The first tests carried out revealed that the phenomenon observed this year in the Gulf of Monastir, marked by a proliferation of microscopic algae (Bloom) and the death of certain marine organizations, differs from previous environmental episodes.
Unlike previous cases, often due to the multiplication of sulfato-reductive bacteria, this phenomenon is mainly attributed to the excessive growth of microalgae, favored by several environmental factors.
In a press release published on Sunday, the authorities said that among the identified causes are the abundance of nutrients in water, a consequence of heavy spring rains and urban discharges. To this is added a massive proliferation followed by a significant decomposition of green algae, the rise in temperatures, the low circulation of the water masses as well as the absence of winds.
These conditions led to a marked fall of the dissolved oxygen in water, accompanied at times with a total absence of oxygen, thus causing the death of many marine species present in the area.
The phenomenon of algae bloom and marine mortality was observed in the Gulf of Monastir from June 18 to 21, 2025, mainly affecting the south-eastern coasts of the Gulf, from Ksibet El Médiouni to Lamta and Sayada.
In order to identify the precise causes of this episode, a joint committee was dispatched to the site from June 18, 2025. It brings together experts from the Ministry of Agriculture through the General Directorate of Fisheries and Aquaculture, as well as the National Institute of Science and Technology of the Sea.
