Hundreds of thousands of tourists visits Green Island each year to enjoy scuba diving and snorkelling among its beautiful reefs, but no sewage treatment exists so an average of 1,500 tons of untreated sewage is flushed into the sea on a daily basis.

According to The China Post , no sewage treatment project has been prepared for the island since land can’t be procured for a sewage plant. Researchers now fear that the untreated sewage is to blame for the spread of the so called “Black Death” among the corals.

Chen Jhao-lun, a senior research fellow at the Academia Sinica who has studied the coral
reefs, describes the affected colonies as being covered slowly with a piece of black cloth.
“As this black sponge which multiplies itself covers the colonies, it shuts off sunlight to stop
photosynthesis by coral polyps,” Chen explains. The polyps die and no new corals are formed.

The “Black Death”, a type of necrosis, typically manifests in the form of black lesions that gradually spread across the surface of an infested colony.

However, very little is known about the Black Death and some researchers think that other factors, such as changing water temperatures or overfishing, might be to blame – not the untreated sewage. It is also possible that a combination of unfavourable factors have tipped the balance of the reef, causing the disease to go rampant. Temperature does appear to be a key variable associated with outbreaks, but it remains unknown if a temperature change alone is capable of causing this degree of devastation.

Molecular studies on lesions have not been able to identify a likely microbial pathogen, and according to Chen, the black layer might actually be an opportunistic second effect rather than the causative agent of the coral mortality. Montipora aequituberculae corals seem to be especially susceptible to the disease, but at least five other coral species from three different genera have been affected as well.

When Chen surveyed the water of Green Island last year, only four colonies off Dabaisha or Great White Sand showed signs of Black Death. In April this year, Chen found 24 affected colonies – six times as many as last year. If nothing is done to remedy the problem, Great White Sand near the southernmost tip of Green Island may have only dead colonies in five to six years, Chen predicts.

Green Island
Green Island is known as one of the world’s best spots for scuba diving and snorkelling. Located roughly 16 nautical miles southeast of Taitung on east Taiwan, Green Island used to house a concentration camp for political prisoners. Today, it is instead famous for its rich coral reefs.

(The picture is not from the green island but rather the great barrier reef)

A recent study on intersex abnormalities in fish living in the Potomac River watershed carried out by researchers from the U.S. Fish and Wildlife Service and the U.S. Geological Survey showed that at least 82 percent of male smallmouth bass and in 23 percent of the largemouth bass had immature female germ cells (oocytes) in their reproductive organs. This number is even larger than anticipated.

This type of intersex indicates that the fish has been exposed to estrogens or chemicals that mimic the activity of natural hormones. The condition is believed to be caused by hormone-like chemicals, so called endocrine disruptors, found in medicines and a variety of consumer products. Earlier, researchers suspected that the contaminants were entering the Potomac from the wastewater treatment plants that discharge into it, but further sampling showed that the problem existed in areas located upstream from sewage plants as well. Officials are now investigating if multiple chemicals, and not just those from sewage plants, may be responsible. A larger study that includes the entire Potomac River and other East Coast rivers will be launched to find out how widespread the problem actually is.

“At the moment we don’t know the ecological implications of this condition and it could potentially affect the reproductive capability of important sport fish species in the watershed,” said Leopoldo Miranda, Supervisor of the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office.

The Potomac River is the fourth largest river along the Atlantic coast of the USA (in terms of area), with a length of approximately 665 km (383 statute miles) and a drainage area of roughly 38,000 km² (14,700 square miles). It flows into the Chesapeake Bay along the mid-Atlantic coast of the U.S. The river is shared by West Virginia, Maryland, Virginia, and District of Columbia, and all of Washington, D.C., the nation’s capital city, lies within the Potomac watershed.

More information is available in the Intersex fact sheet released by the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office.