The Mediterranean Sea harbors extensive underwater meadows formed by a marine plant, Posidonia oceanica. This species creates lush, green underwater landscapes, providing a complex and stable environment beneath the waves. These expansive beds are a feature of the Mediterranean’s shallow coastal waters.
The Mediterranean’s Underwater Forests
Posidonia oceanica is a true flowering plant with roots, rhizomes, and long ribbon-like leaves up to a meter in length. It reproduces both sexually through flowers and seeds, and asexually by extending its underground rhizomes. This allows it to form dense, continuous meadows across the seabed.
This seagrass is endemic to the Mediterranean Sea. It forms productive and stable meadows, extending to depths of 40-45 meters and covering an estimated 25-50% of the Mediterranean’s infralittoral bottoms.
Ecological Importance
The meadows of Posidonia oceanica support a rich variety of marine life. They serve as a habitat and nursery ground for numerous marine organisms, including diverse fish. Research has shown that fishing prohibitions in marine protected areas can positively impact the species richness and density of target fish within these seagrass beds.
Posidonia oceanica contributes to the marine environment by releasing oxygen into the water. The plant also sequesters large amounts of carbon, storing it within its biomass and sediments. This ability to capture and store carbon, often referred to as “blue carbon,” contributes to regulating carbon-related variables in the surrounding seawater.
The presence of Posidonia oceanica has a strong correlation with the biogeochemical properties of the water. Its influence on carbon variables can even be used to indirectly locate its meadows. The plant’s environmental impact is considerable for the entire Mediterranean Sea ecosystem.
Threats and Decline
Despite its ecological significance, Posidonia oceanica meadows are experiencing decline across the Mediterranean. Historical maps and scientific publications document their decline. This decline is attributed to both natural processes and various human impacts.
Human activities, such as coastal development, can lead to direct damage and habitat loss for the seagrass. Alterations to the seabed and increased sedimentation from human activities also contribute to the degradation of these ecosystems. The combined effects of these pressures challenge the survival of Posidonia oceanica meadows.
Conservation Efforts
Recognizing its value, Posidonia oceanica is a protected species, with conservation efforts focused by many organizations. Efforts are underway to monitor the status of these meadows and collect data on their distribution and health. Long-term surveys, including underwater visual censuses, are conducted to track changes over time.
Conservation strategies emphasize the need for effective management of coastal areas to mitigate human impacts. The aim is to assess losses and implement recovery initiatives. Protecting these underwater forests is important for maintaining the overall health and biodiversity of the Mediterranean Sea.