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The Dungeness
crab, Cancer magister, is considered a key marine
species, serving as an indicator of coastal health. This crab
is also commercially harvested and supports a valuable sport
fishery along the California coast. We are using analyses of
genetic variability to investigate dispersal of the C.
magister throughout its geographic range. Our
investigations of crab dispersal have revealed that larvae are
aggregated into patches at sea and recruit into estuarine
systems in discrete pulses. We have developed a simple
procedure for acquiring time series of larvae, and have archived
four years of returning final stage larvae (megalopae). We have
also successfully extracted, amplified, and sequenced the 415
base pair, first subunit of the COI gene of the crab
mitochondrial DNA (mtDNA) and have recently developed
microsatellite markers for nuclear genome characterization.
Proposed Undergraduate Role in the
Investigation
The undergraduate
students participating in RUMBA will serve a vital role in this
investigation by analyzing the mtDNA sequence of the archived
adult crab tissues.
The genetic characteristics of adults are reflected in their
progeny, and so the genetic variability within and among larval
settlement cohorts (groups of megalopae returning together to
adult habitats) reflects present dispersal trajectories and
oceanic mixing processes. Thus, by examining the biogeography
of adult Dungeness crab in combination with the genetic
signature of settlement cohorts, we will have an unparalleled
measure of larval dispersal in C. magister. RUMBA
students will have the opportunity to develop and test their own
ideas within the framework of this research.
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Dr. Parr (left) with two of her
graduate students.
We are using microsatellite analysis in
combination with mtDNA sequence analysis as a measure of genetic
variability within and among populations of both adult and
returning megalopae of C. magister. With these data, we
will determine the biogeography of adult crab populations and
elucidate the nature of larval dispersal of Dungeness crab
throughout its range. My students and I will contribute the
findings of our proposed study to a larger study, which intends
to determine effective size and spacing of marine reserves along
the coast of California, Oregon, and Washington by compiling
larval dispersal data for key species of benthic marine
organisms. This larger study will be done in cooperation with
University of Oregon’s Institute of Marine Biology and the
National Marine Fisheries Service, Astoria, Oregon.
Diagram representation of crab life cycle.
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