4 steps to understand ballast water problems
What is ballast water?
Ballast water provides stability and manoeuvrability to a ship. Usually ballast water is pumped into ballast tanks when a ship has delivered cargo to a port and is departing with less or no cargo. Large ships can carry millions of gallons of ballast water.
The threat of ballast water
The ballast water inside a ship can be seen as an onboard aquarium full of microscopic life forms. That’s because small organisms living in the sea water are pumped into ballast tanks along with the water. Moreover, coastal sediments and any associated organisms may be pumped into ballast tanks.
The ballast water is taken from coastal port areas and transported inside the ship to the next port of call where the water may be discharged, along with all the surviving organisms. This way, ballast water may introduce organisms into the port of discharge that do not naturally belong there. These introduced species are also called exotic species. Populations of exotic species may grow very quickly in the absence of natural predators. In that case they are called ‘invasive’.
Only few species are successful invaders, because most species are not able to survive in new surroundings, because temperature, food, and salinity are less than optimal. However, the species that do survive and establish a population are very hardy species that have the potential to cause major harm (to ecology, economy or human health).
Examples of invasive species in Europe
(source: Globast/GEF, UNDP, IMO-poster)
Mitten Crab (Eiocheir sinensis)
Mitten crabs travels far and in huge numbers to reproduce. They burrows into river banks and dykes causing erosion and siltation. Mitten crabs prey on native fish and invertebrate species, causing local extinction of these species. They also interfere with fishing activities by for example cut nets.
Comb Jelly (Mnemiopsis leidyi)
Reproduces rapidly (self fertilising hermaphrodite) under favourable conditions. It feeds excessively on zooplankton. Depletes zooplankton stocks; altering food web and ecosystem function. Contributed significantly to collapse of Black and Asov Sea fisheries
in 1990s, with massive economic and social impact. Now threatens similar impact in Caspian Sea.
Comb Jelly (JT Carlton)Zebra Mussel (Dreissena polymorpha)
These mussels foul all available hard surfaces in mass numbers and displace native organisms. By doing so, they alter habitat, ecosystem and food web. Zebra mussels cause severe fouling problems on infrastructure and vessels, for instance by blocking water intake pipes. Economic cost are enormous.
Zebra mussels in pipe (JT Carlton)
Toxic Algae (Red/Brown/Green Tides) Various species
Toxic algae may form harmful algae blooms, and can cause massive kills of marine life. Some species may contaminate shellfish and cause fisheries to be closed. Consumption of these contaminated shellfish by humans may cause severe illness and even death.
What can we do about this problem in the North Sea Ballast Water Opportunity Project?
We can deal with invasive exotic species in two ways: prevent them from invading in the first place, or eliminate the exotic species that have invaded. Getting rid of established exotic species is practically impossible and very expensive. Preventing invasions to occur is the more practical and economical solution.
In order to prevent possible invasions, organisms should not be discharged from ballast tanks. This can be achieved by treating the ballast water, for instance by killing organisms that are travelling in the ballast water. Several treatment methods are on the market, for instance using damaging properties of light (UV radiation). Unfortunately, no ballast water treatment method can completely eliminate the risk of introducing exotic species. What we can do is to minimize the risk.
In order to reduce the risk of new introductions of exotic species, the UN International Maritime Organization (IMO) has adopted the International Convention for the Control and Management of Ship’s Ballast Water and Sediments in 2004. This Convention aims ‘to continue the development of safer and more effective Ballast Water Management options that will result in continued prevention, minimization and ultimate elimination of the transfer of harmful aquatic organisms and pathogens’.
The North Sea Ballast Water Opportunity (NSBWO) aims to stimulate the ratification and implementation of the Ballast Water Convention 2004 by North Sea member states. The project is divided into four main subjects to coordinate development in different areas:
- Regional cohesion by means of harmonisation and defining common standards;
- Knowledge transfer, innovation and certification for Ballast Water Treatment Systems;
- Knowledge transfer, innovation and certification for detection, monitoring and compliance enforcement technology;
- Future strategies.
The project is taken care of by over 40 partners and sub-partners, spread over the seven North Sea Region countries. In addition there are close contacts with parties all over the world. The NSBWO is a project partly funded by Interreg funds.
Lab reseach at NIOZ