observable sub-lethal effects from exposure to dispersed oil which do not persist more than a few weeks. In a natural environment, on a medium or long timescale, biota which have been exposed to oil (with and without dispersant) do exhibit some symptoms which could affect their survival rate in the field even though they do not lead to acute toxicity effects. However the DISCOBIOL project demonstrated that effects of dispersed oil were less severe than previously recorded for near shore environments. In terms of applying these results to decision making at an oil spill, it highlights the need in coastal areas prior to the use of dispersant to complete a Environmental Benefit “Net Analysis” (NEBA) to determine whether the use of dispersant is expected to minimize the overall damage resulting from the pollution. As it is difficult to cover the number of possible spill scenarios at the contingency planning stage, instead of completing a NEBA, many countries define geographical limits where dispersion can be undertaken, based on the water depth and the distance to the shore as well as the presence of sensitive resources. The DISCOBIOL study confirmed the appropriateness of these pre-defined limits for France’s coastal waters but demonstrated that they could be less restrictive since the exposure to dispersed oil could be at least five times higher than was previously considered the safe limit. INTRODUCTION Coastal waters are home to some of the world’s most diverse ecosystems as well as also one of the most heavily populated areas and, hence, most affected by discharges, whether from urban, agricultural or industrial sources. Although the risk of oil pollution in coastal areas has considerably dropped since the tightening of safety regulations and maritime surveillance as a result of activities coordinated through the International Maritime Organisation, there is still a risk of oil spills in the marine environment.
observable sub-lethal effects from exposure to dispersed oil which do not persist more than a few weeks. In a natural environment, on a medium or long timescale, biota which have been exposed to oil (with and without dispersant) do exhibit some symptoms which could affect their survival rate in the field even though they do not lead to acute toxicity effects. However the DISCOBIOL project demonstrated that effects of dispersed oil were less severe than previously recorded for near shore environments. In terms of applying these results to decision making at an oil spill, it highlights the need in coastal areas prior to the use of dispersant to complete a “Net Environmental Benefit Analysis” (NEBA) to determine whether the use of dispersant is expected to minimize the overall damage resulting from the pollution. As it is difficult to cover the number of possible spill scenarios at the contingency planning stage, instead of completing a NEBA, many countries define geographical limits where dispersion can be undertaken, based on the water depth and the distance to the shore as well as the presence of sensitive resources. The DISCOBIOL study confirmed the appropriateness of these pre-defined limits for France’s coastal waters but demonstrated that they could be less restrictive since the exposure to dispersed oil could be at least five times higher than was previously considered the safe limit. INTRODUCTION Coastal waters are home to some of the world’s most diverse ecosystems as well as also one of the most heavily populated areas and, hence, most affected by discharges, whether from urban, agricultural or industrial sources. Although the risk of oil pollution in coastal areas has considerably dropped since the tightening of safety regulations and maritime surveillance as a result of activities coordinated through the International Maritime Organisation, there is still a risk of oil spills in the marine environment.
IOSC14_DISCOBIOL.docx