Stowaways in ballast water and in fouling

The introduction into new environments of invasive marine species through the involuntary transport of organisms in ballast waters, or attached to the keels of ships or by means of other vectors, is recognised as one of the gravest threats to marine biodiversity.

What is “fouling”?Marine organisms tend to occupy all the spaces available, even those artificial, that is, the various items and infrastructure produced by man and submerged in the sea.These can be maritime constructions, such as quays and piers, hulls, platforms, buoys, submarine cables: on contact with sea water their surfaces become a substrate for the growth of organisms.The name given to this very complex ensemble of organisms is “fouling”.

Ships hull covered by fouling.

Detail of the encrusting organisms (serpulids) and

epiphytes (tunicates and algae).

The picture shows very clearly the cover by

colonies of invertebrates and

algae on the ropes used in mussel culture.

In order to eliminate these fouling

organisms it is necessary to expose

them to the air.In several cases, “alien”

species that have settled on the mussels

have completely suffocated them,

impeding their growth and causing their

death.

Fouling on a pole submerged in water in Mar Piccolo in Taranto.One can distinguish spirographs, ascidians, botrillids, mussels, oysters, and algae.

There are several thousands of marine species that can be transported in ballast waters and as fouling on ships: bacteria and other microbes, small invertebrates, and eggs, cysts and larvae of various species.Virtually all the marine species have life cycles that include a planktonic stage; hence even those species that as adults would �nd it di�cult to enter ballast waters because of their large size, can be transported in these waters during their planktonic phase.

Cargo of the holds

Akashiwo sanguineasanguinea is a toxic marine dinoflagellate (planktonic microalga) discovered in the ballast water tanks of certain merchant ships.

Planktoniella solis a marine diatom (planktonic microalga) native of the North Atlantic Ocean, which has been discovered in ballast waters of some merchant ships.

Gyrodinium instriatum Resting stage produced by the dinoflagellate (planktonic microalga) and discovered in the sediments of ballast water tanks in certain cargo ships.

Bicarinellum tricarinelloides Resting stage produced by the dinoflagellate (planktonic microalga) and discovered in the sediments of ballast water tanks in certain cargo ships.

Several animal species can be found in ballast waters, most in a larval stage, as well as vegetal material, especially in spore form.Port areas, which are rich in nutrients, are the ideal habitat for these organisms that take hold and develop aided by the particular physico-chemical conditions of the waters. They eventually out-compete and eliminate the autochthonous species.

On the bottoms of ships and on all the submerged surfaces, “sessile” animal and plant species take hold, apart from other “epibionts” that grow on top of the organisms that would have already taken hold on the ship’s surface.Eve in these cases, the port areas are the ideal habitat for the development of these organisms.This phenomenon is more acute when ships are docked, even for a few days.

Research on anti-foulingThe presence of fouling organisms on the hulls of ships drastically reduces the velocity of the ships leading to a higher consumption of fuel (a 5% coverage on the hull results in a 40% increase in fuel consumption). To counteract these encrustations, the use of certain biocidal paints that include chemical substances (synthetic organic pesticides and heavy metals) that partially reduce the growth of these organisms are allowed.At an international level, the use of paints that include arsenic, DDT, and other highly toxic products that can enter the food chain have been banned. Today, the research on anti-fouling products studies methods used by marine organisms to prevent the settlement of other organisms on their own body surfaces (epibiosis). The aim is to have ships that do not leave a stream of poison in their wake, but instead emit specific negative signals to spores and larvae in search of a substrate to settle on.

Zoea (larva of a crab) Jelly�sh

Balanus

Zooids,colonial ascidiantunicate

Amphipod

Ballast waters Fouling

Some organisms, like the amphipods, can travel as larvae in the ballast

waters and as adults in the fouling communities

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