Heat wave devastates Po Delta lagoon, killing mussels and clams

Water temperatures in the Po Delta lagoon reached 32 °C, creating severe low‑oxygen conditions and massive algal blooms. The extreme heat caused a dramatic die‑off of mussels and clams, with the Sacca di Goro area in Ferrara losing up to 90‑100 % of its clam production and the lagoon of Scardovari near Rovigo reporting a sudden loss of around 1,000 quintals of mussels.

Aquaculture operators cite the combined effects of rising water temperature, reduced oxygen, uncontrolled macro‑algae growth and the legacy of the invasive blue crab, whose barriers limit water exchange and worsen heat buildup. Coldiretti fisheries in Veneto warn that the lagoon’s poor circulation and sedimentation exacerbate the problem, calling for revitalisation measures to rescue mollusc cultivation. Direct economic damage to the sector is estimated at 70‑100 % of output in the most affected zones, contributing to the broader €200 million annual climate‑related losses reported for Italian professional fishing.

The crisis highlights the fragility of Italy’s mollusc‑farming districts and the increasing frequency of extreme marine heat events linked to climate change.