Figure 1.
Aerial photograph of riparian manipulations along the South Fork Pysht River, Olympic Peninsula, Washington State, USA.
Red arrows indicate manipulated reaches, yellow arrows indicate intervening unmanipulated (control) reaches sampled.
Table 1.
Summary of physical and chemical variables measured in experimental and control reaches.
Figure 2.
Biological responses to riparian manipulations (mean ± 1 se).
(A) Algal productivity, based on light-dark oxygen production (black bars) and grazer-free algal chlorophyll a accrual (gray bars). (B) Algal standing crop estimated from either ash-free dry mass (gray bars) or chlorophyll a (black bars). (C) Aquatic invertebrate densities. (D) Juvenile salmonid densities, distinguished by species.
Figure 3.
Algal Responses (mean ± 1 se) to Nutrient Addition in River Reaches with Intact (Control) and Manipulated Riparian Vegetation.
All responses measured as rates of chlorophyll a accrual. Top: results from single nutrient manipulations of nitrogen (as NaNO3) and phosphorous (as NaH2PO4). Bottom: results from simultaneous nutrient additions using Osmocote pellets (18 N∶ 6 P).
Figure 4.
Estimated Contributions of Different Energy Sources Entering the River to Juvenile Salmonids Based on Stable Isotope Analysis.
Graphs show Bayesian posterior probabilities of different fractional diet compositions, derived from the MixSIR algorithm [65], assuming a two trophic level energy transfer to salmon via aquatic invertebrates. Top: control reaches. Bottom: treatment with reduced riparian vegetation.
Table 2.
Stable isotope ratios of nitrogen (15N/14N) and carbon (13C/12C) in tissues of potential food web energy sources, and of juvenile salmonids from different riparian zone treatments.