Research Topics Ecosystem Processes
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Sierra Nevada Ecosystems
Sierra Nevada Ecosystems
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Title
Impacts of invasive species (non-native trout) on
native biota of Wilderness lakes and future restoration strategies
for balancing fish stocking and native species.
Study Plan
Research Project Summary
The Research
Since 1995, the US Forest Service Pacific Southwest Research Station
Aquatic Ecology Group has been involved in studying the effects
of the widespread introduction of non-native trout on the native
high elevation lake fauna in the Sierra Nevada. Kathleen Matthews
and Roland Knapp (UCSB, Sierra Nevada Aquatic Research Laboratory)
conducted the High Mountain Lake Project where the impacts of fish
stocking were assessed by surveying over 2000 lakes in the John
Muir Wilderness (where fish stocking continues) and the adjacent
Kings Canyon National Park (where fish stocking was terminated).
The results of the studies indicated a strong negative effect of
introduced trout on the distribution and abundance of the mountain
yellow-legged frog, Rana muscosa, and the Pacific treefrog,
Hyla regilla, and these results are published in Conservation
Biology, and International Journal of Wilderness, and
Copeia. The research also found a deleterious effect of non-native
trout on macroinvertebrates, zooplankton, and the mountain garter
snake Thamnophis elegans elegans, a native predator that
is apparently dependent upon amphibians. The researchers observed
a strong association between amphibian presence and garter snake
presence and the probability of finding snakes in lakes with amphibians
was 30 times greater than in lakes without amphibians. Moreover,
lakes with snakes had higher numbers of amphibians than did lakes
without snakes. The introduction of trout into an ecosystem can
have serious effects, not just on their prey, but also on other
predators in the ecosystem.
More recent analyses of the lake survey data looked at the resistance
and resilience (the degree to and the rate at which a system returns
to its previous configuration once the perturbation is removed)
of the alpine communities once fish were removed and the results
are reported in Ecological Monographs. Faunal assemblages
in the study lakes had low resistance to fish introductions, but
in general showed high resilience once fish were removed. The results
of the high mountain lake study are instrumental for conservation
of native species in the Sierra Nevada.
Objectives
Methods and Design
Application of Research Results
Location
Lead Scientists/Collaborators
1.)Matthews, K.
USDA Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
1.)ph: 510-559-6454
fax: 559-868-3491
Publications and Reports
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