Characterization of 241Am and 134Cs bioaccumulation in the king scallop Pecten maximus: investigation via three exposure pathways

Abstract

In order to understand the bioaccumulation of (241)Am and (134)Cs in scallops living in sediments, the uptake and depuration kinetics of these two elements were investigated in the king scallop Pecten maximus exposed via seawater, food, or sediment under laboratory conditions. Generally, (241)Am accumulation was higher and its retention was stronger than (134)Cs. This was especially obvious when considering whole animals exposed through seawater with whole-body concentration factors (CF(7d)) of 62 vs. 1, absorption efficiencies (A(0l)) of 78 vs. 45 for seawater and biological half-lives (T(b½l)) of 892 d vs. 22 d for (241)Am and (134)Cs, respectively. In contrast, following a single feeding with radiolabelled phytoplankton, the assimilation efficiency (AE) and T(b½l) of (134)Cs were higher than those of (241)Am (AE: 28% vs. 20%; T(b½l): 14 d vs. 9 d). Among scallop tissues, the shells always contained the higher proportion of the total body burden of (241)Am whatever the exposure pathway. In contrast, the whole soft parts presented the major fraction of whole-body burden of (134)Cs, which was generally associated with muscular tissues. Our results showed that the two radionuclides have contrasting behaviors in scallops, in relation to their physico-chemical properties.

Delineation of 134 Cs uptake pathways (seawater and food) in the variegated scallop Mimachlamys varia

“…This has been confirmed experimentally for the king scallop Pecten maximus (Metian et al, 2011). Field surveys (e.g.…”

“…Whole-body uptake and depuration kinetics were fitted using nonlinear regression routines and iterative adjustment (Statistica ® 7) and statistical methods described by Warnau et al (1996aWarnau et al ( , 1996b and Metian et al (2011). The level of significance for statistical analyses was always set at a ¼ 0.05.…”

“…However, levels of radionuclides in organisms are influenced by various factors such as geographical origin, season, sexual maturity or species considered (Bryan, 1963;Mauri et al, 1990;Miramand, 2004, 2005). Laboratory characterization of Cs bioaccumulation by Pectinids is currently limited to one species, P. maximus (Metian et al, 2011) and since phylogenetically-close species may have different accumulation capacities (as shown for metals in scallops, e.g. Metian et al, 2007 andin oysters, H edouin et al, 2010a), it is worth comparing Cs bioaccumulation capacities among scallops species.…”

“…This species is an interesting model to assess Cs contamination in coastal area given the fact that it settles, with its byssus, on rocky substrates (Shumway and Parsons, 2006) whereas P. maximus lives buried in the sediment. The same protocol as described in Metian et al (2011) was used in order to allow easy comparison between the two scallop species. In addition, the relative contribution of the different exposure pathways (dissolved vs. dietary) of Cs bioaccumulation in M. varia was determined.…”

A dynamic model to estimate the activity concentration and whole body dose rate of marine biota as consequences of a nuclear accident

“…Tadeda (1995), 2)Mathews et al(2008), 3)Jeffree et al (2006), 4)Metian et al (2011), 5) Vives et al (2008a, and 6)Tadada et al (2013). a For all biota considered, the 131 I assimilation efficiency is assumed to be the same as that of 137 Cs since there is no data available for marine biota at present.…”