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What is “coralligenous”?

What is commonly called coralligenous is, actually, a complex seascape (i.e. a submerged landscape) developing in dim light conditions, which is present exclusively in the Mediterranean Sea. Coralligenous habitat is mainly created by calcified red algae, which are constructing reef-like structures for thousands of years over marine rocky bottoms. In this respect coralligenous formations are considered to be the Mediterranean equivalent of the tropical coral reefs. At the same time, some other organisms- which are called ‘eroders’ - such as sponges of the genus Cliona or sea urchins pierce and consume the calcareous substrate and thus contribute to increase the structural complexity of the coralligenous formations. This calcareous substrates also support several long-living species (sponges, gorgonians, bryozoans, corals), which are contributing to the structuring of the coralligenous habitat. Finally, a large number of invertebrates (such as nudibranchs, crustaceans, ascidians, echinoderms, molluscs) and fishes are associated with coralligenous habitats, a fact which further contributes toward the characterization of the coralligenous habitat as a unique biodiversity hotspot.


Why do we observe coralligenous habitats?

They are unique habitats worldwide and among the richest and most beautiful seascapes to observe during scuba diving. Thanks to their complexity, they shelter a great number of ecologically, aesthetically and commercially valuable species, some of which are also protected by National and International Laws. Coralligenous habitats are often threatened by the human behaviour. Intense anchoring, irresponsible diving, (over)fishing, litter dumping, alongside with sea surface warming (due to climatic change) and alien species invasions, are among the main threats which can induce negative effects on the health status of coralligenous habitats.

By participating into the CIGESMED for divers activity you contribute to the exploration and the conservation of the coralligenous habitats and the marine environment while at the same you can increase your knowledge about the marine biodiversity.

Your contribution is valuable for Mediterranean marine life.  

  • Download the guidelines of the CIGESMED Citizen Science protocol.
  • Download the fill-in forms (slates) for underwater observations
  • Download the short practical guidelines of the CIGESMED Citizen Science protocol.



CIGESMED: Coralligenous based Indicators to evaluate and monitor the "Good Environmental Status" of the MEDiterranean coastal waters


CIGESMED’s goal is to understand the links between natural and anthropogenic pressures and ecosystem functioning to define and maintain the Good Environmental Status (GES) of the Mediterranean Sea, by studying the typical, complex and not well known habitats built by calcareous encrusting algae, the “coralligenous”

An integrated approach will be applied to share and visualize large datasets, and to manage the knowledge necessary to study coralligenous habitats. Indicators, from communities to infra-specific level (DNA), will be co-constructed and tested by scientists, Marine Protected Areas and reserves, and through the implementation of a “citizen science” network. The outcome will be an integrative assessment of the GES within the Marine Strategy Framework Directive (MSFD).

CIGESMED gathers scientists from France, Greece and Turkey, making it possible to access to sites and to work on the same issues in both the northwestern Mediterranean basin and the Aegean-Levantine one. Ten laboratories of marine ecology are involved. It will also involve observers from other Mediterranean countries. It is coordinated by the IMBE (Mediterranean Institut of marine and terrestrial Biodiversity and Ecology), a unit of research of CNRS-INEE, Aix-Marseille University, IRD and the University of Avignon.

For more info please visit the official website of CIGESMED


Research funding organizations involved in CIGESMED: 

France: Agence Nationale de la Recherche (ANR)

Greece: General Secretariat for Research and Technology (GSRT)

Turkey: Turkiye Bilimsel Ve Teknolojik Arastirma Kurumu (TÜBITAK)