A comparative study of the habitat requirements of two sedges: Carex limosa and Carex paupercula.

Carex limosa and Carex paupercula are two sedges with a circumboreal distribution which grow in similar habitats in northern Michigan and Ontario, Canada. Carex limosa is primarily found in peatlands. Carex paupercula can also be found in peatlands, as well as in coniferous swamps, and in rock crevices along Lake Superior. The purpose of this study is to attempt to compare and contrast these two species and to draw some conclusions about each one's habitat requirements through an analysis of field observations.http://deepblue.lib.umich.edu/bitstream/2027.42/54543/4/2983.pd

Changes in foraging behavior of the crayfish Orconectes virilis in response to a fish predator.

In laboratory aquaria, the physical presence of a rock bass (Ambloplites rupestris) predator significantly reduced the number of the crayfish Orconectes virilis that emerged from shelters to forage. We speculate that this may indirectly lead to decreased food rations and a decline in reproductive capability of O. virilis. No significant change in crayfish behavior was observed when water that had contained a rock bass predator was introduced. This indicates that O. virilis does not sense the chemical presence of a fish predator. Results showed that increased time elapsed since last feeding did not affect the foraging behavior of O. virilis. This may suggest that hunger does not affect its foraging behavior. Overall conclusions are supported by other research which states that by affecting several trophic levels with aquatic systems, the influence of fish on crayfish goes beyond simple interactions of predator and prey.http://deepblue.lib.umich.edu/bitstream/2027.42/54341/1/2777.pdfDescription of 2777.pdf : Access restricted to on-site users at the U-M Biological Station