Crayfish Population and Community Ecology

Since 1999, I have conducted a quantitative sampling program to determine the distribution and abundance of crayfish species in creeks and rivers in the upper Susquehanna River drainage.  The main focus is a non-native species, the rusty crayfish, Orconectes rusticus, which was introduced to New York some time after 1969.  Sampling continues annually to monitor changes in the distribution of both the introduced and native crayfish.  Other current research is aimed at testing hypotheses about how the rusty crayfish is able to invade local streams and displace native crayfish species, the effects on the native crayfish populations, and impacts of the invader on the stream community.
 

Population Ecology of the Mottled Sculpin, Cottus bairdi

The mottled sculpin is a stream-dwelling, shelter-nesting fish that is distributed widely in North America. During the breeding season (spring and early summer), male sculpins occupy cavities under rocks and other stream debris. Females lay eggs in a discrete mass inside the nest of a male, who then fertilizes and guards the eggs until they hatch.

Mating systems ecology

Mating systems theory attributes variation in mating strategies (patterns of mate choice and competition) to variation in the availability of resources required for reproduction. Shelter-nesting fish are excellent for mating systems research because the critical resource, the nest, is easily identifiable. Also, resource availability is likely to vary greatly in nature and the resource can often be easily manipulated experimentally.

Initial phases of research on sculpin mating strategies have included: 1) gathering baseline population data, such as distribution, abundance, size structure, and reproduction; 2) pilot experiments to assess the feasibility of field manipulations; and 3) laboratory shelter competition experiments.

Population genetics (with Peter Hazelton '01 and Dr. Stan Sessions)

We are using molecular techniques to measure rates of gene flow between sculpin sub-populations in the upper Susquehanna River and its tributaries. We are particularly interested in assessing the effects of migration barriers (e.g., dams) on population structure.