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Technical Assistance to the National Park Service
The International Falls Biological Station (IFBS) is a component of the
Field Station Research Branch of the Columbia Environmental Research Center
(CERC), U.S. Geological Survey, Columbia, MO. The CERC has a regional mission of
ecosystem science for large rivers and other ecosystems in the Central Region of
the USGS. The CERC conducts aquatic research that focus on the effects of
various anthropogenic and natural environmental stressors. National Park Service
units in the Great Lakes Basin and adjoining watersheds require the results of
such research as well as science-based monitoring systems to assist in their
management of aquatic ecosystems. The IFBS provides aquatic research and
technical support to these NPS units to assist resource managers in the
protection of the aquatic ecosystems in these units. The efforts of the IFBS are
primarily directed toward the identification and prediction of factors such as
reservoir management regimes, invasive species, environmental contaminants, and
fisheries management practices and the effects of these factors on the health
and viability of natural resources within the parks units. This project is
conducted to provide technical information and guidance to National Park Service
managers in order that they can develop and implement scientifically sound
management programs.
Assessing
Ecological Impacts of Exotic Rainbow Smelt (Osmerus mordax) in the Major Lakes
of Voyageurs National Park
The fish stocks of the four dominant water bodies of Voyageurs National
Park,
Rainy, Namakan, Sand Point, and Kabetogama Lakes, are subjected to many of
the same anthropogenic factors that have affected the nearby Great Lakes. The
most recent perturbation was the invasion of rainbow smelt (Osmerus mordax) in
Rainy and Namakan Lakes. Rainbow smelt, which colonized numerous areas in the
upper Rainy Lake watershed after being introduced by humans (Franzin et al.
1994), first appeared in Rainy and Namakan Lakes in 1990. Based on studies
conducted elsewhere, the rainbow smelt may have a significant effect on the Park's aquatic ecosystem, and in particular its interactions with cool- and
cold-water fish species (Evans and Loftus 1987). Due to their intermediate
trophic position as consumers of plankton, and as
prey for top predators, rainbow smelt have the potential to introduce a wide
array of ecological impacts from both direct and indirect effects (Kerfoot and
Sih 1987, Carpenter 1988). Another ramification of the establishment of rainbow
smelt may be elevated mercury levels in fish-eating animals. Traditional sampling
techniques (gill nets, seines, trap nets, and electrofishing boom shocker) are not effective for sampling
rainbow smelt. The integration of combined hydroacoustic
assessment and mid-water trawling appears to be the most promising method for
quantifying stock structure, distribution, changes in abundance, and other vital
statistics of rainbow smelt as well as other members of the endemic pelagic fish
community. This study will implement an acoustic and trawl
assessment strategy that will integrate quantitative assessments of rainbow
smelt and other pelagic fish species with established fish surveys in Rainy and
Namakan Lakes. This information will be used to summarize the available
knowledge of these aquatic ecosystems, then to derive various system parameters
for predicting the ecosystem response to rainbow smelt with mass balance
modeling (Christensen and Pauly 1992). Also applied will be acoustic
techniques to assess the abundance and ecological distribution of the opossum shrimp
(Mysis relicta) with acoustic techniques. Mysis are an important
constituent of the food web in these and other glacial lakes.
Determine the historical impact of water-level management on Rainy Lake and Namakan Reservoir in Voyageurs National Park. Damming of the Rainy Lake-Namakan Reservoir system in the early 20th century has resulted in nearly 100 years of water-level manipulation for logging and hydropower. In the 21st century, water-level management is a critical issue for managers at Voyageurs National Park. Recent changes in hydro-management were instituted by the International Joint Commission (2000 rule curves) to produce a more natural hydrologic regime in the Rainy Lake-Namakan Reservoir. Critical in this decision was a recommendation for monitoring impacts of the revised controls; however, with few historical or background data, determining the impacts will be challenging. A paleolimnological study of four lakes of contrasting management and size in VOYA is being used to reconstruct the timing and magnitude of environmental impacts of damming, water-level manipulation, and land use changes using quantitative reconstruction of environmental variables from lake sediment geochemistry and microfossils. Pre-damming/pre-settlement trophic conditions and "natural" variability for each lake system is also being determined.
Assess impacts of lake level management with an interdisciplinary/international approach: effects on the fish community of changes in the water management program for Rainy Lake and Namakan Reservoir. In January 2000, the International Joint Commission (IJC), an organization established by treaty to help prevent and resolve disputes over the use of waters along the United States-Canada boundary issued a new supplementary order (2000 Order) for the management of Rainy Lake and Namakan Reservoir, which lie along the international boundary between Minnesota and Ontario. While these lakes existed as natural water bodies, they have been regulated by privately-owned dams since the early 1900s.Water management of these shared border waters is the most significant natural resource issue for Voyageurs National Park (VNP), and is also a significant issue for the Minnesota Department of Natural Resources (MNDNR) and the Ontario Ministry of Natural Resources (OMNR). When the IJC instituted its 2000 Order which restored a more natural hydrologic regime, particularly on Namakan Reservoir, they stated that the new Order was subject to review after 15 years and they charged the natural resource agencies with the task of implementing a monitoring and research program to determine if the new hydrological regime had provided the anticipated ecological benefits.
In 2004, monitoring and studies of fish, common loons, benthos, aquatic plants, and muskrats were initiated that will provide before and after comparisons with the data collected in the 1980s. The fish communities, because of their ecological and economic importance and the significant role they played in the discussions leading up to the water management change, are a critical component of the evaluations. To determine whether the hypothesized habitat limitations for walleye, northern pike, lake whitefish, and cisco have been reduced or eliminated by the water management change, the USGS-IFBS and the resource agencies are conducting a collaborative study utilizing existing long-term monitoring programs, new monitoring programs, and specific research investigations.
Effects of changes in reservoir operations on mercury concentrations in yellow perch and corresponding effects on larger game fish in Voyageurs National Park. Two of the most significant water resource issues in Voyageurs National Park are water management of the Park’s large lakes and mercury contamination of the food web. Long-term monitoring results from one of the Park lakes suggest these issues are linked, with mercury levels in yellow perch being positively correlated with annual water level fluctuations. Thus, the reduced water level fluctuations associated with the International Joint Commission’s 2000 Order for Namakan Reservoir may contribute to lower total mercury concentrations in young of the year yellow perch. The potential food web implications of this are significant since yellow perch are the primary prey of walleye and northern pike, which currently have high enough mercury concentrations to make consumption advisories necessary. This three year study (1) tests the fit of the current prediction by determining the relationship between hydrological conditions and mercury concentrations in yellow perch in 15 lakes, and (2) determines which environmental variables, in combination, are the most reliable for predicting mercury levels in fish.
Relative abundance and distribution of lake sturgeon (Acipenser fulvescens) in Rainy Lake, Minnesota and Ontario. Restoring the lake sturgeon, which is a Minnesota state-listed Species of Special Concern, to their former high levels of abundance in the internationally shared waters of Rainy Lake is a high priority for Voyageurs National Park, the Minnesota Department of Natural Resources, and the Ontario Ministry of Natural Resources. Management efforts of these agencies have been hampered by a lack of information on the current status of the population. This project focuses on determining the relative abundance of lake sturgeon and on identifying and characterizing their preferred habitats, particularly spawning habitats. Lake sturgeon that have been implanted with combined acoustic/radio transmitters are tracked to determine habitat use and spawning locations. The resulting data in combination with existing hydrological and reservoir morphometric data will enable the resource agencies to develop specific water management models that will be beneficial to the lake sturgeon.
Population characteristics and angler use of muskellunge (Esox masquinongy) in Shoepack Lake, Voyageurs National Park, Minnesota. This project addresses the need for basic biological and exploitation information to ensure the long-term viability of the genetically unique Shoepack Lake muskellunge population (SLMP) in Voyageurs National Park. The SLMP, like most of the self-sustaining muskellunge populations that still exist, is potentially at risk from over-exploitation and loss of genetic integrity due to small population size. Objectives of this study are to (1) quantify characteristics such as abundance, sex ratio, age structure, fecundity, growth and condition, (2) quantify angler pressure, catch rates, and exploitation, (3) estimate genetically effective size, and (4) explore potential threats to conservation through population viability size.
Effect
of Exotic Rainbow Smelt on Nutrient/Trophic Pathways and Mercury Contaminant
Uptake in the Aquatic Food Web of Voyageurs National Park
From biological and political perspectives, a significant issue results because
of the possible effects of the introduction, both incidental and intentional, of
exotic fish species and non- native fish genotypes on the aquatic ecosystem of
Voyageurs National Park and many other national parks. Rainbow
smelt, which were
first found in Voyageurs National Park waters in 1990 could have significant
effects on the parks aquatic ecosystem and in particular its cool- and
cold-water fish species. Their invasion could conceivably make an already bad
mercury contamination problem worse since there is some evidence that the rate
of mercury accumulation in top level piscivores accelerates when they switch to
a diet of smelt. In this study, stable isotope ratios of carbon and
nitrogen are being determined from various food web components collected from
four selected lake sites within Voyageurs National Park. Results of this study
will be used to estimate the aquatic food web links between plants, benthos,
plankton, and selected fish. Using
stable isotope differences and similarities to estimate aquatic food web
linkages, implications regarding the bioaccumulation of contaminants will be
studied by measuring mercury and selenium levels in the same samples studied for
isotope ratios. Food habits studies of the principal forage and predator fish
species are also being conducted to further identify linkages in the aquatic
food web. This research will (1) survey the nutrient and trophic pathways for
exotic rainbow smelt and native fish in lakes within Voyageurs National Park and
(2) estimate the role of rainbow smelt in contaminant uptake by game fish for
these lakes.
Evaluation of the Relation Between
Exotic Rainbow Smelt, Osmerus mordax, and Native Cisco,
Coregonus artedii
Rainbow smelt, which colonized numerous waters in the upper Rainy Lake watershed
after being introduced by humans, first appeared in the waters of Voyageurs
National Park in 1990. Based on studies conducted elsewhere, the smelt could
have significant negative effects on the parks aquatic ecosystem, and in
particular its cool- and cold-water fish species. This is particularly true for cisco, (Coregonus artedii) and
lake whitefish (Coregonus clupeaformis), the two
native coregonines in the park. These two fish species have frequently been
found to be adversely affected by the invasion or introduction of rainbow smelt.
Zooplankton communities will be monitored and described for those lakes
where the effects of rainbow smelt are being evaluated. To allow detection of
temporal and spatial variation, sampling will be done at four stations at
biweekly intervals throughout the open water season using vertical haul nets.
Rainbow smelt and cisco will be collected at monthly intervals using mid-water
trawls and small-mesh gillnets. Fish will be measured and stomachs removed and
preserved for food habits analysis. Electivity indices will be calculated using
the proportion of the organisms in the fishes diet and the proportion of the
same organisms in the zooplankton samples. Results of the analysis of the smelt
stomachs will also provide an indication of degree of predation on other fish
species. The existence of zooplankton data collected before the smelt invasion
will allow an assess whether smelt predation is altering the composition of the
zooplankton communities. This research will assess possible competition between
rainbow smelt and cisco for zooplankton and other food resources.
Genetic
and Morphological Distinctness of Three Cyprinid Species from Isle Royale and
Voyageurs National Parks
On the basis of morphological measurements, previous investigators concluded
that three cyprinid species, fathead minnow (Pimephales promelas),
blacknose
shiner (Notropis heterolepis), and pearl dace (Margariscus margarita), from
Harvey Lake in Isle Royale National Park were unique enough to warrant
subspecific status. Other investigators, however, have questioned these
designations and concluded the Harvey Lake fish do not merit such designation. Samples of the three species will be collected from Harvey Lake and other
lakes on Isle Royale, from mainland sites along the north shore of Lake Superior
in Minnesota, from lakes and ponds in Voyageurs National
Park, and from waters
in the upper Mississippi River drainage. This will result in our having samples
from three major drainages: Great Lakes, Hudson Bay, and Mississippi. Genetic
analyses will be conducted using the microsatellite DNA analysis technique.
Allelic type and frequency at each locus will be statistically analyzed to
determine if there is significant population structuring present. The results of
these analyses will be analyzed statistically using Wrights Fst statistics.
Morphological measurements will be made from fish from the same sites as those
for which genetic analyses have been made.
Genetic
Variability of Isle Royale Walleye, Stizostedion vitreum
The fauna and flora of Isle Royale National Park represent a unique assemblage
of species from eastern and western glacial refugia that have seemingly escaped
some of the successional changes that characterize the eastern and western
regions. However; the genetic variability and relatedness of species in the fish
communities are not known. Walleye, which occur in only two lakes on Isle
Royale, is one species where such questions exist. It has been suggested that
the two walleye populations were established by stocking in the 1920s, but there
is no evidence that verifies this. The current study will (1) document the
genetic characteristics and variability of walleye from Chickenbone and
Whittlesey Lakes in Isle Royale National Park and (2) assess the probability of
whether the Isle Royale walleye are native or were introduced by comparison with
genetic characteristics of other walleye populations in the Great Lakes and
possible hatchery sources.
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