CONICET | Buscador de Institutos y Recursos Humanos

The diatom Didymosphenia geminata (D. geminata) is an invasive periphytic species from the Northern Hemisphere. D. geminata occurrence and mat formation in Patagonia Argentina dates from 2010, spreading throughout Patagonia (provinces of Chubut, Neuquén, Río Negro, and Santa Cruz) by 2017. In 2012, the Surveillance and Monitoring Program was implemented by Neuquén government entities. Within this programme, nine sampling campaigns have been conducted at 91 sites including streams, rivers, lakes, reservoirs, and a canal. Presence or absence of D. geminata cells, abundance of D. geminata and other algal species cells as well as environmental variables were determined in samples. Multivariate analysis and generalized linear models were used to determine environmental constraints on habitat suitability and requirements for D. geminata. During 2012?2017, D. geminata cells were detected at 33 out of 91 sites sampled. D. geminata was present in lower streams order, with low values of total and dissolved nutrients, conductivity, alkalinity, ions and solutes, and high values of dissolved oxygen and habitat quality, for the ranges of environmental variables measured at sampling sites. D. geminata abundance was negatively related to stream order. Our results prove that D. geminata is expanding its ecological spectrum, showing a wider tolerance to environmental conditions particularly for phosphorus and nitrogen, some ions such as magnesium, and even temperature, and they confirm some authors´ hypothesis about the ecological behaviour of this invasive species. Range expansion and environmental preferences of D. geminata could modify the state of susceptibility to invasion in numerous waterbodies.

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