## 3 Results and Discussion
### Multivariate Analysis Approach
\begin{table}
\begin{tabular}{c c c} \hline  & **Factor 1** & **Factor 2** \\ \hline \%variance & 82.88 & 12.45 \\ \hline Fines & 0.735 & \\ AsW & 0.817 & \\ PbW & & \(-\)0.977 \\ ZnW & & \(-\)0.754 \\ CuS & & \(-\)0.986 \\ FeS & & \(-\)0.713 \\ AsS & 0.904 & \\ PbS & 0.833 & \\ CdS & 0.957 & \\ MnS & 0.807 & \\ ZnS & & \(-\)0.981 \\ CuA & 0.830 & \\ FeA & 0.894 & \\ AsA & 0.956 & \\ PbA & 0.950 & \\ CdA & 0.944 & \\ MnA & & \(-\)0.915 \\ ZnA & 0.869 & \\ F\({}_{\rm v}\)/F\({}_{\rm m}\) & 0.963 & \\ ETR & 0.987 & \\ E\({}_{\rm k}\) & 0.812 & \\ \(\alpha\) & 0.882 & \\ Chl-\(a\) & 0.894 & \\ \hline \end{tabular}
\end{table} 
Table 5: Sorted rotated factor loading (varimax normalised) of 25 variables on the two main factors. For interpretation, the loading cut-off \(<\) 0.7. The PA site, at the northern border, is within the Pan de Azucar National Park. Despite being a protected area, the results showed critical concentrations of Cu, Pb and Zn in sediments (Table 2), which might result from historical mining disposal in Chanaral Bay. The As concentration in sediments was also detected as dangerous in the area. These are responsible for most of the significant stress shown by the macroalgae, and contamination in the water is associated with the low chlorophyll activity of the phytoplankton (Table 3). PB is located in a tourism and fishing area, also influenced by components grouped in Factor 1; i.e., contamination of elements in sediments, such as As and Cu, reflects the specific stress on the physiology of _L. bertoreana_. Finally, PC is close to a factory; this site recorded low concentrations of toxic elements in water and sediments. The superficial phytoplankton biomass measured as extractable chlorophyll-_a_ in the three studied sites showed greater sensitivity to water contamination; thus, the biomass decreased with rising contamination. The PA biomass was significantly lower than PB and PC (Table 3). Although photosynthetic parameters of photoinhibition (F\({}_{\
u}\)/F\({}_{\rm m}\)) of _L. bertoreana_ showed the same pattern in terms of physiological responses, that is, the algae from PA appeared under higher stress than those from PB and PC, the \(\rm{ETR}_{\rm max}\) and the light saturation index were higher in PA and lower in PC. Due to their cell wall, these photosynthetic adaptations (Figure 3) and the high bioaccumulation capacity of these organisms (Table 4) allow them to survive in these conditions of environmental contamination without threshold. The stations serve as a pollution gradient from north to south; the possible pollution source is Chanaral Bay, due to the nature of the elemental contamination. This anthropogenic source was previously reported by [30]; the Cu tailing disposal in Chanaral, with an estimated mining discharge of 550 kg per year, is located at a beach between PA and PB [34]. Other previous studies detected Cu as responsible for chronic and sub-lethal effects and community distribution alterations [35], and different stress responses (antioxidant-induced) and bioaccumulation in molluscs promoted by Cu, As and Zn [36]. The consequences of contamination in marine environments, such as the physiological stress of algae or the distribution of phytoplankton, are just some environmental responses to the presence of harmful materials. Therefore, the need for a marine regulatory framework for coastal sediments in Chile [1] is also highlighted here. Furthermore, considering the different ecosystems in northern and southern Chile, the recommendation of international organizations to develop sediment quality guidelines for different regions is of utmost importance.