Seasonal Nearshore Occurrence of the Neurotoxin β N methylamino L alanine (BMAA) in Lake Winnipeg, Canada

Abstract

Seasonal fluctuation patterns of the neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) were examined at four-day intervals during the ice-free season in water at three nearshore stations in the south basin of Lake Winnipeg, Canada. BMAA patterns were significantly exponentially correlated with concurrent phaeophytin, and inversely with chlorophyll a, indicating that free BMAA concentrations increased as blooms declined. BMAA was also significantly related to preceding microcystin concentrations, and as chlorophyll a declined, the proportion of BMAA relative to microcystin increased. Cross correlations identified significant relationships between BMAA and immediately preceding nitrate-N/inorganic phosphorus ratios, nitrate-N, rainfall, and a marginal inverse correlation with inorganic phosphorus. Total suspended solids levels were also significantly associated with BMAA, likely due to shading effects. A very high BMAA concentration was found under collapse of intense bloom conditions. These results have implications for water quality monitoring, nutrient management strategies and public health.

Occurrence of β-N-methylamino-l-alanine (BMAA) and Isomers in Aquatic Environments and Aquatic Food Sources for Humans

“…When data are reported per unit of phytoplankton biomass, BMAA concentrations vary from 2.3 ng g −1 in Sweden [ 40 ] to 42 µg g −1 in the Netherlands [ 34 ]. For comparison, the C graded studies report BMAA concentrations varying from 2 µg L −1 in Canada [ 62 ] to 39.6 µg L −1 in USA [ 32 ], or from 0.25 µg g −1 of phytoplankton in South Africa [ 29 ] to 276 µg g −1 of phytoplankton in UK [ 35 ]. Such variability may be attributed to differences in: (i) methodologies used to quantify the metabolites; (ii) the density of BMAA producers in situ; and (iii) the varying capacities to produce BMAA depending on genus, species and even strains of producers.…”

“…An accurate report of BMAA and isomer contents in edible species is crucial to evaluate a human exposure and potent associated risks. Another exhaustive literature review of human dietary exposure to BMAA [ 73 ] was recently published, but is neither systematic (e.g., some references we graded B have not been taken into account [ 21 , 40 , 52 , 54 , 57 , 58 , 60 , 62 ]), nor selective according to the accuracy of the identification or quantification of BMAA (e.g., the reported data on BMAA content in fish mainly derived from studies we graded C [ 25 , 32 , 34 ]). Therefore, the present systematic review offers a supplemental step based on the chemical analytical method accuracy, and is appropriate in view of a health risk assessment procedure.…”

Detection of the Cyanobacterial Neurotoxin β-N-methylamino-L-alanine (BMAA) in Water and Tilapia Fish of a Tropical Fishpond in Egypt

“…The highest concentration of total BMAA detected in phytoplankton samples collected from the fishpond reached 227.66 µg L -1 (corresponding to 42.8µg g -1 dry mass). These values are several orders of magnitude higher than BMAA concentrations measured in cyanobacteria-rich phytoplankton samples (0.001-0.015μg BMAA/g dry mass) from the Baltic Sea [38], Canada (2 μg L -1 ) [39] and South Africa (0.25 μg g -1 ) [40], but they can be compared to those recorded in the Netherlands [42 μg g -1 ) [36], and USA (39.6 μg L -1 ) [41] On the other hand, our concentrations are lower to BMAA concentrations detected in phytoplankton samples in UK (276 μg g -1 ) [42]. Such discrepancy may be due to the difference in the cell density of BMAA-producers in the environment and the varying capacity of BMAA production in different species and strains of producers [43].…”

Microbial Diversity Impacts Non-Protein Amino Acid Production in Cyanobacterial Bloom Cultures Collected from Lake Winnipeg

“…Many recent studies have examined the effects of nitrogen availability on NPAA production by cyanobacteria and related organisms using in vitro techniques or by tracking bloom samples over a season [ 24 , 60 , 61 , 62 ]. During non-favorable environmental conditions, such as a bloom outbreak or collapse, BMAA may accumulate and act as an antagonistic agent to provide a competitive advantage for non-nitrogen fixing cyanobacteria [ 15 , 63 , 64 , 65 , 66 , 67 ]. Additionally, certain microbial phyla may have evolved to co-exist with NPAA-producing organisms using specific mechanisms of protection.…”