Algae blamed for dying reefs

The coral reefs in the waters
surrounding Cayman are dying, and it is algae that is killing them, some marine
experts say.

There is a delicate symbiotic
relationship between coral and algae: The coral feeds the algae, and the algae
uses sunlight to produce carbohydrates and fats that the corals consume. The
reef ecosystem provides food, and it lures tourism that is geared to underwater
adventure in and around the reefs.

When the sea temperatures reach heated
levels, the corals expel the algae, essentially starving themselves. The corals
turn a bright white or lighter shade, something that is referred to as ‘coral
bleaching.’ If there are too many nutrients in the water, often caused by large
deposits of waste from humans that acts like a fertiliser, the algae overtake
everything in the area, including corals.

Thomas Goreau, president of the Global
Coral Reef Alliance, a nonprofit organisation for coral reef protection and
sustainable management, believes that the overabundance of nutrients in the
water caused by sewage and waste runoff causes algae overgrowth that leads to
fewer fish in the areas – known as the ‘bottom up’ theory.

“Every place I dived in Grand Cayman,
there was an overgrowth of algae,” Mr. Goreau said.  “Cayman believes that they are a top diving
place in the world, so they don’t do much to change.”

He said that decisions regarding coral reefs around Cayman are made on
economic and marketing grounds, rather than on the health of the reefs.

“(Cayman) is politically under a ministry who are for development at all
costs,” he said.  “Cayman does have a
nutrient problem, and like most places, they tend to be in denial.”

Unlike the majority of marine biologists who blame over-fishing for fewer
fish in and around the dying coral reefs and overgrowth zones of algae – known
as the ‘top down’ theory – Mr. Goreau stands by the bottom-up theory.

“… in the ‘80s down in the Florida Keys, a green ring formed around the
island from septic tanks overflowing when the rain hit, and flooding occurred.
In general, there’s excess nitrogen in the water, and if you put phosphorus in
the water – wham, you get massive algae overgrowth,” said Mr. Goreau, who is
also coordinator of the UN Commission on Sustainable Development Partnership in
New Technologies for Small Island Developing States.

Referring to another common theory – climate change – Ray Hayes, a
professor at Howard University and an expert on ocean warming and coral reefs,
says climate change by itself cannot be blamed.

He said the accumulation of introduced waste from humans and other sources
in conjunction with warmer water temperatures has led to the algae
overgrowth.  New coral diseases also
contribute to death of coral.

“Nutrient enrichment from fertilizer can lead to more nutrients in the
sea,” he said. “Sewage needs to be treated to a tertiary level before it’s
released.”

Mr. Hayes points to overpopulation and resulting septic overload, and high
human density as agents of algae overgrowth.

Although Cayman has one of the oldest sets of marine protection laws,
according to Mr. Hayes, there is more to be done in Cayman to protect the
coral.

“I like to think of coral reefs as giving a feeling of satisfaction and
recreation that supports human health,” he said, adding that coral reefs are an
attractive resource that provide information and education on marine
ecosystems.

The reefs are also important to human beings’ survival, as well as the
survival of entire islands like the Cayman Islands.

Coral reefs protect the shoreline from erosion and it builds new sand for
the beaches — the beaches could be lost over time.  These are indirect effects on humans.

One of the direct effects of dying coral from waste nutrients is that the
algae overgrowth and blooms of algae can create toxins in the water that could
potentially kill fish and humans.

“The nutrients coming from the waste and sewage can also cause skin
irritations and ear infections from the pathogens in the water,” Mr. Goreau
said.

“The disconnect comes with the idea that people think that the reefs will
somehow be there forever, that they’re inexhaustible,” said Tim Austin of the
Cayman Islands Department of Environment, which has been monitoring coral reefs
here for 14 years.

But there are some things that the average person who’s concerned about
coral survival and clean waters can do.

“Homeowners can look for proper sewage treatment, and removal of waste and
garbage,” Mr. Hayes said.  “Septic
systems need to be checked and drained regularly to prevent overflow.  The government has responsibility as well.”

Mr. Hayes said that marine laws should be observed and enforced.

“It’s important for the public to be alert and aware.  If they see something that doesn’t look
right, tell the authorities,” he said. 
“The Department of Environment can’t be everywhere.  But there’s no reason the public should be
violating these laws.”

The algae growth is reaching a point where decisions by the public, marine
experts and government must be made to act decisively to save the coral reefs
or lose them forever.

“When I see algae overgrowth, you know it’s very late in the day,” Mr.
Goreau said.

“Fundamentally, the reefs around Cayman are instrumental in the quality of
life that we enjoy on this island,” said Mr. Austin, who is assistant director
of research and assessment of the DoE and oversees the department’s diverse
marine and terrestrial research and conservation programmes on all three Cayman
islands..

“They provide the fish, the calm water, the beaches, the protection from
waves, the diving resources. And that does not take into account the ecosystems
services that they provide, the biological diversity.”