## Results
### Accumulation and Elimination of Free and Total MC by D. polymorpha  
Free MC were detected in _D. polymorpha_ tissues only from the third day of exposure regardless of the exposure concentration (Figure 3A). Maximum concentrations of free MC in whole _D. polymorpha_ occurred either at day 14 of exposure for mussels exposed to a density of filaments producing an equivalent of 1 (0.3 \(\pm\) 0.1 \(\mu\)g MC/g DW) and 100 \(\mu\)g MC/L (6.4 \(\pm\) 3.0 \(\mu\)g MC/g DW), or at the first day of depration for mussels exposed to a density of filaments producing an equivalent of 10 \(\mu\)g MC/L (5.2 \(\pm\) 3.8 \(\mu\)g MC/g DW). During the depration, MC ceased to be detected in tissues asynchronously: in mussels exposed to 1 \(\mu\)g MC/L, only one sample out of three was positive (0.1 \(\mu\)g MC/g DW) at the first day of depration and free MC ceased to be detected in all mussels from day three of depration. In mussels exposed to 10 \(\mu\)g MC/L, free MC were detected in all pools at the first day of depration. Then, no MC were detected from day seven to 21 of depration, apart one positive pool at day 21 (mean concentration of 0.1 \(\pm\) 0.1 \(\mu\)g MC/g DW) (Figure 3A). MC were still detected in _D. polymorpha_ exposed to 100 \(\mu\)g MC/L after 21 days of depration (0.4 \(\pm\) 0.1 \(\mu\)g MC/g DW). Over the exposure and the depration, free MC concentrations in mussels exposed to 100 \(\mu\)g MC/L were significantly higher compared to those exposed to 1 \(\mu\)g MC/L (Kruskal-Wallis, \(p\) \(<\) 0.01). However, even if MC concentration in mussels exposed to 10 \(\mu\)g MC/L tended to be intermediary, these concentrations were not were not statistically different from MC content in mussel exposed to 1 and 100 \(\mu\)g MC/L (Kruskal-Wallis, \(p\) \(>\) 0.051).  
Total MC (Figure 3B) were detected from the first day of exposure in whole _D. polymorpha_ exposed to 10 and 100 \(\mu\)g MC/L (0.2 \(\pm\) 0.2\(\mu\)g MC/g DW for each concentration) and from day three in those exposed to 1 \(\mu\)g MC/L (0.3 \(\mu\)g MC/g DW) but only in one sample. During the exposure, total MC concentrations in tissues were higher in _D. polymorpha_ exposed to 100 \(\mu\)g MC/L compared to those exposed to 1 \(\mu\)g MC/L (Kruskal-Wallis, \(p\) \(<\) 0.05). No significant difference was observed between mussels exposed to a 10 \(\mu\)g MC/L and the two other exposure concentrations (Kruskal-Wallis, \(p\) \(>\) 0.05). Highest total MC concentrations in _D. polymorpha_ were observed at different times of the intoxication depending on the exposure concentrations: at day 21 for the densities producing an equivalent of 1 (1.3 \(\pm\) 0.05 \(\mu\)g MC/g DW) and 100 \(\mu\)g MC/L (8.9 \(\pm\) 5.65 \(\mu\)g MC/g DW), and at day one of depration for 10 \(\mu\)g MC/L (4.75 \(\pm\) 2.6 \(\mu\)g MC/g DW). During the exposure, the mean percentage of bound MC in _D. polymorpha_ was of 50 \(\pm\) 9% during the accumulation and 75 \(\pm\) 8% during the depration. During the depration, total MC concentrations were significantly higher in _D. polymorpha_ exposed to 100 \(\mu\)g MC/L, compared to those exposed to 1 \(\mu\)g MC/L (Kruskal-Wallis, \(p\) \(<\) 0.05). No significant difference was observed between mussels exposed to 10 \(\mu\)g MC/L and the two other intracellular MC concentrations (Kruskal-Wallis, \(p\) \(>\) 0.05). After 21 days of depration, total MC were still detected in tissues of _D. polymorpha_ whatever the exposure concentration. At this day, mean total MC concentration were 0.2 \(\pm\) 0.2 \(\mu\)g MC/g DW, 0.7 \(\pm\) 0.4 \(\mu\)g MC/g DW and 1.2 \(\pm\) 0.61 \(\mu\)g MC/g DW, respectively, in mussels exposed to 1, 10 and 100 \(\mu\)g MCs/L.  
Figure 3: _Cont._Total MC concentrations in digestive glands of \(D\). _polymorpha_ (Table 1) did not differ significantly between densities during the experiment (Kruskal-Wallis, \(p>0.05\)). Moreover, these total MC concentrations in digestive glands of \(D\). _polymorpha_ were similar than those quantified in whole individuals during the experiment (Mann-Whitney test, \(p>0.05\)).