With the demand for bioproducts that can provide benefits for biotechnology sectors like pharmaceuticals, nutraceuticals, and cosmeceuticals, the exploration of microalgal products has turned toward extremophiles. This chapter is intended to provide an insight to most important molecules from halotolerant species, the cyanobacteria Phormidium versicolor NCC-466 and Dunaliella sp. CTM20028 isolated from Sfax Solar Saltern (Sfax) and Chott El-Djerid (Tozeur), Tunisia. These microalgae have been cultured in standard medium with a salinity of 80 PSU. The in vitro antioxidant activities demonstrated that extremolyte from Dunaliella and Phormidium as, phycocaynin, lipids, and polyphenol compound presents an important antioxidant potential.
Part of the book: Antioxidants
The saltern of Sfax is a thalasso haline paralic ecosystem were the salinity ranged from 45 to 450 PSU. The microalgae distribution of saltern showed a spatial ecological succession. The specific richness of microalgae decreased with the salinity, accounting 37, 17 and 5 species at three level of salinity from 40 to 80, 80 to 200 and 200 to 450 PSU, respectively. To better understand the behavior of the hyper-halo tolerant microalgae, three autotrophic species Halamphora sp. SB1 MK575516 (Diatom), Phormidium versicolor NCC-466 (Cyanophyceae) and Dunaliella salina (Chlorophyceae) were isolated from each level of salinity and they are grown in batch in artificial seawater at laboratory scale. Growth and metabolites synthesized by these microalgae were assessed. Salinity reacts on the physiology of these three species which possess mechanisms of resistance to more or less effective stresses and generally by the synthesis of different biomolecules such as pigments, sugars, proteins and fatty acids.
Part of the book: Progress in Microalgae Research
The Gulf of Gabès, located in southern Tunisia, is a distinct and ecologically significant area in the Mediterranean Sea. Unfortunately, this dynamic marine ecosystem is experiencing cultural eutrophication, a process where water enrichment with nutrients like phosphorus and nitrogen salts leads to excessive algae growth, disrupting the ecological equilibrium and degrading water quality. In the Gulf of Gabès, key sources of nutrient pollution include industrial discharges, urbanization and agriculture. Eutrophication’s effects here include harmful algal blooms, oxygen depletion, and declining water quality, upsetting the marine ecosystem’s balance and impacting both fish and aquatic life. Nutrient enrichment interacts with trace metal pollution, overfishing and climate change. Future research must acknowledge and consider the complex interactions among these variables. Efforts in the Gulf of Gabès to address eutrophication involve tighter industrial regulations, enhanced agriculture and improved wastewater management, all crucial for preserving the marine environment’s integrity and ensuring sustainability for the future.
Part of the book: Marine Ecosystems
Studying zooplankton variability in coastal lagoons is crucial for environmental monitoring and preserving marine biodiversity. These organisms are highly valued as bio-indicators and helpful in identifying environmental phenomena such as eutrophication and assessing water quality. We studied the distribution of zooplankton in relation to environmental factors, phytoplankton, and ciliates in the coastal waters of the El Bibane lagoon during the summer of 2009 and 2010. Zooplankton assemblages were dominated by copepods, which represented 73–89% and 95–98% of total zooplankton abundance in summer 2009 and summer 2010, respectively. A total of 11 (summer 2009) and 21 (summer 2010) copepod species were identified in all stations, with an overwhelming abundance of Oithona nana in the summer of 2009 and Oithona similis in the summer of 2010. The prevalence of the two Oithona species is attributed to their adaptive strategies, which enables them to withstand environmental disturbances. Other zooplankton developed in association with an important proliferation of Cladoceran and Fish larvae, contributing 51% and 37% of total other zooplankton abundances in summer 2009 and summer 2010, respectively. The abundance of copepods or other zooplankton showed no significant correlation with phytoplankton and ciliates for both periods, suggesting an omnivorous/detritivorous diet hypothesis in El Bibane lagoon.
Part of the book: The Role of Plankton in Freshwater and Marine Ecology [Working title]