Completed Research
January 1995 - December 1996
Contaminants
Avian Exposure to Agricultural Chemicals in Minnesota
Investigators: David E. Andersen
and Pamela F. McInnes
Duration: June 1991 to June 1995
Funding Source: U.S. Fish and Wildlife
Service, Region 3 Division of Environmental Contaminants
Project Location: Western Minnesota, Minnesota Cooperative Fish and Wildlife Research
Unit
Organophosphorus (OP) and carbamate insecticides are commonly used in agriculture across the United States. In Minnesota, farmers and applicators apply these insecticides to a variety of crops including sugar beets, field corn, sunflowers, potatoes, and wild rice. Because of their widespread use it is likely that non-target organisms in agricultural areas are exposed to these insecticides. OPs and carbamates inhibit cholinesterase in animals; this leads to the accumulation of the neurotransmitter acetylcholine. The build-up of acetylcholine in birds can lead to serious physical effects such as loss of coordination, loss of appetite, convulsions and respiratory collapse. Cholinesterase inhibition in blood and brain tissue can be measured in animals that are exposed to OPs and carbamates. We experimented with drawing blood from nestling birds near fields where OPs or carbamates were applied to evaluate the efficacy of this method as a tool for monitoring the exposure of birds to these insecticides.
In May and June of 1992, we selected four wetland sites near sugar beet fields and one site distant from sugar beet fields. We searched for nests of red-winged blackbirds (Agelaius phoeniceus) and other songbirds at these sites and monitored active nests. In addition, we contacted landowners and farmers to gather information regarding type and timing of insecticide applications near these sites. A total of 53 blood samples and 11 carcasses were collected. Serum and carcasses were analyzed for cholinesterase activity and for reactivation of cholinesterase. In addition, intestinal tracts were analyzed for the presence of insecticide residue.
Conclusion: Cholinesterase activity levels were lowest in nestlings at sites near insecticide applications. Plasma acetylcholinesterase reactivation appeared to be the most sensitive indicator of exposure, and provides a non-destructive sampling technique for monitoring exposure of non-target organisms to cholinesterase-inhibiting insecticides.
Effect of Bioturbation on the
Bioavailability of Metals in Sediments:
A Test of the Acid Volatile Sulfide Approach for Determining Metal Bioavailability
Investigator:
Gerald Ankley and Ira Adelman
Student: Gregory S. Peterson
Duration: January 1993 to December 1995
Funding Source: U.S. Environmental Protection Agency
Project Location: U.S. Environmental Protection Agency, Duluth; Minnesota
Cooperative Fish and Wildlife Research Unit
Recent studies have demonstrated the role of acid volatile sulfide (AVS) in controlling the bioavailability of several cationic metals in anoxic sediments. However, metal-sulfide complexes can be relatively labile with respect to oxidation associated with factors such as seasonal changes in rates of oxidation/production of AVS. Another potentially important mechanism of AVS oxidation in surficial sediments is bioturbation. The present study used different densities of the burrowing oligochaete Lumbriculus variegatus, in a series of laboratory experiments, to evaluate the effect of bioturbation on oxidation of AVS, and subsequent bioavailability of cadmium and zinc spiked into freshwater sediments. Metal bioavailability was determined directly by bioaccumulation in the test organisms and indirectly through analysis of interstitial (pore) water metal concentrations. In these studies, horizon-specific sediment analyses were conducted to assess spatial differences in AVS and pore water metal concentrations specifically related to organism activity.
Conclusion: Burrowing activity of the oligochaete significantly reduced AVS concentrations in surficial sediments in a density dependent manner, and resulted in elevated interstitial water concentrations of cadmium, but not zinc. Concentrations of cadmium in pore water from deeper horizons (below the zone of active burrowing) were consistently lower than those in the surficial sediments. The bioaccumulation of cadmium and zinc by L. variegatus was reflective of pore water concentrations of the two metals, i.e., there was significant accumulation of cadmium, but not zinc, by the oligochaetes. Overall, the results indicate that bioturbation can enhance the bioavailability of some cationic metals in surficial sediments, via oxidation of AVS, and demonstrate the importance of analyzing surficial sediments when assessing bioavailability of metals in sediments.
Impact of Sedimentation and Agricultural Chemicals on Wetlands in the Prairie Pothole Region of the United States
Investigators: Deborah L. Swackhamer and Mary Henry
Student: Carl Herbrandson
Duration: July 1992 to January 1996
Funding Source: U.S. Fish and Wildlife Service, Northern Prairie Wildlife Research
Center
U.S. National Biological Service, Northern Prairie Science Center
Project Location: Minnesota Cooperative Fish and Wildlife Research Unit
Wetlands in the Prairie Pothole Region (PPR) are critical to migratory
and resident wildlife in the Northern Great Plains. Wetland loss has been extensive
in the PPR with remaining wetlands occurring primarily in landscapes dominated
by agriculture. Wetland quality has been influenced by agriculture in the PPR,
but there is insufficient information available to guide management efforts.
Runoff from agricultural fields likely affects wetland fauna and flora, but
there are no studies available to guide management efforts. A confounding factor
in understanding agricultural impacts on wetlands and wetland biota is potential
interaction between effects of agricultural chemicals and sedimentation.
As a component of a larger study to identify how agricultural chemicals and
soils from eroded fields impact wetlands, this project involved developing methodology
and apparatus capable of isolating effects of sediments on bioavailability or
uptake toxicokinetics. A suspended solid testing apparatus was designed and
developed as a laboratory model of a contaminated natural environment and studies
were conducted to evaluate the toxicodynamic effects of simultaneous exposure
of an aquatic intertebrate to suspended solids and carbofuran. These experiments
demonstrated a synergism between the combined physical and chemical stressors.
Conclusion: Presence of sediments has an important synergistic effect
on toxicokinetics and bioavailability of carbofuran in aquatic macroinvertebrates.
Further, sensitivity to toxic chemicals alone or combined with suspended solids
can be modulated by adjusting food availability. This study demonstrated the
utility and sensitivity of suspended solid testing apparatus in a bioassay discriminating
between toxicokinetic and toxicodynamic effects of simultaneous exposure to
a chemical and suspended solids.
Human Activities, Management, and Conservation
An Evaluation of the Indirect Effects of Fluridone (Sonar®) on two Minnesota Lakes
Investigators: Bruce Vondracek and Donald L. Pereira
Student: Steven Pothoven, M.S.
Duration: July 1993 to June 1996
Funding Source: Minnesota Department of Natural Resources - Section of Ecological
Services and Section of Fisheries
Project Location: Carver and Hennepin Counties, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
Eurasian watermilfoil Myriophyllum spicatum invaded Minnesota in 1987 and is now found in 65 lakes and rivers. This study was part of a larger project by the Minnesota Department of Natural Resources to investigate using fluridone (tradename SONAR®), a broad spectrum, systemic herbicide to control milfoil. Changes in the fish community structure and predator-prey interactions due to vegetation removal were investigated as part of a three-year study. Three reference lakes and two treatment lakes were monitored one year prior to treatment (1993) and during two post-treatment years (1994-1995). The fish community was sampled with gill nets, trap nets, beach seines, purse seines, and electrofishing. We examined species composition, relative abundance (CPUE), and diversity of the fish community, and diet of the two major predators largemouth bass (Micropterus salmoides) and northern pike (Esox lucius).
In Zumbra Lake (a treatment lake), fish species richness decreased from 23 in 1993 to 16 in 1995. In Parkers Lake, bluegill abundance decreased significantly in 1995 and mean bluegill length increased significantly compared to 1993. Bluegill growth rates increased in both treatment lakes in 1994 compared to the previous 5 years, but remained constant in the three reference lakes.
Largemouth bass feeding efficiency (increased fish per stomach and decreased empty stomachs) increased during the initial treatment year and growth rates were higher in 1994 than the previous 3 years. Northern pike feeding efficiency did not improve, but diet composition related to prey distribution and vulnerability changed following herbicide application.
Conclusion: This study suggests that some species may respond rapidly to plant removal and these changes could influence the long-term composition of the fish community. Lakes with different fish and plant communities should be expected to respond differently to vegetation removal, and these differences should be considered before implementing a plant control program.
Conservation of the Loggerhead Shrike
Investigator: Francesca J. Cuthbert
Student: Matt Etter
Duration: June 1995 through December 1995
Funding Source: Minnesota Department of Natural Resources
Project Location: Minnesota
Historically the loggerhead shrike (Lanius ludovicianus) nested throughout the U.S., southern Canada and northern Mexico. Declines have been recorded in all portions of its breeding range. The most severe decreases have occurred in the upper Midwest and in New England, and it is a threatened species in Minnesota. The purpose of this study was to estimate the distribution and size of the population of loggerhead shrikes in Minnesota in 1995 and to compare these results to data from previous years to evaluate trends in the breeding population in Minnesota. In 1995, surveyors were asked to visit historical loggerhead shrike breeding territories three times each during the breeding season. These visits were planned to correspond to the expected shrike activities of pair-formation, nest-building-incubation, and brood rearing-fledging. Each visit lasted a maximum of two hours. All territories where loggerhead shrikes were known to nest at least once during the last ten years were visited. Additionally, all 1995 reports of shrike sightings were included in surveyors visits from the time of the report. Loggerhead shrikes were observed at 29 locations in Minnesota. Twenty-two shrike nests were discovered and an additional five cases were classified as inferred nesting because more than one shrike was observed on the territory on more than one occasion. We estimate there were 27 nest attempting by loggerhead shrikes in Minnesota in 1995. The 22 confirmed sites were all revisited after the end of the nesting cycle to record vegetation data and other habitat parameters.
Conclusion: This survey suggests that size of Minnesota's breeding population of loggerhead shrikes continues to decline. The 27 nesting attempts documented in 1995 occurred in 14 counties compared to 37 nesting attempts in 12 counties in 1987. In those same counties in 1995, we found 18 nesting attempts, suggesting a decline of 51%. Although our results indicate a decline, we believe there are aspects of shrike breeding behavior that make data interpretation difficult. For example, breeding loggerheads appear to cluster their nesting attempts in certain regions of the state. These clusters may occur in the same area for only a short time (one to several breeding seasons). Therefore, direct comparisons of county estimates may be misleading. Resolution of this survey problem depends on improved knowledge of breeding shrike distribution and habitat preference in Minnesota.
Virtual Reality Interface for Landscape Visualization
Investigator: C. A. Johnston
Duration: June 1995 to June 1996
Funding Source: U. S. National Biological Service
Project Location: University of Minnesota, Natural Resources Research Institute,
Duluth, MN
We developed a software interface that combines the visualization capabilities of virtual reality with the spatial display capabilities of GIS. Landscapes are rendered as perspective views using actual elevation and land cover data, such that they depicted realistic scenery. The user can specify a vehicle (e.g., airplane, all-terrain machine) and a path for travel, viewing landscape features from different perspectives. We use the term "virtual reality" to denote a system that provides the tools for users to interact with a simulated environment, but not necessarily in real time.
The ultimate goal of the research was to develop a prototype virtual reality interface with data from the Mid-Atlantic Integrated Assessment (MAIA) region, in support of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP). The MAIA region falls in the states of PA, VA, WV, DE, NJ, and MD, and the District of Columbia, and includes the entire Chesapeake Bay watershed. Virtual rendering was accomplished with two basic datasets: (1) digital elevation models (DEMs), and (2) land cover data derived from classified satellite imagery.
Accomplishments: (1) interface DEM with virtual reality software, (2) drape classified land cover over DEM, (3) set camera location, elevation, and view angle, and (4) render image, enabling 3-D structures.
Applied Ecology
Ecology of the Boreal Owl in Northeastern Minnesota
Investigator: David E. Andersen
Student: William H. Lane, M.S.
Duration: 1987-1994
Funding Sources: North Central Forest Experiment Station, U.S. Forest Service,
Minnesota Department of Natural Resources Nongame Wildlife Program
Project Location:
Lake and Cook Counties, Minnesota Superior National Forest
Studies of boreal owls (Aegolius funereus) have been conducted primarily in Europe, the western U.S., and boreal Canada. Little is known about boreal owls in eastern North America, especially at the southern extent of their breeding range. In Minnesota, boreal owls occur during winter irruptions, but had been documented as a nesting species only three times prior to 1987. From 1987 through 1992, nocturnal, auditory surveys were conducted to determine the distribution, status, and habitat associations of boreal owls in northeast Minnesota, primarily within the Superior National Forest. During the six years that surveys were conducted, indices to abundance ranged from 0.059 to 0.219 singing males per km of survey route. Analysis of habitat composition along survey routes indicated that both conifer stands and upland hardwoods were associated with owl presence.
Twenty nest sites were located based on auditory surveys and were subsequently monitored, suggesting that boreal owls are a resident, breeding species in the state. Upland trembling aspen (Populus tremuloides) was selected as the substrate tree in 46 (93.9%) of 49 observations of owls at cavities. The average age of cavity trees was over 85 years, and most nest cavities were located in upland hardwood habitats.
Beginning in 1990, 10 male boreal owls were fitted with radio transmitters to document habitat use. Ninety-eight of 107 (91.6%) diurnal roost sites occurred in lowland conifer habitats, with black spruce (Picea mariana) identified as the roost tree on 94 (81.7%) of 115 occasions. Minimum Convex Polygon home range size averaged 425 ha prior to nest failure, and increased dramatically after a nesting attempt failed.
Conclusion: Boreal owls consistently occurred as a breeding resident in northeast Minnesota throughout the 6 years of this study. At the landscape level, boreal owls occurred in association with lowland spruce and upland hardwood habitats. Lowland spruce habitats appeared to be important for hunting, and nest cavities occurred in older aspen stands. Current management considerations that focus only on the nest stand likely underestimate the extent of habitats required by breeding boreal owls in northeast Minnesota.
Population Dynamics of Paddlefish in the Lower Wisconsin River
Investigator: Bruce Vondracek
Student: Ann L. Runstrom, M. S.
Duration: September 1992 to November 1996
Funding Source: U.S. Fish and Wildlife Service, Region 3 Fisheries Wisconsin
Department of Natural Resources
Project Location:
Lower Wisconsin River, Prairie du Sac, Wisconsin
Minnesota Cooperative Fish and Wildlife Research Unit
U.S. Fish and Wildlife Service, LaCrosse
Fishery Resources Office, Winona, Minnesota
Paddlefish (Polyodon spathula) were previously listed as a Category 2 species on the Federal Endangered Species List. Category 2 describes taxa which may be at risk, but for which data on vulnerability and threat are not currently available. Data on the status of paddlefish in the upper Mississippi River basin are particularly lacking. Investigations into the dynamics of this species' populations are necessary to determine the level of endangerment.
A mark-recapture study of paddlefish in the lower Wisconsin River was conducted during 1993 and 1994. Study objectives were to (1) estimate population size, size-structure, age-structure, and mortality rates; and (2) determine the feasibility of transferring adult paddlefish from the study population to an upstream reach of river where immigration is blocked by a hydropower dam and the species has been extirpated.
Paddlefish were sampled in the tailwaters of the Prairie du Sac dam
with drifting and deadset trammel nets. Length (body, fork, and
total) and
weight were recorded for each fish captured. Fish were tagged
on the
mandible with a #16 monel band. Age of each fish was estimated
indirectly using a regression model of age vs fork
length generated with paddlefish sampled from pools 11-13 on
the Mississippi River.
Mark-recapture data from 1993 and 1994 were applied to Chapman's modified Schnabel, Schumacher-Eschmeyer, modified Jolly-Seber, and adjusted Petersen models to estimate population size. Estimates of population size ranged from 540 to 1,714 individuals. Size- and age-structure data indicated recruitment between 1993 and 1994 was minimal. Estimates for annual mortality ranged from 29 to 33%. These results suggest the population could be declining at present.
Conclusion: Population estimates in 1993 and 1994 were not significantly different. Comparison of the age-class structure from 1993 to 1994 indicates that no recruitment took place between sampling periods. Instantaneous mortality rate appears high for an unharvested population. However, these fish congregate in an area used heavily by anglers and mortality may be higher as a result of boat-paddlefish collisions.
Red-Shouldered Hawk Breeding Ecology and Habitat Use in Central Minnesota
Investigator: David E. Andersen
Students: B. Ann Belleman, M.S. and Mary Anne McLeod, M.S.
Duration: April 1994 to June 1996
Funding Source: Minnesota Department of Natural Resources U.S. Forest
Service, Chippewa National Forest
Project Location:
Camp Ripley National Guard Training Site, Minnesota
Pillsbury State Forest, Minnesota
Chippewa National Forest, Minnesota
Red-shouldered hawk ( Buteo lineatus) populations have likely declined throughout the Northeast, Midwest, California, and eastern Canada over the past 50 years. Reduction in extent and changes in quality of habitat have been major factors contributing to this decline. In Minnesota, a recent Generic Environmental Impact Statement on Timber Harvesting and Management in Minnesota predicted that the red-shouldered hawk population would decline statewide under all projected timber harvesting scenarios during the next 50 years. This species has not been extensively studied in Minnesota and limited information exists on population status, density, breeding ecology or habitat selection.
In April 1994, we began studying red- shouldered hawks centered at Camp Ripley Army National Guard Training Site (CRANGTS) and the Chippewa National Forest (CNF) in central Minnesota. Our objectives were to: (1) estimate and describe breeding density and reproductive success, breeding chronology and food habits of breeding red-shoulders, (2) describe habitat characteristics and use of red-shoulder nest sites, (3) compare habitat use of breeding red-shoulders across a range of landscapes in central Minnesota, and, (4) evaluate methods for surveying red-shouldered hawks.
Over the 2-year period, 38 red-shoulder nesting attempts were located on or near the CRANGTS and 81% of nesting attempts fledged at least 1 young and in total produced at least 55 young. On the CNF, 20 nests were located, and of the 10 nests were egg-laying was documented, only 2 fledged young. Analysis of survey data suggests that playback of red-shouldered hawk calls illicit more and quicker responses than playback of great horned owl calls. Response rate was highest during incubation. Habitat analyses indicate that red-shoulders nest in older forests interspersed with small wetlands.
Conclusion: Red-shouldered hawks nest at high densities in north central Minnesota, and on CRANGTS had high nesting success. On the CNF, nesting success and productivity were poor, and may be related to food availability. In north central Minnesota, red-shoulders occur in older hardwood habitats and are not restricted to nesting in forested floodplains, as they seem to be in other portions of their breeding range. Evaluation of survey methodology suggests that call-broadcast from roads may be useful in monitoring population trends, and that using red-shouldered hawk calls during incubation would be most effective.
Spawning Habitat and Summer Microhabitat Use of
a Northern
Population of Adult Smallmouth Bass
Investigator: Bruce Vondracek
Student: Paul Mavrakis, M.S.
Duration: June 1993 to June 1994
Funding Source: Electric Power Research Institute (EPRI)
Minnesota Power
Project Location: Cloquet River, Minnesota
Minnesota Cooperative Fish and Wildlife Research Unit
Little is known about spawning habitat and summer microhabitat use for adult smallmouth bass (Micropterus dolomieu) in the northern part of their range. This study, in a 1.5 km section of the Cloquet River, in northern Minnesota included 3 objectives: (1) Identify sites used for spawning and determine availability of suitable spawning habitat, (2) Determine the availability and use of suitable summer microhabitat, and (3) Test for a relation between adult smallmouth bass and crayfish habitat use.
Habitat availability was quantified by 20 transects (1021 point measurements) distributed throughout the study reach during low flow and high flow conditions. Nine spawning sites were located by snorkeling surveys when water temperature approached 15· C and were monitored throughout the spawning season to determine success of nests. None of the nests were successful, i.e., did not reach fry dispersal stage, during the study due to high water early in the spawning season. Physical characteristics were consistent at all nests: low mean water column velocity (<0.06m/s), intermediate depth (>0.4m), and close proximity to cover.
Adults selected the deepest water available, intermediate mean water column velocities, and course gravel to large boulder substrates. Crayfish were an important part of the adult smallmouth bass diet; 92% of the smallmouth bass that contained food, ingested at least one crayfish. Smallmouth bass used similar mean water column velocities and substrates as crayfish.
Conclusion: Spawning habitat and summer microhabitat for adult smallmouth bass appears to be limited in the Cloquet River. The study reach contained <10% suitable spawning habitat at low flow and 3% at high flow. Less than 7% of the study reach at low flow and 10% at high flow had suitable summer microhabitat.
Minnesota Cooperative Fish and Wildlife Research Unit
University of Minnesota
Department of Fisheries, Wildlife, and Conservation Biology
1980 Folwell Avenue, 138 Hodson Hall
St. Paul, MN 55108
phone: 612-624-3421
fax: 612-625-5299
coopunit@tc.umn.edu