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.
Image analysis of model
organisms
I have used a variety of research approaches to explore the
classification of different model organisms. These include machine
learning techniques to classify unicellular plankton, image analysis
techniques to classify cuttlefish camouflage patterns and responses
to different visual stimuli (Taniguchi
et al., 2015), and machine learning and photogrammetry
techniques to identify differences among subspecies of spotted
dolphins in the eastern Pacific.
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.
