The Coral Sea provides migration corridors for species such as humpback whales, loggerhead turtles and freshwater eels.
Credit: Wikimedia
SYDNEY: Australia's Coral Sea is one of the last remaining places on Earth brimming with large predatory fish such as sharks and tuna, and is a crucial migratory zone for many threatened species.
A new report has found that the 972,000 square km zone stretching from the Great Barrier Reef to the waters of the Solomon Islands and New Caledonia, known as the Coral Sea Conservation Zone, is home to many unique and endangered species. The area is under interim protection while the Australian federal government assesses the area for potential inclusion in a marine reserve.
"The southern edge of the Coral Sea is considered a global biodiversity hotspot for ocean predators such as sharks, tunas and billfish," said the report.
"Oceanic and reef sharks have been documented in large numbers in some parts of the Coral Sea, especially in areas protected from exploitation. Deep-water sharks are known to dwell on the deep continental slopes and plateaux."
52 deep-water shark species
While only a small part of the area had been intensely studied, available data indicated that the sea held important habitats, migration corridors and ecological processes sustaining unique marine life.
According to the report, entitled Australia’s Coral Sea: A Biophysical Profile and written by independent marine ecologist Daniela Ceccarelli from James Cook University in northern Queensland, the Coral Sea has 18 reef systems (which includes 49 little islands, cays and multiple small reefs) that are more vulnerable than the reefs in the Great Barrier Reef because of their isolation from one another.
At least 28 species of whales and dolphins have been recorded in the Coral Sea, including pods of up to 400 false killer whales and 400 melon-headed whales, and 52 species of deep-water sharks and rays - 18 of which are known to exist only there.
Important migratory route
The report also found that the Coral Sea is an important migratory route for many species of threatened turtles; its cays and islands provide critical habitat for endangered green turtles.
It also holds the world's only confirmed spawning aggregation of black marlin and provides migration corridors for species such as humpback whales, loggerhead turtles and freshwater eels - the last of which spawn in the northern Coral Sea and migrate up to 3,000 km to Australian and New Zealand coastlines.
The southern Coral Sea also has large densities of fish and squid which, as middle-rankers in the food chain, play an important role in regulating food web stability, the report said. In total, some 341 species recognised by the International Union for the Conservation of Nature (IUCN) for their conservation significance are present in the Coral Sea.
Deciding the Coral Sea's future
Ceccarelli said that knowledge of the deeper Coral Sea ecosystems is still in its infancy. "However, early studies have revealed a great diversity of habitats, including massive canyons at least 3 km deep, which produce unique ecological communities. Recent discoveries include diverse cold water coral communities and high abundances of predatory fish and sharks in the deeper reaches of coral reefs," she said.
Ceccarelli discovered that average distances travelled by tuna, marlin, swordfish and sailfish that are commonly found in the Coral Sea range from 370 to 1,482 km. The scale of the Coral Sea Conservation Zone is therefore large enough to conserve wide-ranging ocean species. It is anticipated that the Australian federal Minister for the Environment, Tony Burke, will make an announcement about the future of the Coral Sea later in 2011.
Hugh Possingham, director of The Ecology Centre at the University of Queensland, commented that the report is an important contribution to our understanding of the Coral Sea ecosystem.
"The Coral Sea may be the only part of the world's tropical ocean where a permanent marine park of the scale of the interim Conservation Zone could be established and effectively managed with a relatively small impact on users," he said. "This is the chance to have a vast area with large numbers of herbivores and predators functioning over a huge scale in a way that the world once was like without humans."
