Assessing the Food Base of Stream Ecosystems: Alternatives to the P/R Ratio

The ratio of gross photosynthesis to total ecosystem respiration (P/R) indicates whether a stream ecosystem is a net producer or consumer of organic matter, but does not show the extent to which stream consumers are supported by autochthonous or allochthonous matter. The transition between autotroph...

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Bibliographic Details
Published in:Oikos 1987-09, Vol.50 (1), p.141-147
Main Authors: Rosenfeld, Jordan S., Mackay, Rosemary J.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Detritivores
Forum
Fresh water ecosystems
Freshwater
Freshwater ecosystems
Fundamental and applied biological sciences. Psychology
Invertebrates
Lotic systems
Macroinvertebrates
Marine ecosystems
Primary productivity
Respiration
Streams
Synecology
Terrestrial ecosystems
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Summary:The ratio of gross photosynthesis to total ecosystem respiration (P/R) indicates whether a stream ecosystem is a net producer or consumer of organic matter, but does not show the extent to which stream consumers are supported by autochthonous or allochthonous matter. The transition between autotrophy and heterotrophy in streams is not properly expressed by P/R = 1. An index based on the respiration of autochthonous and allochthonous matter would be more direct but almost impossible to measure. A more practical alternative is the ratio PAUT/ PALLderived from values of production in terms of biomass elaborated by macroinvertebrates assimilating either autochthonous or allochthonous matter.
ISSN:0030-1299
1600-0706
DOI:10.2307/3565412