In early December, researchers from Barcelona’s Grup de Recerca en Radioactivitat Ambiental (GRAB) visited  Kotor Bay, Montenegro. For five days, they worked together with the Institute of Marine Biology in Kotor.

The team’s work was part of a UNESCO project aiming at understanding Submarine Groundwater Discharge (SGD) in beneficiary countries around the Mediterranean Sea. SGD is a process where groundwater flows from land to the sea, either as diffuse seepage or as point discharge from submarine springs. This phenomenon occurs below the surface of the ocean and because of that it has long gone unnoticed. With this study, the group aims to answer where, how, and why water seeps into the Mediterranean from underground.

GRAB researchers specialize in environmental radioactivity and use radium isotopes, naturally occurring in the environment, to trace SGD. With these tools, they can estimate how much groundwater flows into the bay and identify the nutrients and contaminants it carries. This is crucial to understand its role in delivering life-sustaining nutrients—or, at times, harmful contaminants—into the ocean.

One particular phenomenon that struck the researchers was the presence of springs bubbling into the bay that could be seen with the naked eye. Local experts noted that these springs are often accompanied by populations of Savalia savaglia, or gold coral—a vulnerable species. This shows us once more how SGD shapes the ecosystem by creating unique habitats.

Kotor Bay is only the first chapter in a larger quest to chart SGD in the Mediterranean Sea. We hope to come back with more discoveries along the Mediterranean.