Figure 1.
Each dot represents a macroinvertebrate sampling location: 3 riffles per reach on the Calapooia River, and 11 transects per reach on the Rogue River.
Table 1.
Characteristics of the study reaches and sediment reservoirs.
Figure 2.
Annual peak discharge for the historical period of record and over the study period for the a) Calapooia at Holley, located 16 km upstream of Brownsville Dam, and b) Rogue River at Grants Pass located 8.6 km downstream of Savage Rapids Dam.
Error bars on historical annual peaks represent 2 standard errors. Error bars for the Calapooia River for study years reflect estimation error associated with multiple regression estimate of peak discharge. Vertical dashed lined indicates approximate date of dam removal.
Table 2.
Geomorphic measures of disturbance from the sediment pulse.
Figure 3.
Longitudinal profiles downstream from the dams over time at a) Calapooia River and b) Rogue River.
On the Rogue River, no longitudinal profile was collected during 2009, and the pre-removal profile is a compilation of surveys from 1999 in the farthest US and DS reaches and from 2002 for the main reservoir, both conducted by the US Bureau of Reclamation.
Figure 4.
Plot of geometric mean grain size by reach over time at a) Calapooia River and b) Rogue River.
Symbols represent the mean value, and lines represent two standard errors from the mean.
Table 3.
Results of MRPP analysis for differences among taxonomically defined assemblages in both rivers.
Table 4.
Results of MRPP analysis for differences among functionally-defined assemblages in both rivers, according to a suite of 20 life-history, mobility, morphological, and ecological traits.
Figure 5.
NMS ordination plot according to the taxonomic structure of A) 3 upstream and 3 downstream riffles associated with the Brownsville Dam removal on the Calapooia River over three collection years, and B) 11 upstream and 11 downstream transects associated with the Savage Rapids Dam removal on the Rogue River over four collection years.
Note that the 11 transects from reach “DS2” have been removed from the figure to reduce clutter (see Table 3 for MRPP analysis of these data, including the DS2 reach). A) Final stress for the two-dimensional solution = 10.1. B) Final stress for a three-dimensional solution was 15.2, and the unpictured third axis had R2 = 0.21.
Figure 6.
NMS ordination plot according to the functional community structure (based on 20 benthic insect traits) of A) 3 upstream and 3 downstream riffles associated with the Brownsville Dam removal on the Calapooia River over three collection years, and B) 11 upstream and 11 downstream transects associated with the Savage Rapids Dam removal on the Rogue River over four collection years.
Note that the 11 transects from reach R-DS2 have been removed from the figure to reduce clutter (see Table 4 for MRPP analysis of these data, including the R-DS2 reach). The symbols follow the same explanation as in Figure 2. A) Final stress for the two-dimensional solution = 6.4. B) Final stress for the two-dimensional solution was 13.2.
Table 5.
Indicator values (IV) and p-values from Indicator Species Analysis (ISA) comparing reaches for each trait modality with a p-value < = 0.05 for A) Calapooia River and B) Rogue River.
Figure 7.
Mean %clingers (expressed as relative abundance, +/−2 standard errors) per reach across A) riffle sample units on the Calapooia, and B) transects sampled on the Rogue.
In both panels, year is on the x-axis, and lighter-colored bars represent the upstream reaches. Vertical dashed line shows timing of dam removal. Note that, in the interest of space, the second downstream reach is not plotted for the Rogue due to the lack of change over time.
Figure 8.
Mean %EPT (expressed as a proportion, +/−2 standard errors) per reach across A) riffle sample units on the Calapooia, and B) transects sampled on the Rogue.
In both panels, year is on the x-axis, and lighter-colored bars represent the upstream reaches. Vertical dashed line shows timing of dam removal. Note that the second downstream reach is not plotted for the Rogue River due to the lack of change over time.