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Biodiversity
and Community Structure in Coastal Marine Sediments
George
Waldbusser
Doctoral Student
MEES Area of Specialty: Oceanography
Advisor: Roberta Marinelli
 One
of the most daunting tasks facing coastal oceanographers is gaining
an understanding of the links between the biological structure of
an ecosystem and the physical, chemical, and biological processes
that constitute
ecosystem function. This knowledge is important because of human and
naturally induced changes to biotic communities, coupled to feedbacks
with valuable ecosystem services, such as nutrient cycling. Integral
to the characterization of marine ecosystem function and biodiversity
is a mechanistic approach to address the process complexity found
in marine sediments. The mechanisms lie in spatially explicit interactions
among infaunal populations, as well as with their surrounding sedimentary
and geochemical habitat. Ecological concepts, such as density dependence,
keystone species, and biodiversity, should figure prominently into
models of transport and reaction of marine sediments (ecosystem function),
even though they currently do not.
My approach
to these types of questions involves experimental field, lab, and
modeling work. Recently, I have conducted field investigations of
a simple benthic community dominated by an arenicolid polychaete
and thalassinid shrimp within False Bay, on San Juan Island, Washington.
Using indirect measures of porewater transport and the measurements
of porewater profiles, I found that rates of transport and overall
concentrations of solutes were modified by the type of organism
present and the interaction between the two taxa. Differences found
in rates of transport and porewater solute concentrations were related
to feeding and burrowing behavior. In addition, reaction rate kinetics
of different solutes also dictated the magnitude of the organism
effect. In all, results indicate the importance of identifying mechanisms
to understand complex system dynamics and point to the need for
more integrative studies of behavior, biogeochemistry, and transport
within sedimentary habitats. Currently, models of sediment dynamics
do not incorporate this level of complexity.
I plan on continuing
this line of research within the Chesapeake Bay. Comparing the role
infauna play in sediment dynamics and biogeochemistry of a pristine
habitat, such as False Bay, to the impacted habitats of the Bay
should prove insightful. I hope to determine whether human induced
coastal impacts, such as eutrophication, create a disconnect between
the biological community and the functioning of the sedimentary
habitats.
Representative
publications:
Waldbusser, G.G. and R.L. Marinelli (in review) Macrofaunal modification
of porewater advection: Single vs. multispecies effects. Mar. Ecol.
Prog. Ser.
Marinelli, R.L. and G.G. Waldbusser (in press) Plant-animal-microbe
interactions: closing the ecological loop. In: Interactions between
macro- and microorganisms in marine sediments. Eds. Erik Kristensen
and Joel Kostka. American Geophysical Union Volume.
Waldbusser, G.G., R.L. Marinelli, R.B. Whitlatch, and P.T. Visscher.
(2004) The effects of infaunal biodiversity on biogeochemistry of
coastal marine sediments. Limnol. Oceanogr. 49: 1482-1492.
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