A rainbow parrotfish in the Caribbean. Photo: © Ken Marks
By Matt Miller, senior science writer
To best protect the coral reefs in the Caribbean, begin by protecting parrotfish.
That’s a key recommendation in a recent report by the Global Coral Reef Monitoring Network, the International Union for Conservation of Nature (IUCN) and the United Nations Environment Program.
Coral reefs face a lot of threats, of course – from climate change to pollution to invasive species.
But the report makes the case that restoring parrotfish, large herbivores that keep seaweed in check on the reefs, could pay big dividends in restoring reefs. You might consider them underwater bison.
Unfortunately, parrotfish and other herbivorous fish have been over-fished in recent decades.
So to save Carribean reefs, could it really be as simple as better protecting parrotfish? Not so fast, says Stephanie Wear, the Conservancy’s lead scientist for coral reef conservation and a current NatureNet Fellow.
Wear agrees that parrotfish and other herbivores are essential for reef health. But she also believes that effective long-term conservation will need to focus on complex causes and solutions.
I recently sat down with Wear to discuss the IUCN report and what it means for conservationists.
Why are parrotfish a key ingredient for keeping reefs healthy?
Stephanie Wear: On coral reefs there is an all-out war happening between corals and seaweeds.
They are both competing for space and light and parrotfish are important coral allies in this battle. In fact, parrotfish act as lawn mowers and help to give corals the upper hand by making sure fast-growing seaweeds don’t overgrow the more slow-growing corals.
If it weren’t for herbivores, corals would quickly become suffocated by seaweeds on many reefs around the world – which is what is happening in the Caribbean.
Coral reefs are transforming into algae reefs in places where parrotfish populations are small. We know that if healthy populations of parrotfish are present – it can be a good indication that the reef is healthy.
In the past, you’ve cautioned that protecting reef fish should not be the only strategy to protect reefs. What else should conservationists be considering?
Wear: While overfishing is the top threat to coral reefs, it is compounded by other serious threats that act in concert to degrade reefs over time.
This is one of the main points of the report – that local threats are the biggest and most immediate concern for coral reefs and that if we don’t get our act together on reducing those threats, climate change will just be the knock-out blow in what has been a long battle taking place over many decades.
“If it weren’t for herbivores corals would quickly become suffocated by seaweeds.” — Stephanie Wear
Coral reefs are negatively impacted by what happens on land, so when we don’t treat our sewage properly and it ends up in the ocean, coral reefs get sick.
When we develop coastal land without making sure there are buffers in place to eliminate dirt eroding and flowing into the sea – we end up suffocating reefs that get smothered in sediment.
If we were to just focus on the overfishing problem – we would miss key threats to coral reefs and our efforts would not achieve our goal of protecting coral reefs.
We need more parrotfish, less sewage and less sediment run-off. It is not a matter of having just one, we need all three to happen to prepare reefs to deal with global threats of warming and increasing CO2.
NatureNet Fellow Stephanie Wear. Photo: © Ian Shive
This report mentions pollution as one of the factors affecting coral reefs, which has been one of your focal areas at The Nature Conservancy. Why is this a major conservation concern?
Wear: Polluted water is one of the top three threats to coral reefs across the world.
Coral reefs depend on clean, clear, and low-nutrient water to thrive and when water quality is compromised, so are coral reefs.
In fact, we would put our other conservation investments at risk (protected areas, restoration, fishing regulations, etc.) by not working to improve water quality.
The pollution comes from both land and sea-based activities, with one of the most common being raw sewage leaking or being directly discharged into the ocean.
I am particularly interested in the sewage problem because untreated sewage in the environment is a problem for both people and reefs. If we can identify creative ways to solve this problem for both people and reefs, it would be a huge win for coral reef conservation and human coastal communities.
What can conservationists do about it?
Wear: Part of the problem until now is that as much as we reach out and partner to get things done, we often don’t reach far enough and miss out on working with folks from totally different but complementary sectors.
Often it is said that it’s difficult to address the water pollution problem because it is managed by another agency, or that there are too many stakeholders involved or that it’s a technology problem.
“If we spent all of our money on parrotfish conservation, we would not save reefs. If only it were so simple!” — Stephanie Wear
if we spent all of our money on parrotfish conservation, we would not save reefs. If only it were so simple! – See more at: http://blog.nature.org/science/?p=43685&preview=true#sthash.4Lpu4SXn.dpuf
There are plenty of reasons that make it difficult to go beyond our current toolbox, but if we want to see a difference in these systems, we need to start addressing the biggest local threats and that means new collaborations.
In the meantime, we can’t forget about the impacts of climate change – which for coral reefs, means warming and acidifying seas that create stressful and even fatal conditions.
The most important thing to come out of this latest report is the reminder that it is not over for coral reefs and if we can get ourselves organized and focused on minimizing the immediate threats, coral reefs have a great chance of persisting over the next century.
Does focusing on a single strategy/species help conservationists focus, or is it too simplistic?
Wear: While protecting parrotfish is critical to maintain reef health, it is not the single key to reef health.
In fact, if we spent all of our money on parrotfish conservation, we would not save reefs. If only it were so simple!
One of the things that makes coral reefs so amazing is their complexity – but this also makes it more difficult to understand how they function.
We are learning new things every day about coral reefs. For example, we have recently learned that there is goby (think tiny cute reef fish) that responds to chemical alarm signals that corals send out when their space is invaded by a seaweed competitor.
“If we can get ourselves organized and focused on minimizing the immediate threats, coral reefs have a great chance of persisting over the next century.” — Stephanie Wear
The little fish show up within minutes and chomp down the algae – in some cases they spit it out – not even swallowing the algae!
It is clear that they are protecting their habitat – coral– from being overgrown. And it’s amazing that these organisms are collaborating on this!
Given these complex interactions, we need to be careful not to oversimplify when it comes to management strategies.
Yes, protecting parrotfish is extremely important and we should be doing everything we can to ensure healthy parrotfish populations but parrotfish conservation is only one part of the solution.
My concern is that if we oversimplify solutions, we miss an opportunity to take a more holistic approach, which is more likely to lead to successful outcomes in the long run.
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.