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MPA CASE STUDY 3

Warm marine waters threaten indigenous
Mediterranean coral

Columbretes Islands Marine Reserve (Spain). Photo: J. M. Dalmau
Cladocora caespitosa is the only colonial coral native to the Mediterranean that lives in permanent symbiosis with
microscopic algae within the living coral. Its colonies may join to form reef-like structures up to several square
metres in diameter and more than 1 metre in height, harbouring a rich community of fauna among their branches.
Large living coral banks are rare but can be seen in locations such as Columbretes Islands Marine Reserve (Spain)
or Mljet National Park (Croatia), and smaller banks are found at Cap de Creus and Medes Islands MPAs (Spain),
Port Cros National Park (France), Miramare MPA (Italy), the National Park of Brijuni (Croatia) and Strunjan Nature
Reserve (Slovenia).

Over the past 10 years, seawater warming has led to recurrent mass mortalities in C. caespitosa. These events are
becoming more frequent and widespread and are severely affecting this coral in many Mediterranean locations, in-
cluding Islas Columbretes, Strunjan and the Gulf of Trieste (Kersting and Linares, 2009; Climaparks News, 2012). A
rise in sea temperature by a degree or more above the average for extended periods of time or an increase in maxi-
mum temperature can cause coral necrosis (tissue death).
Furthermore, the spread of invasive algal species, such as
Caulerpa racemosa and Lophocladia lallemandii, is threat-
ening this coral in Mljet (Croatia), Columbretes Islands and
other locations (Kružic and Benkovic, 2008; Kersting and
Linares, 2012). Since 2003, up to 50% of Cladocora colo-
nies in Islas Columbretes have died in repeated events in
response to higher summer water temperatures (Kerst-
ing, pers. comm.). Comparable phenomena have recently
been observed in Strunjan Nature Reserve as well as other
locations in the Gulf of Trieste (Kersting and Templado,
2006; Climaparks news, 2012).
The percentage of coral cover affected by necrosis and
the presence of disease outbreaks could be valid indica-
tors of Mediterranean climate change and could be used
for monitoring the resilience of coral populations. Necrosis of Cladocora caespitosa in Columbretes Marine Reserve.
Photo: D. Kersting

MEDITERRANEAN MARINE PROTECTED AREAS AND CLIMATE CHANGE: A GUIDE TO REGIONAL MONITORING AND ADAPTATION OPPORTUNITIES 35