The factors ‘‘station”, ‘‘campaign”, and ‘‘farm” on the
phyto- and zooplankton data from all farms showed that
among the three factors considered, only the factor ‘‘station”
showed significant differences (p < 0.05). These differences
were registered between the intake point and the two
studied ponds of each farm. Spearman correlation analysis
presented similarities between the Promares and Secon
farms and among the Aquafort, Cina, Camapi and Potipora
˜ farms. Similar results were found for the differences
in key abiotic parameters, (e.g. nutrient concentrations,
oxygen demand, and total suspended solids) between intake
channels and effluents in shrimp ponds in Texas and Taiwan
(Samocha et al., 2004), showing that the alteration of water
quality through shrimp farming is a wide-spread problem.