| Summary: | . Adult spawning salmon are a key link between the marine ecosystem and the ecosystems inland. . As returning adults approach the streams they will enter to spawn, they stop feeding. Their bodies contain only an insignificant amount (<1%) of residual freshwater-derived biomass, accumulated when they were smolts developing in the stream environment . Thus, the body of an adult salmon is almost entirely constructed from marine sources. These marine-derived nutrients enter the stream ecosystem before, during, and after spawning, through excretion, release of gametes, and carcass decomposition, respectively . Once released, these marine-derived nutrients become available to enter into the food-web dynamics of both the aquatic and the surrounding terrestrial ecosystems. . When fewer salmon return to the spawning grounds, smaller quantities of marine-derived nutrients are supplied to the surrounding ecosystems. Larkin and Slaney (1997) showed that as carcass availability in a stream declined, so did nutrient and carbon sources for developing salmonids. This suggests that salmon parents assist their progeny in the fight for survival long after they are gone themselves. . I plan to construct an ecosystem model that tracks the flow of marine-derived nitrogen through the stream and adjacent forest ecosystem. The model will focus on converting spawning salmon biomass estimates for a particular stream and using these estimates to calculate the amount of marine-derived nitrogen entering the watershed. The pathways taken by marine-derived nitrogen as it travels throughout and across ecosystems will be compiled into a model, using the Ecopath software. .
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