Factors Affecting Autotrophic-Heterotrophic Relationships of a Woodland Stream

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Abstract
The effects of incident light, temperature, and detrital and epilithon standing crops on aspects of community metabolism were investigated at five first to third order riffle sites of Augusta Creek, Michigan Detrital standing crops ranged from 142 to 592 g.m−2 ash free dry weight (AFDW), while annual averages for the five sites ranged from 242.4 to 388.2 g.m−2 AFDW. Epilithon values were higher with annual averages of 1764 to 3508 g.m−2 AFDW, while individual estimates ranged from 1480 to 5030 g.m−2. Epilithon composed 80 to 93% of the total organic matter (TOM) of the riffle sediments. Rates of community productivity were most highly correlated with incident light (r=0.52–0.57), followed by temperature (r=0.33–0.64) and epilithon development (r=0.3–0.42). Community respiration was most highly correlated with temperature (r=0.64), while multiple regression indicated light (n=1957) was more influential for predicting rates of net community productivity (NCP), gross community productivity (GCP), and net daily metabolism (NDM). The importance of epilithon as both an organic base within riffle communities and as an aid in predicting rates of community metabolism was demonstrated.