Ship's ballast water and marine pollution

The introduction of invasive marine species into new environments by ships' ballast water attached to ships' hulls and via other vectors has been identified as one of the four greatest threats to the world's oceans. The other three are land-based sources of marine pollution, over exploitation of living marine resources and physical alteration/destruction of marine habitat. Ballast is any material used to weight and/or balance an object. One example is the sandbags carried on conventional hot-air balloons, which can be discarded to lighten the balloon's load, allowing it to ascend. Ballast water is therefore water carried by ships to ensure stability, trim and structural integrity. Shipping moves over 80% of the world's commodities and transfers approximately 3-5 billion tones of ballast water internationally each year. A similar volume may also be transferred domestically within countries and regions each year. Ballast water is absolutely essential to the safe and efficient operation of modern shipping, providing balance and stability to unladen ships. However, it may also pose a serious ecological, economic and health threat for sea nature life. This paper gives ten dangerous ballast water organisms in the oceans.