Economic losses related to the reduction of Posidonia ecosystem services in the Gulf of Gabes (Southern Mediterranean Sea)

In the early XXth century, the Gulf of Gabes in SE Tunisia used to host the most extended Posidonia oceanica seagrass beds in the Mediterranean basin and was a highly productive hotspot of benthic species. Since the 70's, >500 million t of wet toxic phosphogypsum discharges from a fertilizer industrial complex have led to the gradual loss of -90 % of its initial surface. This drastic shrinkage is accompanied by significant value losses originated from the direct and indirect-use services of which the most important ones are small scale fisheries and carbon storage function. Using market valuations of a number of services we estimate economic losses at 105 million euro in 2014 (-915euro/ha), i.e., around 115 % of the added value of the gabesian fertilizer factories for the same year. Value losses should increase in the near future in relation with the COP26 agreements which boosted the open carbon credit market. Without actions to reduce negative production externalities caused by the fertilizer industry in the Gulf of Gabes it would not be possible to recover Posidonia ecosystems in this region leading to further economic, ecologic, and cultural losses.

Automated summary

In the early XXth century, the Gulf of Gabes in SE Tunisia had extensive seagrass beds, but due to toxic phosphogypsum discharges from a fertilizer industrial complex, it has lost 90% of its surface area. This has led to significant economic losses, estimated at 105 million euros in 2014, affecting small scale fisheries and carbon storage function. Without actions to reduce negative production externalities, recovery of Posidonia ecosystems in the region is unlikely, resulting in further economic, ecologic, and cultural losses.