Research Objectives: The successful management of freshwater harmful algal blooms (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:
First, “Getting There” - what are the factors that affect the cells? 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:
What are the species or groups of species responsible for bloom occurrence in lakes?
What are the genetic markers associated with fHAB species in comparison to non-blooming populations?
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?
Next, “Being There” - what are the factors that enable fHAB species to dominate an ecosystem? We will challenge competing and highly contentious conceptual models of fHAB formation with experimental experiences using mesocosm studies by answering the following questions:
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.
What are the biotic controls on fHAB species presence? The community composition prior toconditions that form fHABs may be the strongest predictor of fHABs (e.g., Dolman et al. 2012) and willtherefore be monitored.
What are the causative factors (e.g., climatic, atmospheric and landuse/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 onfHAB formation on different time scales.
And finally, “Staying There” - what are the factors that induce the production and persistence of toxins by fHAB species? 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 also 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 will determine:
What is the metabolic purpose of cyanotoxins and why are cyanotoxins produced by some strains and taxa and not others?
What is the transfer of cyanotoxins through the food chain?
What are the potential risks for human exposure to cyanotoxins through drinking water and consumption of fish?
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?