Stefan H.G.,University of Minnesota |
Pereira D.L.,00 Lafayette Road
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2010
An empirical model was developed that describes the influence of lake productivity, climate, and morphometry on coldwater fish oxythermal habitat. An oxythermal habitat variable called temperature at 3 mg·L-1 of dissolved oxygen (TDO3) was developed by interpolating the water temperature at a benchmark oxygen concentration (3 mg·L-1) from a temperature-oxygen profile. Coldwater habitat was most available in the least productive lakes (total P < 25 μg·L-1) with the greatest relative depths (geometry ratios < 2 m-0.5) and where mean July air temperatures were less than 17 °C. Species response curves were developed from values of TDO3 measured during the greatest period of oxythermal stress in late summer (maxTDO3). Lake trout was present in lakes with the lowest values of maxTDO3, while cisco was present in lakes with the highest and broadest range of maxTDO3. Projections for a scenario where climate warming (+4 °C in mean July air temperature) was accompanied by eutrophication (doubling of total P) indicated that coldwater fish oxythermal habitat would be devastated in a subset of lakes typical for Minnesota. Protecting deep, unproductive lakes from eutrophication will be a necessary management strategy to ensure that coldwater fish persist in at least some Minnesota lakes after climate warming.
Sietman B.E.,00 Lafayette Road |
Hove M.C.,University of Minnesota
American Malacological Bulletin | Year: 2012
Diverse strategies have evolved in freshwater mussels to promote the transfer of their parasitic larvae to host fish. Among these, modification of the mantle as a host attracting lure has been well-documented in the Tribe Lampsilini, but only recently reported in the Tribe Quadrulini. Here we describe mantle modifications and glochidia release behaviors in five quadruline species, including members of the Quadrula quadrula (Rafinesque, 1820), Q. pustulosa (Lea, 1831), and Q. metanevra (Rafinesque, 1820) species groups. Displays were motionless and consisted of inflated mantle tissue surrounding the excurrent aperture. Gross display morphology was largely variable among species: Q. fragosa (Conrad, 1835) and Tritogonia verrucosa (Rafinesque, 1820) had relatively large, uniquely shaped displays; Cyclonaias tuberculata (Rafinesque, 1820) and Q. pustulosa had smaller, stomate-shaped displays; and Q. metanevra had a diminutive, polyp-like display. Cyclonaias tuberculata exhibited a bimodal host infection strategy where individuals had either a mantle display or released a gelatinous conglutinate. Quadrula pustulosa and Q. metanevra expelled glochidia in a forceful burst when their displays were touched. Quadruline mantle displays do not clearly mimic identifiable aquatic organisms suggesting they may represent non-specific food items to their fish hosts.
Ahrenstorff T.D.,University of Minnesota |
Hrabik T.R.,University of Minnesota |
Pereira D.L.,00 Lafayette Road
Oecologia | Year: 2013
The movement patterns and body size of fishes are influenced by a host of physical and biological conditions, including temperature and oxygen, prey densities and foraging potential, growth optimization, and predation risk. Our objectives were to (1) investigate variability in vertical movement patterns of cisco (Coregonus artedi) in a variety of inland lakes using hydroacoustics, (2) explore the causal mechanisms influencing movements through the use of temperature/oxygen, foraging, growth, and predation risk models, and (3) examine factors that may contribute to variations in cisco body size by considering all available information. Our results show that cisco vertical movements vary substantially, with different populations performing normal diel vertical migrations (DVM), no DVM, and reverse DVM in lakes throughout Minnesota and northern Wisconsin, USA. Cisco populations with the smallest body size were found in lakes with lower zooplankton densities. These smaller fish showed movements to areas of highest foraging or growth potential during the day and night, despite moving out of preferred temperature and oxygen conditions and into areas of highest predation risk. In lakes with higher zooplankton densities, cisco grew larger and had movements more consistent with behavioral thermoregulation and predator avoidance, while remaining in areas with less than maximum foraging and growth potential. Furthermore, the composition of potential prey items present in each lake was also important. Cisco that performed reverse DVM consumed mostly copepods and cladocerans, while cisco that exhibited normal DVM or no migration consumed proportionally more macro-zooplankton species. Overall, our results show previously undocumented variation in migration patterns of a fish species, the mechanisms underlying those movements, and the potential impact on their growth potential. © 2013 Springer-Verlag Berlin Heidelberg.
Pierce R.B.,Grand Rapids |
Tomcko C.M.,Grand Rapids |
Pereira D.L.,00 Lafayette Road |
Staples D.F.,00 Lafayette Road
Transactions of the American Fisheries Society | Year: 2010
Understanding factors that affect catchability is important for interpreting fish catches from research index netting and comparing fish populations from different habitats. Population density estimates and gill-net catch rates were compared for age-2 and older northern pike Esox lucius in 16 north-central Minnesota lakes that varied in physical characteristics and northern pike populations. When northern pike density was calculated using total surface area of the lakes, numerous factors appeared to influence gill-net catchability. Those factors included several lake basin shape metrics, northern pike size structure, and northern pike density, with density dependence in catchability being especially problematic for interpreting gill-net catches. The critical finding in this study was that calculating density using littoral area rather than total surface area caused evidence of density-dependent catchability and all other relationships with catchability to completely disappear. Catchability became independent of northern pike density and lake basin shape metrics when density was calculated using littoral area. Correlations with density (calculated from total surface area) and other factors were simply artifacts of underlying interrelationships between the morphology of lake basins, northern pike population characteristics, and density-dependent processes. Catchability estimates for littoral habitat averaged 0.20 ha/net and ranged from 0.09 to 0.43 ha/net among the lakes. Although the relationship between gill-net catch and population density indicated that gillnetting could be a useful tool for comparing northern pike populations from different lakes, a predictive model fitted to the observed gill-net catch rates and population densities from 16 lakes had low precision. Results from this study illustrate the importance of a comprehensive understanding of fish ecology, including spatial habitat use, when interpreting survey results. © Copyright by the American Fisheries Society 2010.
Schneider K.N.,University of Minnesota |
Newman R.M.,University of Minnesota |
Card V.,Metropolitan State University |
Weisberg S.,University of Minnesota |
Pereira D.L.,00 Lafayette Road
Transactions of the American Fisheries Society | Year: 2010
We obtained Minnesota Department of Natural Resources historical records describing the eggtake from walleyes Sander vitreus at 12 spawning locations to determine whether the timing of walleye spawning runs could be used as an indicator of climate change. We used ice-out data instead of temperature for our analyses because walleyes often spawn soon after ice-out, and ice-out has been previously related to climate change. We used linear regressions to determine (1) the relationship between the start of spawning (based on first egg-take) or peak of the spawning run (greatest egg-take) and ice-out date and (2) whether long-term trends existed in ice-out and date of spawning over time. Linear regressions of the date of first walleye egg-take versus ice-out date showed that walleye spawning begins 0.5-1.0 d earlier for each 1.0-d decrease in ice-out date. All but two regressions had slopes less than 1.0. Similar results were found for peak of spawning runs. Regressions of egg-take and ice-out date versus year showed trends toward both earlier spawning and earlier ice-out. For regressions of first egg-take versus year (16 total with restricted data sets), significant negative slopes (P < 0.10) were observed in 5 of 16 regressions; for peak egg-take, six regressions had significant negative slopes. For regressions of ice-out date versus year, 25 of 26 regressions were negative; there were nine significant negative slopes (P < 0.10). Overall, ice-out and walleye spawning are occurring earlier in Minnesota, and the timing of walleye spawning may be a good biological indicator of climate change. © Copyright by the American Fisheries Society 2010.
Berndt M.E.,00 Lafayette Road |
Bavin T.K.,00 Lafayette Road
Environmental Pollution | Year: 2012
Methylmercury (MeHg), dissolved organic carbon (DOC), and sulfate (SO 4 =) relationships were investigated in the mining-influenced St. Louis River watershed in northeast Minnesota. Fewer wetlands and higher SO 4 = in the mining region lead to generally lower availability and solubility of DOC in mining streams compared to non-mining streams. MeHg concentrations, however, are similarly low in mining and non-mining streams during low flow periods, implying that the extra DOC found in non-mining streams carries little MeHg with it during these periods. High water levels elevated MeHg concentrations in both stream types owing to release from wetlands of DOC species that contain MeHg and remain relatively soluble in streams with elevated ionic strength. In-river methylation appeared to be a negligible component of the MeHg budget for the St. Louis River during this study as MeHg and DOC concentrations were intermediate to those observed in its mining-influenced and wetland-dominated tributaries. © 2011 Elsevier Ltd. All rights reserved.
Schroeder S.A.,University of Minnesota |
Fulton D.C.,U.S. Geological Survey |
Penning W.,00 Lafayette Road |
Doncarlos K.,00 Lafayette Road
Journal of Wildlife Management | Year: 2012
Lead shot from hunting adds the toxic metal to environments worldwide. The United States banned lead shot for hunting waterfowl in 1991 and 26 states have lead shot restrictions beyond those mandated for waterfowl hunting. The Minnesota Department of Natural Resources (MDNR) was interested in studying hunter attitudes about expanded restrictions on the use of lead shot for hunting small game to understand what communication strategies might increase public support for potential restrictions on lead shot. We mailed messages about lead shot, including 1,200 control messages and 400 of each of 9 treatment messages, and surveys to 4,800 resident small game hunters. We compared attitudes and intentions related to a possible ban among control and treatment groups. Compared to the control message, all treatment messages elicited more positive attitudes and intentions to support a ban. A basic factual message, messages with references to Ducks Unlimited, and a first-person narrative message generated the strongest support for a ban. Results also demonstrated a substantial relationship between the use of lead shot and response to persuasive messages supporting a ban. © 2012 The Wildlife Society. Copyright © The Wildlife Society, 2012.
Cornicelli L.,00 Lafayette Road |
Grund M.D.,00 Lafayette Road
Human Dimensions of Wildlife | Year: 2011
State wildlife agencies are charged with managing wildlife populations of harvestable species. Opinions regarding how species should be managed differ dramatically and decisions are often made without comprehensive data. There is interest among deer hunters in Minnesota to change harvest regulations that benefit mature bucks. Beginning in 2005, research focused on the biological and social implications of changing deer regulations. We used data collected via random surveys, public input meetings, and an Internet survey to assist with the decision-making process. We observed demographic differences among respondents for the three data collection methods; however, the attitudinal differences were "minimal" (i.e., Cramér's V ≈.1). We believe that a structured public input process, even if self-selected, can help inform decision-makers. Agencies that use public input meetings should reevaluate their public input process to include an Internet component if there are adequate baseline data available to make comparisons. © Taylor & Francis Group.
Logsdon D.E.,0317 Fish Hatchery Road |
Anderson C.S.,00 Lafayette Road |
Miller L.M.,University of Minnesota
North American Journal of Fisheries Management | Year: 2016
Oxytetracycline (OTC) marking and genetic assignment techniques were used to evaluate the contribution and performance of Walleye Sander vitreus fry stocked to accelerate the recovery of a recruitment-overfished population in the Red Lakes, Minnesota. Three stockings of OTC-marked fry from an egg source on the Pike River were conducted at densities of 274 to 358 fry/ha to expedite the recovery of the spawning stock in which the adult female biomass had fallen below 0.5 kg/ha for 10 consecutive years. Two additional stockings of OTC-marked fry from an egg source on a Red Lakes tributary were then conducted at 33 and 87 fry/ha to help quantify natural reproduction as the spawning stock recovered. Subsequent inspection of fish from seine and gill-net samples indicated that Pike River fish composed 50% to 94 % of the stocked year-classes and that the stocked year-classes were three of the strongest in the past 25 years. The Pike River fish survived, grew, and matured at rates similar to the native fish, contributing to an increase in adult female biomass ranging from 2.5 to 8.0 kg/ha. Natural reproduction also increased from a range of 8–120 fry/ha to a range of 199–908 fry/ha, with 49% to 53% Pike River ancestry. For the first 2 years after maturation of the first stocked year-class, however, Pike River ancestry was 13–31 percentage points below what was expected from the relative abundance of Pike River adults in the population. The proportion of Pike River adults present on the tributary spawning runs was also initially below expectations. Both spawning participation and success of Pike River adults increased in successive years, and the stocked fry were judged to have accelerated the recovery of the population to a sustainable and fishable status without the need for additional stocking. Received October 20, 2015; accepted March 9, 2016 Published online July 7, 2016 © American Fisheries Society 2016.
Holdsworth A.R.,00 Lafayette Road |
Holdsworth A.R.,University of Minnesota |
Frelich L.E.,University of Minnesota |
Reich P.B.,University of Minnesota |
Reich P.B.,University of Western Sydney
Ecosystems | Year: 2012
Earthworm invasion in North American temperate forest reduces forest floor mass, yet the interactions between litter composition, invasive earthworm community composition, and forest floor structure and composition are not well understood. For 2 years, we compared disappearance of leaf litter in field mesocosms in which we manipulated litter composition (monocultures of Quercus rubra, Acer saccharum, and Tilia americana litter, and an equal mixture of all three) and thereby the initial litter chemistry (C, C fractions, N, Ca) in sites with and without the major litter-feeding invasive earthworm species. The disappearance of litter mass followed the same ranking at both the sites: T. americana > equal mixtures > A. saccharum ≥ Q. rubra. However, differences in disappearance rate between the sites depended on litter composition and time. The differences in mass loss among litters of different compositions were greatest at the site invaded by the large litter-feeding earthworm, Lumbricus terrestris, and especially for T. americana and the mixture. Similarly, observed disappearance of the litter mixture was faster than predicted by an additive model at the site with L. terrestris, especially for the higher quality litter component in early summer. Initial litter calcium content was the best predictor (R 2 ≥ 0. 90) of overall litter mass remaining each year, supporting the idea of the importance of calcium in forest floor dynamics, especially in the presence of calciferous, invasive earthworms. © 2012 Springer Science+Business Media, LLC.