Marine Life
Posidonia Oceanica – the secret of Messinia’s crystal clear waters
Written by Scuba Turtles | 03 Jan 2024
One of the main attractions of Messinia lies in their crystal clear waters. The sea often takes on a vibrant turquoise hue, reminiscent of the Caribbean, creating a surreal experience. Interestingly, this breathtaking phenomenon is attributed to Posidonia oceanica, one of the world’s largest and oldest living organisms thriving on the sandy sea floor.
Named after the Greek sea god, Posidonia oceanica is a type of seagrass abundantly found throughout the Mediterranean. Posidonia Oceanica or Neptune grass, is often confused with seaweed because of its shape and colour, but it is actually an underwater plant with fruits, flowers, leaves, stem and roots. It is also an important indicator of the health of the marine ecosystem as it only lives in clean water.
The lungs of the Mediterranean.
Posidonia plays a pivotal role in our marine ecosystem, acting as a vital habitat for a diverse array of species, including fish and seahorses. These organisms depend on Posidonia for essential activities such as feeding, breeding, and seeking shelter. Beyond its ecological importance, Posidonia serves as an exceptionally efficient carbon sink, with seagrass capable of storing up to 15 times more carbon than the equivalent area of terrestrial forest. This carbon sequestration occurs at an accelerated rate, with the carbon trapped for extended periods, spanning millions of years.
The plant further contributes to water purification and oxygenation processes. Through its metabolic activity, Posidonia filters impurities and releases oxygen into the water, constituting more than half of the atmospheric oxygen essential for terrestrial life. Consequently, Posidonia is aptly termed the “lungs of the Mediterranean,” reflecting its critical role in carbon sequestration and oxygen production within the marine environment.
Ensuring the preservation of Posidonia is imperative, given its multifaceted environmental benefits. Posidonia meadows host over 1,000 species of animals and plants in the Mediterranean, serving as crucial spawning grounds for various commercially significant species. Each square meter of these meadows contributes up to 20 liters of oxygen daily, emerging as a primary source of sea and atmospheric oxygenation. Additionally, these meadows function as CO2 sinks, capturing substantial quantities of this greenhouse gas. Notably, they also play a protective role, safeguarding the coastline from erosion. The comprehensive ecological services provided by Posidonia underscore the necessity for its conservation and sustainable management.
Under threat.
Posidonia, an abundant marine plant in the Mediterranean Sea, confronts a precipitous decline attributable to various causative factors. The mechanical damage stemming from trawling, boat anchoring, turbidity, coastal development, and agricultural nutrient discharges, coupled with pollution and climate change, collectively imperil its existence. The plant’s vulnerability to these stressors is heightened by its limited genetic variability and protracted growth, rendering it inherently less resilient in the face of disturbances.
Regrettably, notwithstanding its stature as a paramount natural asset, Posidonia finds itself in a precarious state of endangerment. Over the preceding four decades, the western Mediterranean has experienced a noteworthy depletion, losing approximately one-third of its meadows. Climate change emerges as a formidable threat, with escalating sea temperatures triggering seagrass deterioration once the critical threshold of 28°C is surpassed. Recent observations underscore peak temperatures reaching as high as 29°C.
The escalating pollution in the water, compounded by unregulated boat anchoring, compounds the challenges faced by Posidonia Oceanica. Given its exceptionally sluggish growth rate, measuring less than one centimeter annually, the impact of a solitary vessel deploying its anchor can result in a denuded patch, necessitating centuries for rehabilitation. Urgent and concerted conservation efforts are imperative to safeguard this invaluable marine species and address the multifaceted threats contributing to its precipitous decline.
Taking Action.
To ensure the preservation of Posidonia oceanica, a range of proactive measures and initiatives have been implemented, reflecting a collective commitment to its conservation. Various regulatory frameworks, including EU legislation, the Bern and Barcelona Conventions, as well as national legislations, provide legal safeguards for this species. Additionally, EU fishing regulations impose restrictions on trawling activities near the shore, and several marine protected areas have been established along the Mediterranean Sea to secure the habitats of Posidonia oceanica.
To actively contribute to the protection of Posidonia oceanica, individuals can adopt the following practices:
1. Advocate Responsible Boating:
When embarking on a boat trip, passengers are encouraged to communicate with their captains, urging them to avoid anchoring in Posidonia meadows. The utilization of the Posidonia MAPS app can assist captains in identifying safe anchoring zones, minimizing the impact on these critical habitats.
2. Choose Environmentally Friendly Sunscreen:
Opt for environmentally conscious, chemical-free sunscreen options. Conventional sunscreens often contain pollutants that can contaminate water and pose a threat to seagrass health. Locally produced alternatives, such as those by Sol de Ibiza and Ibisun, offer sustainable choices, with a percentage of proceeds contributing to conservation efforts by organizations like IbizaPreservation.
3. Support Posidonia Protection Projects:
Contribute to Posidonia protection initiatives by making donations through designated platforms available on websites dedicated to conservation projects. Financial support directly aids in implementing and sustaining programs aimed at preserving Posidonia meadows.
4. Become a Posidonia Ambassador:
Actively engage in spreading awareness about the significance of Posidonia oceanica. By becoming a Posidonia ambassador, individuals can play a crucial role in educating others about the importance of this marine plant and advocating for practices that ensure its long-term survival.