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- Title
Direct versus indirect pathways of salmon-derived nutrient incorporation in experimental lotic food webs.
- Authors
Kiernan, Joseph D.; Harvey, Brett N.; Johnson, Michael L.
- Abstract
The objective of our study was to examine how salmon carcass subsidization through alternative trophic pathways affected stream food web productivity. Three salmon carcass treatments (dissolved carcass nutrients only, dissolved carcass nutrients + carcass material, and a carcass-free control) were replicated five times in artificial stream channels. We quantified changes in water chemistry and the production of periphyton, macroinvertebrates, and age 0+ steelhead trout (i.e., sea-run rainbow trout, Oncorhynchus mykiss) over 65 days. Dissolved ammonium and periphyton chlorophyll a concentrations increased for an approximate 2-week period in both carcass-augmented treatments. However, there was no commensurate effect on periphyton ash-free dry mass. Total macroinvertebrate biomass was significantly greater in the presence of nutrients + material after 65 days, but no such increase was observed in response to the addition of dissolved nutrients only. Despite modest and inconsistent effects at lower trophic levels, both the nutrients only and nutrients + material treatments increased the growth and condition of age 0+ steelhead trout, with significantly greater gains occurring in the presence of nutrients + material. These data suggest that while salmon carcasses can enhance the short-term growth of juvenile salmonids via bottom-up pathways, the availability and direct consumption of carcass biomass may promote a substantial amount of additional production.
- Subjects
SALMON; LOTIC ecology; FOOD chains; NUTRIENT cycles; REPLICATION (Experimental design); WATER chemistry; PERIPHYTON; BIOMASS production
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2010, Vol 67, Issue 12, p1909
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/F10-110