Posidonia is still in decline despite protection

PalmPosidonia is still losing ground, despite growing awareness of the importance of its conservation, private and public actions in its defense, and specific regulations that have been in place for the past seven years. The data confirm that the rate of its destruction has slowed considerably, but, unfortunately, they also show that "we still cannot speak of surface area recovery in absolute terms," laments Núria Marbà, research professor at Imedea (CSIC-UIB) and a specialist in this plant that is essential to the ecosystem.

In any case, "the reality is much better than just a decade ago and it shows that, with the commitment of citizens and institutions, we are still in time to save the most important ecosystem of the Islands," concludes the researcher.

The latest report from the Posidonia Network—which has 26 main stations, plus another seven belonging to the Ibiza GEN-GOB—reveals that the Posidonia conservation index (one of the most relevant indicators) is only moderate or poor in 60%. In the case of Ibiza, 77% are in this situation. "Analyzing these data, it's clear that there's still a lot of work to be done. Despite the improvement compared to a few years ago, Posidonia is still suffering too much damage," explains Margalida Monserrat, the Balearic Sea Report (Marilles) technician.

The two human actions that most harm the Posidonia are anchoring and the discharge of poorly treated or untreated water. According to specialists, "there is a noticeable increase in awareness, especially among the local population, who are very alert when anchoring." "We run awareness campaigns in schools and carry out numerous checks. There are already 19 observers patrolling the coast every day," explains Marcial Bardolet, head of the Posidonia Surveillance Service. This government agency has checked 587,322 anchors since 2020. Of these, 7% have had to be moved to be over the protected plant, according to official figures.

It's not always possible to convince skippers that they're doing something wrong. "We also encounter some large yachts that are repeat offenders. In all these cases, we notify the Environmental Protection Agency (EPA) to file a report. Posidonia is important enough to fine those who don't respect it and who also ignore the warnings," says Bardolet. According to data from the Directorate General for the Natural Environment, between 2020 and 2024, 406 reports were issued against boats for anchoring in Posidonia. Sources from the Directorate General explain that "not all reports result in fines; it's necessary to verify the facts, investigate, and, furthermore, those accused have the right to appeal." "To give you an idea, in 2024, 50 reports were issued, and there are 24 ongoing proceedings and five sanctions. Obviously, the fines could be higher."

Pollença's terrible example

Even though the attitude of sailors has radically changed, boating still generates many problems, and the Port of Pollença is a clear example. The municipality reproduces at sea the lack of control and the vortex of illegalities that have also reigned on rural land for decades. According to a study carried out by the local organization Arrels Marines, there are between 1,600 and 2,300 irregular anchoring structures in the Bay of Pollença. These are the traditional "dead" anchors, some of which are no longer used, but the concrete or iron that was used to build them remains, which represents "a very significant impact." "Everything has a limit, and at the local level, we can analyze human activity in detail. Anchoring must be more and better regulated, because if we look at the mapping (attached image) of the Posidonia, we can see where the stains and the impact occur," explains Gigi Torras, a technician with this organization.

"It's extremely important that public institutions get involved in establishing order, because organizations and citizens can do a lot, but, in the end, if existing regulations aren't enforced, people end up ignoring them, and that has very clear consequences for the seabed," Torras claims.

Even so, navigation isn't the main cause of the Posidonia's woes. "Among other reasons, because behavior improves year after year," recalls Núria Marbà. "The big problem is the quality of the water we discharge into the sea. According to our estimates in the Balearic Sea Report, water quality is worsening, mainly due to the presence of nutrients from poor purification," laments Margalida Monserrat of Marilles.

The population has grown exponentially, as has the arrival of tourists. "The infrastructure is not up to standard, which causes runoff that harms the posidonia. The overlapping of marine outfalls and the degradation of the meadows are easily observed," continues Núria Marbà of Imedea. Furthermore, the scientist highlights the importance of updating wastewater treatment systems, because, "in the case of the Islands, unlike other areas such as the Peninsula, there is little presence of iron. And this element helps a lot to reduce the toxicity generated by organic matter when it degrades in the water. We are obliged to be very careful.

As if that were not enough, in recent years a new enemy has appeared for the lungs of the Balearic Sea: the warming of the water caused by climate change. The higher temperature, which in some cases no longer just rubs, but exceeds 30 degrees, causes thermal stress that seriously affects the plant. According to a study in which Núria Marbà participated, if this trend continues, "by the end of the century we will have lost 90% of the posidonia." "It would be a tragedy and we must all act without thinking that it is an inertia that we cannot change," she assures. For the moment, in the short term, the objective is to not lose a single a palm more than the surface covered by this essential plant.