Simulation and Validation of Cisco Lethal Conditions in Minnesota Lakes under Past and Future Climate Scenarios Using Constant Survival Limits

Abstract

Fish habitat in lakes is strongly constrained by water temperature (T) and available dissolved oxygen (DO) that are changed under climate warming. A one dimensional, dynamic water quality model MINLAKE2012 was used for T and DO simulation over 48 years. A fish habitat model FishHabitat2013 using simulated T and DO profiles as input was developed to determine lethal conditions of cisco Corgenous artedi in Minnesota lakes. Twenty-three lakes that had observations of cisco mortality or survival in the unusually warm summer of 2006 were used for model validation. The cisco habitat model used a lethal temperature of 22.1˝C and DO survival limit of 3 mg/L determined through model validation and sensitivity analysis. Cisco lethal conditions in 12 shallow, 16 medium-depth, and 30 deep virtual lakes were then simulated. Isopleths of total number of years with cisco kill and average cisco kill days for the years with kills under past and future climate were generated to understand/extrapolate climate impacts on cisco in 620 Minnesota lakes. Shallow and medium-depth lakes are projected to not be good candidates for cisco refuge lakes, but deep lakes are possible cisco refuge lakes based on lethal condition projection under future warmer climate.

Refuge Lake Reclassification in 620 Minnesota Cisco Lakes under Future Climate Scenarios

“…Contour plots of a total number of years with cisco kill under future MIROC3.2 climate scenario from Jiang and Fang's study [11]. Duluth weather data were used for model simulations, and contours were derived by interpolation from simulated points for (a) 12 shallow and 16 mediumdepth virtual lakes, and (b) 30 deep virtual lakes.…”

“…The H max of the 620 cisco lakes ranges from 3.0 to 64.9 m [29], whereas H max of the 30 deep virtual lakes is 24 m; therefore, only using the contour lines of AvgATDO3 simulated from deep lakes to classify the refuge lakes may not be accurate for shallower lakes. Jiang et al [11] used constant survival limits of T and DO (i.e., lethal temperature and DO limit for cisco) to study the "total number of years with cisco kills" (Figure 4) and the "average cisco kill days for the years with kills" of three different types of virtual lakes (shallow H max = 4 m, medium-depth H max = 13 m, and deep H max = 24 m) and found that above two simulated variables have a big jump from shallow and medium-depth virtual lakes to deep virtual lakes. This further indicates that, to better represent 620 cisco lakes, more types of virtual lakes need to be used for developing contour lines of AvgATDO3 and then classifying refuge lakes.…”

“…Observed T and DO profiles are available from some lakes in weekly, bi-weekly, monthly or random time intervals and have been used for calibration and validation of lake water quality models [8,9], but typically no daily profiles are available for us to identify fish habitat in lakes. Therefore, T and DO daily profiles were simulated in different lakes to calculate various fish habitat parameters [10][11][12][13]. Many temperature models [14] and some water quality models [9,11,[15][16][17] have been developed and applied to simulate T and DO profiles in lakes.…”

“…Therefore, T and DO daily profiles were simulated in different lakes to calculate various fish habitat parameters [10][11][12][13]. Many temperature models [14] and some water quality models [9,11,[15][16][17] have been developed and applied to simulate T and DO profiles in lakes. MINLAKE96 [18], and later version MINLAKE2010 [19], a one-dimensional year-round water quality model originally designed to perform water quality simulation in Minnesota lakes, was applied in the previous studies [11,13].…”

“…Many temperature models [14] and some water quality models [9,11,[15][16][17] have been developed and applied to simulate T and DO profiles in lakes. MINLAKE96 [18], and later version MINLAKE2010 [19], a one-dimensional year-round water quality model originally designed to perform water quality simulation in Minnesota lakes, was applied in the previous studies [11,13]. Building on a previous study by Jiang et al [10] where T and DO were simulated for deep virtual lakes only using MINLAKE2010, Shallow virtual lakes 12 lakes with maximum depth equal to 4 m [11] Medium-depth virtual lakes 16 lakes with maximum depth equal to 13 m [11] Medium-deep virtual lakes 24 lakes with maximum depth equal to 18 m (Table 2) Deep virtual lakes 30 lakes with maximum depth equal to 24 m [10] 82 virtual lakes 12 shallow, 16 medium-depth, 24 medium-deep, and 30 deep virtual lakes to purchase land (conservation strategy) from watersheds surrounding top tiered refuge lakes after considering the threat (potential changes in land use) and the investment efficiency (total surface area of refuge lakes protected per amount invested) to protect lake water quality [23,24].…”