The basin of Rio de la Sabana is the largest tributary of the Tres Palos coastal lagoon in Southwest Mexico, east of Acapulco. This lagoon and its upstream basin areas have become a high priority area for the preserva...The basin of Rio de la Sabana is the largest tributary of the Tres Palos coastal lagoon in Southwest Mexico, east of Acapulco. This lagoon and its upstream basin areas have become a high priority area for the preservation of coastal and marine environments. To obtain information about water quality as affected by urban expansion since 2002, fourteen physicochemical parameters (temperature, pH, electrical conductivity, dissolved oxygen, ammonium, nitrate, nitrite, sulphate, phosphate), biochemical (biological and chemical oxygen demand, methylene blue active substances) and bacteriological parameters (total and fecal coliforms) were determined. This sampling was done for dry and rainy season conditions at seven locations (S1, S2, S3, …, S7) along the river, spaced 3 to 6 km apart to a total of 30.4 km. The results were grouped into four zones: (Z1) reference, (Z2) transition, (Z3) polluted, (Z4) recovery. The Alborada (S5) and Tunzingo (S6) sites, adjacent to dense high-class residential areas (Z3), had the greatest pollution charges in both seasons, while the La Poza (S7) site near the Tres Palos lagoon (Z4) showed a decrease in pollution. All parameters correlated with increasing head- to down-river sampling distance by following linear (pH, DO) or curvilinear patterns (all other parameters). Using sampling location and dry versus rainy sampling season as multivariate regression (predictor) variables led to least-squares capturing: 1) 66% to 95% of the T(°C), pH, DO, and PO3-4 variations, and 2) 57% to 96% of the log-linear variations of the other parameters. Among the parameters, T(°C), DO, and PO3-4 were not significantly affected by sampling season, while pH became so after deleting two higher than usual pH values at the S5 and S6 locations during the dry season.展开更多
Phytoplankton samples were collected in Acapulco Bay during 2011 (January-April and September) and 2012 (April-July, October, and November) with the objective of determining the abundance and species composition. Samp...Phytoplankton samples were collected in Acapulco Bay during 2011 (January-April and September) and 2012 (April-July, October, and November) with the objective of determining the abundance and species composition. Samples were collected in two stations located in the bay. A total of 82 species were identified: 42 dinoflagellates, 35 diatoms, three cyanobacteria, and two silicoflagellates. Dinoflagellates were more abundant in the dry season, while diatoms dominated during rainy season. At least seven dinoflagellate species were recorded as potentially toxic, which may increase their populations and turn into harmful algal blooms (HABs) if environmental conditions within the bay are modified. In April 2012 a HAB of the non-toxic species Neoceratium balechii was documented.展开更多
文摘The basin of Rio de la Sabana is the largest tributary of the Tres Palos coastal lagoon in Southwest Mexico, east of Acapulco. This lagoon and its upstream basin areas have become a high priority area for the preservation of coastal and marine environments. To obtain information about water quality as affected by urban expansion since 2002, fourteen physicochemical parameters (temperature, pH, electrical conductivity, dissolved oxygen, ammonium, nitrate, nitrite, sulphate, phosphate), biochemical (biological and chemical oxygen demand, methylene blue active substances) and bacteriological parameters (total and fecal coliforms) were determined. This sampling was done for dry and rainy season conditions at seven locations (S1, S2, S3, …, S7) along the river, spaced 3 to 6 km apart to a total of 30.4 km. The results were grouped into four zones: (Z1) reference, (Z2) transition, (Z3) polluted, (Z4) recovery. The Alborada (S5) and Tunzingo (S6) sites, adjacent to dense high-class residential areas (Z3), had the greatest pollution charges in both seasons, while the La Poza (S7) site near the Tres Palos lagoon (Z4) showed a decrease in pollution. All parameters correlated with increasing head- to down-river sampling distance by following linear (pH, DO) or curvilinear patterns (all other parameters). Using sampling location and dry versus rainy sampling season as multivariate regression (predictor) variables led to least-squares capturing: 1) 66% to 95% of the T(°C), pH, DO, and PO3-4 variations, and 2) 57% to 96% of the log-linear variations of the other parameters. Among the parameters, T(°C), DO, and PO3-4 were not significantly affected by sampling season, while pH became so after deleting two higher than usual pH values at the S5 and S6 locations during the dry season.
文摘Phytoplankton samples were collected in Acapulco Bay during 2011 (January-April and September) and 2012 (April-July, October, and November) with the objective of determining the abundance and species composition. Samples were collected in two stations located in the bay. A total of 82 species were identified: 42 dinoflagellates, 35 diatoms, three cyanobacteria, and two silicoflagellates. Dinoflagellates were more abundant in the dry season, while diatoms dominated during rainy season. At least seven dinoflagellate species were recorded as potentially toxic, which may increase their populations and turn into harmful algal blooms (HABs) if environmental conditions within the bay are modified. In April 2012 a HAB of the non-toxic species Neoceratium balechii was documented.
