title: Spatio temporal population dynamics of the invasive diatom Didymosphenia geminata in central-southern Chilean rivers.
abstract: We document the distribution of Didymosphenia geminata in central-southern Chilean rivers and identify the chemical and physical factors associated with its presence/absence (p/a). Repeated surveys in five successive years provided evidence that D. geminata could be nearing a biogeographic equilibrium in the region. D. geminata databases from extensive biological and environmental surveys in 187 rivers, within ten catchments, south of 38°S commenced in November 2010 and ran through May 2013. In addition, data from two other field surveys were used. The sites evenly distributed latitudinally were climatically characterized. The recent sampling program, following a published species distribution model, was designed to explore D. geminata distribution within thirteen catchments (34°S-48°S). An extensive river survey in 2014 (spring-summer) and in 2015 (autumn) included the p/a, and relative abundance of D. geminata cells in phytobenthos and in the drift. These p/a results showed that the probability of re-encountering D. geminata cells at sites where the species was previously found was significantly high while the probability of finding D. geminata cells at sites previously without the species was significantly low. This suggests that the distribution of D. geminata cells among suitable habitats was nearing completion. The relative abundance of D. geminata cells in the phytobenthos versus in the drift indicates seasonality with higher proportion of cells in the phytobenthos during the spring-summer than during the autumn. During the final surveys, principal component analysis of chemical and physical characteristics of rivers showed significant differences between rivers with and without D. geminata. Based on our observations of the distribution of D. geminata cells among rivers with suitable habitat conditions and the fluctuating rate of spread between rivers, we conclude that D. geminata is probably in the ending stage of its spatial demographic expansion in Chile surmounting the different barriers of the invasive process.
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile.
authors.forename: V
authors.initials: V
authors.lastname: Montecino
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile; POCH Ambiental SA, Chile.
authors.forename: X
authors.initials: X
authors.lastname: Molina
authors.affiliation: Environment Canada, Nanaimo, British Columbia, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Bothwell
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile.
authors.forename: P
authors.initials: P
authors.lastname: Muñoz
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Pontificia Universidad Católica de Chile, Chile; IEB Institute of Ecology and Biodiversity, Santiago, Universidad de Chile, Chile.
authors.forename: M L
authors.initials: ML
authors.lastname: Carrevedo
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile.
authors.forename: F
authors.initials: F
authors.lastname: Salinas
authors.affiliation: Colorado State University, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa.
authors.forename: M L
authors.initials: ML
authors.lastname: Castillo
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile.
authors.forename: G
authors.initials: G
authors.lastname: Bizama
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Chile; IEB Institute of Ecology and Biodiversity, Santiago, Universidad de Chile, Chile.
authors.forename: R O
authors.initials: RO
authors.lastname: Bustamante
mesh_terms: D002677:Chile; D002980:Climate; D017377:Diatoms / Q000502:physiology*; D017753:Ecosystem; D058865:Introduced Species; D008954:Models, Biological; D011157:Population Dynamics; D045483:Rivers; D013997:Time Factors
keywords: Aquatic invasions; Climatic niche; Patagonia; Phytobenthonic diatoms and drifting algae; Species distribution models