Aquatic biodiversity/Data uncertainties limitations
Parts of Aquatic biodiversity
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Data, uncertainty and limitations
External data used in the model were derived from the global map of surface waters (Lehner and Döll, 2004), the lake depth database (Kourzeneva, 2010), and the map of dams and reservoirs (Lehner et al., 2011). All other input is generated by other IMAGE modules. The empirical relationships between aquatic biodiversity and land use, nutrient budgets and hydrological changes, were derived from an extensive compilation of case studies on rivers, lakes and wetlands.
Uncertainties and limitations
A significant negative impact on biodiversity intactness was found for all types of inland aquatic ecosystems for these dominant categories of anthropogenic stressors. However, there are large variations in the data , and the effects partly depend on the characteristics of the study sites, taxonomic groups and other factors. There is a geographical bias towards well studied regions, and regions where both disturbed systems and comparable reference systems still exist, such as in North America, Australia and New Zealand, and to a lesser extent Europe.
Use of the model for other regions requires some caution, but is considered appropriate for large-scale assessments. The current approach is unique and innovative, because the impact of global environmental change on aquatic biodiversity can be simulated using pressure factors of land use and hydrological disturbance in a consistent global framework.
However, several other pressures are not yet represented in the system, although they may have impact on biodiversity, such as modifications to local rivers and basin morphology, exploitation (fisheries, aquaculture), invasive species, and toxic stress (Revenga et al., 2005). Possible interactions between factors have not yet been included. The rather rough schematisation of the routing network also limits the accuracy of the results.