Arthrospira platensis is an edible cyanobacterium with high nutritional value. Even though A. platensis is not a marine species, it can be adapted to higher salinities, a strategy that could allow mass cultivation using brackish or saline water. In this work A. platensis was long-term adapted at different salinities (5–60 g/L NaCl added as natural sea salt) to evaluate the growth and biochemical composition of the biomass produced. Biomass production was enhanced in salinity up to 40 g/L NaCl, while at 60 g/L NaCl biomass production slightly decreased. However, it displayed higher values compared to the conventional Zarrouk growth medium. By increasing the salinity, carbohydrate content increases, while proteins, phycocyanin, carotenoids, and total phenolics decreased. Biomass content in lipids, and chlorophyll along with the antioxidant capacity of extracts, was not significantly affected. A. platensis tended to increase the unsaturated fatty acids, while amino acid composition was not significantly affected by the increased salinity. However, in vitro protein digestibility was negatively affected when salinity was above 20 g/L NaCl. It was macroscopically observed that trichomes were longer at higher salinities, and especially at 40 g/L NaCl. The results suggest that A. platensis when acclimated in long-term can be grown successfully at various salinities.

Over the last years, the cyanobacteria Spirulina platensis (SP) has attracted special attention, as it possesses remarkable antioxidant activity and high amounts of bioactive compounds, such as phycocyanin, carotenoids and phenolics. Since Spirulina platensis biomass shows extremely high moisture content, dehydration is a crucial treatment step, which ensures the prolonged shelf life of the final product. However, drying affects drastically the qualitative characteristics of heat-sensitive foodstuffs with high nutritional value, such as SP. In this study, four different drying techniques, atmospheric drying (AD), freeze drying (FD), vacuum drying (VD) and accelerated solar drying (ASD), were examined and compared considering crucial parameters, i.e., moisture content reduction, change of structure, colour deterioration, pigment content and antioxidant activity. As shown from the obtained results, vacuum drying achieves faster moisture lowering and higher carotenoid content equal to 0.58 + 0.01 mg (g dry solids)⁻¹. On the other hand, atmospheric drying is efficient in preserving phycocyanin since its content was found equal to 9.65 + 0.19%dry weight, but in general cannot be industrially applied due to the long dehydration time. Finally, accelerated solar dried biomass showed the highest antioxidant activity (31.28 ± 0.90% dry weight) mainly due to the degradation products after heating at high temperatures and stress conditions.

Microalgae have gained significant attention as sustainable sources of high value compounds, such as bioactive polysaccharides that are usually rich in sulfated groups and exhibit antioxidant properties. Here, 14 new microalgae strains of the genera Tetraselmis, Dunaliella, and Nannochloropsis, isolated from Greek coastal lagoons were analyzed to quantify and characterize their polysaccharide content. Heterogeneity was observed regarding the content of their total sugars (5.5–40.9 g/100 g dry biomass). The strains with a total sugar content above 20% were analyzed concerning the content of total, α- and β-glucans. Tetraselmis verrucosa f. rubens PLA1-2 and T. suecica T3-1 were rich in β-glucans (11%, and 8.1%, respectively). The polysaccharides of the two Tetraselmis strains were isolated and they were mainly composed of glucose and galactose. The isolated polysaccharides were fractionated using ion-exchange-chromatography. The anionic fraction from T. verrucosa f. rubens PLA1-2 was rich in sulfated polysaccharides, had antioxidant capacity, and exhibited healing properties. The anionic polysaccharides from the two Tetraselmis strains did not negatively influence the viability of human cells, while exhibiting antiviral properties against the replication of Hepatitis C Virus (HCV), with median efficient concentrations (EC50) at a range of 210–258 μg/mL.

A total of 346 live animals of the endangered species fan mussel Pinna nobilis (Linnaeus 1758) were recorded in situ in the shallow water zone (<2m) within two sites of the marine protected area “Natura 2000” of Maliakos Gulf (Central Hellas). Our results showed that the recorded length (from 11.89 to 72.51 cm) of the fan mussels corresponds to ages that cover the majority of the species life time. Population densities were comparable to the higher values recorded previously in the Mediterranean Sea. The spatial distribution of species was clumped. Estimated total mortality was close to estimated natural mortality indicating that fishing activity does not significantly affect the population density and mortality of fan mussel in the study area. Population densities were related to sediment type, the buried length of animals was related to both sediment type and sea grass leaves size.