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Damage compensation in marine ecosystems: a matter of methods

Prevent, repair or compensate damage caused to marine ecosystems is a complex issue for which there is no such thing as a unique and easy solution. Critical analysis of the system used in Florida where compensation measures are compulsory.



Compensation of damages caused to ecosystems have been the subject of an increasing interest, owing to their multiplication and to the better understanding of the direct or indirect services they provide to society. In the United States, regulation systems dealing with environmental protection require those responsible for damage to ecosystem services to compensate for it "physically" and restore these services with measures whose effectiveness is assessed by quantitative indicators.

This paper deals with the indicators underlying the compensation systems used in Florida, in order to better understand how to estimate the equivalencies between ecosystem services lost due to damage and ecosystem services gained due to compensatory measures.
Equivalency is defined as the equality of two quantities describing the impact on a damaged site and the improvement on another nearby site where ecological compensation were applied. These quantities are calculated from indicators like the area (impacted/compensated), the intensity (of the loss/gains of ecosystem functions or services due to damage/compensation) and the time scale of damage/compensation. To carry out this work, a reports review has been carried out and several interviews were conducted with the main stakeholders responsible for compensatory procedures. The analysis considered the two methods used in Florida to determine the ecosystem equivalencies for marine and coastal environments.

Intensity is measured by the ecosystem services or functions lost because of the damage or gained through compensatory measures. Up until now, indicators have been based on social standards regarding what is important to limit social conflicts. The main goal was to counterbalance the losses sustained by divers and recreational fishers by the deployment of artificial reefs. These reefs efficiently provide a high level of abundance of large fishes and thus maintain the cultural and social ecosystem services (recreational fishing, scuba diving) but they do not offset the loss of regulation (ecological processes, nursery,…) and support (primary production, nutrient cycles,…) services provided by biodiversity, or of specific habitats (seagrass beds, shallow sand bottoms,…). This approach to mitigation results from the fact that the economy of Florida is highly dependent on tourism, including diving and recreational fishing, and to a certain historical tradition of artificial reef deployment. However, it appears that things are changing.


An artificial boulder-type reef, the model most commonly used in Florida (photo Sylvain Pioch)

Time-scale is referred to differently by the two methods used in Florida. It plays an important role through the choice of which species need to be monitored to measure the effectiveness of the project (if monitoring of short-lived species, results are provided sooner but may not be significant on the long term) and the capacity to carry on a scientific monitoring over long periods. Long-term monitoring programmes have shown that there is no "natural convergence" towards a "natural equilibrium" on compensation reefs, and that early conclusions can be misleading with regard to the assessment of compensation success.

Area is concerned through the ratio compensated area/impacted area. The greater are the richness of the impacted habitat, the inadequacy of the compensation measure or the uncertainty on its success, the greater should be this ratio. However in most cases it is highly subjective by lack of a genuine scientific foundation; area then becomes the adjustment indicator which allows all projects to be accepted, even if their chances of success are very poor. The cost of restoration (related to the compensation area) could provide a strong economic incentive to avoid or mitigate rather than compensate ecological damages right from the start of a project. In fact, when compensation measures are chosen, the increasing costs and the area equivalence ratio always lead to reject the minimal option of mere habitat preservation (on an area sixty times larger than the impacted area), in favour of options which are more demanding (creation of a new habitat or restoration of a damaged one) and more expensive but involve much smaller areas (2 to 5 times less than the impacted area). However so far this economic incentive does not seem to work, as compensation is always preferred to avoidance and mitigation.

The process of ecological damage compensation in Florida is driven by the single criterion of area, and is still mainly based on the implementation of artificial reefs. This situation has several explanations. There is a significant lobby of stakeholders having an interest into the use of these reefs (recreational fishers, divers, reef manufacturers). The courts and public offices prefer proven solutions (like boulder reefs) that avoid social conflicts and risks for their careers. Finally, the main problem is the lack of an "environmental champion" without whom the consensus regarding compensatory measures is always oriented toward specific stakeholders' interest and not toward environmental goals. In this situation, even if the capacity for technical innovation is high and the funds are available, it is difficult to use them because of the existing political, social, and legal consensus in Florida on the use of boulder reefs to compensate for impacts.


The paper

H. Levrel, S. Pioch, R. Spieler, 2012. Compensatory mitigation in marine ecosystems: Which indicators for assessing the "no net loss" goal of ecosystem services and ecological functions? Marine Policy 36 : 1202–1210.
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The authors

This work was done in collaboration by researchers of the laboratory Amure of IUEM, the Center for functional and evolutive ecology (Montpellier) and Nova Southeastern University (Florida).


The journal

Published by the international editor Elsevier, Marine Policy is a leading journal of ocean policy studies. Major articles are contributed by specialists in marine affairs, including marine economists and marine resource managers, political scientists, marine scientists, international lawyers, geographers and anthropologists. It covers international, regional and national fields of marine policies institutional arrangements for the management and regulation of marine activities, fisheries and shipping, conflict resolution, marine pollution and environment, conservation and use of marine resources.



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