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RESPONSE OF NUTRIENTS, BIOFILM, AND BENTHIC INSECTS TO SALMON CARCASS ADDITION
Citation:
CLAESON, S., J. LI, J. COMPTON, AND P. BISSON. RESPONSE OF NUTRIENTS, BIOFILM, AND BENTHIC INSECTS TO SALMON CARCASS ADDITION. CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES. NRC Research Press, Ottawa, Canada, 63(6):1230-1241, (2006).
Impact/Purpose:
This study examined stream nutrient, epilithic biofilm, leaf-litter decomposition, and macroinvertebrate responses to carcass addition in three headwater streams of southwestern Washington State
Description:
Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinvertebrate (denisty and biomass) responses to carcass addition in three headwater streams of southwestern Washington State, USA. We used stable isotopes (δ13C and δ15N) to trace incorporation of salmon derived nutrients (SD nutrients) into stream foodwebs. SD nutrients were assimilated by epilithic biofilm, most benthic insects (excluding the shredder Pteronarcys), and age 1 steelhead. SD nutrients peaked ~2 weeks after carcass addition for insects and fish feeding on carcasses, but indirect uptakes of SD nutrients were delayed (~2 months) for organisms downstream of carcasses. At reaches downstream from the carcasses, ammonium concentrations increased, leaf pack decomposition increased, and benthic insect density increased, relative to upstream control sites. The strongest responses were observed near decomposing carcasses, with effects decreasing to undetectable levels 250 m downstream. Carcass additions to headwater streams may have a transient effect on primary and secondary trophic levels, but responses may be limited to a few taxa near the carcass locations.