Understanding the impact of climate change on cold- and cool-water fish habitat.
In the Midwest, cool- and cold-water fish in inland lakes are susceptible to climate change because appropriate oxygen and temperature (oxythermal) habitat is limited during the summer months. These fish can experience a squeezing of habitat as water temperatures near the lake surface become too warm and dissolved oxygen levels in deeper waters drop. My research looks at the drivers of these changes and investigates what management actions could be taken to prevent these changes. For more background, see my contribution to the Fourth National Climate Assessment discussion the impact of climate change on cool- and cold-water fish.
In the Midwest, cool- and cold-water fish in inland lakes are susceptible to climate change because appropriate oxygen and temperature (oxythermal) habitat is limited during the summer months. These fish can experience a squeezing of habitat as water temperatures near the lake surface become too warm and dissolved oxygen levels in deeper waters drop. My research looks at the drivers of these changes and investigates what management actions could be taken to prevent these changes. For more background, see my contribution to the Fourth National Climate Assessment discussion the impact of climate change on cool- and cold-water fish.
Oxythermal habitat of coldwater fish in midwestern inland lakes, illustrated by water depth under (left) a typical ice-free period and (right) a warm ice-free period. The top plots show water temperatures during the ice-free period, and the bottom plots show the dissolved oxygen concentrations. The schematics at the bottom illustrate the area of the lake that is ideal habitat for coldwater fish (in blue) and areas that represent water outside of the temperature or dissolved oxygen limit (in yellow and red, respectively). The left plots show how available habitat "squeezes" during a typical year, while the right plots illustrate a complete loss of suitable habitat during very warm years.
Coupled physical-chemical-biological models to predict losses of cold-water fish from inland lakes under climate warming
Cold-water fish habitat is limited by the availability of dissolved oxygen and sufficiently cold water temperatures. In many Midwestern US lakes, these conditions are met in the hypolimnion (bottom waters) of the lake. However, warming of surface waters and extended anoxic conditions in the hypolimnion as a result of climate changes reduce the depth distribution of fish that require cold, well-oxygenated water, and threaten to limit their habitat entirely. This project is lead by Dr. Peter McIntyre in collaboration with Dr. Jordan Read and Dr. Andrew Rypel to investigate where the changing climate may have caused extirpation of cold-water fishes and where further extirpation may be likely under future warming conditions.
Cold-water fish habitat is limited by the availability of dissolved oxygen and sufficiently cold water temperatures. In many Midwestern US lakes, these conditions are met in the hypolimnion (bottom waters) of the lake. However, warming of surface waters and extended anoxic conditions in the hypolimnion as a result of climate changes reduce the depth distribution of fish that require cold, well-oxygenated water, and threaten to limit their habitat entirely. This project is lead by Dr. Peter McIntyre in collaboration with Dr. Jordan Read and Dr. Andrew Rypel to investigate where the changing climate may have caused extirpation of cold-water fishes and where further extirpation may be likely under future warming conditions.
Developing a cumulative dosage approach to quantify oxythermal fish stress
Lake warming can negatively impact cool-water fishes through both temperature and oxygen stress. We modeled the joint dynamics of water column temperature and oxygen to quantify oxythermal habitat for yellow perch (Perca flavescens) in Fish Lake, Wisconsin, USA. To estimate annual oxythermal stress, we developed a novel metric (Cumulative Oxythermal Stress Dosage; COSD), that integrates both stress duration and stress magnitude. We find that COSD better predicts observed perch declines than the published TDO3 metric (temperature at depth where dissolved oxygen is 3 mg/L), which was developed for cold-water fish. Simulations show increases in COSD between 1911-2014, punctuated by a sharp rise since 1989. Extreme COSD years result from the intersection of high maximum daily dosage and prolonged duration exceeding the tolerance threshold. Temperature perturbation experiments to explore future climate scenarios reveal that COSD would increase greatly if the atmosphere warms by >3°C. Applying the COSD metric broadly to temperate lakes could help direct management efforts toward the ecosystems most likely to serve as climate refugia for cold- and cool-water fishes in the future. This research was supported by the NTL-LTER, University of Wisconsin Water Resources Institute, and the Northeast Climate Science Center.
Lake warming can negatively impact cool-water fishes through both temperature and oxygen stress. We modeled the joint dynamics of water column temperature and oxygen to quantify oxythermal habitat for yellow perch (Perca flavescens) in Fish Lake, Wisconsin, USA. To estimate annual oxythermal stress, we developed a novel metric (Cumulative Oxythermal Stress Dosage; COSD), that integrates both stress duration and stress magnitude. We find that COSD better predicts observed perch declines than the published TDO3 metric (temperature at depth where dissolved oxygen is 3 mg/L), which was developed for cold-water fish. Simulations show increases in COSD between 1911-2014, punctuated by a sharp rise since 1989. Extreme COSD years result from the intersection of high maximum daily dosage and prolonged duration exceeding the tolerance threshold. Temperature perturbation experiments to explore future climate scenarios reveal that COSD would increase greatly if the atmosphere warms by >3°C. Applying the COSD metric broadly to temperate lakes could help direct management efforts toward the ecosystems most likely to serve as climate refugia for cold- and cool-water fishes in the future. This research was supported by the NTL-LTER, University of Wisconsin Water Resources Institute, and the Northeast Climate Science Center.
Magee, M.R., McIntyre, P.B., Wu, C.H. 2018. Modeling oxythermal stress for cool-water fishes using a cumulative dosage approach. Canadian Journal of Fisheries and Aquatic Sciences [pdf]
Factors influencing cisco oxythermal habitat in Lake Mendota
Cisco (Coregonus artedi) are an important indicator species for cold-water lake habitats in the Great Lakes region, and many populations have been extirpated at their southern range limit over the last century. Understanding the roles of climate and water quality in these extirpations should inform protection of cold-water fishes. Using the water temperature at the depth where dissolved oxygen falls to 3 mg L-1 (TDO3) as a metric, we investigated the roles of climate and water quality as drivers of habitat availability for cisco in Lake Mendota, WI, USA from 1976-2013. We find that summer (Jun-Aug) air temperatures, spring (Mar-May) phosphorus load, and spring inflow influence summer TDO3. Warm air temperatures lead to the greatest increases in TDO3, whereas reduced phosphorus loads can reduce TDO3, thus alleviating oxythermal stress. Under air temperatures expected under the A1B climate change scenario, a 25% reduction in phosphorus load would stabilize TDO3 at current levels, while a 75% reduction in phosphorus loading would be required to expand oxythermal habitat. Costs of these reductions are estimated to range from US$16.9 million (-25%) to US$155-167 million (-75%) over a twenty-year period but may be feasible by expanding upon current watershed phosphorus reduction initiatives if sustained funding were available. Identifying targeted reductions will become increasingly important throughout the region as warmer temperatures and longer stratification reduces cool- and cold-water fish habitat in many Midwestern lakes under the expected future climate.
This research was supported by the NTL-LTER, University of Wisconsin Water Resources Institute, and the Northeast Climate Science Center.
Cisco (Coregonus artedi) are an important indicator species for cold-water lake habitats in the Great Lakes region, and many populations have been extirpated at their southern range limit over the last century. Understanding the roles of climate and water quality in these extirpations should inform protection of cold-water fishes. Using the water temperature at the depth where dissolved oxygen falls to 3 mg L-1 (TDO3) as a metric, we investigated the roles of climate and water quality as drivers of habitat availability for cisco in Lake Mendota, WI, USA from 1976-2013. We find that summer (Jun-Aug) air temperatures, spring (Mar-May) phosphorus load, and spring inflow influence summer TDO3. Warm air temperatures lead to the greatest increases in TDO3, whereas reduced phosphorus loads can reduce TDO3, thus alleviating oxythermal stress. Under air temperatures expected under the A1B climate change scenario, a 25% reduction in phosphorus load would stabilize TDO3 at current levels, while a 75% reduction in phosphorus loading would be required to expand oxythermal habitat. Costs of these reductions are estimated to range from US$16.9 million (-25%) to US$155-167 million (-75%) over a twenty-year period but may be feasible by expanding upon current watershed phosphorus reduction initiatives if sustained funding were available. Identifying targeted reductions will become increasingly important throughout the region as warmer temperatures and longer stratification reduces cool- and cold-water fish habitat in many Midwestern lakes under the expected future climate.
This research was supported by the NTL-LTER, University of Wisconsin Water Resources Institute, and the Northeast Climate Science Center.
surface plots showing sensitivity of TDO3 to changes in three drivers in combination (a) air temperature and inflow volume with P load constant; (b) air temperature and P load with inflow constant; and (c) P load and inflow volume with air temperature constant
Magee, M.R., McIntyre, P.B., Hanson, P.C., Wu, C.H. 2019. Drivers and management implications of long-term cisco oxythermal habitat decline in Lake Mendota, WI. Environmental Management [pdf]
