I am broadly interested in microbial ecology. Much of the
nutrient and energy flux of marine ecosystems is mediated through microbial
pathways including both free-living and symbiotic microbes. Despite the
importance of these microbes, little is known about the dynamics of changes
in the structure of these communities over time or space. Often even the
identity of the microbes is unknown due in large part to a bias based on
My work has focused primarily on symbiotic interactions between microbes
and a diverse set of metazoans. These symbiotic systems include bacterial
pathogens as well as mutualistic associations. The metazoan host
organisms provide a visually identifiable marker for the symbiotic microbes.
Also, an individual host is a tractable model of a small scale ecosystem.
Like true ecosystems, much of the nutrient and energy flux in many symbiotic
associations is mediated through the physiology of the symbiotic microbes.
Much of my earlier work was focused on these physiologies in well known
systems such as dinoflagellates in symbiosis with corals and other cnidarians,
and chemoautotrophic bacteria in symbiosis with hydrothermal vent organisms.
Currently I am working on detecting, quantifying, and characterizing the
symbionts of some less well known symbioses.
My thesis work has focused on the invasive acoel (flatworm) Convoluta convoluta
and its algal symbionts using a variety of techniques. Although the acoel
was known to be a recently introduced species in the Gulf of Maine, the
identity of the symbionts was in question. In collaboration with Dr. Seth
Tyler (University of Maine) I have shown the symbiont is a diatom. This
symbiosis is therefore unique as no other metazoans are known to harbor
symbiotic diatoms in this fashion. I have recently brought the symbiont
into culture and identified it as Licmophora paradoxa var. crystallina (=L.
crystallina). I developed a PCR based approach to detect the free-living
form of the symbiont, and have shown the range expansion of the acoel host
is preceded by the presence of the free living form of the algal symbiont.
Together with molecular genetic data on the symbiont population structure,
this suggests the invasion of the host was facilitated by an earlier undetected
invasion of the microbial symbiont. As many marine invertebrates rely on
specific microbes for a variety of interactions including cues for settlement
and/or morphogenesis as well as nutritional interactions, the microbial
community may be having an unrecognized effect on the likelyhood of invasion
by larger organisms.
BACK TO PEOPLE TO MAIN PAGE