From the Field to the Lab (photos: S. Pick, A. Poste, S. Perin)
Successful management of fHABs depends on predicting blooms and preventing the development of large populations of fHAB species while modifying the environmental factors that shift a population from a non-toxic to a toxic strain. Successful policies and practices are linked to finding answers to unresolved questions revolving around the three foundations of invasive species ecology:
(1) “Getting There” – what are the factors that affect the cells?
(2) “Being There” – what are the factors that enable fHAB species to dominate an ecosystem?
(3) “Staying There” – what are the factors that induce the production and persistence of toxins by fHAB
Previous studies have established a dramatic increase in the frequency of complaints of new fHABs (Sinclair & Hall 2008; Winter et al. 2011; Carey et al. 2012). This may be due to the stimulation of constant, ubiquitous, natural populations or the transfer or “invasion” of more prolific strains that out-compete the more moribund natural populations (Paerl & Paul 2012). We will design projects around the following questions to challenge this emerging concern:
(Q1) What are the species or groups of species responsible for bloom occurrence in lakes?
(Q2) What are the genetic markers associated with fHAB species in comparison to non-blooming populations?
(Q3) Can the historical occurrence of blooms be merged with genetic markers to assess whether fHABs are
on the rise due to climate, pollution, land cover/land use changes?
We will challenge competing and highly contentious conceptual models of fHAB formation with experimental experiences using mesocosm studies by answering the following questions:
(Q1) What are the abiotic controls on fHABs? Key to our studies is a systematic assessment of cell nutrient
quota, cell growth conditions and cellular elemental stoichiometry, as well as consideration of lake
thermal stability to assess the relative importance of nutrient supply in relation to the formation of
a stable thermocline.
(Q2) What are the biotic controls on fHAB species presence? The community composition prior to conditions
that form fHABs may be the strongest predictor of fHABs (e.g., Dolman et al. 2012) and will therefore
(Q3) What are the causative factors (e.g., climatic, atmospheric and land use/land cover changes) that have
influenced historical and modern fHAB occurrence? A combination of paleolimnological methods
(Smol 2008) and GIS, remote sensing and modeling approaches (Sass et al. 2007) will be used to
establish process controls on fHAB formation on different time scales.
Society is being warned that cyanotoxins have significant negative health effects with long-term exposure. While all general assumptions will be challenged in this program, there is a standard belief that the release of cyanotoxins produced within the cell occurs at the cessation of the fHAB (Merel et al. 2013). This standard belief is related to a “staying there” phenomenon – a system that promotes the longevity of a bloom promotes the toxicity of the bloom. A critical need is the clarification of the physiological model of cyanotoxin production (toxin/cell) and the environmental loading of cyanotoxins (toxin per volume). Through experimental and empirical studies we determine:
(Q1) What is the metabolic purpose of cyanotoxins and why are cyanotoxins produced by some strains
and taxa and not others?
(Q2) What is the transfer of cyanotoxins through the food chain?
(Q3) What are the potential risks for human exposure to cyanotoxins through drinking water and
consumption of fish?
(Q4) To what extent does a lake’s position within a trophic gradient of hyper-oligotrophic to
hyper-eutrophic dictate the potential for cyanobacteria (and more specifically, toxin-producing
cyanobacteria) to dominate that lake’s biomass?