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The aim of my tropical research is to investigate
the degree to which a single detritivorous fish species regulates carbon and nitrogen
cycling in a tropical Andean stream that contains ~100 fish species in a 2 km
river section. Studying organic carbon flow and nitrogen cycling is
important because organic carbon is the main energy source in rivers and
nitrogen often limits biological systems and nutrient cycling is an ecosystem
service provided by rivers. I am
testing the effects of a dominant sediment-feeding fish, the flannelmouth
characin, Prochilodus mariae, on organic carbon flow and nitrogen
cycling. To
experimentally test whether this single fish species is a major driver of
nutrient dynamics I am using a large-scale approach. I split the stream longitudinally by
installing a 250-meter plastic curtain down the middle. I exclude only Prochilodus from one side
of the curtain using size-selective wire mesh placed at the top and bottom of
one side, whereas on the other side all fishes including Prochilodus
have access. My collaborators and I
have used this approach to predict how losing Prochilodus from overharvesting, dams, and land-use change will
alter ecosystem metabolism, namely heterotrophic respiration, primary
production, and organic carbon spiraling (Taylor et al 2006). Using a nitrogen isotope addition, I have also
tested the impact of this single fish species, Prochilodus mariae, on
multiple components of the nitrogen cycle. This work is supported by a NSF
International Programs Dissertation Enhancement Grant and NSF DEB grant. It
has broad significance from both scientific and societal perspectives. For
example, it examines the importance of individual migratory species to
ecosystem processes, and integrates the often-disparate fields of population
ecology and ecosystem ecology. Moreover, this work suggests that a single
fish species can be a major driver of ecosystem processes, and thus, small
changes in biodiversity can have disproportionately large effects on
ecosystem function, even in a tropical
stream with more than 75 fish species. For society, this work focuses on a
family of migratory fishes that are major protein sources throughout the
Links: Latin American Non-profit Organization
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