Invasive Species: The Case of Didymosphenia geminata in Neuquén, Argentina

Abstract

The diatom Didymosphenia geminata (D. geminata) is an invasive periphytic species from the Northern Hemisphere. This organism presents an ecological paradox since it has the apparently unique ability to rapidly produce large developments of algal biomass in oligotrophic environments. The explanation for this paradox is unclear, but it likely includes aspects of ecology, hydrology, biogeochemistry, and geomorphology. D. geminata occurrence and mat formation in Patagonia date from 2010, spreading throughout Argentinean Patagonia (provinces of Chubut, Neuquén, Río Negro and Santa Cruz) by 2018. Since the appearance of the alga, the General Directorate of Aquatic Biology and the Provincial Directorate of Water Control of the Neuquén Province have worked to establish surveillance guidelines and to identify the presence of D. geminata in aquatic environments to set up protected areas free of the alga, as well as to define the actions to be taken in the provincial territory. In 2012, the Surveillance and Monitoring Program was implemented. In this chapter we discuss the results of the program related to the dispersion and ecology of the alga and its effects on periphytic communities. Historically, D. geminata habitat preferences have been related to pristine-oligotrophic conditions. At present, the alga is expanding its ecological spectrum, showing a wider tolerance to environmental conditions particularly for nutrients such as phosphorus and nitrogen, some ions such as magnesium, and even temperature. Range expansion and environmental preferences of D. geminata could modify the state of susceptibility to invasion in numerous waterbodies. Efforts by state agencies have not been able to prevent the spread of this invasive exotic organism within Neuquén, and between other Argentinean provinces. For the management and control actions of invasive species to be effective, it is paramount to quickly respond to alerts, without administrative delays.