12754 – Longterm Limnological Monitoring

Investigator’s Annual Reports (IAR’s) for Crater Lake National Park

Longterm Limnological Monitoring


Report Number: 12754

Permit Number: CRLA1994AMDN

Date Received: Jan 01, 1998

Reporting Year: 1994

Principal Investigator: Gary Larson, National Biological Survey, College of Forestry, Oregon State University, Corvallis, Oregon

Additional investigator(s): David McIntire, Mark Buktenica

Park-assigned Study Id. #: CRLA1994AMDN

Permit Expiration Date: Jan 01, 1998

Permit Start Date: Jan 01, 1998

Study Starting Date: Jan 01, 1994

Study Ending Date: Jan 01, 1994

Study Status: Completed

Activity Type: Other

Subject/Discipline: Other

Objectives: 1. Develop a data base to compare present and future conditions of the lake.;2. Develop an understanding of lake components and processes.;3. Develop a long-term program for monitoring changes.;4. Determine if the lake has experienced recent changes. ;5. If changes detected, identy causes and recommend mitigation procedures if the changes are related to human activity.

Findings and Status: Water clarity, as measured with a secchi disk, was at record levels in August, with a reading of 40.8 meters. The nitrate-nitrogen concentrations in Spring 42 were at the same levels observed before the sewage facility was removed from the rim in 1991. Asplanchna is a predatory rotifer. Only 1 specimen of this species was collected between 1985 and 1990. The species has been a common member of the zooplankton community since 1991. Daphnia was abundant in the lake in 1988, but was absent in all samples collected in 1994. Kokanee salmon biomass remained greatly reduced in 1994.

For this study, were one or more specimens collected and removed from the park but not destroyed during analyses? No

Funding provided this reporting year by NPS: 226000

Funding provided this reporting year by other sources: 30000

Full name of college or university: n/a

Annual funding provided by NPS to university or college this reporting year: 0


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