Tuesday, March 6, 2018 at 12:00pm to 1:00pm
Allan Hancock Foundation Bldg, Torrey Webb Room 3616 Trousdale Pkwy
Mixotrophic mediators of planktonic communities: Connecting models with data to predict dynamics and function
Mixotrophic organisms, which “mix” photosynthesis and heterotrophy to meet their metabolic needs, are widespread in planktonic communities. This physiological trait allows them to function both as primary producers and as grazers, supplementing their carbon needs with photosynthesis when prey are scarce and scavenging materials from other species when nutrient supplies are low. As such, they play an important dual role mediating community production and nutrient cycling. In recent years, mixotrophs have received increasing attention for this reason, with both empirical and theoretical approaches employed to incorporate them into our understanding of marine planktonic communities. In this talk, I describe recent work focused on how mixotroph traits (particularly those governing photophysiology and grazing) determine community dynamics and function. I formulate mechanistic models for the interactions between mixotrophs, their resources, and their competitors, validate these mathematical models with empirical data, and then use the models to interpret field observations of mixotroph abundance. These models identify environmental conditions under which mixotrophs may be the key mediators of ecosystem function, highlighting new avenues for experimentation and incorporation into ocean-scale approaches.