Temporal variation of phytoplankton functional morphology in a Colombian Caribbean floodplain system

We analyzed temporal variation of morphology-based functional groups of phytoplankton (MBFG) in the Ayapel floodplain system, through the comparison of two previous samplings carried out between 2005 and 2007 and a new one made in 2015. The biovolume (mm3.l-1) and morphological features such as volume, surface area: volume ratio (S/V) and maximum linear dimension (MLD) were performed. Temporal analysis was carried out according to pluvial precipitation levels, and by means of a grouping analysis two previous periods (dry season and transition period) and a new one corresponding to 2015 (msENSO: dry season with ENSO influence) were defined. In the dry and transition seasons, the predominant group was GFBM III with high MLD (108.77 μm) and S/V ratios (1.44 μm), while in msENSO low biovolumes (0.016 mm3.l-1) and the predominance of GFBM V were observed. The comparison of functional morphology between years showed a transition from filamentous forms to flagellated forms of phytoplankton, allowing a better fit to the environmental pressure of the study area.