Scientists at the Marine Forum warn of record levels of microplastics in Ibiza and Formentera

The sea around Ibiza and Formentera, the source of almost all their wealth, is showing alarming signs of degradation.

What is visible to the human eye, plastics on beaches, murkier waters, and fewer fish, takes on a new dimension when considering the work of three prominent scientists: environmentalist Carme Alomar, marine criminologist Esteban Morelle-Hungría, and ecologist César Bordehore, who participated in a roundtable on Wednesday, October 15, as part of the Ibiza and Formentera Marine Forum. They presented previously unpublished data on plastic pollution, brine discharges from Ibiza’s desalination plants, and the collapse of fish stocks.

"Southern Ibiza and Formentera are hotspots for plastics and microplastics," commented Carme Alomar.

Dr. Alomar, representing the Official College of Environmental Scientists of the Balearic Islands, warned that the Balearic Sea suffers from classical pollutants such as pesticides, nutrients, and hydrocarbons, but also from antibiotics, pharmaceuticals, and especially nanoplastics and microplastics.

The Balearic Islands have been a pioneer in marine litter monitoring since 2005. “In 25,000 samples collected over eleven years, 347 tons of waste were recovered, with an average density of 116 kg of debris per square kilometer, over 50% of which is plastic,” explained the expert.

"Southern Ibiza and Formentera present the highest microplastic levels in the archipelago," Alomar added. “In some areas, we detected more than six items per cubic meter of water, up to ten times higher than in marine protected areas.”

The scientist explained that 80% of this plastic pollution comes from land-based sources, such as urban runoff and river discharges, especially from the floods caused by storms Dana Alice and Ex Gabrielle, which carried tons of waste into the sea, while the remaining 20% originates from maritime activities.

Recreational and commercial boating, particularly intense in the Pitiusan Islands, increases the presence of rubber residues and synthetic fibers linked to vessel use.

The data are so serious that, according to the European Marine Strategy Directive, 98% of Spanish Mediterranean waters do not meet the “good environmental status” standard. In the Balearics, more than 50% of waters are in poor or bad condition, and in the Pitiuses there is not a single location with “very good” quality, Alomar warned.

"Ibiza and Formentera have become marine pollution hotspots," she said. “We need permanent monitoring coordinated between science, administration, and private industry to reverse this situation before it becomes irreversible.”

"The brine from desalination plants is legally allowed but ecologically illegitimate," added Esteban Morelle-Hungría.

Dr. Morelle-Hungría, a “green criminologist” and professor at Universitat Jaume I, presented an unusual perspective: blue criminology, which studies environmental damage not as accidents but as forms of ecological injustice.

His research in Talamanca Bay (Ibiza), part of the MarPitius25 project coordinated with IbizaPreservation, analyzes the effects of brine discharges from the Ibiza desalination plant, managed by Abaqua, the Balearic Water Agency.

The results are worrying:

• Increased salinity by over 2 grams per kilogram of water
• Temperature rise of 0.6°C
• Reduction in dissolved oxygen
• Accumulation of chemical additives in sediments
• Severe damage to Posidonia oceanica, a protected species essential for coastal protection and oxygenation

"These discharges are legally authorized but ecologically illegitimate," denounced Morelle.

The researcher suggested applying principles of restorative ecological justice, which go beyond financial penalties and require the restoration of environmental damage, especially since public administration is often the responsible party.

"Complying with the law is not enough: you have to repair," he stressed.

"Ibiza sells its landscape, but its sea is almost empty," said César Bordehore.

Dr. Bordehore, associate professor of Marine Ecology at the University of Alicante and coordinator with Morelle-Hungría of the MarPitius25 project, highlighted the alarming state of fish populations. Initial surveys on Ibiza’s east coast show biomass and fish numbers far below those of similar areas on the Spanish mainland.

"The island boasts Posidonia and crystal-clear waters, but underwater, when compared with mainland marine reserves, Ibiza starts from a very degraded point," Bordehore explained.

He recalled that fish catches in parts of the Mediterranean, such as Dénia, have dropped 40% for shrimp and 80% for octopus in recent decades, and only the creation of fully protected marine reserves can reverse this trend.

"If we protect 30% of the sea, we can fish more in the remaining 70%," he said. “It’s an investment with both ecological and economic returns: increasing fishing, dive tourism, and ecosystem health.”

Bordehore emphasized that the main obstacle is not economic but cultural and political: a lack of understanding of how the sea works, starting with both professional and recreational fishers, who often oppose stricter measures.

"Ignorance breeds resistance. But the sea can recover if we let it rest."

The three experts agreed on a clear diagnosis: the Pitiusan Sea is sick, pressured by plastics, discharges, and overfishing. However, they also agreed that there is still time to reverse the trend if science-based policies and cooperation between institutions, businesses, and citizens are implemented.