The aim of the present work is to broaden our knowledge on the variability of trace metals in mussel tissues, focusing on seasonal fluctuations in the three different sampling sites of Algerian west coast (Oran Harbor (S1), Ain Defla (S2) and Hadjaj (S3)). For this purpose, the bioavailability (metal indices) and bioaccumulation (metal concentrations in soft tissues) of heavy metals (Zn, Cu, Pb, and Cd), and the physiological characteristics (e.g. biological indices such as condition index (CI)) of mussels Mytilus galloprovincialis have been assessed and related to seasons and sites. In S1, the highest levels of metal concentrations and indices were obtained in mussels sampled in winter for Zn, Cu and Cd, but in summer for Pb. The biological indices significantly decreased in winter. In S2, the levels of concentrations and indices of all metals varied whatever the seasons, excepting in summer where the values were the lowest. In summer Peer review under the responsibility of Institute of Oceanology of the Polish Academy of Sciences. § We thank Ms. Nathalie Bendbiko and Ms. Catinca Birna (University Agency of Francophony (AUF-Paris)) for their support through the granting of the Doctoral scholarship.

The physical and optical properties of an atmospheric aerosol mixture depend on a number of factors. The relative humidity influences the size of hydroscopic particles and the effective radius of an aerosol mixture. In consequence, values of the aerosol extinction, the aerosol optical thickness and theÅngström coefficient are modified. A similar effect is observed when the aerosol composition changes. A higher content of small aerosol particles causes the effective radius of an aerosol mixture to decrease and theÅngström coefficient to increase. Both effects are analysed in this paper. The parameters of the size distribution and the type of components used to represent natural atmospheric aerosol mixtures are based on experimental data. The main components are sea-salts (SSA), anthropogenic salts (WS, e.g. NH 4 HSO 4 , NH 4 NO 3 , (NH 4 ) 2 SO 4

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The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated, monounsaturated and saturated fatty acids were utilized as metabolic substrates until day 9. At day 10, all fatty acid levels remained stable or, at least, increased in larval body. Among fatty acids, docosahexaenoic acid 22:6 n-3 was used preferentially (20.3% from total fatty acids utilized) followed by palmitoleic acid 16:1 n-7 (13.9%) and then by oleic 18:1 n-9 (12.3%), linoleic 18:2 n-6 (10.1%), linolenic 18:3 n-3 (9.7%) and eicosapentaenoic 20:5 n-3 (9.1%) acids. On the other hand, arachidonic acid 20:4 n-6 was utilized very lowly (0.3%). In fed larvae, no utilization of body fatty acids was observed during the experiment. It seems that energy requirements (and others) of fed larvae were satisfied by feed.

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