Morpho-functional groups of periphytic algae from rivers of La Planada Reserve and their bioindicator role

Abstract

Freshwater periphytic algae play a vital ecological role in aquatic ecosystems. In this study, we examined the morphological features of periphytic algae in four rivers of the La Planada Reserve. We collected samples by scraping rocks, identified the algae, measured their morphological dimensions, and conducted descriptive and multivariate statistical analyses. We identified 59 morphospecies, mainly belonging to the classes Bacillariophyceae and Cyanophyceae. The functional groups identified included mucilage-forming colonies, simple filaments, hetero-filamentous algae, non-specialized algae, and non-flagellated siliceous algae. The community-weighted mean and variance (CWM and CWV, respectively) of morphological variables did not differ significantly between rivers. In the first-order river, the algae tended to be smaller and had a lower surface-to-volume ratio. Simple filamentous algae and small algae lacking specialized features seem to indicate nutrient-deficient waters. Non-flagellated, silica-shelled algae (diatoms) probably serve as indicators of moderate flow rates, higher nutrient levels, and clearer water. Colonial algae with mucilage tend to prefer waters with moderate to high nutrient concentrations and faster current speeds. Hetero-filamentous algae appear to indicate rivers with low light exposure and slow flow velocity. This initial investigation into the morpho-functional study of periphytic algae suggests that morphology-based groupings could help reflect river environmental conditions through the ecological responses of functional algal associations.

Keywords: biogeographic Chocó, functional ecology, phycoperiphyton.