| dc.description.abstract | Beaver ponds are a characteristic component of northern Ontario stream
ecosystem s and display a great deal of variation through their natural cycle of
establishment and abandonment. Ponds also provide habitat for brook trout (Salvelinus
fontinalis) within small-stream systems. However, the habitat characteristics of ponds
used by brook trout, and the characteristics of brook trout in the ponds is poorly
understood. I evaluated the local and landscape scale habitat characteristics of beaver
ponds that are associated with the presence, relative abundance and physical
characteristics of brook trout. Brook trout were captured in 40% o f 50 beaver ponds
sampled. Angling proved to be the most reliable method to sample brook trout in ponds,
however, catchability appeared to be strongly influenced by temperature. Catch per unit
effort (CUE) was significantly higher in ponds with water temperatures within the
approximate preferred thermal range of brook trout (11 ° C to 18 ° C) (ANOVA , F 2.48 =
5.259, p = 0.026). Peak CUE occurred between approximately 14 °C to 18 °C . Beaver
ponds with brook trout present were generally characterized by greater upstream
catchment area (UCA), lower water temperature, higher dissolved oxygen, higher
conductivity, higher alkalinity, and greater depth. Brook trout were never captured in
ponds with an upstream catchment area (UCA ) less than 2.9 sq. km. In a logistic
regression model, UCA correctly predicted brook trout presence and absence in beaver
ponds (82.4%). In beaver ponds with a mean water temperature greater than 11 ° C,
predicted group membership using UCA was greater (92.9%). Model parsimony and
predictive ability increased when beaver ponds with an overall mean water temperature
greater than 11 °C were used in the analysis. Brook trout captured in beaver ponds were,
on average, 105 mm and 72 g larger than those in adjacent streams (Pi,i32i = 1658.2, P <
.001). Brook trout average size in ponds was larger in smaller UCAs, whereas, brook
trout in streams were larger in larger UCAs. My research illustrates that beaver ponds
provide complimentary and/or supplementary habitat for brook trout living in stream
systems. It is clear that pond characteristics at both a landscape and local scale are
associated with brook trout presence or absence, likely through the ability of brook trout
to colonize the pond and the suitability and stability of habitat within the pond. Further
research is required to better understand the linkage between local and landscape scale
characteristics influencing brook trout habitat and abundance in small headwater streams
and insure the protection of these linkages from disturbance. | |
