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information on the responses of different communities
Refugia: Physical environments that are and sites in these locations.
less affected by climate change than other
areas (i.e., due to local currents, geographic An illustrative example may be found in the north-west-
location, etc.) and are thus a “refuge” ern Mediterranean, where different environmental con-
from climate change for organisms. ditions can modulate the impact of anomalous regional
warming. The local hydrological conditions found in the
Medes Islands MPA (north-eastern Spain) result in the
potentially resilient sites (or refugia) into the manage- absence of extreme temperatures (short-term anoma-
ment design to facilitate the recovery of less resilient ar- lies) even in summer, and in attenuated temperature
eas. The former measure will require collaboration with variations during periods of long anomalies. This makes
other coastal users and planners as well as ensuring the area less vulnerable to mass-mortality events in cor-
that good monitoring information is gathered so as to alligenous communities than areas such as Marseille
be able to take action and identify targeted approaches (close to Port Cros National Park) and Corsica (Scan-
to specific pressures. The second type of measure will dola Nature Reserve), where the hydrodynamics cannot
require the identification of areas that were resilient to buffer anomalous temperatures, resulting in intolerable
past climate change impacts as well as the collection of conditions for many species (Crisci et al., 2011).

Blue carbon sinks

The organic deposits in Mediterranean saltmarshes and seagrass meadows, principally those of Posi-
donia oceanica, are an exceptional example of a natural carbon sink ecosystem as they considerably
reduce the harmful effects of human carbon emissions by capturing and storing part of the excess carbon
dioxide (CO ). Such carbon that is sequestered, stored and released from coastal ecosystems, including
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mangrove swamps, is known as ‘blue carbon’.
Posidonia oceanica meadows can sequester and store large amounts of organic carbon in sediments and
biomass: the average storage rate for the Mediterranean is calculated to be 0.15 to 8.75×10 tC a year, ac-
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cording to several recent studies (Serrano, 2011). Overall, the historical carbon deposits in the mats below
Mediterranean seagrass meadows could amount to as much as 2.5 to 20.5×10 tC. Their large capacity
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together with their extremely long carbon residence time makes Posidonia meadows a very important
carbon sink relative to the total carbon stored in the oceans (Pergent et al., 2012).
When degraded or disturbed (e.g. by trawling,
pollution or other cumulative stressors), however,
these habitats can release the carbon dioxide
back into the ocean and atmosphere, thus having
an adverse effect by increasing greenhouse emis-
sions.

Well represented in many Mediterranean MPAs,
these seagrass meadows are highly biodiverse
habitats whose conservation helps mitigate cli-
mate change effects, in addition to increasing
the MPAs’ natural resilience. MPA managers can
assist by preventing the loss of the carbon that
is currently stored in these habitats and improv-
ing management to enable the seagrass to retain
more carbon, through restoration programmes.
Mediterranean saltmarshes and seagrass mead-
ows could play an important role in national car-
bon accounting schemes and provide a source of
future funding for conservation efforts.
Posidonia oceanica. Photo: M.Otero

MEDITERRANEAN MARINE PROTECTED AREAS AND CLIMATE CHANGE: A GUIDE TO REGIONAL MONITORING AND ADAPTATION OPPORTUNITIES 21