LUSI: Determining Land Pressures And Their Link With Coastal Eutrophication

Abstract

Human activities on land result in the high-level production of nutrients that, when they reach coastal waters, drive the eutrophication process in those waters. Here we present the Land Uses Simplified Index (LUSI), an easy-to-use tool for assessing continental pressures on coastal waters, as it indirectly estimates continental nutrient loads and concentrations. It is based on systematic information describing both the land uses that influence coastal waters (urban, industrial, agricultural and riverine) and the morphology of the coastline. The latter determines the degree of coastal water confinement and therefore the likelihood that continental nutrient-rich freshwater inflows will be diluted. A low LUSI value indicates coastal waters that are not or only slightly influenced by continental pressures, and a high LUSI value coastal waters strongly influenced by continental pressures. An additional and important feature of LUSI is that it allows the establishment of pressure-impact relationships based on the chlorophyll-a concentration as a proxy of the eutrophication impact. For instances, this relationship for the NW Mediterranean has been established as chlorophyll-a concentration = 0.12 * LUSI + 0.22 (p = 8.14*10¿8, R2 = 82%). By providing insights into which land uses trigger the ongoing eutrophication process in coastal waters, the LUSI aids in the design of measures aimed at remediating the environmental damage caused by human activities