Dr. Brante-Ramirez, Antonio

The geographical expansion of invasive species depends mainly on its dispersal potential, and the abiotic and biotic factors affecting it. Knowing the invasive dynamic of non-native species, as well as its behavior at different natural or anthropogenic scenarios, is fundamental for planning conservation management policies and control plans. The invasive sea anemone Anemonia alicemartinae in habits from the north (18 S) to the south-central (36 S) coast of Chile and its distribution range has expanded by approximately 1,928 km in the last 50 years. Previous works have proposed that human-mediated southward transport associated with regional-scale maritime activities could explain its rapid spread. To evaluate this hypothesis, we used ecological niche models (ENM) to evaluate the potential colonization of the southernmost area of South America. Additionally, we conducted a post hoc analysis to evaluate the relationship between the prediction of the ENM and human activity measured as the number of landings of ships in ports. The models were built based on presence records of A. alicemartinae, and oceanographic variables. Results showed that sea surface salinity and annual sea surface temperature (variance) are the best predictor variables to explain the distribution of A. alicemartinae. There was a positive and significant relationship between the geographical distribution of the sea anemone predicted by the ENM and the number of landings, as a proxy of anthropogenic activity. The most susceptible areas to invasion were those that showed the highest variability in both oceanographic predictors. These areas included the Biobío region, Chiloé´s inland sea, Aysén, and Chacabuco regions, which together comprise two biogeographical provinces. These results sustain the proposed hypothesis and, overall, the results suggest that along with the characteristics of the life history of A. alicemartinae, oceanographic conditions and How to cite this article Pinochet J, Rivera R, Neill PE, Brante A, Hernández CE. 2019. Spread of the non-native anemone Anemonia alicemartinae Häussermann & Försterra, 2001 along the Humboldt-current large marine ecosystem: an ecological niche model approach. maritime transport as vector contribute to the southern range expansion of this invasive cryptogenic species in the Humboldt-current large marine ecosystem.

Marine bioinvasions are one of the main threats to biodiversity. According to assumptions based on ecological niche models, the conservatism and equilibrium of species with the environment are vital to understanding the bioinvasion process.However, these assumptions have been evaluated primarily for terrestrial species,with few examples in marine environments. We tested the niche conservatism and niche shift hypotheses in native and invaded environments and evaluated the niche dynamics and invasion stages on three invasive marine species: the algae Asparagopsis armata and Codium fragile, and the ascidian Asterocarpa humilis. We applied the identity and background similarity tests to assess the conservatism, the principal component analysis to evaluate the niche dynamics, the Gallien et al. approach to evaluate the invasion stages, and an ensemble of model to estimate potential distribution. Findings showed that the niche equivalence hypothesis was not rejected for any of the species, indicating equivalent ecological niches. Niche similarity demonstrated that niches in native and invaded ranges were not similar as expected by chance for A. humilis and C. fragile. However, for A. armata, the populations in the native and invaded areas had a very similar environmental niche. In addition, high niche stability is evident in the niche dynamics, and so as the stabilization phase of the invasion phases of the three species; thus, studying the three species supported the hypothesis of niche conservatism. These results indicated that all three species have dispersed and are in biogeographic equilibrium within their invaded regions.

Established non-native sea anemone populations can affect the native community through multiple mechanisms, including predation and competition. The conservation of invaded communities is therefore of great concern, and spatially explicit information is essential for the prevention or early detection of introductions. Here, we used ecological niche modeling to (1) predict areas with invasion risk of 3 successful widespread invasive sea anemone species (Diadumene lineata, Exaiptasia diaphana, and Nematostella vectensis); (2) determine the invasion stage of current non-native occurrences; and (3) test the climatic match hypothesis of invasion success by assessing their environmental niche dynamics. Our results bring new insights to the invasion process of sea anemones, which is relevant considering the scarcity of monitoring efforts, the issues associated with their detection, and the potential ecological effects they generate on invaded communities. First, we provide potential distributions that could help to detect non-native populations early on. Second, we confirm a strong pattern of successful establishment. Finally, we demonstrate that the invasion success of these species has mainly occurred in areas with environmental conditions similar to those from their respective native ranges (i.e. climatic match, niche conservatism).