Below the surface, inside the Montgrí Natural Park, Medes Islands, and Baix Ter, it’s hidden rich biodiversity. Its proximity to the coastline, the Ter and Fluvià river mouth and its geological complexity makes this Natural Park to be the perfect place to become the house of a huge amount of marine communities, from posidonia meadows to coralligen walls, and also extended caves and tunnels karstic systems. These characteristics make this Natural Park one of the 36 hotspots of biodiversity in the world.
The most illuminated rocky background is filled in a dense algae coverage that has its maximal development in the spring. Here, small animals such as molluscs or crustaceans find shelter and food, which also are food for different species of fish, such as sparides (spaids, golds, etc.), labrids or blennids.
The large blocks found at little depth create shade zones where algae are replaced by animals that feed on plancton and particules in suspense. Hydrozoan and sponge colonies are abundant, and it is not rare to find colorful nudibranchs feeding on them. In the holes, we can also find shelter from lobsters and octopuses in morons, meros and sprouts.
Below the -20m, the landscape becomes dominated by coralligen and limestone algae. We will find from soft corals such as Eunicella singularis and Paramuricea clavata, this as a red coral and colonies of bryozoas.
Caves and tunnels
The Montgrí coast has a particular and very characteristic system of very spectacular caves and crates. The calcareous nature of the archipelag favored the formation of caves by the freshwater erosion, which later became submerged under the sea. In these caves and tunnels, lack of light makes plant life impossible and filtering animals dominate the roofs and walls, among the cracks of which we can notice the presence of congers, lobsters and lobsters. The entrances contain abounded red coral, all-colored sponges and large colonies of bryozoa and hydrozoans.