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Impacts of marine-derived nutrients on stream ecosystem functioning
Yixin Zhang1, Junjiro N Negishi, John S Richardson
1Centre for Applied Conservation Research and Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. yixin@interchange.ubc.ca
Proceedings. Biological Sciences
|October 17, 2003
Summary
Spawning salmon, a marine-derived nutrient (MDN) subsidy, temporarily slow leaf decomposition in streams. Detritivores prefer nutrient-rich salmon carcasses over leaf litter, impacting stream ecosystem processing.
Area of Science:
- Ecology
- Aquatic Ecosystems
- Nutrient Cycling
Background:
- Ecosystem boundaries facilitate nutrient and energy transfer, influencing consumer dynamics.
- Spawning salmon represent a significant marine-derived nutrient (MDN) subsidy to connected freshwater ecosystems in the North Pacific.
Purpose of the Study:
- To investigate the impact of salmon carcasses on detrital processing in an oligotrophic stream.
- To understand how marine-derived nutrient subsidies affect freshwater ecosystem functions.
Main Methods:
- Experimental manipulation of marine-derived nutrient (MDN) inputs via salmon carcasses.
- Measurement of detrital decomposition rates (alder leaves).
- Assessment of detritivore (Trichoptera) abundance, biomass, and size.
Main Results:
- Salmon carcasses indirectly reduced detrital processing rates.
- Detritivores shifted diet to salmon carcasses, decoupling from leaf litter.
- Lower abundance and biomass of detritivores were observed on leaf litter in carcass-treated areas.
- Detritivores found on carcasses were larger than those on leaves.
Conclusions:
- Cross-boundary marine-derived nutrient (MDN) subsidies can temporarily retard leaf litter decomposition.
- These subsidies may enhance food-limited detritivorous consumers in the short term.
- Findings have implications for conservation and management of salmon-influenced aquatic ecosystems.