The industrial park of Quintero Bay (QB) in the central coast of Chile was established in the 1960s, presents high levels of pollution due to the industrial activity, and it is known as one of the five Chilean "sacrifice zones". Lessonia spicata is the most important habitat-forming kelp species in the intertidal along the central and south shores of Chile, and currently there are no morphometric and population studies of L. spicata (or other seaweed species) nor studies about the effects of pollution on its development in QB and neighbouring sites. In this context, the aims of this study were (i) to register the abundance and morphological features of L. spicata populations from Ventanas, Horcó n and Cachagua (sites with different pollution histories and located only up to 40 km from the QB); ii) to determine the heavy metals (HMs) concentration in seawater and marine sediments; and (iii) to evaluate in vitro the effects of exposure to seawater from the three sampling sites on spore release and early developmental stages, up to the juvenile sporophyte. Results showed that the chronically exposed Ventanas kelp population had the smallest adult individuals in comparison with the other sites. Ventanas and Horcó n registered high HMs concentration in the seawater and marine sediments exceeding the international permissible limits (e.g in seawater Cu 20-859 μg L-1 ; sediments Cu > 50,000 μg kg-1). Unexpectedly in Cachagua, a site often considered unpolluted, high concentrations of Cu and As were also registered in the seawater (859 and 1,484 μg L-1 , respectively) and of As in marine sediments (20,895 μg kg-1). Exposure of gametophytes to the seawater from Ventanas resulted in a developmental delay compared to the other treatments; however, low sporophyte production was determined in all treatments. Our results indicate that QB, more notably Ventanas, induce highly negative effects on individual development, and consequently on seaweed populations, which suggest a long-term negative impact on the community structure of these marine zones. Furthermore, the high concentrations of HMs reported here at Cachagua suggest a recent expansion of

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The red seaweed Pyropia orbicularis is an economic important species that occurs predominantly in the high intertidal zone along the chilean coast where it experiences extreme conditions under daily turning tides. Its gametophytic phase has been demonstrated to have a high desiccation tolerance, both at the genomic and proteomic levels, but studies at the metabolomic level are still lacking. This research aimed at characterizing compounds related to desiccation stress tolerance by performing several phase solid extractions with different solvents. Bioactivity-guided fractionation (antioxidant and antibacterial activities) was made for a more specific characterization. Compounds identification was done using LC-MS/MS. Results showed that P. orbicularis produces different compounds depending on the state of hydration during the tidal cycle. For example, minoxidil was only found under hydration, while vincamine only during desiccation. It was also found that the main antioxidant activity was most likely due to lutein and the antibacterial activity could be mainly attributed to compounds of lipid nature such as phosphatidylethanolamine (PE), phosphatidylserine (PS) and monogalactosyldiacylglycerol (MGDG). These results help to get a better understanding of the stress tolerance mechanisms in P. orbicularis and place it like a potential source of bioactive compounds.

Abstract.-In primary producers, diverse stressors cause an over-production of methylglyoxal (MG), which is principally detoxified by glyoxalase I (GLO1) activity. A recent proteomic study found that GLO1 was up-regulated during natural desiccation in the red seaweed Pyropia orbicularis, which inhabits the upper intertidal rocky zone and compared to other species, is highly tolerant to air exposure. To better understand and determine differential responses to desiccation stress, this study evaluated MG concentration and GLO1 activity in two species with contrasted vertical distribution, P. orbicularis and Lessonia spicata (lower distribution). Results showed that P. orbicularis successfully scavenges MG via increased GLO1 activity during desiccation. In contrast, GLO1 activity in L. spicata did not increase during desiccation, resulting in MG overproduction. This study is the first to quantify MG and GLO1 levels in seaweeds during natural stress, and partly explain the mechanisms by which P. orbicularis is dominant in the upper rocky intertidal zone.