SS3.07 Headwater Ecosystems in Forested Landscapes and Beyond
Date: Wednesday, June 12, 2002
Time: 12:00:00 PM
Location: View Royal
 
ZhangY, University of British Columbia, Vancouver, Canada, yixin@interchange.ubc.ca
Negishi, J, , University of British Columbia, Vancouver, Canada, 
Kolodziejczyk, R, I, University of British Columbia, Vancouver, Canada, 
Richardson, J, S, University of British Columbia, Vancouver, Canada, 
 
THE EFFECT OF SALMON CARCASSES ON AN ECOSYSTEM PROCESS IN A HEADWATER STREAM
image
Marine-derived nutrients from spawning salmon can influence ecosystem functions in headwater streams. We investigated the effect of salmon carcasses on alder leaf litter breakdown. Three replicated treatments (salmon carcass with leaf litter, leaf litter, and artificial leaf litter) were set up in streamside channels for a 111-day period. Litter breakdown rates were significantly lower in the carcass-enriched channels than those without carcasses. The artificial leaf litter had very low invertebrate abundance. The difference between remaining litter mass, under different treatments, increased with experiment duration. It is apparent that carcasses attracted shredders to shift their diet from leaf litter to the higher nutrition resource. Both abundance and biomass of key shredders (Limnephilidae) in the litter packs in carcass-enriched channels were significantly lower than those without carcass addition. After day 85, a carcass was stolen by a terrestrial mammal, which dramatically speeded up leaf litter breakdown by increasing large shredder density in the litter pack. Thus, salmon carcass-derived nutrients indirectly reduced leaf litter breakdown within a short term, but may enhance litter decomposition with positive long-term effects on the lotic ecosystem process.