Quantifying expert opinion with discrete choice models: Invasive elodea's influence on Alaska salmonids

Joseph Little,Gregory D. Hayward,Tobias Schwoerer

doi:10.1016/j.jenvman.2020.110924

Abstract

Scientific evidence should inform environmental policy, but rapid environmental change brings high ecological uncertainty and associated barriers to the science-management dialogue. Biological invasions of aquatic plants are a worldwide problem with uncertain ecological and economic consequences. We demonstrate that the discrete choice method (DCM) can serve as a structured expert elicitation alternative to quantify expert opinion across a range of possible but uncertain environmental outcomes. DCM is widely applied in the social sciences to better understand and predict human preferences and trade-offs. Here we apply it to Alaska's first submersed invasive aquatic freshwater plant, Elodea spp. (elodea), and its unknown effects on salmonids. While little is known about interactions between elodea and salmonids, ecological research suggests that aquatic plant invasions can have positive and negative, as well as direct and indirect, effects on fish. We use DCM to design hypothetical salmonid habitat scenarios describing elodea's possible effect on critical environmental conditions for salmonids: prey abundance, dissolved oxygen, and vegetation cover. We then observe how experts choose between scenarios that they believe could support persistent salmonid populations in elodea-invaded salmonid habitat. We quantify the relative importance of habitat characteristics that influence expert choice and investigate how experts trade off between habitat characteristics. We take advantage of Bayesian techniques to estimate discrete choice models for individual experts and to simulate expert opinion for specific environmental management situations. We discuss possible applications and advantages of the DCM approach for expert elicitation in the ecological context. We end with methodological questions for future research.

Highlights

Resource managers often face decisions requiring quick action to avoid damage to ecosystems and economies but lack quantitative in formation to support decisions (Maguire, 2004)
Through analysis of data collected with the discrete choice method (DCM), this study informs resource management by providing a new understanding of the potential consequences of elodea establishment in Alaska conditional on a set of ecologically informed scenarios
It em phasizes several advantages and cases where DCM can contribute to expert elicitation in the ecological context

Summary

Introduction

Resource managers often face decisions requiring quick action to avoid damage to ecosystems and economies but lack quantitative in formation to support decisions (Maguire, 2004). Deci sion making with regards to biological invasions to aquatic ecosystems is inherently complex and characterized by high uncertainty. Aquatic in vasions can be associated with regime shifts that can lead to widespread environmental damage and economic harm (Havel et al, 2015). The management of aquatic invasive species has been termed a wicked problem, referring to the high complexity of a system in which cause-and-effect relationships between multiple components are not well understood (Evans et al, 2008; Seastedt, 2015). Decision makers can benefit from a synthesis of broader knowledge when weighing un certainty and complexity (Vanderhoeven et al, 2017)

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Discussion

Conclusion