Our findings document the association of psychosocial factors and primary health care use. We suggest that the effective management of mental health problems from a family-based approach may reduce primary health care high use.

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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Here we report a mechanism that reduces dispersal of early developing stages and larvae in a free-spawning intertidal and shallow subtidal tunicate, Pyura praeputialis (Heller 1878), in the Bay of Antofagasta, Chile. The spawning of gametes by the tunicate into the naturally turbulent aerated seawater decreases their surface tension and induces the formation of a bio-foam. Water collected from foamy intertidal pools and tide channels showed a high concentration of P. praeputialis early developing stages and tadpole larvae in the foam. Because gametes are synchronically spawned for external fertilization and larvae settle near adults, our results suggest that this bio-foam increases fertilization success and effective settlement of their short-lived larvae in the vicinity of the adults spawning the gametes. This mechanism reinforces published evidence suggesting that local retention of intertidal and inshore marine invertebrate larvae may be more common than previously thought, offering, for instance, new perspectives for the design and networking of marine protected and management areas.Chile ͉ surface tension ͉ tide channels ͉ broadcast spawner ͉ settlement I t is well known that surfactants can induce the formation of bio-foams that can ensure egg retention and larval development in organisms such as tropical leptodactylid frogs (1-5) and African and Asian freshwater labyrinth fishes (6). However, such egg-larval retentive mechanisms or ''foam-nests'' have not been reported for marine organisms. In Chile, massive populations of the intertidal and shallow subtidal tunicate Pyura praeputialis form beds almost exclusively along a 60-70 km stretch of the rocky shoreline inside the Bay of Antofagasta (7). This tunicate is an alien species in Chile, and its absence at locations more than 3-5 km outside of the Bay of Antofagasta, and along the Chilean coast, suggests the existence of unknown mechanisms preventing its dispersal (8) and maintaining high settlement inside the Antofagasta tunicate beds. In December 2004 and January 2005, midway through the ebb tides, we observed massive co-spawning of both eggs and sperm suspension from P. praeputialis into naturally turbulent aerated intertidal seawater (Fig. 1A) and the subsequent formation of localized and conspicuous masses of foams. These bio-foam masses persisted for several hours on top of rocky shores and floating in tidal channels, near where they were spawned, because of onshore winds (Fig. 1). Results and DiscussionTo investigate the role of the bio-foam associated with P. praeputialis on the retention of embryos and tadpole larvae of the species, seawater samples were collected (December 10 and 12, 2004; January 14 and 15, 2005) by using a plankton bilgepump equipped with a 50-m elbow end and calibrated with a domestic flow meter (9). The pump was used to collect water samples at different time intervals through the tide cycle from the sea surface just above or near the intertidal rocky shores in Bay of Antofagasta that are dominated by P. praeputialis. Eac...

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