Water Column and Seabed

*Lagoon Environments Around the World - A Scientific Perspective*

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Federal de São Paulo; 2015

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**Chapter 3**

**Abstract**

ecosystems is highlighted.

**1. Introduction**

Hypersaline Lagoons from Chile,

Hypersaline lagoons distributed in arid and semiarid regions are unique ecosystems with unique value stemming from their extremophile biodiversity, limnological properties and services, like mining and waterbird habitat. They are natural laboratories to understand how life evolved in extreme environments and how simple ecosystems function to provide waterbird habitat, an essential noneconomic service. Policymakers need this knowledge to protect these ecosystems increasingly affected by climatic change and human-driven perturbations. Hypersaline lagoons from contrasting latitudinal conditions in Chile provide a study case to evaluate how such conditions affect their microscopic and macroscopic diversities. Those in the hyperarid Atacama Desert in northern Chile are an integral part of mineral-rich salars, whereas Patagonian lagoons are unique among freshwater lakes of glacier origin. Despite latitudinal differences, prokaryotic diversity tends to be similar in both extremes. However, genetically distant brine shrimp (*Artemia*) species, *A. franciscana* (north) and *A. persimilis* (Patagonia), inhabit them. This crustacean is a keystone taxon in the food web, and its abundance indicates ecosystem quality and attracts waterbirds. This chapter stresses the need to systematically monitoring *Artemia* abundance and all factors affecting its fitness (gut microbiota, parasites, environmental conditions). Finally, the need to conserve these unique and extreme

**Keywords:** hypersaline ecosystems, extremophile biodiversity, waterbird habitat,

Hypersaline lakes or brines (over 40 g/L) [1] are unique ecosystems with unique extremophile biodiversity and scientific value, which also have economic, esthetic, cultural, and recreational value [2, 3]. They represent a significant volume (~45%) of inland waters [4] and hence are essential components of the biosphere, mostly located in arid and semiarid regions around the world where high evaporation rates exceed rainfall. However, they also occur in unusually cold places such as Tibet in China and Patagonia in southern Chile and Argentina [5, 6]. Due to their wide ecological diversity related to their coastal (thalassohaline) or inland origin (athalassohaline) [7, 8], altitude, salinity, and island-like distribution, these lagoons display unique extreme biodiversity and limnological features. Besides, hypersaline lagoons are also affected by the combined effect of multiple stressors such as UV exposure, temperature, pH, low nutrient, and oxygen availability [8], which means these lagoons are polyextremophile environments. As a consequence, the microscopic and

natural laboratories, Atacama Desert, Patagonia, Chile

the Southern Edge of the World

*Gonzalo Gajardo and Stella Redón*
