Seasonal Patterns of Water Chemistry into Three Boreal Rivers: Implication for Salmonid Incubation and Rearing in the Frame of Hydrological Extremes and Land Use Contexts

Climate change is expected to alter the timing and intensity of precipitation and river discharge patterns, leading to hydrological extremes. Compared to forested watersheds, highly urbanized and cultivated areas are prone to sediment and nutrient loads from agricultural fields, impacting river water quality. On the other hand, prolonged low discharge periods limit the rivers’ dilution capacity, and result in hyporheic water stagnation and the accumulation of metabolic end products. Hydrological extremes may, therefore, produce severe implications for river water quality and, consequently, for aquatic life; however, this important aspect is poorly explored in the literature. In this context, three boreal streams that represent spawning and juvenile rearing habitats for anadromous salmonids were analyzed comparatively with respect to land use, anthropization level, and seasonal variability in water chemistry, during low and high discharge events. A set of chemical parameters depicting the water quality are discussed in relation to different land cover features, high discharge events, and seasonality. Finally, potential negative implications for the incubation period of salmonid embryos and juvenile rearing are outlined.