Tag Archives: Coral Bleaching

Sunscreens trigger VLPs that cause mass coral bleaching? The case of the blunt razor.

Posted on by
4

I was rung up today by a journalist who wanted me to comment on whether sunscreens could cause coral bleaching. Her question was triggered by an article published this month in Environmental health Perspectives by Danovaro, R. et al. (doi:10.1289/ehp.10966.) which shows that very small amounts of sunscreen can cause corals to bleach. This is potentially interesting given the often close association of tourists and coral reefs.Nature News

Looking closely at the paper, however, I think there may be a few problems. Whereas the article talks about ‘bleaching’ (which involves the specific movement of symbiotic dinoflagellates out of the coral tissue, which remains behind), the photo that accompanies the article shows a white coral which looks as if it has lost all of its host tissue. That is, the coral looks dead in my opinion rather than bleached.

Danovaro et al. (2008) also discuss the mechanism behind the putative bleaching caused by the sun screens. The authors saw a proliferation of viral like particles or VLPs in their ‘bleached’ specimens and concluded that the VLPs were responsible. Why did Danovaro and his team conclude this? Well, there are earlier pieces of work out of Willy Wilson’s laboartory, supposedly showing that mass coral bleaching is triggered by latent VLPs are triggered by elevated water temperatures (Lohr et al. 2007). Willy is pretty straight up about it. “I’m pretty convinced that viruses are instrumental in the whole bleaching process,” says William Wilson from the Bigelow Laboratory for Ocean Sciences Sciences in Boothbay Harbor, Maine (Nature News). Continue reading →

Hurricanes and global warming devastate Caribbean coral reefs

Posted on by
Reply

The Guardian, January 24 2008

Storm damage from waves and death of vital algae likely to become more common, report warns

Warmer seas and a record hurricane season in 2005 have devastated more than half of the coral reefs in the Caribbean, according to scientists. In a report published yesterday, the World Conservation Union (IUCN) warned that this severe damage to reefs would probably become a regular event given current predictions of rising global temperatures due to climate change.

According to the report, 2005 was the hottest year on average since records began and had the most hurricanes ever recorded in a season. Large hotspots in the Atlantic and the Gulf of Mexico powered strong tropical hurricanes such as Katrina, which developed into the most devastating storm ever to hit the US.

In addition to the well-documented human cost, the storms damaged coral by increasing the physical strength of waves and covering the coast in muddy run-off water from the land. The higher sea temperature also caused bleaching, in which the coral lose the symbiotic algae they need to survive. The reefs then lose their colour and become more susceptible to death from starvation or disease.

Impacts

Carl Gustaf Lundin, head of the IUCN’s global marine programme, said: “Sadly for coral reefs, it’s highly likely extreme warming will happen again. When it does, the impacts will be even more severe. If we don’t do something about climate change, the reefs won’t be with us for much longer.” Some of the worst-hit regions of the Caribbean, which contains more than 10% of the world’s coral reefs, included the area from Florida through to the French West Indies and the Cayman Islands. In August 2005 severe bleaching affected between 50% and 95% of coral colonies and killed more than half, mostly in the Lesser Antilles.

The IUCN report highlights pressures on coral reefs in addition to those of overfishing and pollution identified in recent years. A recent study found that reefs near large human populations suffered the most damage.

Continue reading →

Is there a case for the “bacterial bleaching hypothesis’? Oculina patagonica / Vibrio shiloi revisited

Posted on by
3

The idea that mass coal bleaching is caused by bacteria bleaching as opposed to temperature stress has been quite a contentious issue over the past decade. Despite the fact that massive amounts of evidence that have accumulated that support the idea that thermal stress has driven the mass episodes of coral bleaching (pigment loss associated with the dissociation of the symbiosis between coral and their dinoflagellates) over the past 30 years, some oxygen has been given to the alternative idea that mass coral bleaching is triggered by the presence of bacteria from the genus Vibrio.The idea that bacteria were involved in triggering coral bleaching originated from work done on the temperate coral Oculina patagonica from the Mediterranean sea (an invading species from the Atlantic coast of South America) seemed to suggest that the annual coral bleaching was due to a bacterial infection from a putative pathogen, Vibrio shiloi.

This discussion focuses on recent work done by my laboratory and which was published in the Nature journal ISME (download here) and which suggests that bacteria are not responsible for triggering mass coral bleaching (in O. patagonica or anything else). We are interested in your thoughts and hope that you will comment in the hope of resolving debate over this issue for once and for all.

The Bacterial Bleaching Hypothesis is based on a series of eloquent microbiological investigations conducted by Eugene Rosenberg and his group revealed the intra-cellular penetration, multiplication and subsequent cellular lysis of zooxanthellae by V.shiloi resulted in the annual bleaching of O.patagonica in temperatures above 28ºC. Since then, the bacterial bleaching hypothesis has been extrapolated as an explanation for global mass coral bleaching, and more recently, the coral ‘probiotic hypothesis’ (link). To some (including Eugene Rosenberg), the workplace emphasis onto bacteria rather than climate change as the cause for mass coral bleaching – the implications for the future of coral reefs would be highly significant if Rosenberg were correct.

Continue reading →

More on the coral bleaching event in Japan:

Posted on by
Reply

As I blogged earlier, the reefs off Okinawa are undergoing a severe bleaching event. The latest news from researchers in the region suggest that it may be worse than previously thought:

Coral bleaching is observed in Ishigaki Is. since late July. High SST(>30C) has continued around the southwest Ryukyu archipelago this summer. SST is measured at 35 degree C at the most affected area of bleaching (shallow lagoon) in the daytime. – Takanori Sato

As a result of these high sea surface temperatures, the reefs are beginning to show signs of prolonged bleaching and subsequent mortality similar to that of the mass bleaching event in 1998:

Continue reading →

Coral bleaching in Florida & the Caribbean

Posted on by
Reply

Mark Eakin from NOAA posted the following observations on coral list on the 31st July:

Following on to the increased potential for bleaching that we
reported two weeks ago, thermal stress has continued to increase in
the lower Florida Keys. This results from heating of the Florida Bay
waters to an anomaly well over 1 degree C. Another similar region of
anomalous warmth extends along the western coast of the Bahamas from
Andros Island to Grand Bahamas Island. The Florida Bay waters that
bathe the lower Florida Keys and the waters from northwestern Andros
to Bimini have accumulated more than 4 degree weeks of warming,
placing both areas under a Level 1 Bleaching Alert.

Late last week, Billy Causey reported about 10% bleaching of corals
off West Summerland Key around the western side of Bahia Honda
Channel on the ocean side of the bridge. It was especially
disturbing that the bleaching was hitting a diverse group of coral
species, not just the more sensitive ones.

 

Continue reading →

Mass coral bleaching off Okinawa

Posted on by
Reply

Yossie Loya - bleaching It would seem that the beautiful reefs of Okinawa in Japan are experiencing stress again. In 1998, large areas of these unique Japanese reef systems bleached and died. Let us hope that this is not about to happen again. Here is a story that just appeared in the Yomiuri Shimbun (August 5) . Picture by Professor Yossi Loya (1998 bleaching event in Okinawa)

Large swaths of coral off islands around Okinawa Prefecture have been turning white due to a phenomenon known as coral bleaching–a sign that the coral is dying. This phenomenon has been sighted for the first time in four years in locations in the prefecture such as the coast around Ishigakijima island, which boasts the country’s largest coral reef, and is thought have been brought on by high water temperatures in July.

Continue reading →

Looking forwards to 2008

Posted on by
Reply

The Australian Bureau of Meteorology have released their seasonal temperature outlook for August to October 2007 following the Austral winter. Averaged over the next three months, the chances of increased temperatures in Queensland (and the Great Barrier Reef) are between 55 and 80% for above-normal maximum temperatures, and of increased overnight warmth between 50 and 60%.

“The pattern of seasonal temperature odds across northern Australia is a result of continuing higher than average temperatures over much of the tropical Pacific Ocean, and also in parts of the tropical and sub-tropical Indian Ocean. The Indian Ocean has been warming strongly in recent months and this is the dominant influence on the outlook.”

After experiencing the warmest autumn month on record followed by one of the coldest months on record (resulting in significant bleaching of reef-flat corals as I posted here earlier this month), it’s set to be an interesting year.

Oh dear, here comes another expert on the Reef.

Posted on by
20

peter_ridd.jpgThis time it is Dr. Peter Ridd (an expert in marine physics) who is claiming that there is an even greater swindle going on with respect to the Great Barrier Reef. The title of Dr. Ridd’s opinion piece dated 19th of July 2007, says it all – “The Great Barrier Reef Swindle”.

His thesis? Hundreds of scientists who work on the Great Barrier Reef are all also involved in the same sort of cover-up and conspiracy that we were told about in the Great Climate Change Swindle! Big news indeed.

Yes, same story, scientists make up the doom and gloom tale so that they can get lots of research money from unsuspecting agencies and donors.

Sound familiar? Jennifer Marohasy has written similar things in the past (and she loves his opinion piece!). Oh, and guess who Dr. Peter Ridd reports to in his role as Science Coordinator to the newly created” Australian Environment Foundation“? Continue reading →

Photographs from the coldwater bleaching event (17/07)

Posted on by
Reply

 

An update with recent photographs from the 2007 cold-water bleaching event at Heron Island (from Dr Selina Ward, a researcher and lecturer at the University of Queensland). At high tide, the bleaching (loss of the symbiotic algae) is clearly evident in the branching coral from the submerged reef flat (left); at low tide the exposure of massive corals (center) and branching corals (right) results in significant levels of mortality. See my post below (“Winter bleaching again on the southern Great Barrier Reef”) for further comment.