These are (1) Laguna Amarga (Bitter lagoon, 50°29′S, 73°45′W)

(**Figures 1C** and **2**), located in the province of Última Esperanza at 80 m above sea level, close to the eastern border of the Torres del Paine National Park; (2) Cisnes lagoon (53°15′S, 70°22′W) (**Figures 1D** and **2**), close to the city of Porvenir in the northeast of Tierra del Fuego (fireland) and the Magellan Strait; and (3) Laguna de la Sal (salt lagoon, 53°17′S, 70°23′W), a small and shallow lagoon located southern to Los Cisnes lagoon. The lagoon's salinity varies highly year-round and so its biological composition. Minor quantities of salt are extracted during the dry season (December) time at which salinity peaks to the maximum. At that time, the population of the most conspicuous planktonic inhabitant disappears (the brine shrimp *Artemia persimilis* in Patagonia). However, *Artemia* cysts abound, the mechanism that permits population continuity once suitable conditions recover [6, 24]. Although no systematic and long-term studies exist on these subantarctic lagoons, some literature allows getting a glimpse to their basic characteristics. Amarga lagoon is mesohaline [25], shallow (maximum depth: 4.1 m), and alkaline (pH 9.1), whereas the average annual temperature was 11.7°C when authors sampled the lagoon. About the same period, Saijo et al. [26] confirmed that water was strongly alkaline (pH 9.4), salinity was 77 g/L, and the significant ions were sodium and sulfate. Fuentes-González and Gajardo [27] sampled Cisnes lagoon in December, the dry period, when the UV index is the highest (6.84 ± 0.63) and temperatures range from 15.18 ± 1.31 to 6.25 ± 0.85°C according to the 14-year search they report. The salinity was 51 g/L, the water cold (9°C), and the lagoon was considered eutrophic, according to the high concentrations of phosphorous (0.30 ± 0.73 mg L<sup>−</sup><sup>1</sup> ), nitrate (0.66 ± 0.14 mg L<sup>−</sup><sup>1</sup> ), and chlorophyll-a (44.25 ± 2.52 μg L<sup>−</sup><sup>1</sup> ). The microalga *Spirogyra* sp. and the crustacean *Artemia* were the predominating plankton. The salinity of both lagoons was recently reported in 2 consecutive years with values of 55 and 51 g/L in Cisnes lagoon and 86 and 81 g/L in Amarga lagoon, for spring 2017 (November) and autumn 2018 (April), respectively [28].
