*Hypersaline Lagoons from Chile, the Southern Edge of the World DOI: http://dx.doi.org/10.5772/intechopen.88438*

*Lagoon Environments around the World - A Scientific Perspective*

sis-repairing mechanisms in *Artemia.*

**4.1 The** *Artemia***-bacteria relationship**

their presence is correlated with *Artemia* blooms.

[6], the species gene pool is distributed over different safety baskets.

(*A. tibetiana*). The situation in Asia seems now to be a bit complex as a mix of sexual and asexual *Artemia* species, including the invasive *Artemia franciscana* coexist as shown with mitochondrial (COI) and nuclear DNA markers (ITS) [51]. The species has also invaded and even displaced local species in Europe [52]. Such evolutionary plasticity depends on the species overall high genetic variability, which is heterogeneously distributed over the populations [49, 53]. As Gajardo and Beardmore put it

With the advent of massive sequencing and transcriptomics, new information has been reported on the genetics of sex differentiation [54–56] and stress or adaptation-related genes [41]. A transcriptomic study in *A. franciscana* identified genes responding to salt stress by experimentally comparing *Artemia* individuals reared under hypersaline and marine conditions [57]. Authors found ~100 genes differentially expressed under hypersaline conditions controlling critical biological functions such as signal transduction, gene regulation, lipid metabolism, transport, and stress response (Heat shock 70 kDa), all contributing to maintaining homeosta-

The brine shrimp *Artemia* and bacteria coexist and interact in hypersaline lagoons, as demonstrated by Quiroz et al. [30]. One evident expression of this interaction is that *Artemia* gets energy grazing on bacteria [58–60], which also provide enzymes to digest the algae and yeasts that are also *Artemia* food items. Additionally, environmental bacteria colonize and establish in the *Artemia* gut conforming the microbiota, which is known to provide multiple functional benefits to the host such as protection against pathogens, energy balance, immunological enhancement, and behavior [61]. Thus, imbalances (i.e., reduced diversity) in the microbiota composition due to environmental or other factors such as pathogens seriously affect the performance of the host in a given environment. The *Artemia*microbiota is an example of facultative symbiosis in which mutual benefits are provided [62]. The most evident benefit for *Artemia* is fitness, which can be constrained or expanded depending on salinity in such a way that under optimum salinity, fitness should be maximized. Therefore, the *Artemia*-gut microbiota interaction influences *Artemia* abundance, which is a good predictor of waterbird presence in hypersaline wetlands. This would explain why not all hypersaline lagoons attract the same amount of waterbirds. The importance of *Artemia* in this regard was experimentally demonstrated [17] with the introduction of *A. sinica* in a Tibetan hypersaline lake where the species did not exist. Such introduction created the conditions to attract waterbirds not previously present in the lake. Another case was the introduction of *A. franciscana* in Godolphin lakes, an artificial hypersaline wetland created to attract flamingos and charadriiform birds in Dubai [63]. The flamingo species *Phoenicopterus roseus* is a regular visitor in that habitat, as well as other bird groups such as sandpipers, plovers, avocets, grebes, ducks, and gulls, and

The study of Quiroz et al. [30] assessed the microbial diversity of natural brines and those present in the gut microbiota of adult individuals collected in the same environment in lagoons of the Atacama Desert, solar saltworks in Central Chile, and Patagonian lagoons. The microbiota of animals collected in natural brines contains a subsample of environmental diversity, and the authors evaluated some reported functions of the bacterial communities of the gut microbiota to test the hypothesis that they should contribute to *Artemia* fitness. For example, the genus *Sphingomonas* (Alphaproteobacteria), found in the gut of wild *Artemia* individuals, contains a species (*S. wittichii*) reported to degrade polycyclic aromatic

**66**

hydrocarbons (PAHs) that are persistent pollutants accumulated in the food chain [64]. The genus *Chromohalobacter* (Gammaproteobacteria), also identified in the gut of wild individuals collected both in northern and southern lagoons, contains the species *C. salexigens* that produce ectoine (or hydroxyectoine), a compound protecting proteins from degradation, and other environmental stressors such as salinity changes, oxidative stress, and high UV radiation [65]. Ectoine and other compatible solutes also act as osmoprotectants facilitating bacteria establishment in the saline environment. The authors were surprised to find psychrophilic bacteria known to produce antifreeze proteins in Céjar (north) and Amarga lagoons (south). Moreover, some bacteria found in the Atacama Desert are phylogenetically closer to some types found in the Antarctic, similarity that tells about convergent environmental conditions or a similar adaptive pattern despite the latitude difference. Such similarity includes the Great Salt Lake in Utah, where bacterial sequences most closely related to genera *Halomonas*, *Psychroflexus*, and *Alkalilimnicola* were found in the water [66].
