**2. Hypersaline lagoons from Chile: natural heritage at the southern edge of the world**

Chile is a sort of biogeographical island at the southern edge of the world, isolated by the hyperarid Atacama Desert on the north, the Antarctic ice on the south, the Andes Mountains on the east, and the Pacific Ocean on the west. This long and narrow land (**Figure 1**) exhibits a wide latitudinal (18°–56°S latitude, excluding the Antarctic) and altitudinal range, from sea level to the high Andes. Natural hypersaline lagoons or brines exist at both latitudinal and climatological extremes. The Atacama Desert (17°–27°S latitude) is the driest, oldest, and most extreme world environment [20, 21], wellknown as a terrestrial Mars analog, as already mentioned, with microbial life similar to what could be expected to exist in the red planet [21, 22]. This desert contains numerous inland athalassohaline lagoons (**Figure 1A** and **B**), i.e., with salt proportions different from seawater [7, 8], which are an integral part of different evaporitic basins, salars, or salt crusts, located at different altitudes, just to name a few: Salar de Llamará (21°18′S, 69°37′W) at 850 m; Salar de Atacama (23°30′S, 68°15′W) over 2300 m, the largest in the Altiplano-Puna region of the Central Andes (~3000 km2 ); Salar de Huasco (20°18′S, 68°50′W), a protected National Park and Ramsar site at 4000 m; and Salar de Surire (18°48′S, 69°04′W) at 4245 m. Only Andean countries like Perú, Bolivia, Argentina, and Chile share the geomorphological, climatic and hydrological conditions that originated these salars and hypersaline lagoons [7, 20–23].

The Chilean Patagonia belongs to the administrative region of Magallanes and Chilean Antarctica. This steppe-like landscape with cold, semi-humid climate and very windy condition are characteristic of this region where few lagoons exist. Although some are close to the coast such as Laguna Cisnes (**Figure 1D**), it is difficult to classify it as thalassohaline (marine origin) [8] due to mineral runoff from agriculture and other sources.

#### **Figure 1.**

*Hypersaline lagoons from contrasting latitudinal environments in Chile, the southern edge of the world. Atacama Desert: (A) Piedra and Céjar lagoons. (B) Los Flamencos National Reserve, from north to south: Chaxa lagoon (0.37 km2 ), Canal Burro Muerto (0.1 km2 ), Barros Negros lagoon (1.03 km2 ), and Puilar (0.84 km<sup>2</sup> ). Patagonia: (C) Amarga and (D) Cisnes lagoons.*

**61**

nitrate (0.66 ± 0.14 mg L<sup>−</sup><sup>1</sup>

*Hypersaline Lagoons from Chile, the Southern Edge of the World*

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>

*Cisnes (left) and Amarga lagoons in the Chilean Patagonia, the former was declared a national monument to protect waterbird diversity. Both are unique hypersaline ecosystems in an area where freshwater lakes of glacier origin abound. Bacterial diversity and the brine shrimp Artemia persimilis coexist, a subsample of wild* 

), and chlorophyll-a (44.25 ± 2.52 μg L<sup>−</sup><sup>1</sup>

Hypersaline lagoons contain the three domains of life, Archaea, Bacteria, and Eukarya [29], and this section provides a glimpse to the prokaryotic and eukaryotic diversity of lagoons located at the latitudinal extremes already described. As a representative eukaryotic, the brine shrimp *Artemia* is the obvious choice taking into account its key role in the food web of hypersaline lagoons [17] and because it is a model extremophile for studies of evolution and adaptation [10, 6]. Some adaptations explain *Artemia* abundance and the ability of females to perceive forthcoming

*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].

**3. Microscopic and macroscopic biodiversity**

),

). The microalga

*DOI: http://dx.doi.org/10.5772/intechopen.88438*

*bacteria diversity represented in the Artemia-gut microbiota.*

**Figure 2.**
