Heavy metals in Ras Beirut prawns and sea urchin eggs. Whole samples of Palaemon elegans Rathke, 1837 and eggs of Paracentrotus lividus Lamarck, 1816 were collected on the coast of Ras Beirut, Lebanon in the summer and fall of 1977 and the spring of 1978. All were analysed for lead, cadmium, copper and other heavy metals. Lead concentrations in both the prawns and sea urchin eggs appeared to be highest in the summer and lowest in the spring, whereas cadmium was low in all seasons with only a few elevated readings. The strongest tendency towards seasonal variation was seen in the copper levels of the prawns, which were high in summer, much lower in fall, and then high again in spring. Results of the analyses for nickel, iron, zinc and chromium are also discussed. Of the various possible sources of heavy metals in the Ras Beirut coastal area, untreated sewage, pesticide residues, and automobile exhaust are the most important.