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New science: mangrove protection, Caribbean coral loss, dam development and more

© Matthew D Potenski 2011/Marine Photobank

Protecting nature starts with science. Here’s a roundup of recent scientific research published by Conservation International experts. 

1. Mangroves and coral reefs can help protect millions from rising seas 

More than 31 million people worldwide live in regions that are extremely vulnerable to sea-level rise and hurricanes or tropical cyclones. 

According to a new study, mangroves and coral reefs could help protect more than a quarter of people at risk by serving as a buffer between coastal communities and ocean waves or flooding, and by significantly reducing erosion.

Conservation International scientists Dave Hole, Will Turner and Mariano Gonzalez-Roglich looked at mangrove forests and coral reefs situated near coastal populations around the world. They found that communities across Central America, the Caribbean, Eastern Africa, Southeast Asia and the South Pacific region stand to benefit the most from the conservation of these coastal ecosystems. Based on a range of economic and other societal factors, these communities have fewer opportunities to adapt via other means, such as building sea walls or buying insurance. 

In addition to providing extreme weather protection, conserving mangrove ecosystems in these regions also helps slow climate change over the long-term by storing nearly 900 million metric tons of climate-warming carbon emissions a year.

Yet according to the study, only 38 percent of mangroves and 11 percent of coral reefs located along the most vulnerable coastlines are protected. Already, one-third of these coastal ecosystems that lack environmental protections have been lost since 1980 due to development, aquaculture and overfishing. 

“Ensuring the resilience of mangroves is a win-win-win for people, nature and the climate,” Hole said. “Mangroves store more carbon than any other forest ecosystem on Earth, drawing carbon dioxide down from the atmosphere and storing it for decades, thus helping slow global warming.”

2. Caribbean corals are dying. Humans are to blame 

A new study revealed that two crucial coral species in the Caribbean were declining decades before climate change began impacting the world’s oceans — showing that human activities such as overfishing and coastal development can have drastic impacts on coral reefs. 

Over the past 40 years, warming ocean temperatures and acidification have caused mass deaths of coral reefs worldwide — which could have catastrophic implications for marine life and the people who depend on it. But climate change is not the only thing affecting corals around the world, according to Conservation International’s Ocean Science Fellow Katie Cramer, the study’s lead author. 

By combining fossil data, historical records and underwater surveys, Cramer was able to track the decline of elkhorn and staghorn corals in the Caribbean over the past 125,000 years. According to the data, these corals began to disappear in the 1950s to 1960s — at least two decades before the impacts of human-driven climate change were evident. 

“This research shows that local human activities such as overfishing and coastal development have been weakening coral reef health for quite some time,” Cramer said. “Local actions matter for the future of coral reefs. The best way to help them cope with the intensifying impacts of ocean warming is to reduce these other stressors affecting them.”  

3. Unheralded fisheries hold key to sustainable development 

Well-managed fishing areas in freshwater ecosystems could help increase food security, alleviate poverty, provide jobs and protect biodiversity, according to a recent study

Despite the crucial services these inland fisheries provide, they are absent from global policies that aim to achieve the United Nations’ 2030 list of Sustainable Development Goals, or SDGs (goals to address some of the world’s most pressing issues including poverty, disease and food insecurity). 

“The current SDGs focus on the role of freshwater ecosystems for supplying water security to communities around the world, but they offer so much more than that,” explained Ian Harrison, the director of freshwater science and policy at Conservation International and a co-author of the study, “This priority, while important, may be at the detriment of properly managing the habitat itself as well as the species within it, rather than just the water resource flowing through it.”

By comparing the relationships between inland fisheries, freshwater conservation and human well-being, the researchers were able to identify which SDGs could benefit from the inclusion of inland fisheries. For many low-income, food-insecure populations, these ecosystems are critical sources of food and jobs, with inland fisheries employing more than 58 million people.

However, research shows that due to overfishing, climate change and development, more than 30 percent of freshwater ecosystems have been lost since 1970 — and that this loss will continue to accelerate if countries do not increase investments in freshwater conservation.  

“If left unprotected, the health of communities, millions of jobs and nature will be at risk,” Harrison said. “Countries need to recognize the importance of conserving freshwater ecosystems and prioritizing inland fisheries in their SDGs so that they can continue to provide crucial services for humanity.” 

4. Dams in these 3 rivers could threaten lifeblood of Southeast Asia

Three of the most important rivers for conserving fish populations in Southeast Asia’s Mekong Basin are under threat due to rapid agricultural and hydropower dam development, according to recent research.  

The Sesan, Srepok and Sekong rivers — known collectively as the “3S” — lead directly into the Mekong River Basin, which supports the food security and livelihoods of more than 300 million people. Recently, however, dam development has put the health of these rivers — and subsequently the entire Mekong Basin — at risk, causing severe flooding, droughts and declining fish populations.  

Using a tool developed by Conservation International to measure the condition of freshwater ecosystems — known as the Freshwater Health Index (FHI) — a group of researchers identified the sources of stress that are degrading this critical group of rivers. 

“The FHI assessment showed us that if dam development continues at its current pace, the Mekong River Basin will not be able to sustain the crucial services it provides — from fertile land for rice to grow to the livelihoods supported by one of the world’s largest inland fisheries,” said Nick Souter, the lead author on the study and Conservation International’s Greater Mekong Program Freshwater Manager.  

Although dam development has started to slow in parts of the Mekong Basin, countries must also protect the tributaries that feed into it such as the 3S, according to Souter.  

“Only a few decades ago the Mekong was one of the world’s last great free flowing rivers, but development and pollution have left it severely degraded,” Souter explained. “Fortunately, some of its tributaries, particularly the Sekong River, are still in good condition — for now. Conserving them is vital to ensuring the continued ability of the Mekong Basin to provide the ecosystem benefits that millions of people rely on.” 


Kiley Price is a staff writer at Conservation International. Want to read more stories like this? Sign up for email updates here. Donate to Conservation International here.

Cover image: A young lemon shark in a mangrove forest in the Bahamas (© Matthew D Potenski 2011/Marine Photobank)

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