Land cover changes and impact of shrimp aquaculture on the landscape in the Ceuta coastal lagoon system, Sinaloa, Mexico

Abstract

Changes in natural cover and land use within the Ceuta coastal lagoon system, Mexico, were assessed using multitemporal analysis ofLandsat imagery. Global trends of change and the effects of the recent establishment of the shrimp aquaculture industry on the natural cover were examined. On two images from 1984 and 1999, nine information categories (secondary succession, mangrove, irrigated and temporary agriculture, dry forest, bare substratum, lagoons, shrimp ponds, and villages) were evaluated after supervised classification and digitisation processes. The accuracy ofthe 1999 classification was measured by means ofan error matrix that output an overall accuracy of85%, and values of0.8 for the Kappa and Tau coefficients. The classification had a moderate to high accuracy, and showed that agriculture is the main influence on the system, covering 55% ofthe study area, principally replacing dry forest and secondary succession. The development of shrimp aquaculture is causing a new pressure on this environment, and it has changed the coastal landscape covering 3190 ha in less than 15 years, mainly replacing bare soil and salt marsh. Estimations for mangrove cover in the area indicated an annual deforestation rate of around 0.3%, but this rate was not directly related with shrimp-farming growth.