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An evaluation of the algal flora of the Salinas de Huacho on the coast of Peru between 1984 and 1990 was carried out by collection of algal mats and natural waters from a variety of habitats and by microscopic examination. D. salina occurred in lagoons and pools with a salinity range of 165x, to 350x, and formed planktonic and benthic communities. The benthic palmelloid stage of D. salina was found at higher salinities. Aplanospore formation was also observed. Associated halophilic species included D. viridis, Oscillatoria tenuis and Pleurocapsa entophysaloides. D. salina was also found at two other salinas on the central Peruvian coast (Chilca and Otuma).

Cyanobacterial blooms are commonly associated with high concentrations of nutrients in waters. An exception among the species forming heavy water blooms is Limnoraphis robusta Komárek et al. (Fottea 13:39-52, 2013). Until now, heavy water blooms of this species were found only in tropical, rather oligotrophic waters. Filaments of L. robusta contain diazocytes and thus are able to fix molecular nitrogen during night. This ability gives L. robusta an advantage over other phytoplankters to explore nitrogen-poor habitats. In 2014, filaments of this cyanobacterium appeared also in plankton and periphyton in the Bay of Puno, Lake Titicaca, Peru. Accessible data on water chemistry, chlorophyll a concentration, and phytoplankton composition were compared with those from Lake Atitlán, Guatemala, where this cyanobacterium formed a thick brownish layer on the water surface in 2008, 2009 and 2011. Except for shallow bays, both lakes (Atitlán and Lago Mayor of Titicaca) are still oligotrophic in some periods, and phytoplankton growth is limited by lack of nitrogen. In this paper, we are discussing factors which might allow development of heavy bloom of this cyanobacterium in the Lago Mayor and other clear parts of the Lake Titicaca.

In recent years, biodiesel production has attracted worldwide attention due to the awareness of fossil fuel depletion, and microalgae biomass is considered a promising raw material for its formulation. The present study evaluated the effects of different levels of nitrogen limitation (37.5, 18.75, 9.375 mg L -1 NaNO 3 ) on the growth, cell ultrastructure and biochemical composition of Picocystis salinarum as a potential raw material source for biodiesel. During a culture period of 20 days, the growth measurements were estimated, and cell density, dry weight and chlorophylls a, b content decreased with time as nitrogen limitation increase, however, carotenoids content increased. The high N limitation (9.375 mg L -1 ) had a highly signi cant effect on the accumulation of total lipid content (33.87% dry weight), carbohydrate content increase (30.98% dry weight), but protein content decrease (1.89% dry weight). The lipid content showed a differential FAME pro le with high saturated fatty acid values (996.08 µg g -1 dry weight) mainly C16:0, compare with the unsaturated ones that showed low values under high N limitation. The gradual increase of lipid content was also corroborated by transmission electron microscopy images with lipid droplet cell formation. Therefore, evaluation of the algal culture conditions such as N limitation, as a strategy to maximize lipid content and improve the fatty acid pro le in unexplored halophilic P. salinarum showed a potential biomass yield as a suitable candidate for biodiesel production.