Relative Depth (Z r) in % = 50 * Z max * sqrt(π) * (sqrt(A o))-1, where sqrt=square root . The primary factor in pond production is the quality of the water. For most lakes, Zr < 2%. 2011. If a pond has not been limed, the hardness and alkalinity may be too low to make phosphorus available to the phytoplankton (one- celled, microscopic plants that are the start of the food chain). autochthonous and allochthonous production..... vary in systematic ways in lakes, rivers and estuaries. Matala, A.P. 1980) and temporal patterns of productivity have been shown to be constrained by terrestrially mediated light availability (Roberts et al. The number of "extreme streamflow" events observed in river systems have increased significantly across the United States and Canada over the last century, according to a study from Dartmouth College. Definitions: Relative Depth, Z r (Hutchinson, 1957; and Wetzel & Likens, 1991): Relative Depth is the maximum depth as a percentage of mean diameter. rivers through fragmentation or changes to river flow patterns. and B. Parker. Taiga, ‘land of the little sticks’ in Russian, is named for the term for Russia’s northern forests, especially Siberia. Relative extent of stressors in the nation’s rivers and streams ..... 41 Figure 20. The relative importance of terrestrial shading on mediating productivity is expected to vary with river size (Vannote et al. Genetic Stock Structure, Relative Productivity and Migration (Gene Flow) of White Sturgeon Among Bonneville, The Dalles, John Day and McNary Reservoirs in the Lower Mid-Columbia River Region. Deep lakes with small surface areas exhibit greater resistance to mixing and usually have Zr > 4% Annual Report to the Bonneville Power Administration, contract # 50512, project # 2008-504-00. Riparian disturbance in the nation’s rivers and streams..... 39 Figure 19. Taiga, biome composed mainly of cone-bearing needle-leaved or scale-leaved evergreen trees, found in northern circumpolar regions typified by long winters and moderate to high annual precipitation. Relative extent, relative risk, and attributable risk to 2008). Populations of the once abundant Lost River (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) of the Upper Klamath Basin, decreased so substantially throughout the 20th century that they were listed under the Endangered Species Act in 1988. Further, nearly 70 percent of all affected kilometers will occur in freshwater ecoregions with the greatest diversity of fish species. Figure 17.3 Seasonal development of maximum daily gross primary productivity (GPP) for deciduous and coniferous forests in temperate (Europe and North America) and boreal locations (Canada, Scandinavia and Iceland). Valuing Rivers Valuing Rivers 4 5 EXECUTIVE SUMMARY Traditionally, rivers have been valued primarily as water sources to drive the economic engines of irrigation and hydropower. Also, the pH can vary enough to keep the fish stressed and reduce growth rates. 1987) (Figure 1). 2007; Izagirre et al. National Rivers and Streams Assessment, 2008–2009 Figure 18. “Net primary production” • These impacts are projected to occur in many of the river basins with the greatest freshwater fish harvests. “Gross primary production” (GPP) refers to the total rate of organic carbon production by autotrophs, while “respiration” refers to the energy-yielding oxidation of organic car-bon back to carbon dioxide. River ecosystems are flowing waters that drain the landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts. ocean productivity are revealed by the following defi-nitions (Bender et al.