LOS ANGELES, CA (Catholic Online) - Coral reef ecologist at the Australian Institute of Marine Science Katharina Fabricius says he she has been diving and working on the reef since 1988. She has watched the reef's tragic decline.  

"I hear of the changes anecdotally, but this is the first long-term look at the overall status of the reef. There are still a lot of fish, and you can see giant clams, but not the same color and diversity as in the past," she says.

Fabricius and her colleagues surveyed 214 different reefs around the Great Barrier Reef and compiled information from 2,258 surveys to determine the rate of decline between 1985 and 2012. With the overall 50 percent decline, the scientists estimate that the reef is losing about 3.4 percent of itself annually.  

The relatively pristine northern region, however, has shown no decline over the past two decades.

The reef's decline is attributed to several factors. The biggest factors are smashing from tropical cyclones, crown-of-thorns starfish that eat coral and are boosted by nutrient runoff from agriculture and coral bleaching from high-temperatures, which are rising due to climate change.  

Coral bleaching is the process in which ocean temperatures rise and cause the corals to expel their zooxanthellae - the tiny photosynthetic algae that live in the coral's tissues.

"This is a really grim wake-up call," John Bruno says a biologist at UNC Chapel Hill. "The GBR [Great Barrier Reef], which only 10 years ago was considered the world's most pristine and resilient coral reef is clearly not better off and no less threatened than any other reef. I am bullish on the long-term survival of reefs, but science like this is challenging that outlook."

Reducing carbon dioxide emissions are essential in order to maintain the reef. "International efforts to cap and reduce CO2 emissions are equally critical and must occur at the same time as cleaning up local impacts," Les Kaufman, a biologist at Boston University says.

Fabricius says not much can be done in the short term about the climate-change-driven frequency of cyclones - five category 5 storms in the past seven years have pounded the reefs - or high temperatures. There are efforts underway to stem the damage from starfish, which can grow up to 3 feet in diameter and sport long venomous spines and 21 arms. Young starfish feed on coral-making algae, leaving behind the coral's skeleton.

One project encourages farmers to adopt practices that limit the amount of nutrient-rich runoff draining into reef areas. Another would allow tour operators to manually remove starfish from tourist areas, which Fabricius admits isn't a solution, just a temporary fix.

Inaction is not an option at this point. "The problem is entirely soluble, and coral reefs can be saved through concerted effort over this and the following two or three generations," said Kaufman. "There is absolutely no excuse for failure to do this, and if we do fail our generation will forever be remembered for unimaginable, unforgivable stupidity and sloth."

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