Using ecological river types and a biodiversity forecasting approach in freshwater conservation planning
Defining appropriate surrogate features is a critical step in regional conservation planning. An ecological typology of rivers for the Australian state of New South Wales (801,428 km2)was developed to provide a scientifically rigorous tool for prioritising conservation initiatives for freshwater ecosystems. Using data from 372 river reference reaches across the state, four separate typologies were developed for fish species (1), macroinvertebrate families from river edge (2) and riffle (3) habitats, and a large number of abiotic attributes (4). The typologies contained six, eight, five and ten river types respectively. Classification trees and identification keys allow river reaches to be allocated a river type for each of the four typologies. Using these keys, the river types were mapped within one region of NSW (Hunter region, 37,000 km2).We also mapped the biological condition of rivers in this region by extrapolating assessment at river sites and using catchment models we expressed this as a function of nutrient and sediment loads under current landuse. We used this relationship to predict the biological condition of rivers under different landuse scenarios. This exercise was repeated for all four typologies. We used the results to prioritise the rivers of the Hunter region for conservation action and to identify the management actions that would optimise biodiversity outcomes.