The capacity to bioaccumulate trace metals present in San Jorge Bay, Antofagasta, Chile,was determined in northern scallop, Argopecten purpuratus, to examine thevalue of this important commercially species as a bioindicator of heavy metal pollution inareas where it is cultured. Scallops were sampled in summer 2009 in four sites: threenatural populations (Coloso, Historic District and La Rinconada, marine reserve), and acommercial hatchery (Colorado). The concentrations of three heavy metals (copper, cadmiumand lead) were then determined through stripping chronopotentiometric methods, and thelevels of four biomarkers: three genes implicated in the stress and oxidative metabolism,i.e., glutathione peroxidase (GPx), glutathione s-transferase (GST) and heat shock protein70 (HSP70), and a protein marker in the digestive gland and gill, a metallothionein (MT).The Historic District, located in the downtown area of the city, showed the highest metalconcentration of all the sampled sites, as well as the highest levels of the fourbiomarkers. This can be largely attributed to the nearby international port area of thetown and high sea traffic flow, exacerbated by the prevailing winds.

Within the framework of the Chilean molluscan shellfish safety program, blooms of Alexandrium were detected in several aquaculture sites in northern Chile. An outbreak of Alexandrium was detected in May 2006 in Mejillones Bay. Wild and cultured phytoplankton and shellfish samples from this bloom were analyzed by high performance liquid chromatography with fluorescent detection (HPLC-FD). Neither phytoplankton net tows samples nor an Alexandrium culture started from the bloom were found to contain PSP toxins at detectable levels. The shellfish, however, showed the presence of C2, GTX2, GTX3 and dcGTX2. Two new PSP episodes were recorded in June 2006 in Guanaqueros and Tongoy Bays. In these instances, shellfish samples from the two bays were analyzed by mouse bioassay and HPLC-FD, showing PSP toxicities that ranged from 27 to 34 $\mu $ g STX eq 100 g−1 and a toxin profile mainly characterized by the presence of STX, GTX2 and GTX3. Differences between toxin profiles in Mejillones Bay and the two other locations suggest that, in the area, this kind of toxicity is probably produced by different regional populations or strains of the genus Alexandrium other than Alexandrium catenella, since the toxin profile and optimal environmental conditions for this species are noticeably different from those recorded in the proliferations from northern Chile. This paper therefore presents the first report of this kind of toxicity from an area between parallels 13°55'S and 33°5'S, comprising the subtropical zone of the southeastern Pacific Ocean. Results suggest that, as in the northern Pacific coastal area of America, PSP toxicity may be widely distributed on the southern Pacific coast.

Daily striae on the shell of the scallop, Argopecten purpuratus, were used to investigate its growth in a protected population within La Rinconada Bay, near Antofagasta (2nd Region, Northern Chile), and to determine how environmental forcings control shell growth. This sclerochronological approach was useful to describe daily shell growth a posteriori. Mean shell growth rates were calculated daily between February and October 1999 from shells of six specimens harvested on 15 October 1999. A multiple regression analysis performed on shell growth and environmental data shows that a temperature increase stimulates shell growth whereas particulate organic carbon concentration might be stressful above 2.5 mg L−1. The lunar cycle might also have an effect on growth, most potent around New Moons, by synchronizing an endogenous oscillator. The age at commercial size (90 mm) was only 10–11 months in La Rinconada Marine Reserve and the von Bertalanffy growth parameters were K = 2.24 y−1 and H ∞ = 117 mm. Differences in shell growth performances between this study and previous ones dealing with A. purpuratus growth may be explained by the different methods used for shell growth modelling, higher growth rate on the seabed compared to suspended cultures, and particular environmental forcings (e.g. El Niño Southern Oscillation-ENSO events). Growth performance seems better during La Niña than during El Niño events, probably because of the large temperature increase (above the highest temperatures recorded in “normal” conditions) and the decline in coastal upwelling (which affects food availability) during El Niño. La Rinconada Marine Reserve appears as a very favourable site for A. purpuratus growth, probably because of the active upwelling zone off Antofagasta. These new insights on A. purpuratus shell growth confirm the importance of La Rinconada Marine Reserve as an area supporting repopulation of endangered wild stocks and scallop aquaculture in Chile.