Mark Edlund - Academia.edu (original) (raw)

Papers by Mark Edlund

Lake and reservoir management, Oct 2, 2017

Lake of the Woods (LOW), a vast lake covering over 3850 km 2 , is a waterbody of current and hist... more Lake of the Woods (LOW), a vast lake covering over 3850 km 2 , is a waterbody of current and historical significance that spans the borders between Minnesota and the Canadian provinces of Ontario and Manitoba. Over the past 2 decades, there has been concern for the water quality of LOW, sparked by anecdotal evidence of increased intensity and frequency of algal blooms by the public and resource managers. Minnesota's waters of LOW were declared impaired in 2008 due to exceedances of eutrophication criteria, initiating a Total Maximum Daily Load study. LOW's impairment declaration spurred several contrasting challenges and opportunities for water quality management across this diverse lake and basin. Governance challenges are emphasized by the large number of government agencies (>25) with land or water authorities in the 70,000 km 2 basin, the variability in phosphorus standards applicable to LOW between Minnesota, Ontario, and Manitoba, and unequal funding resources allocated to LOW's water quality management agencies. Despite these challenges, there is a long history of international cooperation among agencies, recent funding increases, and the formation of a new International Joint Commission Board with the mandate to monitor ecosystem health in the entire LOW basin. As highlighted by the studies in this issue, the science of nutrient and algal dynamics in LOW is complex, and water quality restoration may take years to decades because major sources of nutrients to the lake are not subject to reductions by conventional lake restoration methods. An overview of papers in this special issue is provided.

Lake and reservoir management, Oct 2, 2017

A historical phosphorus (P) budget was constructed for southern Lake of the Woods. Sediment cores... more A historical phosphorus (P) budget was constructed for southern Lake of the Woods. Sediment cores from seven bays were radioisotopically dated and analyzed for loss-on-ignition, P, Si, diatoms, and pigments. Geochemical records for cores were combined using focusing factors for whole-basin estimates of sediment, total P, and P fraction accumulation. Although historical monitoring shows that external P loads decreased since the 1950s, sediment P continues to increase since the mid-20 th century. Much sediment P is labile and may be mobile within the sediments and/or available for internal loading and resuspension. Two mass-balance models were used to explore historical P loading scenarios and in-lake dynamics, a static one-box model and a dynamic multi-box model. The one-box model predicts presettlement external loads were slightly less than modern loads. The dynamic model showed that water column P was higher in the 1950s-1970s than today, that the lake is sensitive to external loads because P losses from burial and outflow are high, and that the lake is moving to a new steady state with respect to water column P and size of the active sediment P pool. The active sediment pool built up in the mid-20 th century has been depleted through outflow and burial, such that its legacy effects are now minimal. Comparison of historical nutrient dynamics and sediment records of algal production showed a counterintuitive increase in production after external P loads decreased, suggesting other drivers may now regulate modern limnoecology, including seasonality of P loading, shifting nutrient limitation, and climate warming.

Lake and reservoir management, May 2, 2017

ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Pa... more ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Paleolimnology of the Lake of the Woods southern basin: continued water quality degradation despite lower nutrient influx. Lake Reserv Manage. 33:369–385. Despite decades of reduced nutrient inputs, Lake of the Woods, a large, shallow boreal lake on the US-Canadian border, shows little evidence of water quality improvements in the pelagic system. Here we analyzed sediments from 6 sites in the southern basin for diverse biogeochemical (loss-on-ignition, biogenic silica, pigments) and microfossil (diatoms, chrysophytes) remains to reconstruct the environmental history of the lake. Our objectives were to quantify the magnitude and direction of historical trophic change and evaluate reasons for an apparent lack of basin recovery following documented nutrient diversion. Evidence came from fossil indicator profiles and comparisons of these long-term trends with historical land use and monitoring data. Results indicate major changes in algal communities during and following peak nutrient loading in the mid-20th century as well as more recent increases in colonial cyanobacteria and high-nutrient diatom taxa. Combined, fossil indicators reflect an anthropogenically enriched system that has undergone substantial ecological change, particularly since ∼1980, due to multiple drivers. Physical changes in lake thermal regime resulting from climate warming may be exacerbating internal phosphorus release from sediments, thereby lowering nitrogen:phosphorus ratios and enhancing cyanobacterial abundance. These drivers of lake condition in the lake may apply to other large shallow lakes that exhibit only limited biological recovery from reduced external nutrient loading.

ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Pa... more ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Paleolimnology of the Lake of the Woods southern basin: continued water quality degradation despite lower nutrient influx. Lake Reserv Manage. 33:369–385. Despite decades of reduced nutrient inputs, Lake of the Woods, a large, shallow boreal lake on the US-Canadian border, shows little evidence of water quality improvements in the pelagic system. Here we analyzed sediments from 6 sites in the southern basin for diverse biogeochemical (loss-on-ignition, biogenic silica, pigments) and microfossil (diatoms, chrysophytes) remains to reconstruct the environmental history of the lake. Our objectives were to quantify the magnitude and direction of historical trophic change and evaluate reasons for an apparent lack of basin recovery following documented nutrient diversion. Evidence came from fossil indicator profiles and comparisons of these long-term trends with historical land use and monitoring data. Results indicate major changes in algal communities during and following peak nutrient loading in the mid-20th century as well as more recent increases in colonial cyanobacteria and high-nutrient diatom taxa. Combined, fossil indicators reflect an anthropogenically enriched system that has undergone substantial ecological change, particularly since ∼1980, due to multiple drivers. Physical changes in lake thermal regime resulting from climate warming may be exacerbating internal phosphorus release from sediments, thereby lowering nitrogen:phosphorus ratios and enhancing cyanobacterial abundance. These drivers of lake condition in the lake may apply to other large shallow lakes that exhibit only limited biological recovery from reduced external nutrient loading.

Journal of Paleolimnology, Dec 19, 2017

The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, W... more The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, Wisconsin, and the most western point of Lake Superior (46.74°,-92.13°), has a long history of human development since Euro-American settlement * 200 years ago. Due to degradation from logging, hydrologic modification, industrial practices, and untreated sewage, the SLRE was designated an Area of Concern in 1987. Action has been taken to restore water quality including the installation of the Western Lake Superior Sanitary District in 1978 to help remove beneficial use impairments. A better understanding of historical impacts and remediation is necessary to help document progress and knowledge gaps related to water quality, so a paleolimnological study of the SLRE was initiated. Various paleolimnological indicators (pigments, diatom communities, and diatom-inferred phosphorus) were analyzed from six cores taken throughout the SLRE and another from western Lake Superior. Reductions in eutrophic diatom taxa such as Cyclotella meneghiniana and Stephanodiscus after 1970 in certain cores suggest an improvement in water quality over the last 40 years. However, in cores taken from estuarine bay Electronic supplementary material The online version of this article (

Cambridge University Press eBooks, Sep 30, 2010

Palaeogeography, Palaeoclimatology, Palaeoecology, Sep 1, 2022

FIGURES 393–442: LM micrographs. Figs 393–441. Hippodonta arkonensis. Fig. 404. Complete frustule... more FIGURES 393–442: LM micrographs. Figs 393–441. Hippodonta arkonensis. Fig. 404. Complete frustule in girdle view. Fig. 442. Hippodonta baicalorostrata. Scale bar = 10 µm.

FIGURES 219–225: SEM micrographs. Figs 219–222. Hippodonta abunda (type material). Fig. 219. Exte... more FIGURES 219–225: SEM micrographs. Figs 219–222. Hippodonta abunda (type material). Fig. 219. External view of entire valve. Terminal pores of raphe are simple linear depressions. Fig. 220. External view of complete frustule showing broad, unornamented girdle. Fig. 221. Internal view of entire valve. Striae positioned in shallow depressions, helictoglossae in line with raphe slits. Fig. 222. Close-up of one half of valve, internal view. Lineolae covered by quite prominent elliptical volae. Fig. 223. Hippodonta rostratoides (type material). External view of entire valve. Lineolae quite prominent. Terminal pores of raphe slightly deflected towards one valve side. Fig. 224. Hippodonta affinis (type material). External view of entire valve. Lineolae narrow but long. Terminal pores of raphe simple linear. Fig. 225. Hippodonta exigua (type material). External view of entire valve. Lineolae weakly pronounced, short. Terminal pores of raphe slightly deflected towards one valve side. Scale ba...

FIGURES 96–101: SEM micrographs. Figs 96, 97. Hippodonta costulatiformis var. densistriata (type ... more FIGURES 96–101: SEM micrographs. Figs 96, 97. Hippodonta costulatiformis var. densistriata (type material). Fig. 96. External view of complete frustule showing narrow hyaline area present on valve mantle and the unornamented girdle. Fig. 97. Internal view of entire valve; striae positioned in shallow ridge depressions; interstriae strongly pronounced; helictoglossae in line with raphe slits. Figs 98–101. Hippodonta naviculiformis (type material). Figs 98, 100. External view of entire valve. Terminal pores of raphe deflected towards one valve side. Fig. 99. Internal view of entire valve. Lineolae positioned in shallow elliptical depressions. Central raphe endings simple linear and distantly positioned. Fig. 101. External view of broken frustule showing girdle unornamented. Scale bars in Fig. 96 = 2 µm; Fig. 97 = 5 µm; Figs 98–101 = 2 µm.

FIGURES 1–26: LM micrographs of Hippodonta lueneburgensis. Scale bar = 10 µm.

FIGURES 166–218: LM micrographs. Figs 166–179. Hippodonta subrostrata (type material). Figs 180–1... more FIGURES 166–218: LM micrographs. Figs 166–179. Hippodonta subrostrata (type material). Figs 180–191. Hippodonta rostratoides (type material). Figs 192–200. Hippodonta affinis (type material). Figs 201–212. Hippodonta exigua (type material). Figs 213–218. Hippodonta humboldtiana (type material). Scale bar = 10 µm.

FIGURES 102–165: LM micrographs. Figs 102–137. Hippodonta abunda (type material). Figs 138–155. H... more FIGURES 102–165: LM micrographs. Figs 102–137. Hippodonta abunda (type material). Figs 138–155. Hippodonta microcostulata. Figs 156–165. Hippodonta media (type material). Scale bar = 10 µm.

FIGURES 443–498: LM micrographs. Figs 443–469. Hippodonta subelegans. Figs 470–481. Hippodonta ac... more FIGURES 443–498: LM micrographs. Figs 443–469. Hippodonta subelegans. Figs 470–481. Hippodonta acuta (type material). Figs 482–498. Hippodonta microcostulata. Scale bar = 10 µm.

Lake and reservoir management, Oct 2, 2017

Lake of the Woods (LOW), a vast lake covering over 3850 km 2 , is a waterbody of current and hist... more Lake of the Woods (LOW), a vast lake covering over 3850 km 2 , is a waterbody of current and historical significance that spans the borders between Minnesota and the Canadian provinces of Ontario and Manitoba. Over the past 2 decades, there has been concern for the water quality of LOW, sparked by anecdotal evidence of increased intensity and frequency of algal blooms by the public and resource managers. Minnesota's waters of LOW were declared impaired in 2008 due to exceedances of eutrophication criteria, initiating a Total Maximum Daily Load study. LOW's impairment declaration spurred several contrasting challenges and opportunities for water quality management across this diverse lake and basin. Governance challenges are emphasized by the large number of government agencies (>25) with land or water authorities in the 70,000 km 2 basin, the variability in phosphorus standards applicable to LOW between Minnesota, Ontario, and Manitoba, and unequal funding resources allocated to LOW's water quality management agencies. Despite these challenges, there is a long history of international cooperation among agencies, recent funding increases, and the formation of a new International Joint Commission Board with the mandate to monitor ecosystem health in the entire LOW basin. As highlighted by the studies in this issue, the science of nutrient and algal dynamics in LOW is complex, and water quality restoration may take years to decades because major sources of nutrients to the lake are not subject to reductions by conventional lake restoration methods. An overview of papers in this special issue is provided.

Lake and reservoir management, Oct 2, 2017

A historical phosphorus (P) budget was constructed for southern Lake of the Woods. Sediment cores... more A historical phosphorus (P) budget was constructed for southern Lake of the Woods. Sediment cores from seven bays were radioisotopically dated and analyzed for loss-on-ignition, P, Si, diatoms, and pigments. Geochemical records for cores were combined using focusing factors for whole-basin estimates of sediment, total P, and P fraction accumulation. Although historical monitoring shows that external P loads decreased since the 1950s, sediment P continues to increase since the mid-20 th century. Much sediment P is labile and may be mobile within the sediments and/or available for internal loading and resuspension. Two mass-balance models were used to explore historical P loading scenarios and in-lake dynamics, a static one-box model and a dynamic multi-box model. The one-box model predicts presettlement external loads were slightly less than modern loads. The dynamic model showed that water column P was higher in the 1950s-1970s than today, that the lake is sensitive to external loads because P losses from burial and outflow are high, and that the lake is moving to a new steady state with respect to water column P and size of the active sediment P pool. The active sediment pool built up in the mid-20 th century has been depleted through outflow and burial, such that its legacy effects are now minimal. Comparison of historical nutrient dynamics and sediment records of algal production showed a counterintuitive increase in production after external P loads decreased, suggesting other drivers may now regulate modern limnoecology, including seasonality of P loading, shifting nutrient limitation, and climate warming.

Lake and reservoir management, May 2, 2017

ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Pa... more ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Paleolimnology of the Lake of the Woods southern basin: continued water quality degradation despite lower nutrient influx. Lake Reserv Manage. 33:369–385. Despite decades of reduced nutrient inputs, Lake of the Woods, a large, shallow boreal lake on the US-Canadian border, shows little evidence of water quality improvements in the pelagic system. Here we analyzed sediments from 6 sites in the southern basin for diverse biogeochemical (loss-on-ignition, biogenic silica, pigments) and microfossil (diatoms, chrysophytes) remains to reconstruct the environmental history of the lake. Our objectives were to quantify the magnitude and direction of historical trophic change and evaluate reasons for an apparent lack of basin recovery following documented nutrient diversion. Evidence came from fossil indicator profiles and comparisons of these long-term trends with historical land use and monitoring data. Results indicate major changes in algal communities during and following peak nutrient loading in the mid-20th century as well as more recent increases in colonial cyanobacteria and high-nutrient diatom taxa. Combined, fossil indicators reflect an anthropogenically enriched system that has undergone substantial ecological change, particularly since ∼1980, due to multiple drivers. Physical changes in lake thermal regime resulting from climate warming may be exacerbating internal phosphorus release from sediments, thereby lowering nitrogen:phosphorus ratios and enhancing cyanobacterial abundance. These drivers of lake condition in the lake may apply to other large shallow lakes that exhibit only limited biological recovery from reduced external nutrient loading.

ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Pa... more ABSTRACT Reavie ED, Edlund MB, Andresen NA, Engstrom DR, Leavitt PR, Schottler S, Cai M. 2017. Paleolimnology of the Lake of the Woods southern basin: continued water quality degradation despite lower nutrient influx. Lake Reserv Manage. 33:369–385. Despite decades of reduced nutrient inputs, Lake of the Woods, a large, shallow boreal lake on the US-Canadian border, shows little evidence of water quality improvements in the pelagic system. Here we analyzed sediments from 6 sites in the southern basin for diverse biogeochemical (loss-on-ignition, biogenic silica, pigments) and microfossil (diatoms, chrysophytes) remains to reconstruct the environmental history of the lake. Our objectives were to quantify the magnitude and direction of historical trophic change and evaluate reasons for an apparent lack of basin recovery following documented nutrient diversion. Evidence came from fossil indicator profiles and comparisons of these long-term trends with historical land use and monitoring data. Results indicate major changes in algal communities during and following peak nutrient loading in the mid-20th century as well as more recent increases in colonial cyanobacteria and high-nutrient diatom taxa. Combined, fossil indicators reflect an anthropogenically enriched system that has undergone substantial ecological change, particularly since ∼1980, due to multiple drivers. Physical changes in lake thermal regime resulting from climate warming may be exacerbating internal phosphorus release from sediments, thereby lowering nitrogen:phosphorus ratios and enhancing cyanobacterial abundance. These drivers of lake condition in the lake may apply to other large shallow lakes that exhibit only limited biological recovery from reduced external nutrient loading.

Journal of Paleolimnology, Dec 19, 2017

The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, W... more The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, Wisconsin, and the most western point of Lake Superior (46.74°,-92.13°), has a long history of human development since Euro-American settlement * 200 years ago. Due to degradation from logging, hydrologic modification, industrial practices, and untreated sewage, the SLRE was designated an Area of Concern in 1987. Action has been taken to restore water quality including the installation of the Western Lake Superior Sanitary District in 1978 to help remove beneficial use impairments. A better understanding of historical impacts and remediation is necessary to help document progress and knowledge gaps related to water quality, so a paleolimnological study of the SLRE was initiated. Various paleolimnological indicators (pigments, diatom communities, and diatom-inferred phosphorus) were analyzed from six cores taken throughout the SLRE and another from western Lake Superior. Reductions in eutrophic diatom taxa such as Cyclotella meneghiniana and Stephanodiscus after 1970 in certain cores suggest an improvement in water quality over the last 40 years. However, in cores taken from estuarine bay Electronic supplementary material The online version of this article (

Cambridge University Press eBooks, Sep 30, 2010

Palaeogeography, Palaeoclimatology, Palaeoecology, Sep 1, 2022

FIGURES 393–442: LM micrographs. Figs 393–441. Hippodonta arkonensis. Fig. 404. Complete frustule... more FIGURES 393–442: LM micrographs. Figs 393–441. Hippodonta arkonensis. Fig. 404. Complete frustule in girdle view. Fig. 442. Hippodonta baicalorostrata. Scale bar = 10 µm.

FIGURES 219–225: SEM micrographs. Figs 219–222. Hippodonta abunda (type material). Fig. 219. Exte... more FIGURES 219–225: SEM micrographs. Figs 219–222. Hippodonta abunda (type material). Fig. 219. External view of entire valve. Terminal pores of raphe are simple linear depressions. Fig. 220. External view of complete frustule showing broad, unornamented girdle. Fig. 221. Internal view of entire valve. Striae positioned in shallow depressions, helictoglossae in line with raphe slits. Fig. 222. Close-up of one half of valve, internal view. Lineolae covered by quite prominent elliptical volae. Fig. 223. Hippodonta rostratoides (type material). External view of entire valve. Lineolae quite prominent. Terminal pores of raphe slightly deflected towards one valve side. Fig. 224. Hippodonta affinis (type material). External view of entire valve. Lineolae narrow but long. Terminal pores of raphe simple linear. Fig. 225. Hippodonta exigua (type material). External view of entire valve. Lineolae weakly pronounced, short. Terminal pores of raphe slightly deflected towards one valve side. Scale ba...

FIGURES 96–101: SEM micrographs. Figs 96, 97. Hippodonta costulatiformis var. densistriata (type ... more FIGURES 96–101: SEM micrographs. Figs 96, 97. Hippodonta costulatiformis var. densistriata (type material). Fig. 96. External view of complete frustule showing narrow hyaline area present on valve mantle and the unornamented girdle. Fig. 97. Internal view of entire valve; striae positioned in shallow ridge depressions; interstriae strongly pronounced; helictoglossae in line with raphe slits. Figs 98–101. Hippodonta naviculiformis (type material). Figs 98, 100. External view of entire valve. Terminal pores of raphe deflected towards one valve side. Fig. 99. Internal view of entire valve. Lineolae positioned in shallow elliptical depressions. Central raphe endings simple linear and distantly positioned. Fig. 101. External view of broken frustule showing girdle unornamented. Scale bars in Fig. 96 = 2 µm; Fig. 97 = 5 µm; Figs 98–101 = 2 µm.

FIGURES 1–26: LM micrographs of Hippodonta lueneburgensis. Scale bar = 10 µm.

FIGURES 166–218: LM micrographs. Figs 166–179. Hippodonta subrostrata (type material). Figs 180–1... more FIGURES 166–218: LM micrographs. Figs 166–179. Hippodonta subrostrata (type material). Figs 180–191. Hippodonta rostratoides (type material). Figs 192–200. Hippodonta affinis (type material). Figs 201–212. Hippodonta exigua (type material). Figs 213–218. Hippodonta humboldtiana (type material). Scale bar = 10 µm.

FIGURES 102–165: LM micrographs. Figs 102–137. Hippodonta abunda (type material). Figs 138–155. H... more FIGURES 102–165: LM micrographs. Figs 102–137. Hippodonta abunda (type material). Figs 138–155. Hippodonta microcostulata. Figs 156–165. Hippodonta media (type material). Scale bar = 10 µm.

FIGURES 443–498: LM micrographs. Figs 443–469. Hippodonta subelegans. Figs 470–481. Hippodonta ac... more FIGURES 443–498: LM micrographs. Figs 443–469. Hippodonta subelegans. Figs 470–481. Hippodonta acuta (type material). Figs 482–498. Hippodonta microcostulata. Scale bar = 10 µm.