| dc.description.abstract | Smallmouth bass and rock bass co-occur throughout much of their respective ranges and
are believed to be ecologically similar. As a result, they are often placed into the same
functional guild in ecological analyses, yet no such formal analysis of their relationship
has been conducted. Smallmouth bass and rock bass clearly exhibit similar spawning
behavior; both species spawn in shallow water in early spring and timing of spawning,
along with similar habitat use could create competition between these two species,
particularly when habitat is limiting. This study evaluated spatial and temporal overlap
of spawning by sympatric smallmouth bass (Micropterus dolomieu) and rock bass
(Ambloplites rupestris) in three north temperate lakes that have distinctly different littoral
zone habitat compositions. The objectives of the study were to assess spawning habitat
in relation to available habitat for smallmouth bass and rock bass and to assess the degree
of spawning separation that occurred both spatially and temporally. Locations of
smallmouth bass and rock bass nests in lakes were surveyed every other day during the
spawning season using snorkel and SCUBA gear. Initial date of egg deposition was
recorded for nests of both smallmouth bass and rock bass and nest site characteristics
were then quantified. To assess habitat selection, logistic regression was used to compare
sites where nests of each species were found relative to random sites in each lake. Linear
discriminant analysis was used to assess degree of habitat overlap between smallmouth
bass and rock bass nest use. The quantitative data from this study showed that spawning
habitat selection by smallmouth bass and rock bass was similar; coarse substrates (sand
and gravel) and wood or rock cover were selected by both species in all three study lakes.
Smallmouth bass and rock bass were also found to overlap in the time they occupy nest
sites (>50% in all three study lakes). Nest sites can be discriminated by how smallmouth
bass and rock bass utilized similar microhabitat such as the placement of nests relative to
cover and the amount of gravel substrate found in the nest. These results suggested
smallmouth bass and rock bass can be placed in the same spawning guild for use in
ecological analyses, yet show differences that allow both species to successfully coexist. | en_US |
