This report makes projections of potential (refuge) habitat for cisco, a coldwater fish, in
Minnesota lakes under projected warmer climate scenarios. It is about the identification and
selection of potential refuge lakes for cisco under future climate scenarios in Minnesota. This is
the third and final project report in a series that describes computer model simulations of cisco
(tullibee) lakes for the Minnesota Department of Natural Resources (DNR). The first report gave
an overview of the characteristics of cisco lakes in Minnesota, the second gave results of water
quality (temperature and dissolved oxygen, DO) model simulations for selected Minnesota cisco
lakes, and this third report identifies and quantifies in which Minnesota lakes cisco habitat is
most likely to continue to exist under global warming scenarios.
Cisco habitat simulations were first made for continuous, year-round weather time series
from 1962 to 2008 (47 years) at the daily time scale. Simulations were then extended to
projected future climate scenarios. A year-round water quality model MINLAKE 2010, that had
previously been calibrated against 7384 pairs of temperature and DO data points measured in 28
lakes between 1979 and 2008 with overall standard errors of 1.47 oC for water temperature, and
1.50 mg/L for DO, was used in all cisco habitat simulations (Fang et al. 2010).
Adult cisco habitat is limited by critical water temperature and DO conditions in different
strata of a cisco lake. The selection was based on the oxythermal parameter TDO3, which relates
to the survival stress of adult cisco. The lower the TDO3 is, the lower the stress is to cisco.
TDO3 is a water temperature that occurs where DO = 3 mg/L and was used as the oxythermal
parameter to select suitable habitat for adult cisco (Jacobson et al. 2010). Twelve TDO3
parameters ranging from single-day values to multi-year averages, and from extreme values to
mean values, were defined in Table 3.1 and calculated from simulated daily temperature and DO
profiles. The multi-year values AvgATDO3FB and AvgATDO3VB were ultimately chosen from
Table 3.1, lines 6 and 12, for the selection of cisco refuge lakes. Each of these two TDO3
parameters is calculated over the length of a 31-day benchmark period; one uses a fixed
benchmark period from DOY 209 to DOY 239 (July 28 to August 27); the other uses a variable
(sliding) benchmark period of 31 days.
Minnesota Department of Natural Resources; Auburn University
Fang, Xing; Alam, Shoeb R.; Jiang, Liping; Jacobson, Peter; Pereira, Don; Stefan, Heinz G..
Simulations of Cisco Fish Habitat in Minnesota Lakes under Future Climate Scenarios.
St. Anthony Falls Laboratory.
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