Introduction to Mediterranean corals
Coral reefs are often associated with tropical seas, but the Mediterranean Sea is also home to corals of great diversity. Despite their essential ecological role, these corals face many threats. This article explores their biodiversity, their functions in the ecosystem, the challenges they face and the actions implemented for their preservation.
Introduction to Mediterranean corals
Characteristics of corals in the Mediterranean
Unlike tropical reefs, Mediterranean corals evolve in more temperate and less nutrient-rich waters. Their growth is extremely slow, sometimes less than a millimeter per year. They develop on rocky bottoms or form bio-constructions called coralligenous, complex habitats that host exceptional biodiversity (Garrabou et al., 2021).
The main characteristics of Mediterranean corals:
Slow growth: unlike tropical reefs, their development takes longer.
Resistance to fluctuating temperatures: they survive in waters varying between 13 and 25°C.
Absence of massive reefs: they form scattered but essential habitats for biodiversity.
Main species of Mediterranean corals
Notable species in the Mediterranean include:
🔹 Red coral ( Corallia rubrum )
Known for its beauty and its use in jewelry, this coral grows between 10 and 200 meters deep .
Its overexploitation for ornamentation threatens its populations (Bruckner et al., 2018).
🔹 Yellow coral ( Dendrophyllia ramea )
It mainly colonizes deep areas and is home to many species of fish and invertebrates.
🔹 Black coral ( Antipatharia sp. )
Very rare, this coral lives in deep waters (up to 1000 m) and has a unique dark skeleton.
Ecological role of corals in the Mediterranean
Habitat and refuge for marine wildlife
Mediterranean corals are essential to underwater ecosystems. They provide habitat for more than 1,300 marine species, including fish, crustaceans and sponges (UNEP, 2020).
Some species, such as groupers and lobsters, use corals to hide from predators. Coralligenous also play a role in the reproduction and development of juveniles of many marine species.
Contribution to marine biodiversity
Coralligenous formations participate in the stabilization of sediments and the production of underwater oxygen. They shelter fauna and flora that rival those of tropical reefs.
In the Mediterranean:
25% of marine species depend directly or indirectly on corals.
Deep-sea corals support 29 times more marine life than an area without coral (Rowden et al., 2010).
Threats to Mediterranean corals
Threats to Mediterranean corals
Global warming is one of the main threats to Mediterranean corals. Between 1980 and 2020, the temperature of the Mediterranean Sea increased by 1.5°C (IPCC, 2018).
Consequences :
Increased thermal stress causing coral bleaching.
Increased mortality during marine heatwaves, such as that of 2003 which decimated up to 50% of red corals in certain regions (Garrabou et al., 2021).
Marine pollution and human impacts
The Mediterranean is one of the most polluted seas in the world. Every year, more than 600,000 tonnes of plastic are dumped there (UNEP, 2020).
Effects of pollution:
Microplastics impair coral growth and reproduction.
Eutrophication promotes the development of invasive algae which smother corals.
Destructive fishing practices
Some fishing methods seriously damage corals:
Bottom trawling: destruction of coral habitats.
Red coral fishing: overexploitation having reduced its populations by 60% in 30 years (Bruckner et al., 2018).
Conservation and restoration initiatives
Coral habitat protection programs
Marine Protected Areas (MPAs) play a key role in preserving Mediterranean corals by limiting destructive human activities.
📍 Examples of protected areas:
Port-Cros National Park (France): prohibits all forms of fishing and anchoring in certain areas to preserve red corals.
Tavolara MPA (Italy): strict control of human activities and limitation of red coral fishing.
The DEEP CORE project of the Spanish association CORAL SOUL in partnership with the association CORAL GUARDIAN: a major step forward in the conservation of Mediterranean corals
The DEEP CORE (Deep Coral Restoration Effort) project is an innovative scientific initiative aimed at restoring and protecting deep-sea corals in the Mediterranean.
DEEP CORE Objectives:
Identify the most threatened deep coral areas.
Experiment with restoration techniques adapted to deep waters (more than 50 meters).
Develop protection and scientific monitoring protocols.
This initiative is carried out in collaboration with marine biology researchers, conservation associations and government institutions.
Why is this project essential?
Deep-sea corals are less studied but just as vulnerable to the impacts of climate change and pollution.
Traditional restoration techniques, adapted to tropical reefs, are not always effective in the Mediterranean.
DEEP CORE's scientific approach allows the development of strategies specific to Mediterranean coralligenous habitats.
Ecological restoration projects
Different strategies are being implemented to restore damaged corals.
Restoration techniques:
Coral cuttings in the laboratory before transplantation on site.
Use of biocompatible artificial structures to promote the recolonization of degraded reefs.
Genetic monitoring of transplanted corals to maximize their adaptation to environmental changes.
Examples of notable projects:
DEEP CORE: restoration of deep corals and establishment of reinforced protection zones.
The DEEP CORE project complements these efforts by focusing on deep-sea corals, which are often neglected in conventional conservation strategies.
Ecological restoration projects
NGOs such as Coral Soul and Coral Guardian raise awareness about the importance of corals and train divers to protect them.
The “Adopt a Coral” program allows the general public to finance coral conservation in the Mediterranean.
Conclusion
Mediterranean corals, although less well-known than their tropical counterparts, are essential to marine biodiversity. However, the threats of climate change, pollution and destructive fishing weigh heavily on their future.
There is an urgent need to strengthen conservation and restoration efforts to preserve these fragile ecosystems.
The DEEP CORE project is a major step forward for coral restoration in the Mediterranean, targeting habitats that were previously difficult to protect. Combined with the efforts of Marine Protected Areas, it represents a ray of hope for the preservation of Mediterranean corals in the face of increasing threats.
Scientific references
Garrabou, J., et al. (2021). Climate change impacts on Mediterranean coral populations. Marine Ecology Progress Series .
IPCC (2018). Global Warming of 1.5°C - Impacts on marine ecosystems.
NOAA (2021). Coral Reef Conservation: Mediterranean case study.
UNEP (2020). Status of Coral Reefs in the Mediterranean: Threats and Conservation.
Bruckner, AW, et al. (2018). The exploitation and trade of Mediterranean red coral. Biological Conservation .
