Aim: Biological invasions and changes in land and sea use are among the five major causes of global biodiversity decline. Shipping and ocean sprawl (multiplication of artificial structures at the expense of natural habitats) are considered as the major forces responsible for marine invasions and biotic homogenization. And yet, there is little evidence of their interplay at multiple spatial scales. Here, we aimed to examine this interaction and the extent to which the type of artificial habitat alters the distribution of native and non-indigenous biodiversity. Location: Southeast Pacific-Central Chilean coastline.Methods: Settlement plates were deployed upon two types of artificial habitats (floating and non-floating hard substrates) at a total of ten study sites, exposed to either international or local traffic. After colonization periods of 3 and 13 months, plates were retrieved to determine their associated fouling sessile assemblages at an early and late stage of development, respectively. Putative confounding factors (temperature, metal concentrations) were taken into account.Results: While traffic type had no detectable effect, there were strong differences in community structure between habitats, consistent across the study region. These differences were driven by non-indigenous species which contributed to 58% and 40% of the community structure in floating habitats after 3 and 13 months, respectively-roughly 10 times greater than in their non-floating counterparts. Assemblages on floating structures also displayed a lower decline in similarity with increasing distance between sampling units, being thus more homogenous than non-floating habitats at the regional scale. Main conclusions:With the absence of international traffic effect, the colonization success by non-indigenous species appears to be mainly habitat-dependent and driven by local propagules. Floating structures not only provide specific niches but characteristics shared with major introduction and dispersal vectors (notably hulls), and in turn constitute important corridors to invasions and drivers of biotic homogenization at multiple scales. | 63LECLERC Et aL.

A biosensor for malic acid detection in fruit juices, based on malate dehydrogenase (MDH) glutamate oxaloacetate transaminase (GOT) in a powder vitreous carbon, carbon nanotubes and mineral oil, composite matrix has been developed. By employing amperometry at a constant potential of 0.4 V (vs. Ag/AgCl), an enzymatic reaction promoted by these species in a support solution Mc Ilvaine buffer (phosphate/citrate pH 10.0) with glutamic acid was generated, causing the oxidation of electro active species, that was stoichiometrically equal to the amount of malic acid present in the sample. The response was linear over the range 2–50 mM, with an analytical sensitivity of 2.24×10−4 to 2,55×10−4 AM−1 and r2=0.9980 to 0.9983, a LOD of 4.02 μM and LOQ of 13.4 μM. Malic acid concentration detected was 0.23–1.07 g/L in fruit juice samples. Results were validated using an enzymatic spectrophotometric method as a reference. To the best of our knowledge, this is the first bienzymatic biosensor using both malate dehydrogenase and glutamate oxaloacetate transaminase enzymes.

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, we compared biofouling communities in 3 international and 3 nearby local ports, along 100 km of coastline in Southcentral Chile, 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. Our results also suggest that local ports should be considered in NIS surveillance programs in Chile.

IN SEAWATER. A flow injection on-line pre-concentration system coupled to thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determination at sub µg L-1 levels in seawater samples was developed. The on-line system was evaluated by analysing cadmium containing in a synthetic seawater matrix (2.5% m/v NaCl, 0.5% m/v MgCl 2 and 0.8% m/v CaCl 2). A sample volume of 2 mL allows determining Cd with a detection limits of 30 ng L-1 (3* σ blank /slope), pre-concentration factor of 34 and repeatability of 1,8% (calculated as RSD, N=8 and containing 200 ng L-1 of Cd).

Recebido em 14/8/12; aceito em 20/11/12; publicado na web em 28/2/13 CONTENT, DISTRIBUTION AND ORIGIN OF HYDROCARBONS IN SEDIMENTS FROM THREE URBAN LAGOONS IN CONCEPCIÓN-CHILE. Aliphatic hydrocarbon content, distribution and origin in superficial and deep sediments of three interconnected urban lagoons located in Concepción-Chile were studied. In all lagoons, the analysis showed that aliphatic hydrocarbons present were of biogenic and anthropogenic origin, and n-alkanes were predominantly from odd carbon, confirmed by a relatively high Pristane/Phytane ratio. The most abundant Polycyclic Aromatic Hydrocarbons (PAHs) were two high-molecular weight species (Fluoranthene and Pyrene) whose presence may be related with the regular activities of the area as well as with combustion processes.

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