HR: 14:00h
AN: NB13A-03 [Abstracts]
TI: Evaluation of Crayfish Growth and Assimilation on Animal and Detrital Food Sources: Are Stable Isotopes Telling the Whole Story?
AU: * Fortino, K
EM: kfortino@email.unc.edu
AF: University of North Carolina Greensboro, Department of Biology
University of North Carolina Greensboro, Greensboro, NC 27402 United States
AU: Ulseth, A J
EM: aj_ulseth@yahoo.com
AF: University of North Carolina Greensboro, Department of Biology
University of North Carolina Greensboro, Greensboro, NC 27402 United States
AU: Hershey, A E
EM: aehershe@uncg.edu
AF: University of North Carolina Greensboro, Department of Biology
University of North Carolina Greensboro, Greensboro, NC 27402 United States
AB:
Crayfish are the dominant omnivores of many ecosystems and have strong direct and indirect effects through predation and
organic matter processing. Despite this, the importance of detritus for crayfish production is poorly understood. We
conducted a laboratory experiment where we fed crayfish an ad. lib. diet of only detritus, only fish tissue, or a mixture the above. The crayfish grew more on a diet which contained meat but growth was highly correlated with the amount of food
consumed. The least amount of food was consumed in the detritus treatment, an intermediate amount of food in the meat
treatment, and the most food in the mix treatment, suggesting that consumption of detritus by crayfish is related to more
than simply the abundance of detritus. Nonetheless, isotopic evidence indicated that the crayfish were not assimilating leaf
C and N. Additionally, crayfish in the meat containing treatments never exceeded the del 15N signature of their source
by the approximately 3 units expected following fractionation, despite coming to isotopic equilibrium with their source.
These findings suggest that crayfish may fractionate C and N uniquely. This difference may have to do with gut microbial
activity and may have implications for the interpretation crayfish isotopic signatures.
DE: 4239 Limnology
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly