Reef Restoration by 'engineering' techniques: what are the issues?

As I was posting the article "Electricity revives Bali coral reefs" today on wildsingapore news, I realised the significance of the following comments on 'engineering' techniques in reef restoration. In particular, on the practice of such techniques on our shores.

Here are some extracts for thought, emphasis mine.

Extracts from a Resolution "Regarding the Need for Scientific and Financial Evaluation of Coral Reef Rehabilitation Methods" (PDF) submitted at INTERNATIONAL CORAL REEF INITIATIVE (ICRI)General Meeting Seychelles, 25th – 27th April 2005

1. Tropical coral reefs have been extensively damaged by pollution, overfishing, sedimentation, coral bleaching and disease throughout large areas of the Caribbean and Indo-Pacific regions.

More recently there has been damage due to natural events (e.g. tropical storms and the devastating tsunami of 26 December 2004);

2. The area of reefs damaged during these events is often vast, covering hundreds to thousands of square kilometres, such that the economies of local communities and countries are adversely affected;

3. Naturally Governments and the private sector with economic interests in coral reefs will seek ‘quick’ solutions, some based on engineering principles to ‘repair’ the damage and to accelerate natural recovery processes;

4. These agencies, however, may lack the capacity or expertise to evaluate the scientific and costs-to-benefit relationships of proposed coral reef rehabilitation techniques and to apply them in an effective and sustainable way;

5. Most coral reefs have considerable natural recovery capacity, provided that there are supplies of suitable coral, fish and other larvae, and that chronic disturbances such as excess sedimentation, pollution and over-fishing are minimised. Coral reefs can begin to recover immediately, with new coral growth and fish stocks naturally re-colonising the ecosystem within one to two years; complete recovery may take longer depending on the environment;

6. A wide range of ‘engineering’ techniques have been proposed as reef reconstruction or rehabilitation techniques by various commercial and non-commercial organizations. These include:

i. a mechanism using wire frames through which electricity is passed to accrete calcium carbonate and accelerate the growth of transplanted corals;

ii. installation of artificial reefs, including concrete structures; and

iii. mechanisms for re-cementing and re-gluing corals and other organisms to the substratum.

8. [It is} acknowledged that there is often a valid case for rehabilitation of damaged reefs and that some innovative and new approaches to coral reef conservation and management may potentially have applications, however we are concerned that there have been insufficient peer-reviewed, long-term scientific studies of reef rehabilitation using these and other techniques.

Moreover, there have been few cost-benefit analyses to assess effectiveness of the methods over natural recovery processes.

The available evidence suggests that some techniques may be useful in specialized cases, but all have limited or no application and value for large-scale coral reef rehabilitation.

In addition to effectiveness considerations, construction of any engineered structure on a coral reef must be evaluated against any potential environmental damage caused during construction or later degradation;

The proponents of this ICRI Resolution are in agreement that:

• Artificial reefs of any kind cannot replace a natural reef and do not function as effectively as a living coral reef;

• Coral reefs can usually repair themselves quickly if environmental conditions are suitable, and chronic disturbances are reduced;

• These techniques have the potential to cause environmental damage to coral reefs and associated ecosystems during construction and operation;

• Investments in coral reef conservation and preservation should therefore focus on removing the causes of coral reef decline and facilitating natural and longterm recovery.

The proponents of this ICRI Resolution suggest that the following basic questions should be answered prior to applying reef rehabilitation methods:

• Is a lack of colonisable habitat a limiting factor for coral settlement and reef development?

• What it the area of damaged reef that is targeted for rehabilitation?

• What are the chances for natural recovery of the reef? For example: are there available natural sources of coral larvae; are there stable habitats for settlement; and are environmental conditions favourable for reef growth?

• What is the cost per square meter of treatment to achieve a viable functioning reef?

• How much will a proposed treatment cost to repair a substantial area of damaged reef?

• What are the potential economic of sociological returns if a reef is rehabilitated?

• What are the likely impacts on surviving reef areas used as a source of collected transplant colonies?

• What is the likelihood of survival to normal growth and reproduction of colonies transplanted onto artificial structures?

• Have the causative stresses that led to reef damage been addressed/removed?

• Will any added structures be stable in the long-term and not degrade, thereby creating a future problem?

The International Coral Reef Initiative (ICRI) is a partnership among governments, international organizations, and non-government organizations. It strives to preserve coral reefs and related ecosystems by implementing Chapter 17 of Agenda 21, and other relevant international conventions and agreements of the Convention on Biological Diversity, December 1994.