Coexistence between nautical recreation and marine ecosystems: a seasonal urgency. By Maribel Cerezo Sánchez (VIU)

By Dr. Maribel Cerezo Sánchez

Many people look forward to the arrival of summer to enjoy the sea: sailing, anchoring in crystal-clear waters, or simply letting the sea breeze carry them away are synonymous with the perfect vacation. But what seems idyllic from the surface hides a reality beneath the water that we often prefer not to see. Every misplaced anchor, every spill or waste, every excessive noise leaves a mark on the seabed.

In recent decades, nautical tourism has grown rapidly, resulting in an increasing presence of recreational vessels in the Mediterranean Sea during the summer season. While this benefits the local economy, it also impacts marine species and vulnerable habitats such as Posidonia oceanica meadows.

Posidonia, a silent ally

Posidonia remains largely unknown to many. It's often mistaken for just another seaweed: that thing that floats near the shore or gets tangled up in our feet when we go into the water. It even bothers us to see it piled up on the sand, unaware that it's doing its job: protecting our beaches from erosion. But Posidonia oceanica isn't seaweed. It's a marine plant with roots, stems, leaves, flowers, and fruits. It's also a species endemic to the Mediterranean Sea and one of the most important for maintaining the balance of the marine ecosystem.

Its meadows oxygenate the water, stabilize the seabed, prevent coastal erosion, and serve as a refuge and breeding ground for dozens of marine species. However, this largely unknown species is disappearing at an alarming rate due to improper anchoring. Each improperly anchored anchor tears away fragments of the meadow, creating scars that take decades to recover, as Posidonia grows very slowly.

Recreational trafficking and lack of awareness

In areas such as the Balearic Islands and the Valencian coast, more than 70% of maritime traffic in summer comes from recreational vessels, many of which are rented without a license. This exacerbates the situation, as those operating them lack adequate training and are unaware of the damage they can cause. This worsens the conservation status of seagrass meadows, while the behavior of marine mammal species is altered by the noise of their engines.

At the same time, pollution from hydrocarbons, detergents, and organic matter deteriorates water quality and affects organisms that need a clean environment to live. As if that weren't enough, many vessels from other seas or oceans unknowingly carry invasive species attached to their hulls or in their ballast water.

What can we do as sea users?

These invasive species can displace native species and disrupt the ecosystem's balance. And although it often goes unnoticed, recreational fishing also poses a problem: in some areas, it accounts for up to half of catches, adding further pressure to already declining populations.

The good news is that solutions exist, and they're not incompatible with enjoying the sea. The first step is to understand the marine environment where we're going to spend our vacation. We can only care for what we understand and value. Today, with artificial intelligence, learning about marine ecosystems is easier than ever.

Regulated funding and sustainable alternatives

Furthermore, we need more regulated anchorage areas, greater surveillance of rental boats, effective environmental education—for both beach users and boaters—and the promotion of sustainable alternatives such as sailboats, kayaks, and marine ecotourism. These options allow us to enjoy the sea without leaving scars.

Some marine protected areas are already demonstrating that balanced management is possible. But the challenge is significant, especially in summer, when pressure on the coastline soars. This is where collective responsibility comes into play: understanding that every small step counts. Every anchor placed correctly, every piece of waste that doesn't reach the sea, every conscious decision counts.

A shared legacy that we must protect

The Mediterranean is not just a place for summer vacations. It's a shared natural heritage, teeming with life, that deserves to be respected and protected. Doing so doesn't mean giving up enjoying it, but rather learning to do so better, with greater respect and awareness.

Because in the end, if we take care of the sea, the sea will continue to take care of us.

Maribel Cerezo Sánchez

PhD in Science and Technology. She directs the Master's Degree in Environmental Engineering and Management at the International University of Valencia. She combines her teaching with research in environmental management and sustainability, actively participating in the GREENIUS research group. Committed to engaging and rigorous teaching, she combines academic activity with marine environmental outreach and institutional collaboration.

Main photo: File image of an anchor pulling up a posidonia plant in Cala Figuera (Mallorca) provided by @Fundación Marilles

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