Title: TRACE ELEMENTS IN OYSTER BIODEPOSITS

The contents of the trace metals copper, zinc, manganese and iron in adult Pacific Oyster (Crassostrea gigas, Thunberg, 1795) feces, pseudofeces and suspended particles were investigated. The biode-posits were collected on a continuous basis for 28 weeks with a specially designed apparatus. Seston samples were obtained in a sedimentation chamber. The biodeposition rate was calculated from the. relative contributions of feces and pseudofeces. During the experiment. samples were periodically withdrawn and analyzed for: a) trace metal content, by flamne atomic absorption spectrophoto-metry (AAS); b) organic carbon and total carbon and nitrogen, by combustion gas chromatography; and e Redacted for privacy c) total organic matter, by the difference between dry and ash weights. d) Biogenic opal and quartz were analyzed by X-ray diffraction in selected samples. The biodeposition rate for adult oysters under the experimental conditions was 0.63 g dry weight/oyster/week. The feces production rate was 0.33 g dy weight/oyster/week, and the pseudofeces rate 0.30 g dry weight/oyster/week. The mean feces/pseudofeces ratio was found to be 0.90. Both biodeposits were composed main'y of a loose agglomer-ation of very fine particles. The average trace metal concentrations on a dry weight basis were 38.5 iig..cu/g, 117 ug Zn/:g, 686 iig4i/g. and 34.4 mg. Fe/g for feces. For pseudofeces: 39.6 i.tg Cu/g, 121 ug.Zn /g, 778 pg.?.Th/g and 37.2 mg, e'g and for biodeposits: 39.2 pg Cu/g