Just like rivers flow across the landscape,
submarine canyons incise the seafloor. Submarine canyons are large
and deep valleys that provide one of the main conduits through which sediment,
nutrients and pollutants are redistributed from the land and coastal waters to the
deep ocean. Submarine canyons also have a powerful influence on the nature and
distribution of seafloor biological systems. Due to their relevance and
widespread occurrence, submarine canyons are now extensively researched,
particularly as technology advances have allowed us to explore these otherwise
inaccessible environments.
What is the origin of
submarine canyons? Many canyons are thought to have formed when sea levels were
lower than today and they were connected to major terrestrial river systems, such as
during previous Ice Ages. Sea level rise after the Ice Ages disconnected the
canyons from the rivers, and as a result most submarine canyons became
inactive. Some canyons, however, did remain active. Furthermore, recent
expeditions have shown that numerous submarine canyons are located in regions
where the seafloor was never connected to terrestrial river systems or the
coast. Scientists still find it difficult to understand how this is possible.
Gravity flows are the underwater equivalent of snow avalanches , but instead of snow they transport sediment. Gravity flows have long been accepted as one of the main processes
forming submarine canyons, but their origin is not always very clear. For many
years scientists have know that sea water is not a uniform body; instead it
consists of different water masses having different temperatures, salinities,
and thus densities. Differences in water densities drive ocean circulation
through a number of mechanisms, such as ocean currents and cascading events.
These mechanisms may be fast and consistent enough to erode the seafloor, and
thus they have been suggested as a potential process that could form submarine
canyons.
Can oceanographic
processes explain the formation of submarine canyons that have never been
connected to terrestrial rivers or coastal systems? And what is the influence
of such processes on habitats within these submarine canyons?
The CUMECS expedition
CUMECS is
an oceanographic cruise, funded by EUROFLEETS and Marie Curie Actions, which will try to answer the above
questions. We will investigate a poorly-explored region of the Mediterranean Sea known as the Malta-Sicily Escarpment.
The Malta-Sicily Escarpment consists of a 3 km high step, located to the east of Malta and the south-east of Sicily, which separates the
Western and Eastern
Mediterranean Basins.
This region is important because it is a gateway for the exchange of water
masses with different densities between these two basins. Existing low
quality seafloor maps from the Malta-Sicily Escarpment show that this feature
is incised by numerous submarine canyons, despite the fact that the escarpment
was isolated from inputs of fluvial and coastal sediments for many years. The
Malta-Sicily Escarpment thus constitutes an excellent natural laboratory to
study submarine canyon formation in sediment-starved regions.
The CUMECS expedition will explore the Malta-Sicily Escarpment using state-of-the-art technology on board the research vessel RV Urania, operated by the National Research Council of Italy (CNR). During this expedition we plan to compile a detailed map of the seafloor using echosounders, to obtain seafloor samples using gravity cores, and to acquire video imagery of the seafloor and its habitats with a Remotely Operated Vehicle (ROV).
Affiliated projects
The CUMECS expedition is affiliated with the
following projects and initiatives:
CAGE - a Marie Curie Intra-European Fellowship project investigating the evolution of submarine canyons.
CODEMAP - a European Research Council project that maps complex habitats in the deep ocean and studies the biodiversity they support.
HERMIONE - an EU-funded project focusing on deep-sea hotspot ecosystems in European waters.
E-MARSHAL - an IGCP project facilitating the interaction of scientists and professionals interested in submarine mass movements and their geohazard potential.
Funding and acknowledgements
The CUMECS team is receiving funding from the
European Union Seventh Framework Programme (FP7/2007-2013) under grant
agreement n° 228344 (EUROFLEETS), Marie Curie Intra-European Fellowship
PIEF-GA-2009-252702 (CAGE) and a European Research Council Starting Grant
(CODEMAP).
