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PNW
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PNW Project Overview 2001
Effect of Marine Derived Nutrients on Macroinvertebrate Production in Salmon Spawning Streams
Principal
Investigators:
Dr.
Robert
Gara,
University of Washington, College of Forest Resources
Jon
Honea,
University of Washington, College of Forest Resources, PhD Candidate
Awarded: $45,728
Project
Description:
Investigators for this project hypothesize that the
macroinvertebrate community of salmon spawning streams is an
important conduit of marine derived nutrients (MDN) from adult
to juvenile salmonids. The study began in October 1999 with ONRC funding.
Soon after the first samples were collected, data
analysis began with the sorting of aquatic macroinvertebrate
samples. Because
sample processing for secondary production measurements is
notoriously time consuming, data analysis lags considerably
behind sample collection. Preliminary analysis shows that the
stream bed disturbance caused by salmon spawning activities
severely impacts the macroinvertebrate community, reducing
densities and diversity. However,
one to two months after the spawning disturbance ends, the
macroinvertebrate community production in the spawning reach is
similar to or greater than upstream production at a reach with
no spawners. Recovery
is likely aided by fertilization of the stream when MDN is
released from spawning and decomposing salmon as indicated by
the substantial quantities of marine carbon and nitrogen found
in insects shortly after spawning had ceased.
This project continues analysis of macroinvertebrate
production as a response to spawning salmon.
The study will provide a description of the ecology of
the cycle of MDN from adult to juvenile salmonids via
macroinvertebrates. Project
investigators will identify key variables characterizing this
cycle to be studied in a less intensive manner in other streams
in order to determine which ones can be monitored to validate
conservation and restoration efforts.
Understanding the interactions between salmon and
macroinvertebrates in the study stream will provide a necessary
first step to understand the natural variability of these
interactions.
Project Status:
2001
funds will be distributed to projects in September 2001.