*2.3.4 Brazil*

Numerous studies on eutrophication of freshwater ecosystems have been conducted along the Brazilian territory. Prevalence of cyanobacteria under this eutrophic condition has also been reported.

Tundisi [48] reported blooms of the cyanobacteria *Microcystis* spp. and *Anabaena* spp. in the reservoirs of the State of São Paulo, where they are characterized by a severe eutrophication in their waters due to industrial and agricultural wastewater.

Huszar et al. [49] and Dantas et al. [50] also found the dominance of *Microcystis* in highly eutrophic shallow lakes and small reservoirs.

Lake Vaca Brava, in the State of Goiás (Central Western Brazil), is an urban water body that suffers the eutrophication process as a consequence of the human settlement in its neighboring areas [51]. Increased cyanobacterial density accompanies the eutrophication process, where *Planktolyngbya limnetica* (Lemmermann) Komárková-Legnerová and Cronberg 1992 is the dominant species.

Likewise, Chellappa et al. [52] studied the dynamics of phytoplankton in the Armando Ribeiro Gonçalves reservoir, located in the state of Rio Grande do Norte (Northern Brazil), which is used for drinking water supply; this reservoir was classified as eutrophic due to its high nutrient concentrations, and the toxic cyanobacteria dominated the phytoplankton composition, particularly *Planktothrix agardhii* (Gomont) Anagnostidis and Komárek 1988 in drought period and *M. aeruginosa* in rainy season.

Due to inadequate treatment, sewage with high levels of P and N reaches to Pampulha and Ibirité reservoirs in South-Eastern Brazil [53, 54], causing changes in the composition and diversity of the plankton community. *Microcystis* spp. were the main species registered during the blooms in these reservoirs.

Despite resulting in known impacts, such as loss of aquatic biodiversity, the emergence of potentially toxic cyanobacterial blooms, overgrowth of aquatic macrophytes, anoxia and fish mortality, increased eutrophication of Brazilian reservoirs has also, as an additional consequence, the increase of greenhouse gas emission that aggravates the global warming process [55, 56].

#### *2.3.5 Chile*

In this country, it has also been reported that the increase in the concentration of nitrogen and phosphorus leads to an increase in phytoplankton biomass and to the dominance of cyanobacteria [57]. In lakes which have heavy eutrophication process, the dominant cyanobacteria which occur blooms are usually of *Anabaena* spp., *Microcystis* spp., and *Oscillatoria* spp. [58–60], some of them presenting toxic strains [58]. On the other hand, Parra et al. [61] found that green algae (Chlorophyta), particularly Desmidiaceae family members, are the group more sensitive to negative changes in environmental conditions, especially to those associated with pollution and eutrophication.

#### *2.3.6 Argentina*

Quirós [62], analyzing the empirical relationships between nutrient concentrations and biological communities in more than 100 Argentine lakes and reservoirs, found that total phosphorus concentration is the main factor in the control of the phytoplankton biomass. Likewise, he also found that the applied empirical order grouped lakes in two groups which are the lakes located in the lower latitudes which are shallow, warm, and eutrophic where phytoplankton are limited by nitrogen, and the lakes located in higher latitude, temperate-cold, and oligotrophic where phytoplankton are limited by phosphorus [63]. Also, Quirós et al. [64] found that nutrient enrichment of the Pampa's surface water and its multiple negative effects on its lagoons have increased the internal phosphorus load allowing the increase in the frequency of cyanobacterial blooms, especially during relatively dry years.

#### *2.3.7 Uruguay*

The largest reservoirs (Salto Grande, Bonete, Baygorria, and Palmar) have suffered the process of eutrophication, which has led to an intense growth of phytoplankton [65]. De León and Chalar [66], Chalar et al. [67], and Chalar [68, 69] studied the phytoplankton dynamics of the Salto Grande reservoir and recorded the dominance of typical diatoms in eutrophic environments and high densities of cyanobacteria which are predominant with *M. aeruginosa* during algal blooms.

Vidal et al. [70] had detected cyanobacterial blooms, mainly supported by *C. raciborskii* in many eutrophic water bodies of the country, as were the artificial lakes in Canelones, the lake Laguna Blanca in Maldonado, and small dam lakes in Rocha.

**35**

**Figure 1.**

*Eutrophication and Phytoplankton: Some Generalities from Lakes and Reservoirs of the Americas*

RAP-AL [71] also detected that in the eutrophic system of Laguna del Sauce which has a predominance of cyanobacteria throughout the year, there was a marked increase in the frequency and duration of microalgae blooms, particularly of *M. aeruginosa*.

The rapid growth of anthropogenic or human sourced activities has led to the environmental degradation of the Lake Ypacaraí, the most renowned water body in Paraguay [72]. Increasing nutrient concentrations over the last decades have recently resulted in intense cyanobacterial blooms; dominant species in the lake are

González and Quirós [73], when they considered trends in 16 reservoirs that have different trophic status, found both linear relationship, between total phosphorus (TP) and total nitrogen (TN) with the phytoplankton biomass, and empirical relationship, between total phosphorus concentration and the nitrate/ ammonia quotient which determine the dominance of cyanobacteria. According to the authors' empirical ordination, Venezuelan reservoirs were separated in three groups: group 1 includes reservoirs with low TP (<20 μg/L), while groups 2 and 3 include those reservoirs with moderate to high TP concentrations (>20 μg/L) (**Figure 1**). In group 1, green algae (chlorophyta) are dominant. Group 2 is composed by those reservoirs where nitrate is the dominant inorganic nitrogen compound over ammonia (high nitrate/ammonia quotient), with short water residence time, and the dominant phytoplankton taxa are different from cyanobacteria, while

*Relationships between TP and the NO3:NH4 ratio in Venezuelan reservoirs: group 1—TP < 20 μg/L—black circles; group 2—TP > 20 μg/L and non-cyanobacteria dominance—black diamonds; and group 3—TP > 20 μg/L and cyanobacteria dominance—black triangles. The Loma de Níquel reservoir is represented by a white circle, because it represented an intermediate situation between groups. Abbreviation of reservoir names: AFR: Agua Fría, TAG: Taguaza, LAG: Lagartijo, CLA: Clavellinos, TBL: Tierra Blanca, LNI: Loma de Níquel, ECI: El Cigarrón, EPU: El Pueblito, ECU: El Cují, EAN: El Andino, LMA: La Mariposa, LPE: La Pereza, CAM: Camatagua, QSE: Quebrada Seca, PC1: Pao-Cachinche—western wing with uptake point and outlet, and PC2: Pao-Cachinche—eastern wing without outlet, modified from González and Quirós [73].*

*DOI: http://dx.doi.org/10.5772/intechopen.89010*

*C. raciborskii*, *M. aeruginosa*, and *Anabaena* spp.

*2.3.8 Paraguay*

*2.3.9 Venezuela*

RAP-AL [71] also detected that in the eutrophic system of Laguna del Sauce which has a predominance of cyanobacteria throughout the year, there was a marked increase in the frequency and duration of microalgae blooms, particularly of *M. aeruginosa*.

## *2.3.8 Paraguay*

*Microalgae - From Physiology to Application*

Likewise, Chellappa et al. [52] studied the dynamics of phytoplankton in the Armando Ribeiro Gonçalves reservoir, located in the state of Rio Grande do Norte (Northern Brazil), which is used for drinking water supply; this reservoir was classified as eutrophic due to its high nutrient concentrations, and the toxic cyanobacteria dominated the phytoplankton composition, particularly *Planktothrix agardhii* (Gomont) Anagnostidis and Komárek 1988 in drought period and *M. aeruginosa* in rainy season. Due to inadequate treatment, sewage with high levels of P and N reaches to Pampulha and Ibirité reservoirs in South-Eastern Brazil [53, 54], causing changes in the composition and diversity of the plankton community. *Microcystis* spp. were the

Despite resulting in known impacts, such as loss of aquatic biodiversity, the emergence of potentially toxic cyanobacterial blooms, overgrowth of aquatic macrophytes, anoxia and fish mortality, increased eutrophication of Brazilian reservoirs has also, as an additional consequence, the increase of greenhouse gas emission that

In this country, it has also been reported that the increase in the concentration of nitrogen and phosphorus leads to an increase in phytoplankton biomass and to the dominance of cyanobacteria [57]. In lakes which have heavy eutrophication process, the dominant cyanobacteria which occur blooms are usually of *Anabaena* spp., *Microcystis* spp., and *Oscillatoria* spp. [58–60], some of them presenting toxic strains [58]. On the other hand, Parra et al. [61] found that green algae (Chlorophyta), particularly Desmidiaceae family members, are the group more sensitive to negative changes in environmental conditions, especially to those associated with pollution

Quirós [62], analyzing the empirical relationships between nutrient concentrations and biological communities in more than 100 Argentine lakes and reservoirs, found that total phosphorus concentration is the main factor in the control of the phytoplankton biomass. Likewise, he also found that the applied empirical order grouped lakes in two groups which are the lakes located in the lower latitudes which are shallow, warm, and eutrophic where phytoplankton are limited by nitrogen, and the lakes located in higher latitude, temperate-cold, and oligotrophic where phytoplankton are limited by phosphorus [63]. Also, Quirós et al. [64] found that nutrient enrichment of the Pampa's surface water and its multiple negative effects on its lagoons have increased the internal phosphorus load allowing the increase in the frequency of cyanobacterial blooms, especially during relatively

The largest reservoirs (Salto Grande, Bonete, Baygorria, and Palmar) have suffered the process of eutrophication, which has led to an intense growth of phytoplankton [65]. De León and Chalar [66], Chalar et al. [67], and Chalar [68, 69] studied the phytoplankton dynamics of the Salto Grande reservoir and recorded the dominance of typical diatoms in eutrophic environments and high densities of cyanobacteria which are predominant with *M. aeruginosa* during algal blooms. Vidal et al. [70] had detected cyanobacterial blooms, mainly supported by *C. raciborskii* in many eutrophic water bodies of the country, as were the artificial lakes in Canelones, the lake Laguna Blanca in Maldonado, and small dam lakes in Rocha.

main species registered during the blooms in these reservoirs.

aggravates the global warming process [55, 56].

*2.3.5 Chile*

and eutrophication.

*2.3.6 Argentina*

dry years.

*2.3.7 Uruguay*

**34**

The rapid growth of anthropogenic or human sourced activities has led to the environmental degradation of the Lake Ypacaraí, the most renowned water body in Paraguay [72]. Increasing nutrient concentrations over the last decades have recently resulted in intense cyanobacterial blooms; dominant species in the lake are *C. raciborskii*, *M. aeruginosa*, and *Anabaena* spp.
