Brent Knights (Former Employee)
Science and Products
Filter Total Items: 48
Fatty acid composition at the base of aquatic food webs is influenced by habitat type and watershed land use
Spatial variation in food resources strongly influences many aspects of aquatic consumer ecology. Although large-scale controls over spatial variation in many aspects of food resources are well known, others have received little study. Here we investigated variation in the fatty acid (FA) composition of seston and primary consumers within (i.e., among habitats) and among tributary systems of Lake
Authors
James H. Larson, William B. Richardson, Brent C. Knights, Lynn Bartsch, Michelle Bartsch, J. C. Nelson, Jason A. Veldboom, Jonathan M. Vallazza
Persistent disturbance by commercial navigation afters the relative abundance of channel-dwelling fishes in a large river
We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation.
Authors
S. Gutreuter, J.M. Vallazza, B.C. Knights
Mercury in soils, lakes, and fish in Voyageurs National Park (Minnesota): Importance of atmospheric deposition and ecosystem factors
Concentrations of methylmercury in game fish from many interior lakes in Voyageurs National Park (MN, U.S.A.) substantially exceed criteria for the protection of human health. We assessed the importance of atmospheric and geologic sources of mercury to interior lakes and watersheds within the Park and identified ecosystem factors associated with variation in methylmercury contamination of lacustri
Authors
J.G. Wiener, B.C. Knights, M.B. Sandheinrich, Jeffrey D. Jeremiason, M. E. Brigham, D.R. Engstrom, L. G. Woodruff, W. F. Cannon, S.J. Balogh
A comparison of internal and external radio transmitters with northern leopard frogs (Rana pipiens)
Abstract has not been submitted
Authors
S.E. Weick, M. G. Knutson, B.C. Knights, B.C. Pember
Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the Upper Mississippi River
Populations of paddlefish Polyodon spathula have been adversely affected by dams that can block their movements. Unlike high-head dams that preclude fish passage (unless they are equipped with fishways), the dams on the upper Mississippi River are typically low-head dams with bottom release gates that may allow fish passage under certain conditions. We evaluated the relation of dam head and river
Authors
S. J. Zigler, M. R. Dewey, B.C. Knights, A.L. Runstrom, M.T. Steingraeber
Movement and habitat use by radio-tagged paddlefish in the upper Mississippi River and tributaries
We used radio telemetry to evaluate the movement and habitat use of paddlefish Polyodon spathula in the upper Mississippi River and two tributary rivers. Radio transmitters were surgically implanted into 71 paddlefish in Navigation Pools 5A and 8 of the upper Mississippi River, the Chippewa River, and the Wisconsin River during fall 1994 through fall 1996. Radiotagged paddlefish were located throu
Authors
S. J. Zigler, M. R. Dewey, B.C. Knights, A.L. Runstrom, M.T. Steingraeber
Habitat and movement of lake sturgeon in the upper Mississippi River system, USA
Lake sturgeon Acipenser fluvescens, which are now protected from harvest, are considered rare in the upper Mississippi River and little information is available on the remaining populations. Transmitters were implanted into 31 lake sturgeon from two sites in the upper Mississippi River to describe their habitats and movement. The areas surrounding the tagging sites were core areas for both groups
Authors
Brent C. Knights, Jonathon M. Vallazza, Steven J. Zigler, Michael R. Dewey
Diel movement and habitat use by paddlefish in Navigation Pool 8 of the upper Mississippi River
We studied diel movement and habitat use by paddlefish Polyodon spathula implanted with radio transmitters in Navigation Pool 8 of the upper Mississippi River. We radio-tracked five paddlefish during three randomly chosen 24-h periods each month in May, Aug, and Oct 1995. Paddlefish were located by boat one to three times every 3 h during each 24-h period. At each location, geographic coordinates
Authors
Steven J. Zigler, Michael R. Dewey, Brent C. Knights
Estimating flow rates to optimize winter habitat for centrarchid fish in Mississippi River (USA) backwaters
The backwaters of large rivers provide winter refuge for many riverine fish, but they often exhibit low dissolved oxygen levels due to high biological oxygen demand and low flows. Introducing water from the main channel can increase oxygen levels in backwaters, but can also increase current velocity and reduce temperature during winter, which may reduce habitat suitability for fish. In 1993, culve
Authors
Barry L. Johnson, Brent C. Knights, John W. Barko, Robert F. Gaugush, David M. Soballe, William F. James
Effects of implanted transmitters on adult bluegills at two temperatures
Laterally compressed panfishes are small and have limited intraperitoneal space; thus, they may suffer adversely from surgically implanted transmitters even if the transmitter meets the generally recommended ratio of transmitter weight to fish weight of 2%. We studied the effects of intraperitoneal transmitters (2.81 g) on survival, growth, healing, and health of bluegills Lepomis macrochirus (
Authors
Brent C. Knights, Becky A. Lasee
Responses of bluegills and black crappies to dissolved oxygen, temperature, and current in backwater lakes of the upper Mississippi River during winter
We conducted a radiotelemetry study to examine the effects of dissolved oxygen (DO), water temperature, and current velocity on winter habitat selection by bluegills Lepomis macrochirus and black crappies Pomoxis nigromaculatus in the Finger Lakes backwater complex, Pool 5, on the upper Mississippi River. When DO was above 2 mg/L, both species selected areas with water temperature greater than
Authors
B.C. Knights, B. L. Johnson, M.B. Sandheinrich
A sediment suspension system for bioassays with small aquatic organisms
Exposure of aquatic organisms to suspended sediments can impair growth and survival and increase bioaccumulation of sediment-associated contaminants. However, evaluation of the effects of suspended sediments and their associated contaminants on aquatic organisms has been hampered by the lack of a practical and inexpensive exposure system for conducting bioassays. We present a cost-effective system
Authors
M. J. Schmidt-Dallmier, G.J. Atchison, M.T. Steingraeber, B.C. Knights
Science and Products
Filter Total Items: 48
Fatty acid composition at the base of aquatic food webs is influenced by habitat type and watershed land use
Spatial variation in food resources strongly influences many aspects of aquatic consumer ecology. Although large-scale controls over spatial variation in many aspects of food resources are well known, others have received little study. Here we investigated variation in the fatty acid (FA) composition of seston and primary consumers within (i.e., among habitats) and among tributary systems of Lake
Authors
James H. Larson, William B. Richardson, Brent C. Knights, Lynn Bartsch, Michelle Bartsch, J. C. Nelson, Jason A. Veldboom, Jonathan M. Vallazza
Persistent disturbance by commercial navigation afters the relative abundance of channel-dwelling fishes in a large river
We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation.
Authors
S. Gutreuter, J.M. Vallazza, B.C. Knights
Mercury in soils, lakes, and fish in Voyageurs National Park (Minnesota): Importance of atmospheric deposition and ecosystem factors
Concentrations of methylmercury in game fish from many interior lakes in Voyageurs National Park (MN, U.S.A.) substantially exceed criteria for the protection of human health. We assessed the importance of atmospheric and geologic sources of mercury to interior lakes and watersheds within the Park and identified ecosystem factors associated with variation in methylmercury contamination of lacustri
Authors
J.G. Wiener, B.C. Knights, M.B. Sandheinrich, Jeffrey D. Jeremiason, M. E. Brigham, D.R. Engstrom, L. G. Woodruff, W. F. Cannon, S.J. Balogh
A comparison of internal and external radio transmitters with northern leopard frogs (Rana pipiens)
Abstract has not been submitted
Authors
S.E. Weick, M. G. Knutson, B.C. Knights, B.C. Pember
Hydrologic and hydraulic factors affecting passage of paddlefish through dams in the Upper Mississippi River
Populations of paddlefish Polyodon spathula have been adversely affected by dams that can block their movements. Unlike high-head dams that preclude fish passage (unless they are equipped with fishways), the dams on the upper Mississippi River are typically low-head dams with bottom release gates that may allow fish passage under certain conditions. We evaluated the relation of dam head and river
Authors
S. J. Zigler, M. R. Dewey, B.C. Knights, A.L. Runstrom, M.T. Steingraeber
Movement and habitat use by radio-tagged paddlefish in the upper Mississippi River and tributaries
We used radio telemetry to evaluate the movement and habitat use of paddlefish Polyodon spathula in the upper Mississippi River and two tributary rivers. Radio transmitters were surgically implanted into 71 paddlefish in Navigation Pools 5A and 8 of the upper Mississippi River, the Chippewa River, and the Wisconsin River during fall 1994 through fall 1996. Radiotagged paddlefish were located throu
Authors
S. J. Zigler, M. R. Dewey, B.C. Knights, A.L. Runstrom, M.T. Steingraeber
Habitat and movement of lake sturgeon in the upper Mississippi River system, USA
Lake sturgeon Acipenser fluvescens, which are now protected from harvest, are considered rare in the upper Mississippi River and little information is available on the remaining populations. Transmitters were implanted into 31 lake sturgeon from two sites in the upper Mississippi River to describe their habitats and movement. The areas surrounding the tagging sites were core areas for both groups
Authors
Brent C. Knights, Jonathon M. Vallazza, Steven J. Zigler, Michael R. Dewey
Diel movement and habitat use by paddlefish in Navigation Pool 8 of the upper Mississippi River
We studied diel movement and habitat use by paddlefish Polyodon spathula implanted with radio transmitters in Navigation Pool 8 of the upper Mississippi River. We radio-tracked five paddlefish during three randomly chosen 24-h periods each month in May, Aug, and Oct 1995. Paddlefish were located by boat one to three times every 3 h during each 24-h period. At each location, geographic coordinates
Authors
Steven J. Zigler, Michael R. Dewey, Brent C. Knights
Estimating flow rates to optimize winter habitat for centrarchid fish in Mississippi River (USA) backwaters
The backwaters of large rivers provide winter refuge for many riverine fish, but they often exhibit low dissolved oxygen levels due to high biological oxygen demand and low flows. Introducing water from the main channel can increase oxygen levels in backwaters, but can also increase current velocity and reduce temperature during winter, which may reduce habitat suitability for fish. In 1993, culve
Authors
Barry L. Johnson, Brent C. Knights, John W. Barko, Robert F. Gaugush, David M. Soballe, William F. James
Effects of implanted transmitters on adult bluegills at two temperatures
Laterally compressed panfishes are small and have limited intraperitoneal space; thus, they may suffer adversely from surgically implanted transmitters even if the transmitter meets the generally recommended ratio of transmitter weight to fish weight of 2%. We studied the effects of intraperitoneal transmitters (2.81 g) on survival, growth, healing, and health of bluegills Lepomis macrochirus (
Authors
Brent C. Knights, Becky A. Lasee
Responses of bluegills and black crappies to dissolved oxygen, temperature, and current in backwater lakes of the upper Mississippi River during winter
We conducted a radiotelemetry study to examine the effects of dissolved oxygen (DO), water temperature, and current velocity on winter habitat selection by bluegills Lepomis macrochirus and black crappies Pomoxis nigromaculatus in the Finger Lakes backwater complex, Pool 5, on the upper Mississippi River. When DO was above 2 mg/L, both species selected areas with water temperature greater than
Authors
B.C. Knights, B. L. Johnson, M.B. Sandheinrich
A sediment suspension system for bioassays with small aquatic organisms
Exposure of aquatic organisms to suspended sediments can impair growth and survival and increase bioaccumulation of sediment-associated contaminants. However, evaluation of the effects of suspended sediments and their associated contaminants on aquatic organisms has been hampered by the lack of a practical and inexpensive exposure system for conducting bioassays. We present a cost-effective system
Authors
M. J. Schmidt-Dallmier, G.J. Atchison, M.T. Steingraeber, B.C. Knights