Ocean

Restoring the forests of Gorgonians

By 24/10/2019 No Comments


Despite their great resemblance to plant organisms – Gorgonians, also known as sea fans – are colonial animals that belong to the large group of cnidarians. They live attached to the substrate and are organized in dense populations that, like trees in terrestrial ecosystems, thanks to their structural complexity create a suitable habitat for hundreds of marine species, to which they offer shelter and areas suitable for food and reproduction .

In the Mediterranean Sea, gorgonians are the main species of underwater forests from shallow to continental shelf and slope (~ 60–1000 m deep). However, it is in these deeper areas, from 50 meters deep, where much of the fishing activity is concentrated, becoming a serious threat to the viability and survival of these gorgonian forests in recent years.

Due to their arborescent morphology, gorgonians easily become entangled in fishing nets, suffering partial damage (for example abrasions that result in tissue necrosis) or are directly removed from the substrate. As species with slow population dynamics (long-lived, slow-growing species with late sexual maturity), the effects of fishing activities can seriously compromise the survival of gorgonian populations and, consequently, of all fauna associated with these underwater forests.

For this reason it is of relevant importance to develop conservation and restoration strategies that help protect the seabed dominated by gorgonians so relevant to marine biodiversity. On the one hand, it is important to mitigate or put an end to destructive activities in these areas, but it is also important to carry out active restoration projects that will accelerate the slow recovery of these impacted gorgonian forests.

A close example is the pilot project being carried out by scientists from the Institute of Marine Sciences (ICM-CSIC) together with fishermen of Port de la Selva and Cadaqués, on the Catalan coast of Cap de Creus (Girona). In this pilot restoration action, the gorgonians that are entangled in fishnets are recovered and kept in aquariums until they are fully recovered. Next, the colonies are transplanted on boulders and returned to their natural habitat on the continental shelf (80-90 m deep), pulling them directly from a boat. The gorgonians attached to the boulders act as “badminton feathers”, thus ensuring that a correct landing and subsequent long-term survival is ensured. The project began in March 2018 and has proved to be a success, having managed to recover and return to the sea more than 450 gorgonians to date. The next step and challenge for the near future will be to carry out a quality monitoring of these gorgonians after they have been returned to their habitat in order to control and evaluate their long-term survival. Finally, it should be noted that, as a result of this project, local fishermen are increasingly aware of the importance of protecting the seabed, preserving key species, such as gorgonians, which are indispensable for the survival of many other species.

From Maria Montseny, published in the magazine InMare https://www.revistainmare.com/

With the collaboartion of Núria Viladrich, Jordi Grinyó, Stefano Ambroso, Patricia Baena, Andreu Santín, Janire Salazar, Josep-Maria Gili, Andrea Gori

Photography : 
Nemo ROV
Gavin Newman