Riffle insect community structure in eight Northern California streams

Graduation Date

1990

Document Type

Thesis

Program

Other

Program

Thesis (M.A.)--Humboldt State University, 1990

Committee Chair Name

David Lauck

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Stream measurements--California, Northern, Stream insects, Insect populations--California, Humboldt State University -- Theses -- Biology

Abstract

Riffle sections of eight streams in northern California were sampled for aquatic insects using a kick net. Eleven chemical and physical stream parameters were measured at each riffle sampled. Biological data was analyzed using Simpsons diversity index and Chandlers Biotic Score index. Calculated values were plotted against measured chemical/physical parameters. The resulting scattergrams were examined for relationships between chemical/physical data and the indices values. No relationships were observed. Biological samples were inspected for trends not apparent in the scattergrams. Insect community structure varied among streams and seasonally within streams. The ten most abundant taxa from each sample were plotted by percent abundance and their cumulative percentage was totaled for each sample. The resultant graphs carry more information on community structure than the diversity or biotic indices. A qualified community structure and a diversity component can be observed. Streams are separated into "headwater" and middle order streams based primarily on degrees slope and annual temperature range. Notes are made on insect taxa typical of these streams types. Recommendations are made for regional expansion of Chandlers Biotic Score table and further taxonomic and life history research, particularly within the dipteran family Chironomidae.

https://scholarworks.calstate.edu/concern/theses/dr26z0497

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