benthic filamentous cyanobacterium Lyngbya wollei (Farlow ex Gomont) Speziale and Dyck collected in two fluvial lakes of the St. Lawrence River (Canada) over the 2006-2013 period. The study was aimed at documenting the spatial (between fluvial lakes, between sites within each lake) and temporal (inter-annual, monthly) variations of toxin concentration in relation with hydrological (water level), physical (water temperature, conductivity, transparency), chemical (nutrients in overlying water) and biological (L. wollei biomass and mat condition) characteristics. Toxin concentration was hypothesized to vary seasonally with biomass accumulation and environmental conditions. Toxin concentrations measured in Lake Saint-Louis (51±40μg LWTX-1g^-1 DM, N=29 days in 2007, 2009-2011) were double those in Lake Saint-Pierre (25±31μg LWTX-1g^-1 DM, N=26 days in 2006-2008, 2012-2013); however, August 2007 measurements taken from both lakes did not differ significantly. Ten of the twelve highest values (>100μg LWTX-1g^-1 DM) were obtained from Lake Saint-Louis, between April and October in 2007, 2010 or 2011. Under ice samples showed intermediate concentrations of LWTX-1 (42±9μg LWTX-1g^-1 DM, N=2). Concentrations of LWTX-1 were positively correlated with Secchi depth (r=0.59, p<0.001), L. wollei biomass (Spearman r=0.31, p<0.01) and %N in filaments (r=0.48, p<0.001), suggesting toxin production was linked to mat growth and metabolism rather than water quality. Although LWTX-1 has been reported to have a low toxicity, monitoring of L. wollei abundance is required to assess the environmental and human health risks posed by this taxon in the St. Lawrence - Great Lakes system.

Keywords: Benthic cyanobacterial mats; Cyanotoxins; Fluvial lakes; Lyngbya wollei; PSP toxins; St. Lawrence River.