Many people, even those with only a passing interest in ocean conservation, know that many of the world's coral reefs are being threatened by a variety of environmental impacts. Ocean acidification, pollutants, runoff from urban development, and increasing water temperatures are having their effect, usually in the form of coral bleaching. Corals are supported in a symbiotic fashion by zooxanthellae, algae embedded in the very tissues of the coral. When environmental conditions are not right, the algae dies off and the weakened coral loses its color and starts a slow decline that can often lead to death.
With each summer, as tourism swells and swimmers, snorkelers, and divers entire the water, another threat takes aim at these beautiful but fragile marine ecosystems. And it is an unusual and seemingly unlikely danger. Sunscreen.
That's right. The very stuff that keeps you from looking like a lobster right out of the pot, is also a proven danger to coral. The effects of sunscreen on coral has been the subject of several studies over the past several years. One of the most revealing was conducted in 2008 and published in Environmental Health Perspectives. Researchers from Italy's Polytechnic University of Marche Region, studied the effect of several sunscreen compounds on corals in a controlled laboratory setting and found that four common ingredients caused dormant viruses in the zooxanthellae to awaken and replicate, killing the zooxanthellae and spilling into the surrounding water to do more damage to other corals.
The four ingredients - paraben, cinnamate, benzophenone, and camphor derivatives - are found in many leading brands of sunscreen. The research showed that even very small amounts of these compounds can induce coral bleaching in as little as four hours.
But really, how much of a threat can this be? The World Trade Organization (WTO) has some numbers to illustrate the problem's potential. Ten percent of all tourism takes place in tropical areas, amounting to approximately 80 million people visiting coral reefs annually. With that, the WTO estimates that as much as 6,000 tons of sunscreen lotions are released in reef areas each year, putting as much as 10% of the reefs at risk of death by sunscreen.
You can check your sunscreen label for the chemical culprits or look for sunscreens that are labeled as "coral or reef-safe." No one is suggesting that you fry in the sun and spend your later years in the dermatologist's office, dealing with skin damage. But by reading labels and purchasing sunscreen known to be safe for corals, you'll be taking a personal proactive step to protect coral reefs - while we focus worldwide efforts on the other challenges to the ocean's colorful undersea gardens.
Read a summary of the study in Environmental Health Perspectives.
Read more about coral death by sunscreen in National Geographic News.
Was perusing through two articles on coral reefs that addressed the same basic issue - coral health - and had an interesting connection.
First, for those of you who are not familiar with the coral-zooxanthella relationship, within the tissues of coral are forms of algae, zooxanthellae, that provide much of the coral's color. This algae exists in a symbiotic relationship with the coral: basically, the coral generates wastes and nitrogen which the algae feed on and, in return, the algae produces nutrient sugars that the corals require.
Healthy coral exists only within very specific parameters and when environmental conditions are not ideal, as with an increase in water temperature, the algae disappears and the overall health of the coral is weakened, a condition called "coral bleaching" which can often prove fatal for the coral. Coral bleaching can be a naturally occurring event, like lightning-induced forest fires, which nature can withstand or handle. But climate change has been cited as a leading cause of an alarming increase in coral bleaching events worldwide.
A study published in Ecological Applications (Vol. 19[6]), detailed how better coral reef management which would produce clearer and cleaner water can help improve the coral's ability to withstand the effects of temperature change, thereby better resisting coral bleaching events. The article, Improved water quality can ameliorate effects of climate change on corals, cited coral's inability to genetically adapt or to alter the coral-zooxanthella relationship to better resist changes in temperature. The study reviewed data from coral bleaching events occurring in Australia's Great Barrier Reef during 1998 and 2002, examining relationships between heat stress and nutrient flux (what's in the water). Areas of poorer water quality played a significant role in the severity of the coral bleaching event.
So, what kind of factors can impact the water quality surrounding coral reefs and how can coral reef management be of help?
Another study, published in Environmental Pollution (Vol. 157[8-9]), also examined the Great Barrier Reef - this time focusing on pollution, specifically herbicides which, along with insecticides and fungicides, make their way into the coral reef ecosystem as runoff from agricultural areas through rivers and creeks. According to the article, Herbicides: A new threat to the Great Barrier Reef, even at low trace levels, these pollutants can impact the overall health of the corals, thereby reducing their ability to withstand any other adverse changes to the environment, such as temperature change, and making them more susceptible to coral bleaching.
Proper coral management must be a far-reaching holistic approach encompassing activities, such as agricultural development in developing countries, that can contribute to a compromised marine ecosystem already beset with worldwide issues like climate change. Healthy coral reefs provide home and food for a variety of sealife, a natural barrier to protect island communities from weather-inspired wave action and, at the very least, serve as a barometer for the overall health of the oceans.
To learn more about coral reef conservation:
Some good news for coral reefs within U.S. territorial waters: the National Marine Fisheries Services (NMFS) will spend the next year conducting an evaluation on the status of 82 different coral species in light of data presented by the Center for Biological Diversity (CBD). The review will determine the current health of the various corals in Florida, Hawaii, and other island territories. By doing so, the NMFS can ascertain whether any coral species warrant threatened or endangered status under the Endangered Species Act, similar to elkhorn and staghorn coral which are currently listed as threatened.
Corals are the building blocks of tropical reefs but exist within a narrow band of environmental factors. Changes in water temperature, ocean acidification, pollution from commercial development - any one of 
these can lead to a degradation of the reef, often through a process called "coral bleaching." Unhealthy or dead reefs can be torn down by wave action, and this can have a serious effect on coastline or island erosion - not to mention the disruption to tropical reef ecosystems when corals that provide shelter and food for a variety of aquatic species disappears.
"The status review is an important step forward in protecting coral reefs, which scientists have warned may be the first worldwide ecosystem to collapse due to global warming," said Miyoko Sakashita, lawyer for CBD.
Read Washington Post article.
In the United States, the Obama administration is considering ordering all federal agencies to evaluate any major actions to be taken by considering either their impact upon or how they would be affected by climate change.
As reported by Jim Tankersley in the Los Angeles Times, the order would expand the scope of the National Environmental Policy Act and represents a step forward in recognizing the impact of global warming in the U.S. and is considered a victory for environmentalists."The act already requires federal agencies to consider environmental impacts such as land use, species health and air and water quality when approving projects. By formalizing a requirement to consider effects on climate -- a step some agencies already take -- the administration would introduce a broad new spectrum of issues to be considered."
But it's not a done deal yet. According to Nancy Sutley, head of the White House Council on Environmental Quality, the decision is not yet final. This will provide time for climate change opponents and business interests to get their lobbying efforts into high gear. Admittedly, the current environmental impact report process is a drawn out one that has delayed more than a few projects in the past. Having to make the additional consideration as to whether a shoreline road project might impacted by rising sea levels or whether rising temperatures might mean that different species of trees would replace trees cut down in a clear-cutting project - as was cited in the Times article - will provide environmentalists with additional reasons to question certain federal agency plans. So, expect the battle lines to be drawn.But if the current administration is going to hold true to its concerns about addressing climate change, then this step is probably a good one. The article quoted David Bookbinder, chief climate counsel for the Sierra Club as saying, "People will think longer and harder and smarter about what they build when they understand that the environment around them is changing." Read the LA Times article. On the other side of the globe, in Australia, the Great Barrier Reef Marine Park Authority (GBRMPA) has dismissed claims from some local scientists that the corals of the Great Barrier Reef are currently not at risk from climate change. GBRMPA chairman, Dr. Russell Reichelt said there is strong scientific consensus, research and fieldwork to confirm that the increase in ocean temperatures brought on by global warming poses the greatest risk to the future health of Australia's coral reefs. This refutes the contrary position taken by Dr. Peter Ridd,
who believes the threat is greatly exaggerated.According to an article in the online Cairns.com.au, Dr. Reichfelt says that coral bleaching is the most compelling evidence of the effects of temperature change and that the incidence of coral bleaching and its severity have been increasing over the past two decades."You’ve got animals and plants there that are adapted to withstand up to the normal [temperature] limits," Dr. Reichfelt said. "If you’ll take it above what they’re adapted to, they’ll die." Read Cairns.com.au article.
Coral reefs are one of the ocean's most colorful and complex creations. I'm sure you have read about how they are in peril. Climate change, acidification, human development - all are having an impact, most often represented by coral bleaching which is the result of the loss of the symbiotic algae that lives within the coral.
I was reviewing several scientific papers and found that there are many studies going on to determine more specifically what is happening to the reefs. As it turns out, the external factors of temperature, pollutants, and others can trigger a variety of eco-systemic or internal components that adversely affect the coral. Oh, if it were only simple, then the solutions might be simpler too.
One study examined the impact on several species of reef fish and their aerobic scope, or ability to breath, in elevated temperatures. Ever felt your breathing was a bit more labored on a really hot day? Well, according to this study, reef fish can have a similar reaction when water temperatures rise. This causes a reduced capacity to absorb oxygen which weakens the health of the fish, its level of immunity, and overall lifespan.
Water quality was found, in another study, to impact the sensitivity of corals to coral bleaching. "Terrestrially-sourced dissolved inorganic nitrogen" or DIN was found to make coral more sensitive to the temperature threshold that triggers coral bleaching. Higher levels of DIN are often found in areas of human development in the form of runoff from urban development or construction.
The levels of nutrients within a coral reef system can also effect the balance between hard corals, anemones, and algae. All three live in relative harmony, with hard corals as the dominant species. But in the typically low-nutrient world of a healthy coral ecosystem, warmer temperatures can increase nutrient levels and, at various levels, the anemones become more aggressive towards the coral and at the highest levels, the algae becomes dominant.
Coral reef ecosystems are tremendously complicated and we are continually learning more about the inter-relationships of species and the environment. And not everything falls into perfect agreement. One study that reviewed the relationship between temperature and salinity at a mass bleaching in Thailand, found that salinity did not seem to play a critical role in triggering the event. Whereas, another study concluded that higher salinity levels can impact both the coral host and its symbiotic algae, effecting its long-term health.
We still have much to learn but the research must continue so that we have a clear understanding as to what is happening to the earth's coral reefs so that we can both potentially treat and prevent the abuses that are impacting these critical marine ecosystems.
Healthy coral reefs include a multitude of nooks and crannies that provide a base and secure haven for a variety of organisms - from algae and plants to mollusks, lobster and fish. But according to Seaweb.org, a new study released by the University of Anglia in England shows strong evidence that Caribbean reefs are "flattening" and providing a less than favorable architectural structure that threatens the reefs' survival.
Comparing 460 studies done since 1968, the report identifies the reef "rugosity index" which measures the habitats' architectural complexity. An index number of 1.0 is considered flat, while at the other end of the scale (a healthy reef), anything greater than 3.0 is very rare. Apparently most reefs that were studied with an index of 2.5 have now disappeared and 75% of the reefs are around 1.5.
What is causing this? The report lists several potential causes - all naturally induced calamities.
White-band disease in the 1970's (which impacted Acropora coral species), followed by a disease-induced mortality in the mid-80's of a predatory urchin species (though a predator, the urchin serves to keep coral reefs healthy and free from overcrowding; like thinning a forest through natural processes). Then there was coral bleaching in the late 90's, where stressed coral expels its symbiotic algae. All of this could represent the natural ebb and flow of a reef: calamities that the reef could withstand and recover from in time.
But add to that, the impact of human activities - everything from pollution, acidification, excess sediment from land development, destructive fishing practices - and the reefs could be pushed far beyond their ability to recover. The loss of coral reefs would have immediate impact on fish populations (which have been in decline in the Caribbean for years), in addition to impacting commercial fish and lobster businesses. Lastly, the flatten architecture of the reefs would reduce their ability to act as important coastal protection from wave energy, exposing coastal communities to increased wave action, higher sea levels, and greater exposure to hurricanes.
Not only do we need to not threaten reefs with our own activities, but we must actively study and judiciously and carefully protect reefs when they are threatened by natural events to insure their long-term survival . . . and ours.
Many people, even those with only a passing interest in ocean conservation, know that many of the world's coral reefs are being threatened by a variety of environmental impacts. Ocean acidification, pollutants, runoff from urban development, and increasing water temperatures are having their effect, usually in the form of coral bleaching. Corals are supported in a symbiotic fashion by zooxanthellae, algae embedded in the very tissues of the coral. When environmental conditions are not right, the algae dies off and the weakened coral loses its color and starts a slow decline that can often lead to death.
The four ingredients - paraben, cinnamate, benzophenone, and camphor derivatives - are found in many leading brands of sunscreen. The research showed that even very small amounts of these compounds can induce coral bleaching in as little as four hours.
