Zooplankton studies in Colombian fresh and brackish water ecosystems: A review and future perspectives

Colombia is a global biodiversity hotspot, yet its zooplankton fauna remains poorly explored. In Colombian inland waters, 253 species of rotifers, 119 cladocerans and 82 copepods (not included benthic species) have been reported, in contrast with only 14 genera of protozoa. Most publications report on the Magdalena-Cauca basin, with the highest number of records for lowland areas (< 1000 m.a.s.l.). The least explored regions are the Chocó, Orinoco and Amazon basins. Colombian zooplankton checklists often include several taxa recognized as groups of cryptic species or ones described as cosmopolitan. Integrative taxonomic approaches are scarce, and diversity data need to be validated by molecular analyses and detailed morphological descriptions using optical and scanning electron microscopy. Historical, regional, and local environmental factors that explain the richness, distribution, and the abundance of zooplankton include: water bodies size, hydrological connectivity, trophic status; physical stability and, hydro-climatic patterns of variation. The analysis of ecosystem processes related to patterns in zooplankton communities highlights the importance of detritus as an alternative energy flow path in aquatic ecosystems at all altitude ranges. We propose to strengthen regional studies on functional groups, ecological redundancy, and adaptive traits to evaluate zooplankton responses to climatic, global and local stressors. Due to the great diversity of aquatic ecosystems in the extensive altitudinal gradient of Colombia, it is necessary to expand the coverage of ecological and taxonomic studies to understand zooplankton biodiversity and its role in ecosystem functioning.