engleski

CONSERVATION SCIENCE MEETS MEDICINE: ECONOMICS OF DECISION LOGIC IN SCREENING TESTS FOR MARINE ECOLOGICAL HEALTH

The measurement of degree of health of an organic system is a fundamental goal in both medicine and conservation science. In medicine, a large population of individuals is treated via a three-tiered process: 1) an inexpensive screening test is used to screen out individuals who then are assumed healthy ; 2) those remaining with positive test result are then given a series of more expensive and accurate tests to further screen out healthy individuals ; 3) those remaining with positive tests in both tiers are then given expensive treatment. Conservation science has a similar goal: to distinguish between healthy and impacted ecological populations, processes, and habitats, so that the high cost of intervention is not wasted but applied exactly where it is needed. In the marine environment, assessment of ecological health is especially difficult and costly, and screening tests that are fast and inexpensive can potentially realize large savings in the cost of identifying and conserving marine values and resources. Here we develop a decision tree with associated economic costs in a three-tiered conservation context. We find that, in contrast to medical application with rare disease, in marine environments with high probability of human impact, false positive results have a low economic cost, and the major cost risk is the loss of ecological services due to false negative results, which greatly increase in a two-tiered testing framework, and can become catastrophic even if the second-tier tests have low false-negative error. Ecological screening tests should be avoided in sites likely to be impacted, and instead, accurate assessments using tests with very low false-negative rates (i.e. high statistical power) should be the first line of attack and greatly reduce overall costs. Our analysis shows a fundamental contrast between medical and conservation economics, caused by the high marginal cost of loss of ecological services. The common use of screening tests in marine conservation (e.g. in seagrass monitoring) should be reevaluated and in many cases abandoned to avoid loss of ecological services due to false negative results. There is an ongoing urgent need for the development of fast and inexpensive marine screening tests with low false-negative error rates. This work was partly supported by the Croatian Science Foundation, under project COREBIO (3107).

degree of health, screening tests, conservation science, ecological health, cost of lost ecological services

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