Ballast waters as vectors for the introduction of alien speciesThe bio-invasions in the Mediterranean Sea are on the increase due to the high mariti-me traffic and the degradation of the environment.Cargo ships transport the non-native species settled on their hulls or in the ballast waters that are taken on board in special reservoirs for reasons of stability and structu-ral resistance.The problem of the introduction of allochthonous species by way of the ballast waters is particularly important for planktonic organisms, since many species, throughout their life cycle, produce resting stages that can survive in the sediments of the ballast tanks, even though the environmental conditions here are harsh.

1. The cargo ships take on ballast water in special reservoirs in the departu-re ports when they need to travel with empty holds or, however, to impro-ve their stability during navigation;

2. During the voyage many organisms that are taken on board with the bal-last water die, but many others survive, especially in a dormant phase;

3. In the port of arrival the ballast water is discharged and with it the orga-nisms that would have survived;

4. The ship departs with its holds full of cargo and heads towards its next destination.

This is water transported by ships in special reservoirs to provide stability, order, and structural integrity.Ships use water as ballast since it is much easier to load and unload. When a ship does not have cargo, it fills its ballast tanks and vice-versa.The ballast waters are essential for the security of the ship, but can constitute a serious threat to the environment, the economy, and human health.

In the past 50 years, the volume of ship movements and loading and unloading at ports in the Mediterranean Sea has increased by 77%. Every year, around 200,000 commercial ships cross the Mediterranean Sea, 30% of which head towards one of the 300 ports within the basin. It is estimated that over the next 20 years naval traffic in the Mediterranean will increase some 3 to 4 times.

The reccomendations of IMO IMO, International Maritime Organization, recommends that the discharge of ballast waters is carried out in open sea or in far areas 200 nautical miles from the nearer coast and in deep waters at least 200 meters. Moreover it would have to avoid the cargo of waters of ballast in presence of algal bloom and during the night, when zooplancton get up in sea surface; to use pumps of cargo and drainage to high speed in order to increase mortality of the organisms, and at last to subject waters of ballast to a mechanical treatment of filtering and centrifuge. In the February of the 2004 International Maritime Organization has adopted a convention that it has the objective to define common rules of uniform implementation in order to prevent upgrades them determined harmful effects from the organisms transported in the ballast waters. The “convention for the control and the management of ballast waters and se-diments of the ships” previews that all the ships must have a plan of management of ballast waters and sediments, must have a registry of ballast waters and manage them according to de-termined standards and procedures. The Convention establishes, moreover, that the ports must have adequate systems for the collection of ballast waters and sediments.

Ballast water

Discharge of the holds

Charge ofthe holds Full

holds

Emptyholds

Completely empty tank of ballast waters

4. During the navigation

Discharge of the ballast waters3. in the port of destination

Full tank of ballast waters2. During the navigation

Charge of ballast waters1. Starting port

Ballast waters cycle

Phooto of A. Grassi - Ecotaras S.p.A.

BilgeLower tanksSide tanks for ballast Bow water tank

Engine roomUpper deck

Stern water tank Tank for ballast

Realized by

Maritime Admiral Michelagnoli Foundation NGO non-profit Fondazione Marittima Ammiraglio Michelagnoli Onlus - Taranto - Italy

Photo archive "Mare Nostrum" , property of Fondazione Michelagnoli & Giuseppe Pignataro (international champion)www.fondazionemichelagnoli.it

English version translated byDr Adrian Mallia - Adi Associates Environmental Consultants Ltd - Malta

In agreement with

National Interuniversity Consortium For Marine Sciences - ItalyCo.N.I.S.Ma. - Consorzio Nazionale Interuniversitario di Scienze del Mare

With the grant of

Ministry of the University and Scientific and Technological ResearchMinistero dell'Università e della Ricerca Biodiversity and Maritime Traffic