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Restoring Marine Coastal Ecosystems: What’s the Cost?

By Megan Saunders and Elisa Bayraktarov

A review of the costs and feasibility of marine restoration projects reveals that they are often very expensive and risky.

Coasts are popular areas for tourism, recreation, transportation and development. Unfortunately, our love affair with coastal regions has resulted in significant damage to large areas of natural habitat. The result has been extensive and rapid rates of decline in a range of important ecosystems including seagrass, coral reefs, mangroves, saltmarsh and oysters. This decline is being witnessed worldwide.

Along with the loss of habitat comes a decline of the ecosystem services they provide. These include the provision of habitat for threatened, iconic or fished species, shoreline protection from waves and storm surges, water filtration, and carbon storage to help mitigate climate change.

There is now considerable interest in reversing trends in the decline of coastal ecosystems. This means restoration – the process of removing the factors causing ecosystems to disappear, and/or establishing plants or animals to replace those that have been lost. Restoration is also an important element of biodiversity-offsetting projects, where losses of biodiversity from a development at one site are “offset”, or replaced, by restoration of a degraded site.

There is one important catch. For restoration to achieve a particular goal we must be able to anticipate how likely the project is to succeed, and how much it will cost.

Our study examined the cost and feasibility of restoration in marine coastal ecosystems, including seagrass, corals, mangroves, saltmarsh and oyster reefs. We accomplished this by reviewing the peer-reviewed literature and reports on this topic, and by filling in data gaps by talking to people who perform restoration. This was particularly important for oyster reefs, for which data were largely absent from the published literature.

Our review quickly established there is a huge range of costs for different types of marine coastal restoration. The least expensive projects, conducted by volunteers in “inexpensive” developing countries, could be accomplished for less than US$2000 per hectare. But these were more the exception than the rule.

The median price for coastal restoration was typically around US$80,000 per hectare. The average price, however, was up at US$1.6 million per hectare. The big difference between the median and average cost is because some marine restoration projects are incredibly expensive, costing many millions of dollars per hectare. Examples of these types of projects involve the use of artificial structures to rebuild the ecosystems in “expensive” countries like the USA and Australia.

As an aside, we observed that investment in restoration can be up to 30 times more cost-effective in developing countries than in developed countries. Yet many projects in developing nations are undocumented as there is a lower incentive to publish and report on restoration outcomes.

Information on the liklihood that a restoration project will meet its objectives was largely unavailable. Failed projects are often not reported. Instead, for project feasibility we only documented the percentage of restored organisms that survived over the reporting period.

Project duration was typically up to 1 year. Only in a few instances were restoration projects monitored for more than a decade. Feasibility ranged from 38% for seagrass to 65% for coral reefs and saltmarshes.

We were surprised to find that project success was unrelated to the amount of money spent. And restoration cost-per-unit did not decrease for larger project areas – there were no economies of scale.

This suggests that marine restoration techniques still need a bit of work. Further studies will be required to achieve a transition from small-scale to large-scale restoration of marine coastal ecosystems.

Restoration may be a critical tool used to secure a sustainable future in marine coastal ecosystems. If that’s the case, a lot more effort needs to go into understanding how we can do it more effectively.

Megan Saunders and Elisa Bayraktarov are members of the ARC Centre of Excellence for Environmental Decisions (CEED). They are based at The University of Queensland.