Tapes japonica

Firstly, Takagi and Simidu (25) examined the correlation between the organic acid content of 9 species of shellfish and their taste, and found that the more palatable species were not necessarily richer in succinic acid, as exemplified by the hard clam, Meretrix lusoria. These results led them to conclude that succinic acid does not dominate the delicious taste of shellfish. Secondly, Konosu et al. (26) reported that the succinic acid content of the short-necked clam, Tapes japonica, when determined immediately after collection, was very low (20-40 mg/100 g of edible part) as compared with Aoki s value (330 mg), and that the flavor of a fresh sample was as good as that of a commercially available sample that had accumulated a large amount of succinic acid. 

A number of short-term exposure experiments have shown rapid half-lives for PAHs. For example, Neff et al. (1976) found that clams (Rangia cuneata) that had accumulated 7.2 ptg/g of benzo[a]pyrene over 24 hr lost 60% of this compound after 10 d in clean seawater. Clams (Tapes japonica) exposed for a few days to several PAHs exhibited half-lives that were relatively short (4-8 d) (Obana et al. 1983). Fast elimination rate constants (k were measured in a clam (Macoma balthicd), and only a 1.6-fold difference was detected between naphthalene (0.0141 hr" ty = 49.1 hr) and chrysene (0.0087 hr ty, = 79.7 hr) (Foster et al. 1987). 

Several studies have shown rapid attainment of steady-state BCFs in marine organisms exposed to PAHs in water. For example, similar values (BCFs 50) were calculated for Mytilus edulis after 4 hr of exposure to labeled naphthalene and after 4 wk exposure to unlabeled naphthalene, indicating rapid equilibration with exposure concentrations (Widdows et al. 1983). Rapid accumulation was also noted by McLeese and Burridge (1987) in clams Mya arenaria), mussels Mytilus edulis), shrimp Crangon septem-spinosa), and polychaetes Nereis virens) exposed for 4 d to several PAHs in water. They concluded that these species had accumulated sufficient PAH to have BCFs within a factor of 2-5 of steady-state BCFs (based on kx/k. Clams Tapes japonica) placed in the Port of Osaka, Japan to measure accumulation at natural levels of PAHs in seawater exhibited BCFs of 12,800 for pyrene, 2,800 for benzo[b]fluoranthene, 5,700 for benzo[k]fluoranthene, and 4,600 for benzo[a]pyrene after 7 d exposure... 

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