Diet variably affects the trophic transfer of trace elements in the oyster Crassostrea gigas
2020
Pouil, Simon | Metian, Marc | Dupuy, Christine | Teyssié, Jean-Louis | Warnau, Michel | Bustamante, Paco
Although it has been shown that trophic transfer of trace elements in oysters can be influenced by the diet, most of the studies investigating the ability of oysters to bioaccumulate trace elements from their diet are based on experiments using phytoplankton alone. Wild oysters feed also on large bacteria, ciliates or detritic organic matter. The present study aimed at examining the influence of food quality on the assimilation efficiency (AE) of trace elements in the Pacific cupped oyster Crassostrea gigas. Oysters were exposed via their food to the radiotracers of essential (⁵⁷Co, ⁵⁴Mn and ⁶⁵Zn) and non-essential (¹¹⁰ᵐAg, ²⁴¹Am and ¹⁰⁹Cd) trace elements under different diets (protozoan ciliates Uronema marinum and diatoms Thalassiosira pseudonana). Significant differences were found only for Ag and ²⁴¹Am, with lower AEs measured in oysters fed with ciliates than in individuals fed with diatoms (Ag: 54 ± 3% vs. 67 ± 4% and ²⁴¹Am: 62 ± 4% vs. 76 ± 4%). Interestingly, no significant difference was found among estimated depuration rates (kₑₗ) for all trace elements ingested with the two diets tested. These findings indicate that the differences observed are driven by the digestion process, presumably due to difference of bioavailability of trace elements dependent on the quality of the food ingested.
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