Involving local stakeholders of Schinias – Marathon National Park towards the integration of Posidonia banquettes into a legal framework for coastal management

HSPN holds the first workshop for the local stakeholders of the Schinias - Marathon National Park

Schinias – Marathon National Park belongs to the Natura 2000 network of protected areas. Given the high ecological value and rich interactions of this coastal ecosystem, it is important to develop a management approach that takes into account all of its different components. At the seabed of Schinias Bay, we can find Posidonia (Posidonia oceanica) forming large meadows, which indicates clean waters and presence of diverse forms of life. By dropping its leaves several times during the year, the sea currents wash the leaves ashore and thus the Posidonia banquettes are formed on the shoreline.

Posidonia banquettes in Schinias – Marathon National Park have not been removed from the area since 2017, following to the recommendations of the previous project, PosBeMed. Thanks to this, the monitoring team is being able to implement a set of activities in order to extract key data and establish relevant recommendations for managing the Posidonia-dune ecosystem sustainably.

On the 19th of May, 2021, the first local workshop was organised by the Hellenic Society for the Protection of Nature (HSPN) in collaboration with the Hellenic Centre for Marine Research (HCMR), who is responsible for the monitoring activities in the region of Schinias – Marathon National Park, in Attica region, in the framework of POSBEMED2 project. The purpose of the meeting was to present the preliminary results of the activities that have been undertaken so far. The meeting attended representatives from the Management Board of the Schinias Marathon National Park, as well as the local authority of Rafina Hellenic Coast Guard, both of them playing a vital role at management and decision making regarding the area.

The HCMR presented their interventions, with Mr. Dimitris Vandarakis, Geomorphologist PhD, leading the activities at the site, in order to evaluate the relation between the banquettes and the sediments, as well as their significance as a natural protection of the beach. The surveys aim to identify the differences in volume, shape and area covered of the banquettes, as well as to analyze the relationship between banquette deposition and morphological changes of the underlying sedimentary substrate of the beach. Having conducted three in-situ interventions, the HCMR has been able to come to a number of preliminary conclusions, which shows in practical terms the key role of Posidonia banquettes regarding beach erosion. Specifically, Mr. Dimitris Vandarakis noted that the Posidonia banquettes covering that specific area, contain so much volume of sand, that it would fill 10 trucks, in case of banquettes removal. This in fact proves to be a significant finding, given the fact that in the last 70 years the shoreline displacement rate of the area was 20 – 40 cm per year. In other words, the presence of Posidonia banquettes, along with their wider ecosystem services seem to be able to halt beach erosion.

In conclusion, these preliminary results brought to surface very important scientific extracts that enhance the understanding of the functionality and services of Posidonia beach-dune system. The very accurate and frequent monitoring can help identify the differences of the extension of the banquettes and the volume of the sediments, as well as to provide the baseline for the development of a holistic and targeted coastal management strategy.