July Plant of the Month: Neptune Seagrass (MT: Alka) Posidonia oceanica


Photo by Annalise Falzon


Next time you visit a beach along the Mediterranean coast with Posidonia leaves washed ashore take some time to appreciate the incredible number of ecosystem and landscape services which this unique marine plant contributes to our region. The banquettes, which form especially after storms, are nature’s way of defending our coast from erosion while providing the only humid microhabitat providing refuge for several species (some of which are also endemic in their own right).

This plant’s importance increases in its true realm – that of the underwater meadows which have been identified as a priority habitat type for conservation under the Habitats Directive in the EU.

The Neptune Seagrass is a marine plant endemic to the Mediterranean Sea i.e. it is only found in this region (not including the Black Sea). Due to its Maltese name ‘Alka’ it is often thought to be an alga/seaweed but it is a true flowering plant – it has roots, stems and leaves and blooms underwater (occasionally producing fruits known as sea olives). Its ribbon-like leaves can grow up to one metre long but are only one centimetre wide. For healthy growth it requires clear, nutrient-poor waters and it prefers conditions of stable salinity and temperature. This unique seagrass creates extensive underwater meadows of crucial importance for supporting an incredible array of biodiversity – it is home to around 1,000 animals and plants in the Mediterranean! It is also no wonder that it has been dubbed ‘The lungs of the Mediterranean’ – every square metre can generate 20 litres of oxygen daily! Today, in view of our climate crisis these marine plants are finally being appreciated also for their role in carbon sequestration.

Photos and text by Annalise Falzon

About Project Poseidon:

Blue EcoTech Ltd. is the Maltese start-up part of this new Citizen Science initiative Project-Poseidon led together with Malta Chamber of Scientists, Spark15, and Żibel with the aim of learning how to monitor and clean up the plastic pollution of our beaches and begin to reforest the seagrass underwater. This is the first time a reforestation project for Posidonia is taking place in Malta. Participants will be helping to gather data in support of research while being involved at different stages and in a number of different roles, including photography, design, data collection, writing, reforestation, and the co-creation of an artwork for the Science and the City festival. For more info contact emma.clarke@um.edu.mt


Donate now!