The first known coral reef off the coast of Iraq has just been discovered, according to a paper in the journal Scientific Reports.
The conditions at the site -- the mouth of the Shatt al-Arab River in southeastern Iraq -- are surprisingly turbulent and chilly for a reef, with seawater temperatures often in the 50s (Fahrenheit).
"We were entirely surprised to find a living coral reef under such harsh conditions," lead author Thomas Pohl of Germany's Institute for Geology Scientific Diving Center and his colleagues wrote. They added that the waters are often polluted with oil and are sediment loaded, making the discovery all the more surprising.
From a distance, this brown coral might look like a crater, but it's very much alive. Coral reefs are thought to be environmentally sensitive marine ecosystems. They tend to develop in sites with clear water, ambient temperature, moderate salinity and strong wave action.
This reef, named the Palinurus Rock Reef, clearly falls at the edge of that spectrum, given the harsher conditions.
Political instability, affecting scientific exploration, likely hindered discovery of the reef. The water's low visibility also didn't help. Pohl and his team struggled to study the reef -- measuring 2.5 by 4.4 miles -- and capture images of it, given the challenges.
The authors identified a number of living stony corals and octocorals (which lack a stony skeleton), as well as sponges and aquatic mollusks that may compete with the corals for space on the reef -- or that may cause the coral structure to erode.
Despite the intense competition between species at the reef, the closeness between some organisms is very evident. Here, colorful marine animals known as brittle stars intertwine like snakes around octocorals.
Sediment, light levels, sponges and the coral itself give much of the scene a greenish hue. Four of the coral groups identified at the reef are slow-growing, massive species that are robust enough to develop under the harsh environmental conditions.
Brittle stars typically have five thin, segmented arms extending from a central disc. They are called "brittle" because, when disturbed, they can cast off parts of their arms, leaving predators hunting them completely befuddled.
Related animals called serpent stars and basket stars are also found at the Iraqi reef.
Brittle stars have a mouth, but no anus. They feed, usually at night, on small organic particles. Sea stars at reefs may exhibit an array of different colors and body patterns.
Although underwater visibility is often limited to 3 feet or less at the reef, you can find fish in the Shatt al-Arab river. The river is the only continuous freshwater source in the region.
Green-colored sponges are well distributed within the Palinurus Rock coral reef system.
Mounds of coral within the reef sometimes take on mammal-like shapes. Like gazing at clouds, interpreting what those shapes may resemble is up to the viewer.
The discovery of this unique coral reef could provoke the interest of the international scientific community working to understand coral ecosystems and climate. These habitats urgently need protection, conservation and research, especially given their location in areas of oil and gas exploration, the authors conclude.