Predicting impacts of agricultural land use on stream and river biota: method review, evaluation and guidance

Predicting land use and land management effects on stream and river biota is an important aspect of land-water management, yet there are no collations of what methods are available to carry out those assessments nor guidance on which methods to use. This paper summarises a range of methods with examples of their applications, comments on their strengths and weaknesses, evaluates them against a set of criteria, and provides guidance on method selection. Assessment methods include empirical statistical and mechanistic models, Bayesian Networks, likelihood-consequence risk assessments, scoring methods, and hybrid methods, some of which can be informed by expert elicitation. An evaluation matrix for methods indicated that no single method is ideal, and selection of methods needs to carefully consider factors such as the physico-chemical stressor or biotic impact of interest, the intended stakeholders, and the scales of assessment. One emergent principle is the separation of relationships between land use and stressors from assessments of stressors and biota, for which alternative methods could be used. A tiered approach is recommended, whereby simple methods with low resource and time requirements are applied first, followed by more sophisticated methods for selected aspects if needed. There is a need for more ready-made methods at the screening level, as well as development of new methods to address remaining gaps such as multiple stressors.