Ashley Moerke | Lake Superior State University (original) (raw)
Papers by Ashley Moerke
Journal of The North American Benthological Society, 2004
... Ashley H. Moerke 1 , Kerry J. Gerard 2 , Jo A. Latimore 3 , Ronald A. Hellenthal 4 , and Gary... more ... Ashley H. Moerke 1 , Kerry J. Gerard 2 , Jo A. Latimore 3 , Ronald A. Hellenthal 4 , and Gary A. Lamberti 5 ... Several important scholarly works on restoration of aquatic ecosystems exist (eg, Gore 1985, Brookes and Shields 1996, FISRWG 1998), but many basic questions remain ...
North American Journal of Fisheries Management, 2003
Stream restoration has accelerated in the Midwestern United States during the past decade, but th... more Stream restoration has accelerated in the Midwestern United States during the past decade, but the effects of restoration on stream biota are rarely evaluated. From 1997 to 2000, we studied the responses in fish communities to the attempted restoration of two channelized streams (Juday Creek and Potato Creek) in northwestern Indiana, each of which received two new meanders to a 1-km reach of stream length. The restored meanders of Juday Creek also received major improvement to instream habitat, bank stabilization, and silt control. In contrast, Potato Creek received only reconnection of the stream to historical meanders. Fish were monitored for 3 years after reconstruction by use of electroshocking and salmonid redd surveys. In Juday Creek, trout size-class distribution broadened and redd construction increased in the restored reaches. However, most fish metrics for reconstructed reaches did not surpass the levels in the channelized reaches after 3 years. Continued sedimentation from upstream sources, which reduced habitat quality, likely counteracted the positive effects of the restoration. In contrast, unanticipated geomorphic changes in Potato Creek led to decreased current velocity and highly altered fish community structure. The American brook lamprey Lampetra appendix, a sensitive species, was not collected after restoration, and the fish community changed from rheophilic species to highly tolerant, slow-water species. Overall, changes in fish community structure revealed strengths and weaknesses in contemporary stream restoration approaches, findings that will aid future restoration efforts.
Aquatic Sciences, 2006
In 2002, we investigated regional versus local influences of 22 streams in the Kalamazoo River ba... more In 2002, we investigated regional versus local influences of 22 streams in the Kalamazoo River basin, MI (USA) to: 1) determine how stream water quality, habitat, and fish communities were influenced by environmental variables at multiple spatial scales, and 2) examine linkages among watershed, riparian corridor (total and local stream corridors), and instream characteristics. Our data show that environmental patterns and processes operating at different spatial scales regulated stream water quality, habitat, and fish communities in Michigan streams. Broader spatial scales, including the watershed and total stream corridor (100-m riparian buffer extending the entire stream length upstream of the site), were the best predictors of water quality (R a 2 = 0.26–0.74), whereas the local stream corridor (50-m riparian buffer extending 200 m upstream of the site) was the best predictor of stream habitat (R a 2 = 0.23–0.59). Fish community structure was explained by various factors operating at both the watershed and local scales (R a 2 = 0.24–0.61). Anthropogenic factors (e.g., land use) had a greater influence on fish species composition (46% of the explained variation) than did natural environmental features (e.g., geology; 16%) or spatial variables (e.g., latitude, 13%). Understanding how environmental factors constrain stream ecosystem structure at multiple scales will help water resource specialists target appropriate scales and factors for management and restoration efforts.
Restoration Ecology, 2004
Freshwater Biology, 2003
1. In deciduous forest streams, fallen leaves form a large component of the total organic matter ... more 1. In deciduous forest streams, fallen leaves form a large component of the total organic matter budget, and many leaves become buried within stream sediments. We examined the processing of buried leaves as compared with those at the surface, and the influence of subsurface hydrology on processing rates. 2. Leaf packs were secured on the streambed surface or buried 10 cm deep in upwelling and downwelling reaches of a second-order stream in Michigan, U.S.A. Mass loss and invertebrate colonisation were measured from October to February. 3. Leaves buried in upwelling reaches lost mass more slowly (exponential decay coefficient, k ¼ )0.0097) than did leaves from the other treatments (buried downwelling: )0.017; surface upwelling: )0.022; surface downwelling: )0.021). 4. Initially, more invertebrates colonised surface leaf packs than buried packs. During the remainder of the study, however, hydrology had a greater effect on invertebrate abundance than did burial, as more invertebrates were found in packs in downwelling reaches than in upwelling reaches. 5. Local subsurface hydrology and degree of burial, factors rarely considered in studies of detritus processing, can significantly influence mass loss and invertebrate colonisation of fallen leaves in streams. Furthermore, because of slower processing, subsurface zones may function as organic matter reservoirs that gradually 'spiral' carbon to downstream subsurface and surface habitats.
Environmental Management, 2006
Monitoring of stream restoration projects is often limited and success often focuses on a single ... more Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids), even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in Cook’s Run, a 3rd-order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat improvement increased trout abundances and enhanced other ecological variables (overall habitat quality, organic matter retention, seston concentration, periphyton abundance, sediment organic matter content, and macroinvertebrate abundance and diversity) following rehabilitation. The addition of skybooms (underbank cover structures) and k-dams (pool-creating structures) increased the relative abundance of harvestable trout (>25 cm in total length) as intended but not overall trout abundances. Both rehabilitation techniques also increased maximum channel depth and organic matter retention, but only k-dams increased overall habitat quality. Neither approach significantly affected other ecological variables. The modest ecological response to this habitat improvement likely occurred because the system was not severely degraded beforehand, and thus small, local changes in habitat did not measurably affect most physical and ecological variables measured. However, increases in habitat volume and in organic matter retention may enhance stream biota in the long term.
Environmental Management, 2006
Monitoring of stream restoration projects is often limited and success often focuses on a single ... more Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids), even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in CookÕs Run, a 3 rd -order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat improvement increased trout abundances and enhanced
Lancet, 2011
The St. Marys River, the sole outflow of Lake Superior, was historically inhabited by lake sturge... more The St. Marys River, the sole outflow of Lake Superior, was historically inhabited by lake sturgeon (Acipenser fulvescens); until recently it was unclear whether a population was still present in the river. From 2000 to 2007, the population status of subadult and adult lake sturgeon in the St. Marys River was characterized. Setlines were deployed at multiple water depths (2-20 m) for 3400 setline nights. Biological measurements including total length and weight were recorded and each individual was affixed with unique identification tags before being released. A total of 192 unique lake sturgeon were captured with a recapture rate of 16%. The population size of lake sturgeon in the St. Marys River was estimated to be near 500 individuals. Fish captured exhibited a mean weight of 13 kg (range 2-37 kg) and a mean total length of 125 cm (range 80-175 cm). The mean age of lake sturgeon captured was 20 years (range 7-59 years) and 36 age classes were represented. Lamprey wounds were observed on 23% (N = 53) of sturgeon and nearly 19% (N = 44) of lake sturgeon had visible external parasites classified as Argulus spp. This study suggests that a recovering lake sturgeon population exists in the St. Marys River, however, it remains unclear as to whether this is a self-sustaining population reproducing in the river. Additional information is needed on metapopulation dynamics, habitat use, and younger age classes to assess recruitment success and population status.
Lancet, 2011
The St. Marys River is the sole surface outlet from Lake Superior, flowing over 100 km to Lake Hu... more The St. Marys River is the sole surface outlet from Lake Superior, flowing over 100 km to Lake Huron, and forming part of the international border between Canada (Ontario) and the United States (MI). The river system has been severely impacted by modifications to the hydrology as well as local industrial and municipal discharges, and was designated in 1985 as an Area of Concern (AOC). Since that time, sediments on the Canadian side of the river have been systematically re-sampled, but the US side of the river has received less attention. This paper discusses two recent projects, one completed in 2003 and one completed in 2005, that sought to revisit a variety of sediment localities within the St. Marys River to update sediment contaminant data, and to expand sampling into additional areas of interest on the US side of the border: Munuscong Lake at the southern end of the AOC, and the Little Rapids adjacent to Sugar Island. The primary focus was on surficial sediment contamination, particularly metals shown to be elevated during previous sampling (chromium, nickel, copper). Results show that while Cr, Ni and Cu contamination remains slightly elevated in surficial sediments at some sites in the St. Marys River, the overall trend shows metal concentrations declining to levels consistent with background levels in sediments found in Lake Superior, Whitefish Bay and the St. Marys River.
Lancet, 2011
Zooplankton communities of the Great Lakes have received significant attention in light of recent... more Zooplankton communities of the Great Lakes have received significant attention in light of recent food web changes. No recent attempts have been made, however, to characterize the zooplankton community of the St. Marys River, the sole connecting channel between Lake Superior and Lake Huron. The purpose of this study was to provide new reference information for St. Marys River zooplankton communities and discuss the patterns observed in relation to recent changes in the Great Lakes. To address these objectives, sampling occurred at Lake Superior State University's Aquatic Research Laboratory from 2003 to 2007, and at 9 coastal wetlands in 2005. Compared to historical studies of St. Marys River riverine zooplankton, relative densities of calanoid copepods and daphnids have decreased while cyclopoid copepods and bosminids have increased. Coastal wetland communities continue to be diverse and exhibit similar community structure to previous studies, although Leptodora kindti, historically an abundant nearshore taxa, is now absent. Mechanisms driving differences in present community structure as compared to that noted in past studies of the St. Marys River are unknown but may be explained by the presence of the predatory, invasive zooplankton, Bythotrephes longimanus, local environmental variables, or changes upstream in Lake Superior. Temperaturezooplankton abundance patterns and nearshore community structure of Lake Superior are reflected in the St. Marys zooplankton community; thus, local environmental factors including changes in planktivory and proximity to upstream feeder communities likely play an important role in structuring St. Marys River zooplankton communities seasonally and spatially.
Because of the important role science plays in peoples’ lives and the significant (and increasing... more Because of the important role science plays in peoples’ lives and the significant (and increasing) impact of humans on the environment, there is a great and growing need to improve links between scientists and society [e.g., Lubchenco, 1998]. Some funding agencies recognize this need and have shaped their priorities accordingly. For example, the U.S. National Science Foundation (NSF) requires grant applicants to address the broader impacts of proposed work, including “promoting teaching, training, and learning” [NSF, 2007]. NASA, the U.S. National Oceanic and Atmospheric Administration (NOAA), and other agencies also encourage and fund education and public outreach activities [e.g., Franks et al., 2006; NASA, 2009].
Eos, Transactions American Geophysical Union, 2009
... Petersburg, Fla.; Elizabeth Hinchey, Illinois-Indiana Sea Grant College Program, Purdue Unive... more ... Petersburg, Fla.; Elizabeth Hinchey, Illinois-Indiana Sea Grant College Program, Purdue University, US Environmental Protection Agency Great Lakes National Program Office, Chicago, Ill.; Ashley Moerke, Department of Biological Sciences, Lake Superior State University ...
Journal of The North American Benthological Society, 2004
... Ashley H. Moerke 1 , Kerry J. Gerard 2 , Jo A. Latimore 3 , Ronald A. Hellenthal 4 , and Gary... more ... Ashley H. Moerke 1 , Kerry J. Gerard 2 , Jo A. Latimore 3 , Ronald A. Hellenthal 4 , and Gary A. Lamberti 5 ... Several important scholarly works on restoration of aquatic ecosystems exist (eg, Gore 1985, Brookes and Shields 1996, FISRWG 1998), but many basic questions remain ...
North American Journal of Fisheries Management, 2003
Stream restoration has accelerated in the Midwestern United States during the past decade, but th... more Stream restoration has accelerated in the Midwestern United States during the past decade, but the effects of restoration on stream biota are rarely evaluated. From 1997 to 2000, we studied the responses in fish communities to the attempted restoration of two channelized streams (Juday Creek and Potato Creek) in northwestern Indiana, each of which received two new meanders to a 1-km reach of stream length. The restored meanders of Juday Creek also received major improvement to instream habitat, bank stabilization, and silt control. In contrast, Potato Creek received only reconnection of the stream to historical meanders. Fish were monitored for 3 years after reconstruction by use of electroshocking and salmonid redd surveys. In Juday Creek, trout size-class distribution broadened and redd construction increased in the restored reaches. However, most fish metrics for reconstructed reaches did not surpass the levels in the channelized reaches after 3 years. Continued sedimentation from upstream sources, which reduced habitat quality, likely counteracted the positive effects of the restoration. In contrast, unanticipated geomorphic changes in Potato Creek led to decreased current velocity and highly altered fish community structure. The American brook lamprey Lampetra appendix, a sensitive species, was not collected after restoration, and the fish community changed from rheophilic species to highly tolerant, slow-water species. Overall, changes in fish community structure revealed strengths and weaknesses in contemporary stream restoration approaches, findings that will aid future restoration efforts.
Aquatic Sciences, 2006
In 2002, we investigated regional versus local influences of 22 streams in the Kalamazoo River ba... more In 2002, we investigated regional versus local influences of 22 streams in the Kalamazoo River basin, MI (USA) to: 1) determine how stream water quality, habitat, and fish communities were influenced by environmental variables at multiple spatial scales, and 2) examine linkages among watershed, riparian corridor (total and local stream corridors), and instream characteristics. Our data show that environmental patterns and processes operating at different spatial scales regulated stream water quality, habitat, and fish communities in Michigan streams. Broader spatial scales, including the watershed and total stream corridor (100-m riparian buffer extending the entire stream length upstream of the site), were the best predictors of water quality (R a 2 = 0.26–0.74), whereas the local stream corridor (50-m riparian buffer extending 200 m upstream of the site) was the best predictor of stream habitat (R a 2 = 0.23–0.59). Fish community structure was explained by various factors operating at both the watershed and local scales (R a 2 = 0.24–0.61). Anthropogenic factors (e.g., land use) had a greater influence on fish species composition (46% of the explained variation) than did natural environmental features (e.g., geology; 16%) or spatial variables (e.g., latitude, 13%). Understanding how environmental factors constrain stream ecosystem structure at multiple scales will help water resource specialists target appropriate scales and factors for management and restoration efforts.
Restoration Ecology, 2004
Freshwater Biology, 2003
1. In deciduous forest streams, fallen leaves form a large component of the total organic matter ... more 1. In deciduous forest streams, fallen leaves form a large component of the total organic matter budget, and many leaves become buried within stream sediments. We examined the processing of buried leaves as compared with those at the surface, and the influence of subsurface hydrology on processing rates. 2. Leaf packs were secured on the streambed surface or buried 10 cm deep in upwelling and downwelling reaches of a second-order stream in Michigan, U.S.A. Mass loss and invertebrate colonisation were measured from October to February. 3. Leaves buried in upwelling reaches lost mass more slowly (exponential decay coefficient, k ¼ )0.0097) than did leaves from the other treatments (buried downwelling: )0.017; surface upwelling: )0.022; surface downwelling: )0.021). 4. Initially, more invertebrates colonised surface leaf packs than buried packs. During the remainder of the study, however, hydrology had a greater effect on invertebrate abundance than did burial, as more invertebrates were found in packs in downwelling reaches than in upwelling reaches. 5. Local subsurface hydrology and degree of burial, factors rarely considered in studies of detritus processing, can significantly influence mass loss and invertebrate colonisation of fallen leaves in streams. Furthermore, because of slower processing, subsurface zones may function as organic matter reservoirs that gradually 'spiral' carbon to downstream subsurface and surface habitats.
Environmental Management, 2006
Monitoring of stream restoration projects is often limited and success often focuses on a single ... more Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids), even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in Cook’s Run, a 3rd-order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat improvement increased trout abundances and enhanced other ecological variables (overall habitat quality, organic matter retention, seston concentration, periphyton abundance, sediment organic matter content, and macroinvertebrate abundance and diversity) following rehabilitation. The addition of skybooms (underbank cover structures) and k-dams (pool-creating structures) increased the relative abundance of harvestable trout (>25 cm in total length) as intended but not overall trout abundances. Both rehabilitation techniques also increased maximum channel depth and organic matter retention, but only k-dams increased overall habitat quality. Neither approach significantly affected other ecological variables. The modest ecological response to this habitat improvement likely occurred because the system was not severely degraded beforehand, and thus small, local changes in habitat did not measurably affect most physical and ecological variables measured. However, increases in habitat volume and in organic matter retention may enhance stream biota in the long term.
Environmental Management, 2006
Monitoring of stream restoration projects is often limited and success often focuses on a single ... more Monitoring of stream restoration projects is often limited and success often focuses on a single taxon (e.g., salmonids), even though other aspects of stream structure and function may also respond to restoration activities. The Ottawa National Forest (ONF), Michigan, conducted a site-specific trout habitat improvement to enhance the trout fishery in CookÕs Run, a 3 rd -order stream that the ONF determined was negatively affected by past logging. Our objectives were to determine if the habitat improvement increased trout abundances and enhanced
Lancet, 2011
The St. Marys River, the sole outflow of Lake Superior, was historically inhabited by lake sturge... more The St. Marys River, the sole outflow of Lake Superior, was historically inhabited by lake sturgeon (Acipenser fulvescens); until recently it was unclear whether a population was still present in the river. From 2000 to 2007, the population status of subadult and adult lake sturgeon in the St. Marys River was characterized. Setlines were deployed at multiple water depths (2-20 m) for 3400 setline nights. Biological measurements including total length and weight were recorded and each individual was affixed with unique identification tags before being released. A total of 192 unique lake sturgeon were captured with a recapture rate of 16%. The population size of lake sturgeon in the St. Marys River was estimated to be near 500 individuals. Fish captured exhibited a mean weight of 13 kg (range 2-37 kg) and a mean total length of 125 cm (range 80-175 cm). The mean age of lake sturgeon captured was 20 years (range 7-59 years) and 36 age classes were represented. Lamprey wounds were observed on 23% (N = 53) of sturgeon and nearly 19% (N = 44) of lake sturgeon had visible external parasites classified as Argulus spp. This study suggests that a recovering lake sturgeon population exists in the St. Marys River, however, it remains unclear as to whether this is a self-sustaining population reproducing in the river. Additional information is needed on metapopulation dynamics, habitat use, and younger age classes to assess recruitment success and population status.
Lancet, 2011
The St. Marys River is the sole surface outlet from Lake Superior, flowing over 100 km to Lake Hu... more The St. Marys River is the sole surface outlet from Lake Superior, flowing over 100 km to Lake Huron, and forming part of the international border between Canada (Ontario) and the United States (MI). The river system has been severely impacted by modifications to the hydrology as well as local industrial and municipal discharges, and was designated in 1985 as an Area of Concern (AOC). Since that time, sediments on the Canadian side of the river have been systematically re-sampled, but the US side of the river has received less attention. This paper discusses two recent projects, one completed in 2003 and one completed in 2005, that sought to revisit a variety of sediment localities within the St. Marys River to update sediment contaminant data, and to expand sampling into additional areas of interest on the US side of the border: Munuscong Lake at the southern end of the AOC, and the Little Rapids adjacent to Sugar Island. The primary focus was on surficial sediment contamination, particularly metals shown to be elevated during previous sampling (chromium, nickel, copper). Results show that while Cr, Ni and Cu contamination remains slightly elevated in surficial sediments at some sites in the St. Marys River, the overall trend shows metal concentrations declining to levels consistent with background levels in sediments found in Lake Superior, Whitefish Bay and the St. Marys River.
Lancet, 2011
Zooplankton communities of the Great Lakes have received significant attention in light of recent... more Zooplankton communities of the Great Lakes have received significant attention in light of recent food web changes. No recent attempts have been made, however, to characterize the zooplankton community of the St. Marys River, the sole connecting channel between Lake Superior and Lake Huron. The purpose of this study was to provide new reference information for St. Marys River zooplankton communities and discuss the patterns observed in relation to recent changes in the Great Lakes. To address these objectives, sampling occurred at Lake Superior State University's Aquatic Research Laboratory from 2003 to 2007, and at 9 coastal wetlands in 2005. Compared to historical studies of St. Marys River riverine zooplankton, relative densities of calanoid copepods and daphnids have decreased while cyclopoid copepods and bosminids have increased. Coastal wetland communities continue to be diverse and exhibit similar community structure to previous studies, although Leptodora kindti, historically an abundant nearshore taxa, is now absent. Mechanisms driving differences in present community structure as compared to that noted in past studies of the St. Marys River are unknown but may be explained by the presence of the predatory, invasive zooplankton, Bythotrephes longimanus, local environmental variables, or changes upstream in Lake Superior. Temperaturezooplankton abundance patterns and nearshore community structure of Lake Superior are reflected in the St. Marys zooplankton community; thus, local environmental factors including changes in planktivory and proximity to upstream feeder communities likely play an important role in structuring St. Marys River zooplankton communities seasonally and spatially.
Because of the important role science plays in peoples’ lives and the significant (and increasing... more Because of the important role science plays in peoples’ lives and the significant (and increasing) impact of humans on the environment, there is a great and growing need to improve links between scientists and society [e.g., Lubchenco, 1998]. Some funding agencies recognize this need and have shaped their priorities accordingly. For example, the U.S. National Science Foundation (NSF) requires grant applicants to address the broader impacts of proposed work, including “promoting teaching, training, and learning” [NSF, 2007]. NASA, the U.S. National Oceanic and Atmospheric Administration (NOAA), and other agencies also encourage and fund education and public outreach activities [e.g., Franks et al., 2006; NASA, 2009].
Eos, Transactions American Geophysical Union, 2009
... Petersburg, Fla.; Elizabeth Hinchey, Illinois-Indiana Sea Grant College Program, Purdue Unive... more ... Petersburg, Fla.; Elizabeth Hinchey, Illinois-Indiana Sea Grant College Program, Purdue University, US Environmental Protection Agency Great Lakes National Program Office, Chicago, Ill.; Ashley Moerke, Department of Biological Sciences, Lake Superior State University ...