Made up of tiny, nearly invisible coral polyps, barrier reefs are in fact the largest living organisms on earth and visible from outer space. But while Australia’s Great Barrier Reef is a world heritage site and remains one of the country’s main tourist attractions, coral reefs in Papua New Guinea are known only to a few adventurous divers and, now, scientists.
A recent study led by Katharina Fabricius, a principal research scientist from the Australian Institute of Marine Science (AIMS), has drawn fresh attention to the effect of carbon dioxide on marine life, after observing fish behaviour in the proximity of three shallow volcanic seeps (or bubble reefs as they are known) in PNG. The findings confirm laboratory experiments conducted by Geoffrey Jones from the James Cook University in Australia, who has been studying PNG’s coral reefs for over 18 years and published extensive studies on the effects that acidification has on the sense of smell in fish. “As humans continue to pump carbon dioxide into the atmosphere, the oceans are becoming increasingly acidic. Volcanic seeps are similar to what surface waters will be like by the end of the century,” said Jones.
The research conducted by the AIMS team confirmed that the sense of smell for fish living in these acidic waters is seriously impaired, affecting their capacity to pick up on important chemical clues such as the smell of nearby predators. This makes them particularly bold and fearless, increasing their mortality rate by predation by more than fivefold. “PNG continues to experience plenty of seismic activity because of its recent geological formation, and the diversity of its coral reef offers a critical alternative to controlled laboratory experiments,” said Jones. Similar conditions do not currently exist in Australia, he pointed out.
In Kimbe Bay, located in West New Britain Province, scientists have recorded more than 860 species of coral reef fish and over half of the world’s coral species – a diversity that puts PNG on par with the Philippines and Indonesia, which were previously believed to be the world’s most species-rich coral seas. However, the Global Coral Reef Monitoring Network issued a report estimating that 25% of the world’s reefs are severely damaged and PNG’s reefs are not immune, although they are still in relatively good condition. “Coral reefs are extremely sensitive organisms that are adapted to clear tropical waters. Any human activity impacting water quality may have devastating consequences,” said Jones.
“If forests are our lungs, the oceans, which account for 75% of the planet’s surface, is certainly our body, and we better look after it,” Princess Laurentien of the Netherlands, the president of Flora & Fauna International, said recently while addressing a large audience in Sydney about the danger of micro plastics. Ingested by marine life, especially by molluscs, these tiny particles present in exfoliating products such as toothpaste are a growing concern for both animal and for human health, as they end up in our food chain.
Warmer waters, the result of climate change, have been producing massive coral bleaching events. PNG’s waters are among the warmest in the world and may provide an early indication of how coral reefs can adapt to ocean warming.
Waters in PNG are typically about 31°C all year round and any further increase to this may be devastating for organisms that primarily thrive in temperatures between 23°C and 29°C. According to recent studies, the oceans have currently absorbed around one-third of humanproduced greenhouse gas emission, amounting to 530bn tonnes of carbon dioxide, and for the first time in nearly 300m years their pH is starting to change with consequences that are still unclear. “We can speculate that marine life will adapt to these new conditions and the experiment in PNG is testing exactly that, but it is too early to tell,” said Jones.
In the meantime organisations such as the Centre for Biological Diversity are lobbying governments to list certain species of corals and reef-dependent fish as endangered to offer protection from acidification and preserve these areas for future research efforts.
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