## 4 Discussion
The most bioaccumulated elements in clams were Mn, Ce, La and Sm, mainly found as fuel additives in the form of methylcyclopentadienyl manganese tricarbonyl [23], cerium oxides and oil-treatment soaps to improve the performance of low octane petroleum distillates or reduce particulate emissions (Sm and La). La is also relatively abundant in the earth's crust and is used in fuel additives to reduce particulate emissions and also in rechargeable batteries for electric/hybrid cars [24]. This is consistent with the significant correlations of tissue Ce levels with V and Sm. Mn was recognized as a neurotoxic manifesting as Parkinson-like symptoms [25]. Studies on the toxicity of the Mn organic complex found in gasoline in bivalves and fish are scarce. Exposure of the freshwater bivalve _Anodontites trapesialis_ to ionic Mn (0.5 mg/L) suppressed gill metabolic rates [26, 27]. This is in keeping with the negative correlation with the clam mass and CF found in the present study. However, the reduced metabolism (lower production of reactive oxygen species during respiration) could have contributed to increase air survival time (significant correlation between Mn and LT) in clams. Fuel additives comprise other elements in addition to Mn, such as Nd (increased at polluted sites), Sm (increased at polluted sites) and Ce (increased at BSM). Ce levels in clams were significantly increased 2.5-fold at BSM only. The third most accumulated metal was Ag. Although no direct source of Ag is found in this area, Ag contamination is a result of human activity, such as smelting and coal burning activity, erosion of natural sources, mining, and municipal wastes [28]. Hence, the elemental profiles suggest contamination principally from combustion emissions of fuel and crude oil release, which is consistent with harbors and sustained boat traffic. It is noteworthy that contaminants were sometimes higher at BSM compared to the two polluted sites MAB and TAD, suggesting that this food source could pose a risk to organisms feeding on this resource. This study also permitted us to examine the temporal changes of clam health by pollution based on the proposed morphological biomarkers (CF, GI and LT) [10]. Based on these endpoints, long-term memory analysis revealed time effects deviating from random changes in time (white noise) at both polluted and BSM sites. A decrease in the CF and GI with an increasing trend in the LT over time was globally observed, i.e., all sites confounded. However, the decrease in the CF was stronger at the polluted sites and showing more intense amplitude changes (instability). At BSM, the CF tended to increase in contrast to the reference and polluted sites. With respect to GI, the decrease in time was much more severe at the polluted sites and growth instability in (high amplitude changes), while no long-term changes were observed at BSM. The LT tended to increase more steeply in time at the polluted and BSM compared to the reference site. It is possible that decreased metabolism from the elements discussed above could have contributed to the increased LT. However, the increased air survival time occurred at the expense of growth and size/condition (mass/length ratio). Reduced growth and condition of freshwater mussels was found in those caged downstream of a municipal effluent [29]. This was further supported by the fact that mussel recruitment was sparse downstream of the effluent discharge. In another study, shell length of the wild mussel _Elliptio dilatata_ was smaller with increasing tissue concentrations of Cd, Pb and Zn from a river supporting zinc mining activities [30]. The BSM site contained clams that were mostly contaminated by Ce, Co, Ga, La, Hg, Ni, Sm and V. This raises the issue of beluga whales being contaminated by these elements. In beluga tissues collected in the Arctic near Alaska, some elements were present in beluga skin samples [31]. For example, these metals/elements were higher at some sites compared to Cook Inlet site: Ag (6.6-fold), Cd (4.4-fold), V (4.6-fold) and Hg(9.6-fold).