Table 1: Laser Ablation parameter LA-ICP-MS analysis of otoliths: a new prospecting tool of marine metal pollution A. Pennettaa , G. E. De Benedettoa, A. Di Francob, P. Guidettib aLaboratory of Chemical Analyses for Cultural Heritage, Department of Fine Arts and History, University of Salento, 73100 Lecce, Italy bDepartment of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy E-mail: antonio.pennetta@unisalento.it Introduction Trace elements in otoliths may provide information on dispersal history of marine fishes. The longitudinal section of otoliths of fish shows, indeed, daily growth rings whose elemental composition reflects the composition of the waters where the fish has been (fig. 1, fig. 2). Analysis showed (fig. 4) three statistically different groups, suggesting three possible different natal origins (i.e. spawning areas): group A, B and C include 6.8, 22.0 and 71.2% of the total number of settlers, respectively. The group A includes specimens mostly from sites located south of TGMPA, whereas groups B and C are a mixture of specimens from all the sampling sites (i.e. only two spawning areas replenished all sampling sites). Post-settlers from the 2 sites inside TGMPA were found in group B and group C suggesting that the two settlement sites sampled at TGMPA were replenished by 2 different spawning areas. ... Mg, Mn, Cu, Pb, Sr, Ba ... Fig. 1 Common spawning area Same larval origin C L G Fig. 2 Otoliths incorporate into their calcium carbonate matrix both minor and trace elements as they grow. Some elements (e.g. Sr and Ba) are incorporated at rates related to ambient concentrations . Interest in analytical mass spectrometry associated with laser ablation for sample introduction has increased markedly during the past few years. Extended research on otolith chemistry showed the possibility of using of the fish otoliths as biomarkers of marine pollution. 10 20 30 40 ~ 6 - 8 ~ 15 ~ 20 ~ 30 Frequence % Dispersal (in Km) Fig. 4 Experimental ICP-MS parameters were optimized to achieve stable signals for ubiquitous matrix elements while reducing oxides, doubly charged species and other potential interferences. NIST 610 and NIST 612 external calibration standards were used for calibration and calcium was used as internal standard. Standards and samples were ablated for 10s each and all analyses were started using 30s background acquisition. New Wave Research UP-213 Energy 65 % Fluence 5.2 J/cm2 Spot Size 40 μm Pulse Frequency 2 Hz Carrier Gas (Helium) 700 ml/min A comparison was made between the mode of single-hole drilling ablation and the scanning mode ablation. The single-hole drilling mode also guaranteeing a greater spatial resolution. Was used a 10s ablation, performed with the parameters on Table 1 prodiced a crater about 10 microns deep. Table 2 collects the analytical performance oh the method. The carbonate matrix also incorporate elements environmental important like Pb or Hg. In figure 5 it is possible to see that in the otolith core and juvenile stages there is no Hg whereas in the same (not all) larval rings Hg was clearly detected. As a results geotagging fishes could also give info on sea of source pollution. Table 1: Laser Ablation parameter Fig. 5 Element NIST 610 (mg/Kg) NIST 612 (mg/kg) % Accuracy NIST 610 % Accuracy NIST 612 LOD (mg/kg) 24Mg 465.3 77.44 101 107.2 1.146 55Mn 433.3 38.43 100.99 112.31 2.876 66Zn 456.3 37.92 99.94 120.7 1.763 88Sr 497.4 76.15 100.57 92.51 0.02 138Ba 424.1 37.74 101.43 88.39 0.227 208Pb 413.3 38.96 99.26 122.89 0.104 Table 2: Concentrations of elements in Nist610 and Nist612, estimates of accuracy and limits of detection (LOD). Results and discussion To estimate larval dispersal, post-settlers of D. sargus sargus were collected long ~200 km of the Apulian Adriatic coast (approx. from Bari to Otranto). Sampling was performed at 14 sites, two located inside the Torre Guaceto marine protected area (TGMPA) and twelve outside (six northward and six southward, within ~100 km from the TGMPA) (fig. 3). Conclusion The use of LA-ICP-MS allowed to provide quantitative evidence of dispersal and connectivity to larval and post-establishment of a littoral fish, if available for a number of fish species, could be crucial for the design and the placement of marine protected areas. In addition as LA-ICP-MS allows to deteminate trace elements incorporated in the otolith matrix, it permits to gathering information on the health of the waters where the fish has been. Experiments on correlation between fish and otolith metal concentration are in progress. North Centre South Fig. 3 References P. Guidetti, M. Petrillo, G. de Benedetto, G. AlBertelli, Natal origin of European anchovy: a case study in the Ligurian Sea (NW Mediterranean), Biol. Mar. Mediterr., 17, 2010, 149 A. Di Franco, G. De Benedetto, G. De Rinaldis, N. Raventos, R. Sahyoun, & P. Guidetti Large, Large scale-variability in otolith microstructure and microchemistry: The case study of Diplodus sargus sargus (Pisces: Sparidae) in the Mediterranean Sea, Italian Journal of Zoology, 78, 2011, 182 Melinda M. Ranaldi, Marthe M. Gagnon, Trace Metal Incorporation in Otoliths of Black Bream (Acanthopagrus butcheri Munro), an Indicator of Exposure to Metal Contamination, Water Air Soil Pollut, 94, 2008, 31