Factors determining the Phytoplankton variability in the swamps of the Momposina depression (Colombia)

Description of the main environmental factors that structure phytoplankton dynamic in 27 swamps of the Momposina Depression located in the area of influence of the Cicuco-Boquete oil field. Accor- ding to the results, the parameters that determined the variations in the physics and chemistry of the water are related to system hydrology, followed by the variables associated with the industrial operation, particularly in relation to chloride content and natural mineralization, which is due to conductivity and alkalinity. The euglenoids were the most common throughout the study, particularly during low water periods; cyanobacteria density increased in high waters and pennate diatoms in rising water. The lowest average diversity and richness were reported in the systems with the highest domestic and industrial impact as well as in the swamp referenced herein. Variations in phytoplankton composition were not related to the hydrological periods studied. pH, NO3, conducti- vity and the organic load (BOD5), as well as variables indirectly related to the industrial operation (chlorides and COD) were determining variables. Total hydrocarbons were not a significant variable in the community structure.