On Saturday 9 March 2024 we went on a volunteer trip to Begur, to Sa Riera beach, specifically to transects C26 and C27 for the LIFE medCLIFFS project.
One of the volunteers of the project, María José Chesa (member of the bryophytes and lichens study group of the Catalonia, Alichenology), commented some time ago that she had observed a possible impact of invasive alien flora on the lichens of the cliffs that had not been previously assessed, and the trip was organised with the proposal to consider it in the project when observations were made by the volunteers.

The main objective of the field trip was to increase knowledge about another biological group that grows in the cliffs: lichens. It was also the aim of the outing to raise awareness of the impact of invasive alien flora on coastal habitats. The itinerary was organised to visit 6 observation points to learn about the saxicolous, terricolous and epiphytic lichens found around Sa Riera beach.

Map of the stops done to observe lichens. Map source: http://srv.icgc.cat/vissir3/

We started the day at Sa Riera beach to explain the basic concepts of the biological group of lichens, their biology, the species we found along the route, as well as aspects of ethnolichology, such as, for example, the use of epiphytic lichens for the bio-monitoring of air quality, lichenometry (dating of surfaces with saxicolous lichens), or the use of lichens as fabric dyes.

Explanation of the basic concepts of lichens and observation.

The rain accompanied us throughout the day, which made it impossible to visit all the scheduled locations, but despite this inconvenience, we were able to enjoy a morning full of new learning for the whole group.

During the day we also had two journalists from Euronews who were making a special documentary about citizen science projects, and how they are driving change and disruptive solutions in the protection of the natural environment. You can watch the documentary here.

Some examples of lichens according to the substrate where they live.

During the trip we saw the following lichens found in rocks and rocky areas in Catalonia:

Hydropunctaria amphibia is a crustraceous lichen, episubstratous, gelatinous when hydrated; photobiont green algae; sexual reproduction-perithecia; Mediterranean and Atlantic distribution. It is found on both calcareous and siliceous rocks, in the supralittoral zone. During the trip we were not able to see it up close, but it is very important to explain it because of its abundance along the Mediterranean coast.

Hydropunctaria amphibia.

Roccella phycopsis is a grey fruticose lichen with white soralis. Photobiont Trentepohlia. Very rare black apophthecae. It grows on vertical and extra-plummeted surfaces, close to the sea (up to 30 km from the coastline). It has a Mediterranean-Macaronesian distribution, extending along the Atlantic coast. It is included in the red list of the lichens of Catalonia with the threat level of Vulnerable, and we were able to observe it on the C-26 route, which we could see with a magnifying glass. We also saw it at Begur Castle.

Roccella phycopsis.

During the outing we also talked about Ethnolichenology, about the uses and symbolic aspects of this and other lichens throughout history. The common name of Roccella phycopsis is cradle (“orseille” in French). It is known to have been used by the Phoenicians, Greeks and Hebrews as a fabric dye to obtain the colour purple. Other sources of purple were molluscs of the family Muricidae as well as insects of the family Coccoidea.

One aspect to note is that we were able to see how some of the invasive non-native flora species, such as Drosanthemum floribundum, grow rapidly over the surfaces, impeding the life of lichen species, bryophytes and cliff plants.

Imatges que demostren com en algunes zones d’aquest tram Drosanthemum floribundum esta cobrint tota la roca del penya-segat i no deixa créixer cap espècie vegetal.

To finish the day, we observed the lichens on the trees of the stream and we were able to see a lichen that has recently been included in the list of endangered species of Catalonia, the species Ramalina pusilla, with the degree of threat Vulnerable.

Ramalina pusilla sobre l’escorça d’un arbre.

In short, this meeting between participants of Alichenology and participants of LIFE medCLIFFS represents an opportunity to collaborate in the conservation of fragile cliff ecosystems.

Text: Maria José Chesa and Neus Ibáñez