Relationships between metabolic parameters and stream order in Oregon

The light regime, standing stock of chlorophyll, and five metabolic parameters were meas-ured seasonally at four Oregon stream sites; Devils Club Creek (1st order), Mack Creek (3rdorder), Lookout Creek (5th order), and the McKenzie River (7th order). Periphyton from poolsand riffles, aquatic moss (Fontinalis), fine particulate organic matter (FPOM: 0.5 urn-1 cm),and coarse particulate organic matter (CPOM: >1 cm) were examined separately for grossproduction (GP), net community production (NCP), diet respiration (R24), net daily metabolism(NDM), and the production to respiration (P:R) ratio. Total autotrophic production was foundto increase in a downstream direction where more light is available; however, the efficiency oflight utilization is greatest in heavily shaded Mack Creek. Detrital metabolism, per unit weight,is similar in all streams for each metabolic parameter. The standing stock of detritus though, ishighest in headwater streams, decreasing as streams become larger. Therefore, the relative con-tribution of the detritus community to total metabolism decreases downstream. Mosses occur insignificant quantities only in the McKenzie River and have an areal community respiration rateabout twice that of periphyton ; other metabolic parameters are nearly equal in this case. On anareal basis periphyton metabolism is much greater than detrital metabolism and, as a conse-quence, total stream metabolism and the P:R ratio increase downstream.
Gross production rates measured for these sites are some of the lowest recorded (0.1-1.0 g 02.M-2•d-1). These rates are compared to those from other streams in the northwesternUnited States and western Canada, and the importance of photosynthesis to stream systems isdemonstrated. The decomposition rate of the detrital standing stock is estimated to be 0.0029-0.0057c7c • m--2•d--, and the turnover time is calculated to be 48-93 yr for particles Key words: streams, rivers, metabolism, primary production, detritus, photosynthesis, chloro-phyll, respiration, light, Oregon