Presence of the tunicate Asterocarpa humilis on ship hulls and aquaculture facilities in the coast of the Biobío Region, south central Chile

Early detection of marine invasive species following the deployment of an artificial reef: Integrating tools to assist the decision-making process

Early detection and rapid response plans are a set of principles to reduce the establishment, spread and impact of invasive species and it is a critical step in management in marine ecosystems. Two potentially invasive ascidians attached to the hull of a recently sunk fishing vessel were early detected in Patagonia. With the aim of assisting in the management decision-making process during the early steps of a rapid response, we conducted several analyses through different approaches. First, we identified the species through classic taxonomical and genetic analyses. Then, we evaluated the regional and international shipping connectivity to study potential donor regions and finally, we used species distribution models (SDMs) to predict the potential distribution of these species. The potentially invasive ascidians were identified as Styela clava and Styela plicata, and this is the first record for both species in the Nuevo gulf, Patagonia Argentina. Both species have a widespread distribution around the world with strong ecological and economic impacts documented. Shipping traffic analysis suggested that S. plicata could have arrived by secondary spread from regional ports, while the arrival of S. clava was likely to be associated with international shipping traffic. Furthermore, the SDM predicted that S. clava has suitable coastal areas along the entire Southwestern Atlantic shoreline, where it is currently absent. On the contrary, the SDM predicted that further southward spread of S. plicata is unlikely, being limited by the minimum annual temperature. We discussed the different approaches, tools, and expertise integrated in this work in the light of the decision-making process for the early detection of marine invasive species in the Southwestern Atlantic. Moreover, we call attention to the increased creation of artificial habitats through the intentional sinking of ships and the potential consequences of these actions in the conservation of marine ecosystems.

Plastic as a Vector of Dispersion for Marine Species With Invasive Potential. A Review

Plastic debris constitutes up to 87% of marine litter and represents one of the most frequently studied vectors for marine alien species with invasive potential in the last 15 years. This review addresses an integrated analysis of the different factors involved in the impact of plastic as a vector for the dispersal of marine species. The sources of entry of plastic materials into the ocean are identified as well as how they move between different habitats affecting each trophic level and producing hot spots of plastic accumulation in the ocean. The characterization of plastic as a dispersal vector for marine species has provided information about the inherent properties of plastics which have led to its impact on the ocean: persistence, buoyancy, and variety in terms of chemical composition, all of which facilitate colonization by macro and microscopic species along with its dispersion throughout different oceans and ecosystems. The study of the differences in the biocolonization of plastic debris according to its chemical composition provided fundamental information regarding the invasion process mediated by plastic, and highlighted gaps of knowledge about this process. A wide range of species attached to plastic materials has been documented and the most recurrent phyla found on plastic have been identified from potentially invasive macrofauna to toxic microorganisms, which are capable of causing great damage in places far away from their origin. Plastic seems to be more efficient than the natural oceanic rafts carrying taxa such as Arthropoda, Annelida, and Mollusca. Although the differential colonization of different plastic polymers is not clear, the chemical composition might determine the community of microorganisms, where we can find both pathogens and virulent and antibiotic resistance genes. The properties of plastic allow it to be widely dispersed in practically all ocean compartments, making this material an effective means of transport for many species that could become invasive.

Morphology, genetics, and historical records support the synonymy of two ascidian species and suggest their spread throughout areas of the Southern Hemisphere

Taxonomic uncertainties and the lack of ecological knowledge can hinder the correct identification and the assignment of biogeographic status of marine species. The ascidian Asterocarpa humilis (Heller, 1878), originally described from New Zealand, has a broad distribution in shallow temperate areas of the Southern Hemisphere, having recently colonised areas of the Northern Hemisphere. A closely related species, Cnemidocarpa robinsoni Hartmeyer, 1916, has been reported in the South-Eastern Pacific and the South-Western Atlantic, and several authors considered it a junior synonym of A. humilis. We gathered for the first time morphological and genetic data from specimens from distant areas. We studied the morphology of specimens collected at seven locations of South America. We also re-examined specimens from museum collections and revised the available literature on these species. Genetic data were obtained from specimens from Argentina and compared with available sequences of A. humilis from Chile, New Zealand, England and France. Morphological and genetic analyses showed that all compared specimens were conspecific. Furthermore, specimens from different continents shared haplotypes and exhibited low genetic distance among them. These results, the biological characteristics of this ascidian, and its longstanding presence in different habitats from disjoint areas, allow us to question its native range. We support the idea that A. humilis is a cryptogenic and neocosmopolitan species that has been transported by maritime traffic through the Southern Hemisphere, revealing frequent processes of exchange through this wide area for more than a century, with presumably associated alterations in the marine biota.

Spread of the non-native anemone Anemonia alicemartinae Häussermann & Försterra, 2001 along the Humboldt-current large marine ecosystem: an ecological niche model approach

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 maritime transport as vector contribute to the southern range expansion of this invasive cryptogenic species in the Humboldt-current large marine ecosystem.

Non-indigenous species contribute equally to biofouling communities in international vs local ports in the Biobío region, Chile

Growing coastal urbanization together with the intensification of maritime traffic are major processes explaining the increasing rate of biological introductions in marine environments. To investigate the link between international maritime traffic and the establishment of non-indigenous species (NIS) in coastal areas, biofouling communities in three international and three nearby local ports along 100 km of coastline in south-central Chile were compared using settlement panels and rapid assessment surveys. A larger number of NIS was observed in international ports, as expected in these 'invasion hubs'. However, despite a few environmental differences between international and local ports, the two port categories did not display significant differences regarding NIS establishment and contribution to community structure over the studied period (1.5 years). In international ports, the free space could be a limiting factor for NIS establishment. The results also suggest that local ports should be considered in NIS surveillance programs in Chile.