Invasion by marine nonindigenous species (NIS) is a spread phenomenon. The tunicate Pyura praeputialis shows pronounced disjoint geographical distribution: along thousands of kilometers in wave-swept headlands on the southeastern coast of Australia, from where it appears to have originated, and exclusively along 60 -70 km inside the Bay of Antofagasta, Chile. mtDNA sequences suggested that the species invaded this rocky shore recently. We used field manipulations and juvenile P. praeputialis transplant techniques to test hypotheses regarding the capacity of the tunicate to survive and grow at different sites and tidal heights inside and outside Antofagasta, and its competitive performance for primary space (inside the Bay) against the native mussel Perumytilus purpuratus. We conclude that survival and growth of P. praeputialis showed no significant differences among sites inside and outside the Bay, and suggest that the restrictive distribution of the species in Chile is caused by a specific oceanographic retention mechanism and͞or its brief larval dispersal. We demonstrated that, inside the Bay, P. praeputialis outcompetes Perumytilus from the Mid-Low intertidal, constraining Perumytilus to the Upper MidIntertidal, modifying the local pattern of intertidal zonation. We show that predation on P. praeputialis juveniles by starfish and snails constitutes a regulatory mechanism for the setting of its low intertidal limit. Major ecological impacts caused by NIS invasions to rocky shores by aggressive primary space users may result in negative aspects, but also may contribute to biodiversity enhancement. We call attention to the need for increment manipulations and testing of ecological hypotheses regarding marine NIS.

BackgroundBiological invasions affecting rocky intertidal zonation patterns, yield information on species interactions. In the Bay of Antofagasta, northern Chile, the non-indigenous tunicate Pyura praeputialis, originally from Australia, has invaded (in the past century or so) and monopolized a major portion of the mid-intertidal rocky shore, displacing upshore the native mussel Perumytilus purpuratus. In Antofagasta the tunicate is subjected to intensive exploitation. Monitoring protocols show that in the past 10 years Antofagasta's tunicate population has experienced a drastic decline, affecting the intertidal zonation pattern.Methodology/Principal FindingsA 12.5 km of coastline, on the southern eastern shore of the Bay of Antofagasta, was studied. Eight sites were systematically (1993–1994) or sporadically (2003–2014) monitored for the seaward-shoreward expansion or reduction of the tunicate Pyura praeputialis, and native mussel and barnacle bands. A notable reduction in the mid-intertidal band of P. praeputialis and a seaward expansion of the mussel, Perumytilus purpuratus, and barnacle bands was observed. We suggest that the major cause for the decline in the tunicate is due to its intensive exploitation by rocky shore Pyura-gathers. The rate of extraction of tunicates by professional Pyura-gathers ranged between 256–740 tunicates hour−1. Between 2009–2014 the density of professional Pyura-gather ranged between 0.5–4.5 km−1 per low tide. Hence, 10 professional Pyura-gathers working 1 h for 10 low tides per month, during 6 months, will remove between 307–888 m2 of tunicates. A drastic decline in tunicate recruitment was observed and several P. praeputialis ecosystems services have been lost.Conclusion and SignificanceIn Antofagasta, the continuous and intensive intertidal gathering of the invasive tunicate Pyura praeputialis, has caused a drastic reduction of its population modifying the zonation pattern. Thereby, native mussel Perumytilus purpuratus has regained its ecological center in the intertidal zone. We recorded a Pyura recruitment failure and loss of ecosystem services.

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The continued degradation of marine ecosystems, along with the ecosystem services they provide, suggest that new, innovative approaches are needed to scale up marine biodiversity protection and promote sustainable fishery practices. We synthesize information from Chile on the key processes involved in the development of alternative strategies for scaling up marine biodiversity conservation and discuss the complementarities with marine protected areas. Defined as "ancillary" marine conservation initiatives under the Convention of Biological Diversity, we suggest that these alternative strategies have the potential to capitalize on local stakeholders' participation and contribute to solving livelihood and governance issues while playing a significant role in scaling up marine conservation. We specifically focus on two recent ancillary initiatives being piloted in Chile. The development of business model innovations which could enable biodiversity benefits from territorial user rights fisheries policies and the creation of municipal conservation areas. We identify how these initiatives could eventually help scale up marine conservation, discuss opportunities and challenges from these pilot experiences and conclude with the need for developing policy frameworks and cross-scale governance approaches which formally acknowledge marine ancillary conservation measures as part of an integrated way to manage marine biodiversity. Exploring and supporting alternative complementary marine conservation strategies is particularly relevant in Chile and Latin America, if biodiversity conservation initiatives are to scale in coverage, contribute to livelihood improvement of local communities, replenish fisheries and play key roles in adaptation to climate change.

Non-indigenous marine species have significant effects on rocky intertidal native biota and ecological processes. The tunicate Pyura praeputialis, a recent invader in the Bay of Antofagasta, Chile, has monopolized the low and mid-low rocky intertidal fringe and apparently constrained the native mussel Perumytilus purpuratus to the mid-upper fringe. We performed field experiments to determine interspecific competitive strengths and quantify survival and growth rates between these species at 2 intertidal heights: mid-low and mid-upper intertidal fringes. Our results showed that at the mid-low fringe P. praeputialis had greater competitive strength than P. purpuratus. In fact, the survival and growth rates of P. praeputialis were not significantly affected by the presence of P. pur-puratus. Further, while the survival of P. purpuratus was not significantly affected by the presence of P. praeputialis, its growth rate was affected by the degree of encroachment by the tunicate. Mussels encroached by P. praeputialis grew significantly less than non-encroached ones. At the mid-upper intertidal fringe, the survival of P. praeputialis was significantly decreased by the presence of P. pur-puratus: the tunicate is unable to grow at this intertidal fringe. At the low-intertidal fringe mussel growth rates were significantly greater than at the mid-upper fringe, while survival rates were similar. Our results support the hypothesis that in the Bay of Antofagasta the invading tunicate P. praeputialis is responsible for a major rocky intertidal ecological impact, outcompeting the native mussel from the mid-low fringe and thereby substantially modifying the zonation pattern. KEY WORDS: Invasion · Pyura praeputialis · Perumytilus purpuratus · Tunicate · Rocky intertidal · Antofagasta Bay Resale or republication not permitted without written consent of the publisher Editorial responsibility: Roger Hughes,

In northern Chile, Pyura praeputialis is an invasive species inhabiting rocky intertidal and subtidal habitats restricted exclusively to the Bay of Antofagasta where it forms extensive aggregations. The negative impact of Pyura gathering on mid-intertidal abundances of this species has recently been reported at the south-eastern end of this bay. In the present study we have increased sampling sites to cover the entire bay toward the north-western end and the northern section, where a coastal marine reserve for the scallop fishery partially restricts shellfish gathering. Therefore, the sampling sites were chosen to represent different levels of shellfish gathering access along the northern shore of the bay. Long-term monitoring (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) of changes in tunicate cover and the abundances of larvae and recruits at seven sites are reported. The opening of a remodelled artificial and recreational beach in 2012, on the central-eastern shore of the bay, has increased accessibility to rocky intertidal platforms that started to be massively visited by Pyura gatherers from the summer of 2013. This allowed for the implementation of an intensive short-term monitoring program of changes in tunicate cover and the abundances of their larvae and recruits. When gathering access was present the reduction in intertidal cover was generalized to the entire bay and followed by reductions in larvae and recruits. However, these reductions were not found in sites with more restricted gathering access. We conclude that continuous extraction by Pyura gatherers followed by reductions of conspecific larvae and recruits are the main drivers behind the reduced abundance of P. praeputialis in the entire bay of Antofagasta. Thus, if gathering is not stopped important ecosystem services provided by this tunicate in the bay may be threatened. Similar consequences may be expected if other massive and irreversible reductions in other species of the Pyura complex, that inhabit other coasts in the southern hemisphere, occur. The controversy concerning the impacts of invasive species and whether they cause negative, positive or neutral impacts to original ecosystems and fisheries is discussed.

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Abstract.-The literature on marine bio-fouling (MBF) in Chile was revised and complemented with field data from the Chacao channel (Chiloé), identifying both the bio-fouling species associated with man-made structure s (MMS) in the intertidal zone and species of algae, sessile and hemi-sessile invertebrates, present on natural substrata in the same area. In addition, to quantify settlement potential of the MBFA, artificial substrate plates (AS) were deployed in inter-and sub-tidal areas of the Chacao channel. The review identified 211 species, 85% of which were marine invertebrates and 15% macroalgae. The most representative taxa were arthropods, molluscs, annelids, which contributed 58% of the species of the Chilean MBF. The field data associated with MBF and with intertidal substrates indicated 133 species as potential components of the Chacao channel´s MBF. On natural substrata and in decreasing order of abundance were recorded gastropod molluscs, crustaceans and seaweed. The most abundant species on MMS were molluscs, seaweeds and crustaceans. The species that settled on AS deployed in the intertidal zone were mussels, barnacles and macroalgae. In the subtidal zone the most abundant groups were macroalgae spores and bryozoans. Based on the litera ture review, the fished giant barnacle Austromegabalanus psittacus, the ascidian Pyura chilensis and the mussel Mytilus chilensis appear to be highly frequent and dominant species on subtidal natural hard-bottom. Because of their biological and ecological characteristics, these species have high degree of potential for colonising MMS deployed in the subtidal zone of the Chacao channel .Key words: Bio-incrusting, C hacao channel, Chiloé, natural substrata, man-made substrata , Pyura chilensis, Austromegabalanus psittacus, Mytilus chilensisResumen.-Se revisó literatura sobre los bio-incrustantes marinos (BIM) de Chile, complementado con campañas de terreno en el canal de Chacao (Chiloé), para registrar los BIM asociados a estructuras manufacturadas por el hombre (EMH) en la zona intermareal así como las especies de algas e invertebrados sésiles o hemisésiles presentes en l a misma zona y potenciales BIM. Además, un tipo de sustrato artificial (SA) fue instalado en el inter y submareal del canal de Chacao para cuantificar el asentamiento de potenciales BIM. La revisión indicó una diversidad de 211 especies, correspondiendo 85% a invertebrados y 15% a macroalgas. Los taxones más representativos fueron artrópodos, moluscos y anélidos, los cuales contribuyeron al 58% de las especies de BIM registrados en Chile. La información de terreno indica 1 33 especies potencialmente BIM en el canal de Chacao. En sustratos naturales y en orden decreciente de abundanci a se registraron los moluscos gastrópodos, crustáceos y macroalgas. En EMH del canal de Chacao los BIM más abundantes en orden decreciente fueron los moluscos, macroalgas y crustáceos. Sin embargo, los BIM más representados en SA desplegados en la zona intermareal fueron mitílidos, cirrípedos y macroalgas; mientras que ...