What Are Seagrasses?

Seagrasses are flowering underwater plants, often referred to as “sea grass.” Their structure includes roots, rhizomes, leaves, and flowers.
Posidonia oceanica is the key species in the Mediterranean and is endemic to the region.
It grows on clean sandy or rocky seabeds up to 40–50 meters deep, where sunlight can reach.
Leaves can reach one meter in length, and the species survives in water temperatures between 10 °C and 29 °C.

Ecological Value and Services

• Oxygen source and water quality: Through photosynthesis, seagrasses release net oxygen into the seawater and atmosphere. They also trap suspended particles, clarifying the water and reducing pathogens.
• Biodiversity and habitat: These meadows provide shelter and breeding grounds for hundreds of species like starfish, shrimp, crabs, sponges, and cuttlefish. Many commercial fish species spend their juvenile phases here.
• Blue carbon storage and climate balance: Among all plant habitats, seagrass ecosystems store the most carbon (~2000 tons/ha), making them long-term carbon sinks and key blue carbon sources.
• Coastal protection and sediment stabilisation: They absorb wave energy, reduce coastal erosion, trap sediments, and protect shorelines during storms. Leaves and rhizomes stabilise the seabed and buffer against shoreline interventions.
• Socio-economic benefits: By supporting fish stocks, they contribute to fisheries; cleaner waters also boost coastal tourism and stimulate local economies.

Threats They Face

• Anchoring by boats and unstable mooring practices
• Invasive underwater plants (e.g., Caulerpa taxifolia)
• Excess feed waste from fish farms
• Coastal degradation
• Coastal development: marinas, roads, and piers
• Tourism pressure (artificial beaches, dredging, marina/harbour construction, etc.)
• Bottom trawling
• Increased salinity (from water treatment plants)
• Invasive algae and herbivorous species
• Climate change (sea temperature rise)
• Marine pollution (plastic, ballast water, urban runoff, etc.)
• Ghost nets and marine debris blocking light from reaching the meadows

Conservation and Management Practices

Kaş-Kekova Marine Protected Area Zoning Map

Sustainability and awareness: Organisations like the Mediterranean Conservation Society are installing fixed mooring buoys to prevent anchoring damage.

“The Mediterranean Conservation Society is establishing monitoring stations to track the distribution and growth of Posidonia oceanica.
Ghost net cleanup projects remove discarded fishing gear and waste that block light and oxygen.
They also study the carbon stored in sandy substrates by seagrass roots and raise awareness through their Marine Guardianship System by warning boats not to anchor on seagrass beds.”

Ecosystem restoration and monitoring: Local NGOs and universities conduct studies to restore biodiversity, monitor seagrass degradation, and raise public awareness.

What Can We Do?

• Boats should moor to fixed buoys instead of anchoring.
• Inform sailing clubs, property owners, and visitors.
• Set and enforce coastal development boundaries.
• Support ecological restoration in degraded areas.
• Reduce plastic, nets, and marine debris; conduct regular cleanups.
• Act to control invasive and non-native species.
• Protect seagrass from bottom trawling and illegal fishing.

Why Does It Matter?

Seagrasses are not just underwater plants—they are life engineers that release oxygen, store carbon, support biodiversity, and protect coastal ecosystems. Their benefits span from fisheries to tourism, from climate action to the local economy. Though threatened in the Mediterranean, these vital habitats can be preserved for the future through active protection, awareness, and sound policies.