Uptake and Accumulation of Cadmium by Ophryotrocha diadema (Polychaeta)

Abstract

Cadmium uptake by the deposit-feeding polychaete Ophryotrocha diadema is a non-linear process related to exposure time and metal concentration in the ambient seawater (20°C; salinity 31). Maximum body loads of 1700ppm Cd were found in adult worms (up to 0.1 mg dry weight) after 64-day exposure to 1OOOppb Cd. Distinct saturation of absorption was not reached dur~ng this time. Accumulation factors decreased exponentially with increasing contamination levels. Accumulation factors were 7900 to 1700, calculated on a dry weight basis, corresponding to 3400 to 660 estimated on a theoretical volume basis of single worms in levels of 10 to lOOOppb Cd. Cd content of 62- to 116-day-old worms of three consecutive generations subjected to permanent contanl~nat~on did not increase from the P- to the F,-generat~on. A linear correlation exists between Cd absorption of newly deposited egg masses and experimental Cd concentrations. Cd loads of egg masses were extremely low (12 to 280ppm Cd dry weight in 50 to lOOOppb Cd contamination) compared with parental organisms. Cd content of the egg masses also did not increase within consecutive generations. It is, therefore, assumed that parentally accumulated Cd loads are not transferred to the offspring. Contamination of egg masses probably occurred after spawning, due to sorption of the metal by the mucoid layer encapsulating the eggs, since similar results were noted for Cd sorption by food part~cles (fragmented spinach). INTRODUCTION