I. Siokou-Frangou et al.: Mediterranean plankton
1573
the DYFAMED site, other long term offshore stations should
be established in key geographical locations to investigate
seasonal patterns, fluxes of the major components, and re-
sponses of the planktonic biota to anthropogenic and climatic
changes.
Not all the components of the pelagic system have been
addressed with comparable efforts, also because of the lack
of appropriate sampling and identification tools. The diver-
sity and distribution patterns of autotrophic and heterotrophic
prokaryotes, viruses, and eukaryotes that are the major com-
ponent of the MS epipelagos are still largely understudied.
The few molecular studies conducted since the late 90 s have
shown their great potential in advancing our knowledge on
the microbial component of the sea. Different communities
likely characterize the spatial and temporal texture of this
diversified basin, playing distinct roles in terms of energy
transfer and food web structure. The proper identification of
their components is a prerequisite for our understanding of
the functioning of the Mediterranean pelagic realm.
The intriguing picture of heterogeneity emerging from this
review points at a difference between the pelagic Mediter-
ranean and other oceanic sites, which might be explained
considering the small scale and the enclosed nature of this
basin.
This “miniature ocean” surrounded by populated
coasts, hosting a surprising and still largely underestimated
variety of planktonic organisms linked together by dynamic
and plastic trophic pathways, is an intriguing system. The
relatively close proximity with land intensifies the effect of
climatic changes and anthropic-driven impacts such as in-
creased nutrient fluxes and/or overfishing. These might af-
fect the biological structure of the basin more rapidly com-
pared to the large oceans, thus strongly supporting the role of
Mediterranean as a sensitive sentinel for future changes. The
question is: which signals the sentinel will send? From our
survey, we speculate that, in such a flexible biome, the first
signals might regard the spatial re-organization of communi-
ties. Indeed, as a consequence of scales much smaller than
in comparable oceanic regions, the MS is highly flexible and
can shift from one regime to another, since all the players are
already present. The MS offers then an attractive marine en-
vironment to study general ubiquitous processes across mul-
tiscale and multidirectional physical, biological and trophic
gradients. In some areas, many pieces of this multidimen-
sional puzzle are already in place, meaning that new research
efforts can grow on some already existing ground and that the
relevance of new results can be amplified in the frame of old
data.
In general, basic exploratory research is still needed, while
gaps in knowledge should be filled taking advantage of mod-
ern technologies and new approaches. Among these, a great
opportunity is represented by a clever merge of modern
oceanographic tools such as Autonomous Systems and the
sophisticated methods of the “omics”, whose results may
feed tentative integrated conceptual models of the system dy-
namics. Such models could be used to approach a broad
range of marine environmental issues such as fisheries, cli-
mate change impact, harmful blooms, emerging diseases and
pollution. All of these could more easily be tested due to
the scale and accessibility of the MS, and inferences later
extended to other less tractable marine systems.
Acknowledgements. The authors wish to thank Fereidoun Ras-
soulzadegan for his help in the data compilation and his contribu-
tions during the first stages of this work, as well as Miquel Alcaraz,
Marta Estrada, Mike Krom and two anonymous referees for their
careful and constructive comments. This review has also benefited
from discussions with Alessandro Crise, Fabrizio D’Ortenzio,
Maria Luz Fernand´ez de Puelles, among other colleagues.
We
finally thank Roland Louis Daguerre for his revision of the English
usage.
This paper was supported by a grant provided by the
European Network of Excellence EUR-OCEANS contract number
511106-2. We thank the authors who directly provided their data.
Additional funds were provided to D. Vaqu´e by the MICROVIS
project (CTM 2007-62140) (Spanish Ministry of Science) and
to M. Ribera d’Alcal´a by the EU IP SESAME (contract number
036949).
Edited by: E. Mara˜n´on
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