How do we save the world’s coral reef systems?
Diverse underwater areas have been woefully degraded by human activity
As some of the most diverse ecosystems in the world, coral reefs have intrinsic natural value. But they also supply “ecosystem services” — benefits to us. “Protecting them and managing them well is in the interests of everybody around the world,” says Canadian marine biologist Aaron MacNeil.
Yet many are woefully degraded, and scientists still work under a cloud of unknowns when it comes to restoring reef biodiversity. MacNeil is the lead author of a new Nature study that “gives us the road map.” WHY DO REEFS MATTER? Food Reef fisheries supply sustenance for hundreds of millions worldwide, particularly in developing nations. The UN says 275 million people depend directly on reefs for a livelihood, but rich countries benefit. The U.S. National Oceanic and Atmospheric Administration pegs the commercial value of U.S. reef fisheries at more than $100 million. Drugs New drugs rely on the discovery of novel compounds, and diverse eco- systems like coral reefs are a particularly ripe for “bioprospecting.” A few marine finds: AZT, the antiretroviral HIV drug, is derived from a sea sponge, and a class of compounds called bryostatins extracted from an organism called Bugula neritina is in clinical trials as a cancer and Alzheimer’s drug. Protection Coral reefs are a natural buffer. They protect coastal areas from incoming waves and prevent erosion of beaches and shorelines. As sea levels rise due to climate change, that becomes increasingly important: one 2005 study estimated that waves hitting the vulnerable Seychelles islands have doubled in energy, mostly due to reef destruction. HOW DO WE FIX REEFS? Baseline Surprisingly, until now scientists had no way of knowing what the fish population in a healthy reef looks like. By examining data from remote, barely touched reefs and long-standing marine reserves, the Nature paper establishes an all important baseline: healthy reefs have approximately 1,000 kilograms of fish per hectare.
“It’s one of the first (studies) that looks across a large number of coral reef ecosystems and tries to evaluate how many fish were there once upon a time. That’s an important benchmark,” said Villy Christensen, co-director of the UBC Fisheries Centre, who was not involved with the research. Timeline By charting fish biomass in marine reserves of different ages, the researchers were also able to estimate how long it takes for a reef to fully recover. If protected, the most degraded reefs would reach full biomass after 60 years. Previous estimates were much lower, but the Nature study is actually good news.
“If you realize it’s going to take at least one human generation to recover the biomass on a coral reef, then you think twice about purposely damaging it,” says Nick Dulvy, Canada Research Chair in Marine Biodiversity and Conservation.
This paper will help manage conservation expectations, and “reminds us you need to be in there for the long term.” Restrictions Most importantly, scientists said, the Nature study examined options other than expensive, all-encompassing marine reserves. Limiting harmful fishing equipment, restricting what species can be caught, and managing access can bring reefs toward 50 per cent of full fish biodiversity, enough to sustain both human livelihoods and the ecosystem.
“People live there. To think we’re going to close off large parts of the world to resource use is a throwback to neocolonial thinking,” says Dulvy. Climate change: the X Factor Fishing is the most pervasive source of reef degradation globally. But a fiercer challenge looms: climate change, which presents an existential threat to temperature-sensitive coral. “To work on coral reefs is to work under a bit of a rain cloud. The spectre of climate change is hanging over everybody’s head,” says MacNeil, senior research scientist at the Australian Institute of Marine Science. “But for our group, we’re the optimists. We tend to think, ‘Well what can we do right now?’ ”