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Se realizo un estudio multitemporal con imagenes Landsat MSS de 1973, 1986 y 1992 y la composicion pancromatica Landsat ETM+ de 2001 para detectar cambios en el paisaje asociado a humedales costeros en el sistema estuarino de San Blas, Nayarit (Mexico). Se definieron siete clases de coberturas de terreno para producir mapas tematicos por medio de clasificacion supervisada y digitalizacion de datos auxiliares. La exactitud de la clasificacion, considerando las superficies acuaticas, fue alta (exactitud total > 80%), reduciendose a moderada cuando esta categoria fue excluida del analisis (exactitud total = 78% coeficiente de Kappa = 0.68), siendo todavia mas exacta que una clasificacion generada al azar. Los mapas resultantes fueron transpuestos para detectar direccion y proporcion de los cambios, incluyendo la evaluacion de la estabilidad de localizacion y residencia a nivel de clase. La proporcion de cambio a nivel de paisaje fue significativa, 20% de 1973 a 1986 y 30% de 1986 a 1992, aunque los humedales costeros permanecieron relativamente estables. El paisaje estuvo dominado desde 1973 por coberturas inducidas, desplazando principalmente a la selva, la cual perdio la mitad de su cobertura en 19 anos con una tasa media de deforestacion anual de 3.4%, presentandose asi un proceso de homogenizacion del paisaje costero. Para 2001 se estimo un total de 1900 ha de estanqueria para el cultivo de camaron, alterando principalmente las planicies de inundacion e impactando al conjunto de los humedales por la interrupcion de la conectividad entre ellos  A multitemporal study using Landsat MSS images from 1973, 1986 and 1992, and a panchromatic Landsat ETM+ scene from 2001 was conducted to detect changes in the landscape associated with coastal wetlands in the San Blas estuarine system, Nayarit (Mexico). Seven land cover classes were selected to produce thematic maps based on supervised classification techniques and digitization of ancillary data. The accuracy of the classification was high when the aquatic surface category was included (overall accuracy > 80%), but moderate when it was excluded from the analysis (overall accuracy = 78%; Kappa coefficient = 0.68), and it was better than that of a random classification. The output maps were cross-tabulated to detect the trends and proportion of the changes, and to assess the location and residence stabilities at class level. At landscape level the proportion of changes was significant, around 20% from 1973 to 1986 and 30% from 1986 to 1992, although the coastal wetlands remained relatively stable. Since 1973, the San Blas landscape has been dominated by induced coverages that have gained areas formerly occupied by forests, which have lost about 50% of their coverage in 19 years, with an annual deforestation rate of 3.4% that is homogenizing the coastal landscape. Around 1900 ha of shrimp culture ponds were determined from the 2001 image, mainly located in the floodplains, with an overall impact on the wetland areas due to the loss of connectivity among them.

Assessment of landscape changes and their effects on the San Blas estuarine system, Nayarit (Mexico), through Landsat imagery analysis