## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Response Range**} & \multirow{2}{*}{\begin{tabular}{c} **Length** \\ **(mm)** \\ \end{tabular} } & \multirow{2}{*}{**Mass** \\ **(g)** \\ \end{tabular} } & \multirow{2}{*}{**Age**} & \multirow{2}{*}{**CF**} & \multirow{2}{*}{**GI**} & \multirow{2}{*}{\
\begin{tabular}{c} **Air Survival** \\ **Time** \\ **(Days)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Maximal** \\ **Dehydration (\%)** \\ \end{tabular} } \\ \hline Natural & & & & & & **(Air Survival** \\ Mean & 61.7 & 32.6 & 7.2 & 0.52 & 8.5 & 13.2 & 20.7 \\ Percentiles & 25–75 th & 56–66 & 23.1–41 & 6.3–8 & 0.4–0.62 & 8.2–9.5 & 11–14. & 16–24 \\
5–95 th & 42–72 & 19.4–52.1 & 5.8–9 & 0.36–0.73 & 6.8–10.6 & 10–19 & 9.8–34 \\ \hline Impacted & & & & & & \\ (BSC and TAD) & & & & & & \\ Mean & 59.3* & 26.6* & 7.2 & 0.43* & 8.2* & 12* & 24.5* \\ Percentiles & & & & & & \\
25–75 th & 54–63 & 16.1–31.6 & 6.1–8 & 0.3–0.52 & 7.5–9.1 & 10–13.6 & 19–29 \\
5–95 th & 49–78 & 12.3–57.1 & 5.4–10 & 0.26–0.73 & 6.3–9.1 & 7–16 & 11–34 \\ \hline BSM & & & & & & \\ (SLE Beluga area of high residency) & & & & & & \\ Mean & 62.4 & 28* & 7.3 & 0.43* & 8.6 & 13.6 & 29.9* \\ Percentiles & & & & & & \\
25–75 th & 57.4–68.6 & 17.8–36.8 & 6.3–8 & 0.3–0.54 & 7.5–9.3 & 10.9–14 & 24–36 \\
5–95 th & 46–75 & 11.9–47.9 & 5.7–10 & 0.24–0.54 & 6.5–11.8 & 8–21 & 13–48 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Establishment of boundaries for natural variation of morphological changes in clams. percentile approach over in the confidence interval, as it will tend to reduce as replication increases for the latter. All clams' morphological parameters (length, mass, age, CF and GI) and air survival (lethal time and maximal dehydration rate) differed between the polluted sites and the reference sites based on this approach. For example, the GI and air survival time mean values are 8.6 mm/year and 13.2 days, respectively. The natural variation ranges for GI and air-time survival are within 6.8 (5 th percentile) to 10.6 mm/year (95 th percentile) and 10-19 days, respectively, based on percentiles. Thus, responses occurring outside this range are considered atypical for clam populations. For example, the mean GI at polluted sites BSC and TAD is 8.2 with a 5-95 th percentile range 6.3-9.1 showing lower GI responses than the natural range (6.3 to 6.8 mm/year). This suggest that clams from polluted sites display much lower growth rate. It is noteworthy that the mean GI value of the polluted sites were significantly different (\(p<0.05\)) from the reference site but not with the BSM site. The BSM site generally differed from MAB for most parameters, with the exception of length, age, GI and air-time survival. In other words, clams at BSM are similar to the reference site MAB for the above endpoints, while they identical or worse to the polluted sites for mass, CF and maximal dehydration rates. Indeed, clam mass and CF were lower compared to those from the polluted and BSM sites. With respect to the maximal dehydration rate (weight loss during air emersion), clams at the polluted and BSM sites lose more weight (dehydration) than clams from the reference site MAB. Based on multiple regression analysis, age was the only explanatory predictor for dehydration rates (r = 0.22; \(p<0.001\)), suggesting that age contributed modestly to weight loss during air emersion. Increased wet loss and decreased survival time to air emersion is a sign of pollution stress in these clam populations. We examined the yearly changes in CF, GI and air survival time. For CF, the values were closer to the 5 y mean value but a drop in CF in 2018 was observed at all sites (Figure 2). The polluted sites BSC and TAD displayed lower CF most of the times, with the exception of 2017 where no significant changes were obtained between sites. The GI was determined in clams at the reference, polluted and BSM sites for over 5 years (Figure 3). The GI at the polluted site (BSC) was lower than the reference site MAB.