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WLF impacts (Physical effects (Sediments (Resuspension (Rhodes & Wiley…
WLF impacts
Physical effects
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Sediments
WL drawdown enhnaces sediment erosion and focusing has the potential to change littoral sediment and biogeochemical characteristics. (Furey et al 2004)
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Bedford (1992) explored the physical effects of the Great Lakes on tributaries and wetlands, particularly the effects of short and long-term WLF and accompanying transport disruptions, including flow and transport reversals. (as cited by Leira & Cantonati 2008) what does it mean?
Light penetration
Higher WL means less bottom is exposed to light. Is suggested by Loiselleet al. (2005) but is not tested in their study.
"Exposure of new substrate during periods of extreme low water levels may facilitate the expansion of emergent plants." Said by Leira & Cantonati without more explanation. They cite Hudon (1997) and the strong negative realtionship between seasonal water level and pct of emrgent plant cover in their study but it isn't clear how this is physical.
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Water chemistry
WLF affects water chemistry which exerts a strong influence on habitat conditions at different sites of the lakes (Dinka et al, 2004). As cited by Leira & Cantonati, needs more info.
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Biota
Plants
Drawdown enables germination and establishment of many plant speices on exposed soils (Keddy and Reznicek 1986, Nishihiroet al 2004, Naimanet al. 2005
Saturated, reduced soils a high water levels can kill terrestrial vegetation such as shrubs
Higher water levels reduce light penetration to underwater sediments, reducing growth rates or killing light-limited submersed aquatic vegetation
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Many plants are adapted to moderately fluctuating water levels, which may maximize the extent and species richness of plants in the shore zone (Keddy and Reznicek 1986, Hill et al. 1998)
Species richness and area occupied by aquatic plants can be reduced by decreasing, increasing, or changing the seasonal pattern of WLFs (Hill et al. 1998)
Stabilized WLs may have lower species richness and higher cover of invasive plants (Hill et al. 1998, Van Geest et al. 2005, Boers and Zedler 2008).
Animals
Predictable changes in WL allow animals to access different habitats over the course of the water year. Ex: northern pike and yellow perch spawn on seasonally flooded vegetation (Wilcox and Meeker 1992; Farrell 2001).
Unpredictable changes in WLs can make parts of the shore unsuitable for animals or kill them outright either through drowning or dessication.
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