Planktonic traits and tradeoffs and how they affect predator-prey interactions and community structuring I am investigating the properties of an emergent planktonic community built up from fundamental traits and tradeoffs. Within this context, I am specifically examining predator-prey interactions and how specific prey choices affect the community structure. This biological model is coupled with the Massachusetts Institute of Technology General Circulation Model (MITgcm) to examine how predator and prey communities interact in an environmental setting. Such findings have important ramifications for the abundance of organisms in an ecosystem, the complexity of food webs, and the transfer efficiency of energy across different levels of a food web.
The role of functional groups in size-structured planktonic ecosystems I am also examining size-dependent rates and properties among functional groups of planktonic consumers. Distinct size-dependent relationships within different functional groups could translate into differing patterns of dominance across the globe, which can be tested by simulating natural selection for each group in the MITgcm. This work will help provide improved representations of the diversity of planktonic organisms in a global context, increasing our understanding of and ability to predict changes in the base of the food web.
Size-specific rates and community structure under different environmental conditions
Much of my work is centered on measuring size-specific rates and properties of planktonic communities. To estimate size-dependent rates under artificial and natural conditions, I developed the size-dependent dilution method, a technique that can be used to quantify both laboratory and in situ size-specific growth and grazing mortality rates of plankton (Taniguchi et al. 2012). I also devised a method to estimate the error associated with these rates. Using the size-dependent dilution method, I estimated size-specific in situ growth and grazing mortality rates of picoplankton (organisms between 1 and 4 µm in diameter) in different areas of the Pacific Ocean (Taniguchi et al. 2014a).
To investigate the size-dependency of a greater variety of rates and properties across a much wider size range (~1 to 150 µm in cell diameter), I synthesized data from the literature to parameterize three size-structured ecosystem models of increasing food web complexity (Taniguchi et al. 2014b). Each model, under a variety of nutrient conditions, reproduced several properties observed in natural limnetic and marine ecosystems, including an increase in biomass with increasing nutrients and a decrease in normalized abundance with increasing size.
Image analysis of model organisms I have used a variety of research approaches to explore the classification of different model organisms. These include image analysis techniques to classify cuttlefish camouflage patterns and responses to different visual stimuli and machine learning (Taniguchi et al., 2015) and photogrammetry techniques to identify differences among subspecies of spotted dolphins in the eastern Pacific.