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Natalie's Project Page - CAMP Summer 2007 |
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Intern: Natalie Wilson, Biological Sciences
Mentor: Aubrey Cano
Faculty Supervisor: Craig Carlson
Department: Ecology, Evolution, and Marine Biology |
BACTERIAL ABUNDANCE IN THE SOUTH PACIFIC: A FURTHER APPROACH TO ELUCIDATING DEVELOPMENTAL PATHWAYS
Bacteria play an important role in the microbial food web. They take up
dissolved organic carbon (DOC), which can be passed to higher trophic levels of
the microbial food web or respired to CO2. Bacterial abundance is
extensively studied in estuaries and oceanic coastlines, but little is known
about overall distributions of bacteria in open oceans. This project sought
to find how bacterial abundances change in the open South Pacific. Samples of
seawater were taken from up to 500 meters along the P16South (150°W
longitude) line, starting at the equator and ending near Antarctica. Bacteria
were collected onto a filter and stained with a DAPI nucleotide fluorescent
stain, which enabled us to count them under epi-flourescent microscopy.
Abundance data was analyzed to examine if relationships existed with changes
in latitude, depth, temperature, chlorophyll a, and DOC. There was no large
change in abundance with latitude, which suggests that bacteria may have become
well adapted to a wide range of temperatures and environments. Abundance was
always higher at the surface (0-150m) than lower depths (150-500m). Surface
waters at different latitudes can have a wide range of bacterial abundances,
which may be a function of water stratification due to temperature (near the
equator) or salinity (near Antarctica). Chlorophyll a and DOC show weak
positive relationships with abundance in the South Pacific. Although
chlorophyll a and DOC are required for bacteria to grow and divide,
variability in bacterial abundance seems to be more closely related to
water stratification due to temperature or salinity.
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