Proposal for controlling ballast water in ships visiting ports of central Chile marine ecoregion

Abstract

Shipping is essential to the economy. With the technological advance and faster vessels, the frequency of transoceanic trips has increased, increasing the risk of negative environmental and socio-economic impacts associated with the uncontrolled discharge of ballast water. Being this the water loaded by the ships to conserve its stability and maneuverability, but that takes matters in suspension, including biological agents, which can generate bioinvasions. Due to the above, and recognizing the importance of a precautionary approach, it is necessary to have a preventive management tool that allows to discern when unload ballast water is potentially dangerous. In this review, a tool based on the frequency and volume of ballast water coming from the same source port, the environmental similarity between the source and recipient port, and the presence of risky species in the source port, is proposed. A Coefficient of Global Risk (CRG) has to be estimated for each vessel arriving at the port in order to evaluate if the ballast water can be unloaded. For values of CRG > 16%, which means it is likely the risk, it is necessary to verify if the required replacement of ballast water in the open sea has been done in compliance with international regulations. It is recommended in situ measurements of the Chromophoric Dissolved Organic Matter (CDOM) since it allows the discrimination between coastal and oceanic water. If the ballast water turns out to be of coastal origin the lack of compliance of the regulation can be detected, thus preventing the discharge of that water in the port area.