Plankton trait flexibility and lake food web functioning

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Ecological communities are increasingly exposed to high degrees of temporal and spatial variation as multiple forcing factors related to the Anthropocene influence their structure and function. There are a number of factors that may potentially drive communities to new configurations via feedbacks through ecological and evolutionary processes. In lakes, anthropogenic forcing factors, such as climate-related variation in inorganic or organic nutrient availability, water colour or thermal shifts can influence standing functional trait variation in populations to affect the structure and function of planktonic food webs. The long-term goal of the proposed research program is thus to examine how plankton communities are likely respond to such forcing factors via the variation in functional traits expressed within their component populations. My lab will thus continue to be a leader in functional trait approaches to plankton commmunities, expanding on approaches that have to date, largely involved assigning an unvarying capacity for certain physiological or behavioural traits to species in community lists identified using primarily classical taxonomic methods. I propose original new research, which will incorporate a dynamical perspective of phytoplankton resource acquisition traits, which are actually highly flexible, dependent on local conditions. In particular, mixotrophy characterizes the feeding phenotypic plasticity present in certain phytoplankton taxa enabling them to obtain energy and resources through phagotrophy or photoautotrophy. We will determine the degree to which feeding trait plasticity (mixotrophy) is implicated in generating plankton coexistence and diversity in relation to seasonal variation and climate change, and assess how the relative expression of community mixotrophy affects food web structure and function. We will conduct reciprocal transplant and mesocosm experiments across different seasons to test for relations with water column stability and ice cover variation, as well as under different food web contexts. This evolution in my research program will involve the incorporation of novel technologies and experimental approaches from community ecology, microbiology, molecular ecology and limnology in an integrated way, including: flow cytometry, next-generation sequencing, stable isotope probing, and submersible fluorometry. Through the training of several HQP, the research will contribute to basic ecological understanding of the ecological interactions between plankton and the role of resource acquisition trait plasticity in contributing to biodiversity. The proposed research program is highly innovative and has the potential to shift how we view the contribution of the microbial loop to the higher planktonic food web structure and to fluxes within typical north temperate lakes, ensuring more novel and more accurate representation of lake food web functioning under anthropogenic influence.