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USE OF SLACK-WATER ENVIRONMENTS BY COHO SALMON JUVENILES IN A COASTAL OREGON STREAM AS INDICATED BY 34S STABLE ISOTOPE ANALYSIS
Citation:
CHURCH, M., J. L. EBERSOLE, C. KENDALL, K. RENSMEYER, B. MILLER, P. J. WIGINGTON JR, AND H. LAVIGNE. USE OF SLACK-WATER ENVIRONMENTS BY COHO SALMON JUVENILES IN A COASTAL OREGON STREAM AS INDICATED BY 34S STABLE ISOTOPE ANALYSIS. Presented at American Fisheries Society, San Francisco, CA, September 02 - 06, 2007.
Description:
Stable isotopes of sulfur are rarely used in studies of elemental cycling, trophic position or use of marine-derived nutrients by salmonids. The main reason for this probably is the reluctance on the part of isotope labs to expose their instruments to SO2 (because of its corrosive potential). The trophic shift of 34S also makes it less useful than the minimal shift of 13C for identifying the food web basal resource and less useful than the greater shift of 15N for identifying trophic position.
In our studies of Oregon Coast Range streams, however, analyses of stable isotopes of sulfur complement more traditional analyses (13C, 15N). For example, we observed highly depleted 34S in muscle tissue of juvenile coho salmon smolts from a low-gradient stream system. This finding indicates the significant incorporation of reduced sulfur into salmonid food webs, and reflects lengthy occupation of habitats with reducing environments (e.g., beaver ponds) during a major portion of their stream rearing. We propose that 34S might serve as an easy and highly useful indicator of habitat use patterns in mixed-environment systems, especially ones with a range of redox conditions. These new findings pose interesting implications for food web dynamics in such systems.