Simulation of thermal/dissolved oxygen habitat for fishes in lakes under different climate scenarios: Part 1. Cool-water fish in the contiguous US

Abstract

Fish habitat is strongly constrained by water temperature and available dissolved oxygen (DO). Thermal/DO habitat for cool-water fish in small lakes was therefore determined from simulated daily water temperature and DO profiles. Twenty-seven types of lakes were simulated with past (1961–1979) climate conditions observed at 209 weather stations in the contiguous USA as input, and with a 2×CO 2 climate scenario that is projected to occur at the same locations. The output of the Canadian Climate Centre General Circulation Model (CCC GCM) was used to determine the climate data increments for a doubling of atmospheric CO 2. A verified, process-oriented, unsteady and one-dimensional (vertical) lake water quality model (MINLAKE96) was used for the year-round temperature and DO simulations, which were run in a continuous mode over a 19-year simulation period. Water temperature and DO criteria for survival and good-growth of cool-water fish were provided by the United States Environmental Protection Agency. Cool-water fish in this study comprise seven species, northern pike, white sucker, black crappie, white crappie, yellow perch, sauger, and walleye. Nine fish habitat parameters were developed to quantify thermal habitat of cool-water fish and were extracted for the 27 lake types at 209 locations of the contiguous US. Fish habitat parameters were found to depend more strongly on lake geometry (surface area and maximum depth) and less on trophic state. Winterkill which occurs in eutrophic and mesotrophic, shallow lakes of the north-central and northeastern states of the contiguous US under present climate conditions, is projected to disappear under the 2×CO 2 climate scenario due to a shortening of the ice cover period. Climate warming is projected to increase the good-growth period of cool-water fish by up to 137 days in lakes in the north-central and northeastern states and to decrease it by up to 103 days in lakes at several south-central and southeastern states of the contiguous US. Due to climate warming, the good-growth period, the good-growth habitat areas and the good-growth habitat volumes of cool-water fish are projected to increase by 20, 10, and 8% from the past values, respectively, in medium-depth lakes of the contiguous US. Climate warming is projected to reduce the number of locations, where lakes have suitable cool-water fish habitat, by up to 62 out of 209 (30%). Average reductions are 56, 42, and 7 locations (27, 20, and 3%) for shallow (4 m), medium-depth (13 m), and deep (24 m) lakes, respectively. Summerkill under the projected 2×CO 2 CCC climate scenario is a projected significant negative impact on cool-water fish in southern lakes of the contiguous US, where suitable habitat existed under past conditions.