Assessing the marginal dollar value losses to an estuarine ecosystem from an aggressive alien invasive crab

This paper reports on a case study to establish dollar values for loss of biodiversity in the New Zealand coastal marine environment. The study uses the European Shore Crab (Carcinas maenas) as the example alien invasive species and the Pauatahanui Inlet, Wellington, New Zealand, as the ecosystem representative of the coastal marine environment. Choice modelling is the stated preference tool used to elicit marginal dollar values for these various attributes of the inlet. Reallocation of existing government expenditure is used as the payment mechanism. Results indicate a wide range of dollar values for the marginal losses to the environment, with no clear trend on a distance-decay relationship. The probability distributions of the dollar values of the environmental attributes tended to have a concentration around the median with very wide tails, especially on the high side. This indicates that most people generally agreed on a dollar value, but a very few individuals expressed extremely high values. The study concludes that the dollar values for loss of biodiversity and other environmental attributes do provide useful information to decision makers, but considerable caution needs to be exercised when applying these values in benefit cost studies. Marginal rate of substitution estimates between environmental attributes will be useful for estimating money values for attributes identified given future work estimates a statistically significant money value for one.