Sensitivity and Vulnerability in Marine Environments: an Approach to Identifying Vulnerable Marine Areas

TLDR

Marine environments lack quantitative tools to delineate areas sensitive or vulnerable to stresses, with sensitivity defined as the degree of response beyond expected conditions and vulnerability as the probability of exposure to such stresses. The study proposes a quantitative framework to identify vulnerable marine areas by evaluating valued ecological features and their sensitivity to specific stresses. The framework calculates vulnerability as the product of a feature’s sensitivity to a stress and the probability of exposure, using acoustic stress surfaces for ferry, shipping, oil production, and small‑boat traffic, and is applicable to any set of features and stressors. Applying the method to endangered whale species revealed that inshore whales were more sensitive to on‑shelf activities, while offshore whales showed similar vulnerability to all stressors, illustrating the approach’s utility for locating management and conservation zones.

Abstract

Abstract: Marine environments have suffered from a lack of quantitative methods for delineating areas that are sensitive or vulnerable to particular stresses, natural and anthropogenic. We define sensitivity as the degree to which marine features respond to stresses, which are deviations of environmental conditions beyond the expected range. Vulnerability can then be defined as the probability that a feature will be exposed to a stress to which it is sensitive. Using these definitions, we provide a quantitative methodology for identifying vulnerable marine areas based on valued ecological features, defined as biological or physical features, processes, or structures deemed by humans to have environmental, social, cultural, or economic significance. The vulnerability of the valued ecological features is a function of their sensitivity to particular stresses and their vulnerability to those stresses. We used the methodology to demonstrate how vulnerable marine areas for two groups of endangered whale species (inshore and offshore) could be identified with a predictive habitat model and acoustic stress surfaces. Acoustic stress surfaces were produced for ferry traffic, commercial shipping traffic, potential offshore oil production, and small‐boat traffic. The vulnerabilities of the two whale groups to the four stressors considered in this example were relatively similar; however, inshore species were more sensitive to on‐shelf, coastal activities such as offshore hydrocarbon production, ferry traffic, and small‐boat traffic. Our approach demonstrates how valued features can be associated with stresses and the likelihood of encountering these stresses (vulnerability) in order to identify geographic areas for management and conservation purposes. The method can be applied to any combination of valued ecological features and stressors.