Sea transportation has been the largest carrier of freight throughout recorded history. Modern vessels are designed to carry specific cargoes and will often transit with partially filled or empty cargo holds. Ballast water in dedicated ballast water tanks is used to increase the ships draft, trim, to maintain stress loads on the hull within acceptable limits and to ensure a safe stability during these voyages.
As a vessel discharges cargo, ballast water is pumped through the sea chest into the dedicated ballast water tanks. This water will contain organisms, bacteria and viruses inherent to the port water. As the vessel reaches its target destination and commences loading cargo, ballast water is pumped out in order to offset the weight being loaded. The discharged ballast water contains potential invasive species which can have a disastrous effect on a Eco system.
The spread of marine invasive species is recognized by IMO as one of the worlds greatest ecological and economic threats. Invasive species unrivaled by natural predictors cause direct and indirect health effects and serious damage to the environment which is often irreversible.
Aquatic organisms transferred to areas where they do not naturally belong, is considered one of the most serious threats to biodiversity. Ships’ use of ballast water represents the most common pathway to the introduction of non-indigenous organisms.
The spreading of harmful aquatic organisms when brought into coastal habitats via ships’ ballast water may cause irreversible changes affecting human health and industries as well as the ecological balance of the seas. These problems have already been experienced by a number of the world’s coastal states and their effects well documented.
Copyright ©: Water pollution by ballast water de.svg by Maxxl² dertivative work by Thorsten Hartmann
International Convention for the Control and Management of Ships’ Ballast Water and Sediments (IMO BWM Convention)
Recognising the severity of this issue, the International Maritime Organization (IMO) initiated work on the development of a regulatory framework in the late 1980’s.This materialised in guidelines introducing the concept of ballast water exchange between ports. Later, the IMO initiative brought real merit to the matter when it adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments on February the 13th. 2004.
The Ballast Water Convention will require all ships to implement appropriate management plans and recording procedures – but more importantly, it defines a Ballast Water Performance Standard to which ships must comply. The development of Ballast Water Treatment Systems, introduces unique challenges to the industry. OceanSaver BWTS has been developed to comply with the strictest regulations and ensure compliance in all Ballast water operations.
Impacts: Some cholera epidemics appear to be directly associated with ballast water. In 1991 a cholera epidemic started simultaneously in three separate ports in Peru with a strain native to Bangladesh. The epedemic spread across South America, affecting more than a million people and killing more than ten thousand by 1994.
North American Comb Jelly
Impacts: Reproduces rapidly under favorable conditions. Depletes zoo-plankton stocks altering it’s new food web and ecosystem function. Has contributed greatly to the collapse of the anchovy and spat fisheries in the Black and Azov Seas. Losses in the region is estimated to cost US $ 200 million annually.
Image Copyright©: (2008) Steven G. Johnson
Impacts: Fouls all available hard surfaces in mass numbers. Reduces amount of algae in the water causing reductions in natural fisheries. Causes severe fouling problems to underwater infrastructure and vessels. Economic costs to USA alone estimated between to US $ 750 million and US $ 1 billion between 1989 – 2000.
Image accreditation: (2007) NOAA, Great Lakes Environmental Research Laboratory
European Green Crab
Impacts: Highly adaptable and invasive species. Becomes dominant crab in new ecosystem and consumes and depletes a wide range of prey species. Resistant to predators due to hard shell and few predators in new environment.
Image Copyright©: (2006) Luis Miguel Bugallo Sánchez