Climate Change and the European Water Dimension - Agri ...

Po River Delta lagoons, the long drought from spring to late summer 2003 caused an
estimated loss of about 50% of the current mussel crop, and an almost total loss of
recruitment.
Sea level rise (SLR) would
o increase water depth in the lagoon
o alter water circulation
o affect solid transport and erosion-sedimentation equilibria
o increase ingression of salt water into inland coastal areas
Sea-level rise will gradually inundate coastal lagoons and surrounding lands. Coastal
lagoons could potentially migrate inland with rising sea levels; however, most of the
Mediterranean coast is obstructed by human development, therefore they face the
risk of annihilation. Even a limited increase can submerge part of sandy barriers
separating lagoons and sea. The first consequence may be an increase of the
hydrodynamic exchange with the sea. It may happen that for some lagoons,
submergence will only displace the equilibrium between accretion (sedimentation
accumulation) and SLR rates, leading to the maintenance of the same volumetric
capacity (Nichols and Boon, 1994). If the relative rate of sea level rise is accelerated,
or for lagoon with small barriers, accretion may not be sufficient to maintain
equilibrium with SLR, certain lagoons may disappear. Overall, these processes are
influent on coastal lagoon persistence.
Most of the coastal lagoons and their watershed in the Mediterranean area are
influenced by sea eustatism and are subjected to a natural subsidence that has been
accelerated by marshland reclamation and, especially, by groundwater and natural
gas extraction. For example, in the Po River Delta, areas below the sea level can be
found up to 40 km inland (Gambolati et al., 2002). The cost of maintaining these
areas dry (by means of pumps) increase with SLR and therefore substantial changes
in coastal land use (e.g reclaimed land for agriculture returns to wetland) can be
expected. Changes in sea level and increasing episodes of extremely high riverine
discharge can cause persistent flooding of the subsidence areas. Flooding
persistence associated with temperature raise and different land use may allow the
development of human pathogens that were commonly found until the 1950’s, among
these malaria, Mediterranean fever, etc. Still and warm water are a suitable
environment for several harmful phytoplankton and cyanobacterial species producing
toxins with acute and chronic effects also on humans. Finally, floods, by covering the
land near the lagoon, can cause the dissolution of buried pollutants.
Freshwater inland resources can be contaminated due to the intrusion of saline
water, both underground and on surface, increasing drought problems (e.g.
experienced in 2003 in the southern region of the Venice lagoon), both for human
use and agriculture production.
The protection adopted to defend the coastline from SLR could by itself be a cause of
alteration of a natural equilibrium, as they necessarily modify the water flow and/or
the tidal regime. Sea barriers, even if partially mobile as proposed in the case of
Venice, defend the coasts from inundation and flooding, but may lead to a complete
“artificialisation” of the lagoons and loss of the natural dynamics of the system.
UVBR increase
UVBR has been demonstrated to have deleterious effects on numerous planktonic
organisms and processes (Mostajir et al., 1999, Worrest, 1989), and can penetrate
lagoon water masses due to their shallow depth. However, to our knowledge no
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