CSU Fisheries Ecology Laboratory
Chemic
Funded by: U.S. Bureau of Reclamation, Upper Colorado River Endangered Fish Recovery
Program
2006-2009
Students
and Postdocs
Collaborators
Patrick Martinez, Colorado Division of Wildlife
Alan Koenig, USGS Mineral Resources Team
Background/Rationale
Nonnative fishes are present throughout the Upper Basin (Martinez 2002, Trammel
et al. 2002), and can adversely impact the recovery of endangered fishes
through predation or competition at critical life stages or in critical
locales. However, the recruitment sources and origins of nonnative fishes
are not well known. Immigration of nonnative fishes from nearby reservoirs has
been demonstrated in some cases by the recapture of fishes that had been tagged
as part of other studies. However, large scale tagging efforts to address
the growing concern about escapement of nonnative piscivores from multiple
reservoirs throughout the Upper Basin is impractical. This project seeks
to verify fish escapement from reservoirs as a source of nonnative fish entering
critical habitat by applying newly developed techniques for identifying
naturally occurring markers via microchemical analysis of otoliths.
Otolith microchemistry provides a means to trace the origins and movements of
fishes in marine and freshwater environments. In freshwater systems
differences in underlying geology can result in water chemistry that varies
among watersheds. Limnological processes and chemical transformations
within reservoirs impart further distinctiveness to water chemistry among lentic
and lotic water bodies. Chemical composition of ambient water is imparted
to otoliths of resident fish in a highly predictable and temporally referenced
manner. Because otoliths are physiologically inert structures their
chemical composition does not change after material is accreted. Thus,
otoliths record the environmental history of a fish and that information can be
used to determine the fish’s provenance (origin and movements).
Recent
work by our lab has demonstrated that otolith microchemistry has excellent
potential for tracing the provenance of nonnative fishes in the Upper Colorado
River Basin. Further, graduate work by CSU students Ryan Fitzpatrick and Daniel
Gibson-Reinemer is showing that many water bodies (ponds, streams,
reservoirs) and hatcheries in Colorado possess unique chemical fingerprints,
and that these fingerprints are imparted to the otoliths of fish originating
from each location. It also appears that transfers of fish can be
detected in otoliths as shifts in the chemical composition along laser
transects performed with laser ablation inductively coupled plasma mass spectrometry
(LA-ICP-MS). These findings coupled with the highly heterogeneous nature
of the Colorado Plateau’s geology suggest that otolith microchemistry is likely
to reveal new insights into the movements of nonnative fishes within the Upper
Colorado River Basin.
Hypotheses
We hypothesize that:
a. the chemical composition (fingerprints) of otoliths from nonnative
fishes will differ among reservoirs,
b. inter-annual variation in otolith fingerprints will be small relative
to inter-reservoir differences,
c. otolith core signatures of fishes that were reared in reservoirs and
immigrated to rivers in critical habitat will be distinct from signatures
of fishes inhabiting rivers since hatching, and
d. otolith core signatures can be used to identify fishes as having
originated from a particular reservoir.
Study Goals
Determine chemical “fingerprints” of nonnative fishes in reservoirs that are
potential sources of nonnative fishes to critical habitat and investigate
provenance of nonnative fishes in rivers downstream of potential sources.
Study Objectives
- Quantify
chemical “fingerprints” of fishes within study reservoirs and evaluate the
degree of inter-annual variation in those fingerprints.
- Determine
if fish sampled in rivers the vicinity of study reservoir possess otolith
core signatures that identify them as having originated from one of the
study reservoirs.
- Improve
our understanding of the degree to which immigration or transfers from
reservoirs contributes to the load of nonnative fishes in critical habitat
of the Upper Colorado River basin.
- Provide
recommendations to guide management efforts to reduce the influx of
nonnative fishes from reservoirs.
Dr. Brett M. Johnson
Department of Fish, Wildlife and Conservation Biology
1474 Campus Delivery, Colorado State University,
Fort Collins, CO 80523-1474
voice: 970-491-5002, fax: 970-491-5091
email:
brett.johnson"at"colostate.edu (replace “at” with @)
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