Manila Clam (Tapes philippinarum Adams & Reeve, 1852) in the Lagoon of Marano and Grado (Northern Adriatic Sea, Italy): Socio-Economic and Environmental Pathway of a Shell Farm - Aquaculture and the Environment: A Shared Destiny - page 70

recorded since the beginning of the 1990s (Sfriso & Marcomini, 1996). In this way, the
resuspended sediment could be transported by natural hydrodynamics, e.g. tidal currents,
and eventually reach deeper channels and be driven outside the lagoon. Even if the
resuspended sediment is redeposited in other shallow areas, it would not be well stabilized
and would therefore be more exposed to erosion processes. So in the Venice Lagoon,
resuspension due to mechanical clam harvesting could produce an additional effect on the
natural erosion of the shallow bottoms, which is at present one of the major points in the
safeguard policy of the Venice Lagoon (Pranovi et al., 2004).
Experimental studies were conducted also in the Lagoon of Marano to test the impact of the
“maranese rake”, the shallow hydraulic escalator harvester and the hand harvesting on
benthic communities and sediment texture and to estimate the regeneration times of
macrozoobenthos after the employ of these harvester methods (Orel et al., 2001; 2002; 2005).
Everyone leads to a drop of richness and abundance of macrozoobenthos and a loss of fine
sediments after the haul of harvesters or the hand method. Nevertheless, after 4-5 months from
the experimental harvesting, sedimentary and biological conditions were restored. In this way
we could assume that harvesting of Manila clam in the Lagoon of Marano and Grado not
involve any relevant environmental modification in the short term and space, but on the
contrary the reiteration of the activities in term of space and time could induce long term
negative impacts, by progressive reduction of sediment thickness (Orel et al., 2001; 2002).
7. Future approaches and production sustainability
7.1 Trends
Given forecasts of increasing air and sea temperatures (Hulme et al., 2002) it might be
expected that the Manila clam will spread to more sites around the coasts of Britain and
Europe. The magnitude of the environmental consequences of the naturalisation of the
Manila clam at these sites is likely to depend upon the density that the species attains. This
in turn is likely to depend upon the future environmental conditions and the intensity of
any fishery for this commercially valuable resource. Thank to Regulation (EC) No 708/2007,
concerning use of alien and locally absent species in aquaculture, the risk assessment to
cultivate Manila clam in the EU is no more necessary. After 25 years from its introduction,
this species has never threatened the original ecosystem of the Lagoon of Marano and
Grado. On the contrary the development of its sustainable culture could represent a benefit
to the local fisheries economy.
7.2 Responsible practices toward sustainable production
In the Lagoon of Marano and Grado a temporary association among business operators was
constituted in 2009. This association includes ALMAR Society, Molluschicoltura Maranese
Society and the Cooperative of fishermen St. Vito of Marano Lagunare. The goal of this
historical cooperation is to start together a pathway towards the sustainable aquaculture of
Manila clam in the Lagoon of Marano. After many years of conflicts, the results, the prestige
and the reliability got by ALMAR and Molluschicoltura Maranese in the shell farm business,
the Cooperative St. Vito, grouping the major part of the fishermen in Marano Lagunare,
perceived the necessity to enter the way of the cultivation in the lagoon. Anyway before the
constitution of the temporary association, the cooperative already got in 2005 a financial