In my last post, I talked about “building resilience” – in fact, that was one of the recommendations in our 2022 Annual Coral Survey Report for Malaysia.

But how do we actually go about doing that?

Resilience factors

According to colleagues who know more about coral reef resilience than I do, resilience comprises three key elements:

Water quality
Physical impacts
Herbivores

If each of these is optimal, reefs will be resilient – they will be as “healthy” as possible. This increases the chances of them surviving a major external threat such as warming oceans or bleaching – of which we are seeing the first signs in Malaysia right now.

Water quality

Coral reefs thrive in clear, nutrient-poor water. Why?

Because the coral animal (or polyp, as it is termed) has microscopic algae living inside its tissue. These algae use sunlight and the photosynthetic process (because they are, after all, plants) to produce what becomes food for the coral. The algae get a home, the coral gets food – a perfect symbiotic relationship. Hence, corals survive in nutrient-poor water, which is clear.

So why is nutrient-rich water a problem?

Partly because the nutrients reduce clarity - reducing the amount of sunlight the corals can get. But the main problem is that the nutrients can encourage the growth of fleshy algae (that’s seaweed to you and I).

When fleshy algae start to proliferate, they compete with corals for space. If they grow big enough, they can smother the coral, cutting off the sunlight completely and eventually killing the coral.

Several sources of pollution contribute to this. Poorly treated sewage effluent that is released into rivers or directly into the sea can reduce water quality. Water quality tests around the islands off the East Coast – which is where most of our coral reefs are in peninsular Malaysia – suggest that there are problems with sewage pollution.

Fertilisers from agricultural activities inland are a further contributor. Land clearing and coastal development also release pollution, as well as silt – which can also smother corals.

And finally, shipping creates some pollution, too.

So one of the key steps we can take in “building resilience” would be to improve sewage treatment, particularly on the islands with their numerous resorts and local populations, but also in coastal areas.

Physical impacts

Every time I see a boatman throw an anchor over the side of a boat when mooring near a coral reef…I cringe. I can almost hear and feel the crunch as the heavy metal anchor comes to rest on a coral formation.

Such physical impacts not only degrade the reef, but the breaks can allow disease to enter the coral colony. And it weakens the whole colony.

Similar physical impacts arise from snorkelers and divers “interacting” with the reef too closely – fins, dangling gear, cameras…Maybe each physical impact is small in and of its own, but imagine a busy tourist island with thousands of visitors during the year, each possibly creating its own little physical impact.

And that’s not the only physical impact. Trash, discarded fishing nets, and other debris cause damage to reefs that are cumulative over time. Not to mention the marine life (sharks, turtles) that get caught in discarded fishing nets.

Marine debris found floating in the ocean

Programmes to educate divers and snorkelers to make them more aware of the fragility of reefs can make a significant difference (our own Green Fins project is one example). Some countries have introduced successful net recycling programmes that reduce the incidence of discarded nets.

Herbivores

What, there’s grass in the sea? Well, back to those fleshy algae.

One of nature’s controls on too much fleshy algae growing on reefs is herbivorous (or grass-eating to the non-technical) fishes. Parrot fishes are the best known algae grazer, but there are others.

The problem is, where fishing pressure on reefs is high, these fish are targeted for food. This reduces natural herbivore populations, creating conditions in which algae can start to grow and smother corals.

Herbivore populations can be protected by establishing marine protected areas (MPAs) or no-fishing areas, as discussed below.

The role of MPAs

Put all this together, and in busy tourism destinations, there is the potential for numerous impacts to become cumulative – sewage pollution, physical impacts, trash, over-fishing – it’s almost a perfect storm for coral reefs.

In coastal areas, these impacts can be managed by establishing Marine Protected Areas (MPAs) and in many countries MPAs form the cornerstone of marine conservation efforts.

The post-2020 Global Biodiversity Framework calls for MPAs to be “effectively conserved and managed”. But the problem with MPAs is that many are actually not that well managed – they are what are termed “paper parks”.

Research (1) has shown that there are five key common factors that determine the success and failure of MPAs across the world, as shown in the diagram below.

Interestingly, the researchers found that most factors indicating success were found to also point to failure, i.e. when the presence of a factor was considered to lead to success, its absence led to failure. Double whammy.

This research guides us in the direction of understanding how we can better manage our MPAs (or Marine Parks, as they are called here in Malaysia).

So now the challenge: are we up to undertake an honest assessment of marine resource management against these findings? The IUCN Green List standard provides one such framework for improving management, and that’s what we are working on in Tioman Island, one of our field sites.