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This work describes the generation of a database of algal species richness at two spatial scales -regional (Gulf of Mexico and the Caribbean) and global (coastal zones). As a first approach to the definition of the temporal variability, and to produce the corresponding maps, a previously published decision tree is used in order to select the best spatial interpolation technique according to the characteristics of the spatial data. The methods presented are ordinary Kriging (since no relationship exists with any environmental variable that could function as an external variable) and inverse distance squared, for comparative purposes. The methods to generate the spatial layers are evaluated using the leave-one-out cross validation technique. Although the evaluation did not find a large correspondence (in terms of linear regression) between the interpolated and measured values, it was possible to capture the spatial variability of the process and produce the cartography of this variable, with which future ecological analyses can be performed..

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The aquifer system in the Metropolitan Zone of the Mexican Basin is comprised by a higher, middle, and a lower aquifer, separated by less permeable elements. This study integrated a geographical database from which aquifer vulnerability values were obtained using the SINTACS method. The results show the lowest vulnerability values in the lacustrine zone of the basin, where most of the urban area is settled. The medium vulnerability indices are at the edges of the basin and are associated with tuffs, pyroclasts and alluvial deposits. The highest vulnerability values are in the ranges bordering the basin. High water quality values are toward the limits of the basin and in the recharge zones while lower quality water is in the Tlahuac and Iztapalapa zones. The results of this study enable a cause-effect relationship to be established between potential sources of contamination and groundwater quality indices only for Tlahuac and Iztapalapa, a notable finding since most of the urban area is settled over low and very low vulnerability zones.

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