Pre-Habitat Enhancement Construction Monitoring (2016)
Habitat characteristics for egg incubation indicated statistically
significant differences in substrate composition, with a higher use of
hard substrates observed at locations with eggs than without (Table I).
We observed substantial variations in substrate composition in the
Tailrace Area, where egg plots had a mean percentage of fines of 0.8%
compared to non-egg plots with 77.5% fines (Figure 2A). Similarly, the
mean percentage of gravel in the Tailrace Area was 58.3% in egg plots
and 4.2% in non-egg plots (Figure 2A). Similar trends were observed in
Reach 1, although the magnitude of the effect was less pronounced
compared to the Tailrace Area, with an interacting effect of fines and
study reach (Table I). Within Reach 1, the largest absolute difference
in substrate composition was observed for cobble, with a mean percentage
of 58.1% in egg plots compared to 37.8% in non-egg plots. The dominant
habitat types differed between the two study reaches, with gravel cover
(31%) and fines (39.2%) being more prevalent in the Tailrace Area,
while boulder cover (37.9%) and cobble cover (34.5%) dominated in
Reach 1 (Table I). Additionally, the survey data indicated that plots in
the Tailrace Area were significantly deeper, with a mean depth of 0.74
m, compared to plots in Reach 1, which had a mean depth of 0.59 m (Table
I).