A Reduced Parameter Stream Temperature Model (RPSTM) for Fluvial Ecosystem Forecasting.

Abstract

As stream water temperature helps shape the biology of riverine ecosystems, it is important to understand how varied human activities alter the natural spatial and temporal thermal regimes. To predict the effects of human-induced thermal changes on fish communities, a modeling approach is required. However, the current models are either too simplistic to capture the dynamic of the system, or too complex to practically apply in a large-scale setting. The goals of my dissertation were to develop a spatially explicit and easy to parameterize heat balance model integrated with a pre-existing multi-modeling system, and to apply it in several different river management contexts. I first describe a newly designed Reduced Parameter Stream Temperature Model. I then use my model to explore the effects of anthropogenic stressors on the distribution and dynamics of thermal habitat conditions for fishes. I included simulation studies of water withdrawal, dam removal, and climate change, and examined the potential shifts in thermal habitat and provided predictions of the timing shifts in the early life history staging of Great Lakes anadromous fishes in the Muskegon River Watershed. In a water withdrawal simulation my model predicted that thermal impacts varied with the patterns of local groundwater flux, surface water to groundwater mixing ratios, and distances of pumping activities to the river. The dam removal simulation predicted that summer stream temperature would be effectively lowered without the dams. This could cause a 8~10 day delay in the timing of spawning, and a 7~15 day delay in fry emergence for steelhead, walleye, and chinook. Removal of the dams could also bring more usable habitat upstream for all the three fish species. In a climate change simulation I found that monthly water temperature could increase 2 to 4.5oC, with the greatest changes occurred in spring. These changes could cause spawning and fry emergence to shift about 3 weeks earlier for steelhead and walleye. Meanwhile, warming climate could cause the early spawning cohort of chinook to delay about 2 weeks, and the late spawning about one month. However, global warming could induce a one month earlier fry emergence for chinook.