Abstract

BARRERA-HERRERA, July Andrea et al. Incidence of hydraulic retention time in the plankton of the La Chapa reservoir (Santana, Boyacá), Colombia. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2020, vol.44, n.171, pp.407-422.  Epub June 09, 2021. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.1022.

The hydraulic retention time (HRT) is a determining factor in the expression of the biological structure and the functioning of aquatic ecosystems; it is associated with the dynamics of the water entering and leaving the system, but little is known about the effect of its variability in the structuring and functioning of aquatic communities. The HRT was determined for six months in a small reservoir in the Andean region of Colombia analyzing how its variation affects the behavior of physical, chemical, and biological variables. We measured the physical and chemical variables of the water and we determined the bathymetry of the system and the taxonomic (richness and density) and functional (richness and divergence) diversity of the plankton. The TRH was estimated as the relationship between the retained volume and the flow balance. The results suggested that: 1) an HRT of less than 30 days promotes an increase in nutrients which, in turn, increases the primary productivity, the concentration of dissolved oxygen, and the pH associated all of them with an increase in plankton taxonomic and functional richness, especially accentuated in phytoplankton; 2) an HRT of more than 30 days corresponds to a lower concentration of nutrients and an increase in temperature and electrical conductivity corresponding to the simplification of plankton community structure. We highlight the use of the intermediate disturbance hypothesis to understand the observations and of HRT as a determining factor in the functioning of this type of ecosystem.

Keywords : Hydraulic retention time; Reservoir; Phytoplankton; Zooplankton.

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