Fate and effects of oil and dispersed oil
on mangrove ecosystems in Australia

1) Before an oil spill is reported.

Thoroughly assess past spill incidents and identify successful and unsuccessful practices. Conduct research to improve techniques and knowledge for controlling, collecting and dispersing oil at sea. Transport less toxic oils where possible. Improve awareness of environmental values and concerns. Support ecological research monitoring past spill events as well as promoting specific studies addressing key issues in advancing our understanding of how oil affects mangrove habitats and their ecological functions.

2) Soon after an oil spill. Reduce the amount of oil getting into mangrove areas by using booms and collection devices. Apply appropriate low toxic dispersants in deeper waters away from mangroves. Reduce the toxicity of oils which reach mangroves by delaying the arrival of spilled oil reaching mangroves. Accelerate degradation of spilled oil on the water by promoting weathering and biodegradation. If oil cannot be prevented from reaching mangroves then attempt to control the time of its arrival to match higher tidal heights which will deposit oil in less vulnerable parts of the inner tidal zone and forest. The goal is to protect seaward fringing trees which maintain stand integrity.
3) After oil reaches mangroves. Map the extent of oiled mangrove habitat and quantify the amounts of oil present, using a simple classification system. The survey of impacted areas needs to be backed Up with a collection of surface sediments for later detailed analysis of hydrocarbons, as needed. Map and describe the amount and types of oiled and dead mangrove fauna and seedlings.
4) After oil has killed mangroves. Map deforested areas and describe species involved. Survey and measure levels of hydrocarbons in sediments. Promote appropriate rehabilitation of damaged areas. Support natural recruitment of seedlings in deforested sites and provide supplemental planting, only if necessary. Promote growth and survival of surviving trees and seedling recruits until stand integrity is self-sustaining.

Figure ES.1: Response strategies and actions during the three critical phases when oil spills threaten or affect mangrove habitat.

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April 7, 2010