Maintenance of genetic and phenotypic diversity is widely recognized as an important conservation priority, yet managers often lack basic information about spatial patterns of population structure and its relationship with habitat... more
Maintenance of genetic and phenotypic diversity is widely recognized as an important conservation priority, yet managers often lack basic information about spatial patterns of population structure and its relationship with habitat heterogeneity and species movement within it. To address this knowledge gap, we focused on the economically and ecologically prominent yellow perch (Perca flavescens). In the Lake Michigan basin, yellow perch reside in nearshore Lake Michigan, including drowned river mouths (DRMs)—protected, lake-like habitats that link tributaries to Lake Michigan. The goal of this study was to examine the extent that population structure is associated with Great Lakes connected habitats (i.e., DRMs) in a mobile fish species using yellow perch as a model. Specifically, we tested whether DRMs and eastern Lake Michigan constitute distinct genetic stocks of yellow perch, and if so, which habitats those stocks occur in throughout the year. To do so, we genotyped yellow perch at 14 microsatellite loci collected from 10 DRMs in both deep and littoral habitats during spring, summer, and autumn and two nearshore sites in Lake Michigan (spring and autumn) during 2015-2016 and supplemented our sampling with fish collected in 2013. We found that yellow perch from littoral-DRM habitats were genetically distinct from fish captured in nearshore Lake Michigan. Our data also suggested that Lake Michigan yellow perch likely use deep-DRM habitats during autumn. Further, we found genetic structuring among DRMs. These patterns support hypotheses of fishery managers that yellow perch seasonally migrate to and from Lake Michigan, yet, interestingly, these fish do not appear to interbreed with littoral fish despite occupying the same DRM. We recommend that fisheries managers account for this complex population structure and movement when setting fishing regulations and assessing the effects of harvest in Lake Michigan
Research Interests: Genetics, Earth Sciences, Gene Flow, Population Genetics, Biology, and 15 moreEcology, Invasive Species, Biological Sciences, Population structure, Environmental Sciences, Population, Genetic Structure, Ballast Water, Genetic Differentiation, Long Distance Dispersal, Population Genetic Structure, Aquatic Invasive Species, Non native Species, Isolation by distance, and Lake Michigan
Macroconsumers, such as fish, decapod crustaceans, and amphibians, can be important determinants of stream structure and function. In this chapter, we present three types of manipulative field experiments to evaluate top-down effects of... more
Macroconsumers, such as fish, decapod crustaceans, and amphibians, can be important determinants of stream structure and function. In this chapter, we present three types of manipulative field experiments to evaluate top-down effects of macroconsumers in stream food webs and illustrate the role of macroconsumers in shaping the prey communities and resource availability. The most basic approach described is to use mesh exclosures and open-cage controls to test how stream invertebrate density, benthic algal biomass, and/or leaf breakdown rates respond to the absence of macroconsumers. Next, we present a more advanced approach to address similar ecological questions with electric exclosures, which reduce the cage artifacts resulting from the physical effects of cage exclosures. Finally, we describe an optional enclosure/exclosure experiment to directly manipulate macroconsumer density in mesh cages. We also discuss modifications to these three approaches to evaluate macroconsumer roles in algal- or detrital-based food webs and in initiating trophic cascades.
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The Pigeon River, a small coolwater stream in western Michigan, has a history of hydrologic, stream habitat, and water quality degradation that led to the loss of its trout population by the late 1980s. After regulatory and watershed... more
The Pigeon River, a small coolwater stream in western Michigan, has a history of hydrologic, stream habitat, and water quality degradation that led to the loss of its trout population by the late 1980s. After regulatory and watershed management efforts to reduce point- and nonpoint source pollution in the 1990s, the Michigan Department of Natural Resources reinstituted brown trout ( Salmo trutta ) stocking in 2003. As part of these efforts, we monitored water quality in the Pigeon River each fall between 1996 and 2008, and conducted stream surveys in 2006 and 2007 to evaluate the fish community and outcome of trout stocking. Water quality tended to improve and stabilize through time, although point- and nonpoint source pollution still contributed to water quality problems. Hydrologic instability, caused by wetland drainage, agricultural land use, and irrigation withdrawals from the lower mainstream, created periods of environmental stress. As a result, the fish community of the Pige...
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ABSTRACT Freshwater river mouths in large lakes are centres of biological activity, yet little is understood about the spatial and temporal dynamics of fish communities in these systems. In the Laurentian Great Lakes, we sampled littoral... more
ABSTRACT Freshwater river mouths in large lakes are centres of biological activity, yet little is understood about the spatial and temporal dynamics of fish communities in these systems. In the Laurentian Great Lakes, we sampled littoral fishes over 3 years in six drowned (i.e., protected) river mouths to: (i) quantify spatial (among river mouths) and temporal (among years) variation, (ii) evaluate associations with environmental conditions and (iii) assess spatial patterns of community similarity. We sampled 6787 fish representing 43 species over the course of the study. Multivariate analyses indicated that variation in fish species composition was more strongly partitioned among river mouths than among years. Fish communities across the six river mouths were partitioned into three groups, a pattern we attribute to variability in anthropogenic disturbance and environmental conditions. Canonical correspondence analysis showed that fish species composition was associated with specific conductivity, vegetation cover, turbidity and pH, suggesting species–environment relationships are similar to those shown for Great Lakes coastal wetlands. Finally, we found a negative relationship between geographic distance and community similarity, suggesting that dispersal and/or environmental gradients play a role in shaping these river mouth fish assemblages. We conclude that Great Lakes drowned river mouths can harbour diverse and spatially variable fish assemblages that are driven by a combination of local and regional factors.
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ABSTRACT Most studies that investigate biases in stream fish abundance estimators focus on salmonines, yet nongame species comprise a major portion of fish assemblages. We evaluated mark–recapture (the Lincoln–Petersen estimator with... more
ABSTRACT Most studies that investigate biases in stream fish abundance estimators focus on salmonines, yet nongame species comprise a major portion of fish assemblages. We evaluated mark–recapture (the Lincoln–Petersen estimator with Chapman correction) and removal (constant capture probability and generalized removal estimators) methods for estimating abundance of Mottled Sculpin Cottus bairdii, and we tested whether assumptions of the abundance estimators (i.e., the population is closed during sampling; and marks are detected) were reasonable. Over 2-d periods, fish in eight streams were sampled by using backpack electrofishing in 90-m reaches (each divided into three 30-m subreaches) to assess movement. Removal abundance estimates were significantly lower than mark–recapture estimates. Moreover, removal estimates were 52% lower than the known number of marked individuals, likely because capture probability (q) was low and declined with subsequent sampling passes. Survival of fish held in cages was 100%; there were no undetected marks among fish held overnight. For all streams combined, 11% of recaptured fish that were marked in the core subreach were recaptured on day 2 in an adjoining subreach. In five of the eight study streams, movement of marked fish from the core subreach was not detected, suggesting that in most streams the population was closed to movement. Using computer simulations, we found that low numbers of recaptures (mean q is low (e.g., 0.21 in our study), with the caveat that study reach length must be sufficient to minimize fish movement across reach boundaries when block nets cannot be maintained between sampling events.Received January 14, 2014; accepted September 22, 2014
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ABSTRACT We assessed recruitment dynamics of juvenile Yellow Perch Perca flavescens in coastal habitats of eastern Lake Michigan. To investigate recruitment patterns and associations with environmental factors in a coastal drowned river... more
ABSTRACT We assessed recruitment dynamics of juvenile Yellow Perch Perca flavescens in coastal habitats of eastern Lake Michigan. To investigate recruitment patterns and associations with environmental factors in a coastal drowned river mouth (DRM) lake, we sampled juvenile Yellow Perch seasonally in Muskegon Lake, Michigan, during 2003–2011. We also sampled three nearshore sites in Lake Michigan each fall to evaluate synchrony between the DRM lake and nearshore habitat. In Muskegon Lake, age-0 Yellow Perch CPUE during fall was high in 2005 and 2007; moderate in 2008, 2010, and 2011; and low in other years. Fall CPUE (age 0) was positively associated with CPUE in the next spring (age 1; slope = 0.98; R 2 = 0.95), which we attribute to high overwinter survival. Fall CPUE of age-0 Yellow Perch showed a positive relationship with June air temperature (R 2 = 0.76), suggesting that warm conditions at early larval stages positively influence recruitment of juveniles. Juvenile recruitment in Muskegon Lake was not synchronized with juvenile recruitment in nearshore Lake Michigan. The lack of synchrony may be an indication that (1) age-0 Yellow Perch recruitment in DRM lakes and Lake Michigan are influenced by different environmental controls and (2) dispersal between the two habitats does not strongly affect age-0 recruitment dynamics.Received August 6, 2012; accepted December 1, 2012
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Knowledge of gear bias is critical for conducting valid population and community assessments. We studied the biases in fyke netting by investigating the individual effects of soak time (fyke nets were fished for 6, 24, or 48 h), fish... more
Knowledge of gear bias is critical for conducting valid population and community assessments. We studied the biases in fyke netting by investigating the individual effects of soak time (fyke nets were fished for 6, 24, or 48 h), fish density (fyke nets were stocked with 0, 30, or 60 fish/net), and predators (fyke nets were stocked with one or zero
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... Key words: vacuum benthos sampler; demersal eggs; gravel Cecil A. Jennings, Georgia Cooperative Fish and Wildlife Research Unit, Daniel 6. Warnell School of Forest Resources, University of Georgia, Athens GA 30602, USA Accepted for... more
... Key words: vacuum benthos sampler; demersal eggs; gravel Cecil A. Jennings, Georgia Cooperative Fish and Wildlife Research Unit, Daniel 6. Warnell School of Forest Resources, University of Georgia, Athens GA 30602, USA Accepted for publication September 3, 1997 ...
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... Tudorache, C., De Boeck, G. & Eens, M. 2007. Evaluation of passive integratedtransponder tags for marking the bullhead (Cottus gobio), a small benthic freshwater fish: effects on survival, growth and swimming capacity. Ec.
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ABSTRACT We examined seasonal spatial distribution and diel movements of juvenile lake sturgeon Acipenser fulvescens in Muskegon Lake, Michigan (a protected, drowned river mouth lake that links the Muskegon River to Lake Michigan). We... more
ABSTRACT We examined seasonal spatial distribution and diel movements of juvenile lake sturgeon Acipenser fulvescens in Muskegon Lake, Michigan (a protected, drowned river mouth lake that links the Muskegon River to Lake Michigan). We surgically implanted ultrasonic tags in 20 juveniles (age 1–7) captured in gill nets to track their locations during August–December 2008/2009 and September 2010–October 2011. Most juveniles were observed ≤1.5 km from the mouth of the Muskegon River in Muskegon Lake at a mean depth of 7.5 m (SE = 1.3 m) during summer. In fall, juveniles moved away from the river mouth to the deepest part of Muskegon Lake and were observed at a mean depth of 15.8 m (SE = 1.3 m) during winter. The shift in spatial distribution coincided with fall turnover (i.e., loss of thermal stratification) and with changes in dissolved oxygen (DO) concentrations in the hypolimnion. During summer, DO concentrations in the hypolimnion were typically 7 mg·l−1 in 94% of instances. Tracking in 2009 revealed no significant change in depth distribution or movement over the diel cycle. We only observed two tagged juveniles immigrating to Lake Michigan, suggesting that juveniles use Muskegon Lake for multiple years. Our results suggest that: (i) Muskegon Lake serves as an important nursery habitat for juvenile lake sturgeon that hatched in the Muskegon River before they enter Lake Michigan and (ii) seasonal changes in DO concentration in the hypolimnion likely affect the spatial distribution of juveniles in Muskegon Lake.
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We monitored 94 mottled sculpins ( Cottus bairdii ) marked with passive integrated transponder (PIT) tags to examine seasonal movement patterns. High detection efficiency (mean ± standard error = 0.76 ± 0.03) of PIT-tagged fish was... more
We monitored 94 mottled sculpins ( Cottus bairdii ) marked with passive integrated transponder (PIT) tags to examine seasonal movement patterns. High detection efficiency (mean ± standard error = 0.76 ± 0.03) of PIT-tagged fish was obtained with a portable antenna. Nighttime searches were more effective than daytime relocations in summer, and smaller fish (<65 mm) were detected more readily than larger fish (≥65 mm). Sculpins used erosional habitats more than depositional habitats, particularly during summer and nighttime. Search attempts within a 150 m reach showed that displacement, mean movement distance, and home range did not differ significantly between summer and winter, suggesting that season did not strongly influence movement. Additionally, movement metrics were unrelated to sculpin size. However, supplementary searches of a larger reach (700 m) showed that 16% of PIT-tagged fish moved more than 100 m over 1 year, with a maximum displacement of 511 m, and mobile fish ty...
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Biotic indicators are useful for assessing ecosystem health because the structure of resident communities generally reflects abiotic conditions integrated over time. We used fish data collected over 5 years for 470 Great Lakes coastal... more
Biotic indicators are useful for assessing ecosystem health because the structure of resident communities generally reflects abiotic conditions integrated over time. We used fish data collected over 5 years for 470 Great Lakes coastal wetlands to develop multi-metric indices of biotic integrity (IBI). Sampling and IBI development were stratified by vegetation type within each wetland to account for differences in physical habitat. Metrics were evaluated against numerous indices of anthropogenic disturbance derived from water quality and surrounding land-cover variables. Separate datasets were used for IBI development and testing. IBIs were composed of 10-11 metrics for each of four vegetation types (bulrush, cattail, water lily, and submersed aquatic vegetation). Scores of all IBIs correlated well with disturbance indices using the development data, and the accuracy of our IBIs was validated using the testing data. Our fish IBIs can be used to prioritize wetland protection and resto...
Research Interests: Environmental Science, Wetlands, Water quality, Ecology, Environmental Monitoring, and 13 moreBiodiversity, Multidisciplinary, Lakes, Canada, Wetland, Birds, United States, Animals, Fishes, Environmental monitoring and assessment, Ecosystem, Water Quality, and Environmental Pollution Assessment and Monitoring
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ABSTRACT
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... ACKNOWLEDGEMENTS We thank the Michigan Department of Environmental Quality, especially Peg Bostwick and Alisa Gonzales-Pennington, for supporting this research. ... Freshwater Biology 53: 205 1-2060. Brazner, JC, DK Tanner, DA Jensen,... more
... ACKNOWLEDGEMENTS We thank the Michigan Department of Environmental Quality, especially Peg Bostwick and Alisa Gonzales-Pennington, for supporting this research. ... Freshwater Biology 53: 205 1-2060. Brazner, JC, DK Tanner, DA Jensen, and A. Lemke. 1998. ...
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Research Interests: Environmental Science, Environmental Monitoring, Invasive Species, Phytoplankton, Eutrophication, and 15 moreMedicine, Multidisciplinary, Macrophytes, Shallow Lakes, FISH, Chlorophyll, Animals, Michigan, Environmental Assessment, Environmental monitoring and assessment, Fresh water, Fish Community, Best management practice, Chlorophyll a, and Nutrient Concentration
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Abstract We conducted an enclosure/exclosure experiment during summer 1998 and 1999 to test the strength of top-down control by slimy sculpins (Cottus cognatus) on benthic macroinvertebrates and periphyton. We used 1-m2 cages to... more
Abstract We conducted an enclosure/exclosure experiment during summer 1998 and 1999 to test the strength of top-down control by slimy sculpins (Cottus cognatus) on benthic macroinvertebrates and periphyton. We used 1-m2 cages to manipulate slimy sculpin density within 6 riffles in Valley Creek, Minnesota. Each riffle contained an enclosure stocked with 3 slimy sculpins, a fishless exclosure, and an open control cage. In 1998, densities of total invertebrates and grazers on clay tiles were significantly higher in exclosures than enclosures and control cages; however, densities of individual grazer taxa (Glossosoma and Baetis) on tiles did not differ significantly among treatments. Fish had no significant effect on invertebrates inhabiting gravel substrate. In 1999, densities of total invertebrates and grazers on tiles and inhabiting gravel substrate did not differ significantly among treatments. Slimy sculpins did not have a detectable effect on the drift propensity of invertebrates during either year. Regardless of the effect of fish on grazers in either year, periphyton biomass did not differ significantly among the fish treatments even though there was a strong, negative correlation between Glossosoma density and periphyton biomass. Periphyton biomass was significantly higher on tiles with a barrier that excluded Glossosoma larvae from the surface, indicating that Glossosoma limited periphyton biomass. We conclude that the strength of top-down control by slimy sculpins on invertebrates was weak. We did not detect an algae-based trophic cascade during either year because Glossosoma larvae were relatively invulnerable to fish predation and did not alter their behavior in the presence of fish.