Italy Struggles With Algae Overgrowth Caused by Heatwaves

Italy is grappling with an unprecedented proliferation of algae, a direct consequence of record-breaking heatwaves that have dramatically elevated water temperatures. This phenomenon is transforming coastlines, with the usual azure waters frequently replaced by unsightly green, yellow, or brown hues, according to La Repubblica.

In response, numerous municipalities have mobilized specialized intervention teams to tackle the growing problem. The algae pose a dual threat: some species are toxic, causing health issues such as respiratory ailments, fever, nausea, and conjunctivitis, while others disrupt the aquatic ecosystem by reducing vital oxygen levels. A particularly concerning invader is the toxic alga Ostreopsis ovata, which has become widespread in Italy over the past two decades.

The situation has escalated since June, with permitted limits frequently exceeded. This has led authorities to issue warnings and impose temporary swimming bans in affected areas. The impact spans from Puglia in the south, through Lazio, to Tuscany. Notable hotspots include the Molfetta and Giovinazzo areas in Puglia, Santa Marinella near Rome, the vicinity of Palermo, Marina di Pisa, and Genoa.

Beyond the toxic varieties, other algae are causing aesthetic and ecological issues. In Liguria, near the French border, the Pyramimonas genus has turned waters green, while east of Genoa, Alexandrium cf. taylori, a type of single-celled photosynthetic organism, caused a temporary yellowing of the sea. An international study also confirmed the presence of the invasive Australian alga Caulerpa cylindracea in the Gulf of Trieste.

The problem extends inland, affecting major waterways and lakes. The Po River near Turin is experiencing extensive green deposits, and in Padua, intervention units have cleared canals choked with algae. Many Italian lakes are now risky for swimming due to algae overgrowth, with authorities on Lake Iseo removing over 1,000 tons of algae.

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Instead of the usual azure hue of the water, the coast is increasingly appearing green, yellow, or brown.