Abstract

MORALES, Eduardo A.; RIVERA, Sinziana F.; VEIZAGA, Adriana  and  FIORINI, Roberto. Didymosphenia geminata (Lyngbye) M. Schmidt (Bacillariophyta), an invasive species and potential threat to Bolivian aquatic ecosystems. RevActaNova. [online]. 2012, vol.5, n.3, pp.327-343. ISSN 1683-0789.

Didymosphenia geminata (Lyngbye) M. Schmidt is a photosynthetic unicellular alga that lives in freshwater and causes considerable ecological damage through production of massive growths or blooms on rocky beds of rivers and oligotrophic lakes. The alga produces stalks to attach to rocks, which cover the water bed and persist even after the death of the cells. While studies on the autecology of the species are still under development, the first experiments show that the dense mats that form during blooms act as redox pumps favored by the pH and dissolved oxygen conditions created in them; pumps that allow the adsorption of nitrogen and phosphorus from the water column through a stalk mechanism that permits the luxury comsumption and accumulation of polyphosphate bodies in the cytoplasm. The adsorption of nutrients produced in high light conditions, which favors high photosynthetic rates, supports an effective asexual reproduction mechanism that allows the exclusion of potential competitors and the rapid colonization of large geographic areas. The high resilience to adverse processes such as drying, also determines the rapid spread of this alga in large geographical areas. The arrival of D. geminata is relatively new to South America and to date it has only been reported from Argentina and Chile. In this manuscript, the particular vulnerability of Bolivian aquatic ecosystems and the need of programs for monitoring and prevention of the spreading of this harmful organism are presented.

Keywords : Didymosphenia geminata; diatoms; Bacillariophyta; South America; Bolivia; biological invasions.

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