The coral biomass of the population found in Corsica (left) is 100 higher than other populations in the Mediterranean (right).
The experts Cristina Linares and Bernat Hereu, from the Faculty of Biology of the University of Barcelona.
How were red coral populations in the Mediterranean Sea before overfishing? Which were the maximum dimensions of coral colonies –nowadays admired by the industry of ornamentation? Did centenary colonies dominate the populations? These are some of the questions scientists tried to answer to set objectives for management and conservation plans and reverse the effects of millenary exploitation in these natural ecosystems. Discovering the original or pristine status is a key factor to ecologically recover the habitat and populations of this emblematic species in the Mediterranean.
Before the overfishing, the Mediterranean had coral populations (Corallium rubrum) with relatively high-density in big –probably centenary- colonies, even at shallow depths, according to a study published in the journal Scientific Reports, with the participation of the experts Cristina Linares, Ignasi Montero-Serra and Diego K. Kersting, from the Faculty of Biology of the University of Barcelona.
The new study, led by Joaquim Garrabou, from the Institute of Marine Sciences (ICM-CSIC), has been made possible thanks to the 2010 findings of a virgin population of red coral in Corsica, in a submarine cave in the Scandola Nature Reserve. This population shows a conservation status which was unknown so far, near the shallows and considered to be a door to the past. The study also counts with the participation of the experts from CEAB-CSIC, University of Girona, the Mediterranean Institute of Oceanography, the Corsica Regional Nature Park in France, the University of Oporto (Portugal) and the University of Zagreb (Croatia).
Corsica’s coral population, a door to the past
In this research, researchers analyzed the status, biomass and density of population of this population and compared it with others, some of which have been protected over the last decades.
This population, an authentic door to the past, reveals that before being exploited, red coral populations were abundant in big colonies, more than what people thought. In particular, the coral biomass of the population found in Corsica is 100 higher than other populations in the Mediterranean, even the ones in areas which have been protected for more than forty years. This means that “this study will make us reconsider the reference status of red coral populations as well as the sustainability of coral fishing”, says Joaquim Garrabou (ICM-CSIC).
According to Cristina Linares, from the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB, “this red coral population shows an exceptional conservation status thanks to its location in the Scandola Marine Reserve, which is one of the best managed reserves in all the Mediterranean thanks to the security effort. Furthermore, it is located in a place which is hard to find even inside the reserve, that is why it was not found until 2010, although this reserve had been studied by French and Catalan researchers for years”.
For the authors, the new study suggests that the reference status of red coral populations and the objectives in protection plans should be reconsidered.
Coral populations about to collapse
Red coral has been used as decoration and jewelry for more than a thousand years, but during the last century overfishing has increased the decline of this species’ population and they are about to collapse now.
Red coral is a fragile and vulnerable organism, from the Antozoan group (plant-shaped animals). It has a slow growth (1mm and 0,25 mm per year in height and diameter respectively) and its populations need long periods of time, probably centuries, to recover from exploitation.
Ecologically, red coral populations play an important role in the marine ecosystems: they structure habitats, allow the development of other species in coral-rich colonies and are shelter areas for other invertebrates and young fish.
It is worth mentioning that some of the signing authors of the article in Scientific Reports are also authors of a report for the Generalitat de Catalunya which shows the critical situation of red coral in Catalan coasts. After this report, in which experts from de University of Barcelona, ICM-CSIC and ICTA-UAB have participated, the Generalitat de Catalunya (Catalan Government) has announced a moratorium of 10 years for which red coral extraction will be banned. This moratorium, to be operational from 2018 onwards, could also be extendable. The report about the critical situation of red coral in Catalan coasts counts with the participation of the UB experts Cristina Linares and Mikel Zabala (Department of Evolutionary Biology, Ecology and Environmental Sciences) and Bernat Hereu, from the mentioned Department and the Biodiversity Research Institute (IRBio).
Images: Medrecover research group and Joaquim Garrabou (ICM-CSIC)