Taste and odour and cyanobacterial toxins: impairment, prediction, and management in the Great Lakes

Abstract

This paper reviews the issues associated with algal–cyanobacterial taste–odour (T&O) compounds and toxins in the Great Lakes. As with other remediated water bodies, the Great Lakes have undergone significant shifts in nutrient and food-web regimes and are exhibiting erratic blooms and noxious algal metabolite (NAM) outbreaks, despite reduced offshore nutrient levels. We appraise the chemistry, biota, and distribution of NAM impairments and conclude that management strategies based on lakewide monitoring and remedial action plans are often unsuccessful because they attempt NAM control through an unsustainable reliance on water treatment and broad-scale nutrient–biomass models. This approach is undermined by several factors: (i) only some species produce NAMs; (ii) different taxa show disparate patterns across nutrient and mixing regimes; (iii) nuisance species may be planktonic or benthic and located outside remedial boundaries; and (iv) species differ significantly in NAM biochemistry and release. Thus, there are no robust relationships between total plankton biomass, toxins, and T&O compounds in these and other source waters. Given the potential ecological and socioeconomic threats posed by NAM outbreaks, there is a critical need to develop a multistep management framework based on more stringent restoration targets, combining broad-scale screening and nutrient management with system and taxa-specific approaches.

Off-flavor compounds from decaying cyanobacterial blooms of Lake Taihu

“…β-Cyclocitral, which was identified as the product of Microcystis spp., can be released during the growth of Microcystis and the disruption of cell integrity (Watson, 2003;Watson et al, 2008). In the present study, high concentrations of β-cyclocitral were observed in the anoxic water samples, far exceeding its odor threshold concentration (Deng et al, 2010).…”

“…Massive cyanobacterial blooms in our sampling area resulted in the accumulation of a large amount of organic matter, and DMS and DMTS production can be stimulated during the decomposition of cyanobacterial blooms. The highest concentrations of DMS and DMTS observed in the decay phase of cyanobacterial blooms may have been caused by the fact that the bacteria synthesized volatile organic sulfur compounds from dead algae more efficiently than from living algae cells (Watson et al, 2008).…”

In situ enclosure experiments on the occurrence, development and decline of black bloom and the dynamics of its associated taste and odor compounds

“…(Watson, 2003;Watson et al, 2008), both can be released during the growth of Microcystis spp. and by the disruption of their cellular integrity (Suurnakki et al, 2015).…”

Microcystis aeruginosa/Pseudomonas pseudoalcaligenes interaction effects on off-flavors in algae/bacteria co-culture system under different temperatures

“…They are synthesized by a selected number of planktonic bloom-forming and benthic-littoral cyanobacteria as well as by some actinomyces, myxobacteria, and fungi and soil microbiota (Watson et al, 2008). In treated drinking water supplies, Microcystis rarely produce either of the more resilient taste and odor compounds GEO and MIB (Watson et al, 2008).…”

“…Cyanobacteria blooms affect both the nature and the magnitude of their metabolite-related impacts on water quality. In more eutrophic systems, cyanobacteria are frequent sources of VOCs, such as terpenoids, thiols, and pigment derivatives (Watson et al, 2008). Meanwhile, phototrophic non-sulfur bacteria could produce methylated sulfur compounds, such as DMS and DMDS (McCarthy et al, 1993).…”