Aquatic Botany 65 (1999) 311–320 Environmental impact identification along the Corsican coast (Mediterranean sea) using image processing Vanina Pasqualini * , Christine Pergent-Martini, Gérard Pergent University of Corsica, Equipe Ecosystèmes Littoraux, B.P. 52, 20 250 Corte, France Abstract Endowed with an exceptionally rich natural heritage, the Mediterranean islands are subject to degradation exacerbated by their insularity (e.g. the influx of tourists in the summer). The man- agement of these coastal areas thus requires the identification and quantification of anthropogenic impacts which affect the distribution of seagrass beds. To this end, studies were carried out along the Corsican coast by combining image processing of (i) aerial photographs for the surface layer (from 0 to -20 m) and (ii) sonograms, generated by side scan sonar, for the deeper layers (from -20 to -40 m). These techniques, which are particularly adapted to the analysis of vast areas with a precision of less than 2 m, were used to identify and accurately evaluate the impact of natural and anthropogenic pressures (e.g. fresh water input, coastal facilities, mechanical aggressions). In addition to a decline in the surface area occupied by seagrass beds, significant erosion of the coastline (80 m in 25 yr) was observed, brought about by the building of marinas. Based on the results generated in the present study, it would appear that these techniques may prove useful in the examination of other coastal regions. ©1999 Elsevier Science B.V. All rights reserved. Keywords: Mediterranean; Posidonia oceanica; Image processing; Aerial photography; Side scan sonar; Human activities 1. Introduction Human activities by their very nature tend to provoke a decline or even the disappearance of marine phanerogams. This is particularly true in proximity to large urban and industrial centres (Larkum and West, 1983; Cambridge et al., 1986; Fortes, 1989; Shepherd et al., 1989; Short and Wyllie-Echeverria, 1996). In light of their crucial role in ecology and sedimentology, the protection and management of these benthic ecosystems are of primary * Corrsponding author. Tel.: +33-4-95-45-00-55; fax: +33-4-95-46-24-41 E-mail address: pasquali@univ-corse.fr (V. Pasqualini) 0304-3770/00/$ – see front matter ©1999 Elsevier Science B.V. All rights reserved. PII:S0304-3770(99)00048-0