Monday, October 29, 2007

Marine methuselahs

Andrew Baker notes a BBC report about the discovery of 'Ming the Clam' an Icelandic bivalve thought to be 405 to 410 years old and the 'oldest known animal'. He tells Coral Bones:

"Although this is an impressive lifespan for such an unassuming mollusc, many corals are probably much older. Off the island of Ta'u in American Samoa, in approximately 13m (40ft) of water, lives an enormous helmet-shaped coral at least 7m (22ft) high and 12m (37ft) in diameter. This coral, a colonial invertebrate in the scleractinian genus Porites, consists of at least 100 million polyps and is likely to be at least 600 years old. It may well be much older, given the fact that it began life in relatively deep water and therefore may have grown more slowly during its first few centuries. In fact, it's not inconceivable that it dates back as far as the fall of the Roman Empire or the birth of Christ. Chuck Birkeland and others at the University of Hawaii have studied this coral for some time, and have identified it as a candidate for the title of "world's largest coral".

The photo shows this coral, which I believe is affectionately nicknamed 'Big Momma', next to a diver for scale. Note that a large tumor-like growth is visible on the side of the colony (which the diver is inspecting), indicating that methuselahs like this coral may show cancerous signs of their age.

Not only is this coral almost certainly older than Ming the Clam, but it is also still alive (unlike Ming). If we can protect this coral, and others like it, from the combined effects of climate change, overfishing, nutrient pollution and disease - stressors which, combined, ravage reefs worldwide - there is every reason to expect it might continue living for centuries to come.

Although colonial invertebrates like this coral might not fit the standard idea of (solitary) 'animals', they nevertheless qualify for the longevity title, particularly considering the fact that all of the coral's polyps are genetically identical to one another (minus some somatic mutations along the way). Indeed, there is every reason to expect that this enormous coral is the same genetic individual that first settled as a planktonic larva on this distant reef over a thousand years ago.

Saturday, October 20, 2007

500 million years of moon gazing

The discovery suggests that the basic mechanisms for responding to light were in place
at the origins of multicellularity in animals.
-- Reported in the New York Times as Sexy Corals Keep ‘Eye’ on Moon, Scientists Say.

Friday, October 19, 2007

At loggerheads

Peter Aldhous reports:
In March 2006, the entire Hawaiian swordfish fishery was shut down for the season - 120 boats consigned to port after their hooks snagged their 17th loggerhead turtle of the year. Now it turns out that a dozen Mexican fishermen, sailing six tiny boats with outboard motors, posed an even greater threat, drowning 700 loggerheads in a year.

...researchers calculate that in 2005 the gill nets killed at least 299 turtles and the long lines more than 680. That is catastrophic, as the US National Marine Fisheries Service estimates that the loss of just a few dozen large juveniles per year would "appreciably increase" the population's risk of extinction.

Under a project called GloBAL researchers are looking to see if similar disasters are unfolding elsewhere. But in Mexico, at least, there is some good news. [Hoyt] Peckham [of the University of California, Santa Cruz] and his colleagues worked hard to stress the value of conservation - even bringing over fishermen from Japan, who told their Mexican colleagues of crashing turtle populations on the nesting beaches.

Last month, the long-line fleet agreed to use alternative fishing gear. "That was the most powerful conservation action I'll probably be able to make in my career," Peckham says.
This story is tragic, with a dash of hope. The direct relevance to coral reef protection may be limited but here are three possible links:

1) There may be lessons for more sustainable small-scale fisheries directly affecting reefs;

2) Some of the seven sea turtle species play a direct role in the ecology of coral reefs. I understand that green turtles, for example, are important herbivores on reefs. Other species may play a role indirectly through their consumption of seagrass and other organisms. Healthy reefs produce sand in which, ultimately, many but by no means all turtles nest; and

3) Mexico's Pacific coast is not entirely devoid of hard coral, as there is Cabo Pulmo. A whole eco-region conservation approach could better protect both coral and turtle.

Why care? David Rains Wallace quotes John Steinbeck: "There is some quality in man than makes him people the ocean with monsters...An ocean without its unnamed monsters would be like a completely dreamless sleep".

Without its known wonders the ocean would be a desolate waking.

Wednesday, October 17, 2007

Reef shark/coral reef movie

David McGuire circulates a note about Sharks: Stewards of the Reef, a film about shark/reef interactions, finning and threats to coral reefs (with reference to analysis by Bascompte et al published in PNAS in 2005).

[The film has been out for some months, but this note is prompted by a short exchange on Coral-List.]

Saturday, October 13, 2007

Ocean acidification blog

Ove Hoegh-Guldberg praises a blog on ocean acidification by Jean-Pierre Gattuso.

I'm embarassed to say I wasn't previously aware of this blog, and am happy to discover it. But with titles like Dynamics of dimethylsulphoniopropionate and dimethylsulphide under different CO2 concentrations during a mesocosm experiment, some of the posts may take a little chewing before digesting.

Easy finger food to whet your appetite is provided by Elizabeth Kolbert's article in the New Yorker, and my earlier piece in New Scientist.

Friday, October 12, 2007

Al Gore and coral reefs

A UK high court judge has criticised Al Gore's An Inconvenient Truth for innacuracies, including the statement that "coral reef bleaching events are due to global warming".

In New Scientist's enviroment blog Catherine Brahic reminds us that:
[According to] the IPCC [2007 Fourth Asssessment] report, if the temperature were to rise by 1 °C to 3 °C, there would be increased coral bleaching and widespread coral mortality, unless corals could adopt or acclimatise, but that separating the impacts of climate change-related stresses from other stresses, such as over-fishing and polluting, is difficult.

The IPCC states that most corals will bleach if temperatures rise by more than 1 °C over what they were in the 1980s and 1990s (Table SPM-1 in IPCC's WGI ). Temperatures over the past 50 years have warmed by 0.13°C per decade (p 5 of WGI summary for policy makers).

Many scientists agree that limiting warming to 2°C above 1900 temperatures will need CO2 emissions to be cut by more than half from their 2006 levels by 2050. So unless drastic, world-wide policy measures are agreed, increased coral bleaching looks pretty likely.

Bleaching is caused by other factors as well, namely disease. There is some evidence warming will also increase the incidence of disease.
Other factors that can cause bleaching include a sudden influx of large amounts of fresh water. This happened, for example, to coastal reefs in Jamaica after exceptionally heavy rainfall associated with a hurricane some years back. The link has, I think, been quite well understood for years.

Understanding of the role of diseases in coral mortality, and the interaction of disease with other factors, including warming, has been developing over a number of years (see, for example this article from back in 1997) and has a long way to go. Among those publishing in the field are James Cervino and colleagues, and Drew Harvell and colleagues. But I doubt any knowledgeable scientist would deny that Al Gore's statement captures an essential truth and a central concern, if not the whole truth plus footnotes.

I'll hazard that most scientists in the field would say that, pace the IPCC, the chances of coral reefs acclimatising and thriving under a temperature rise of more than 2 °C during the 21st century are about as great as my acclimatising to having a tonne of concrete dropped on my head (which may be a good idea for other reasons).

[As Spencer Weart tells Andy Revkin, “The I.P.C.C. was set up to be the lowest common denominator, to weed out anything anyone could disagree with. It was deliberately created, largely under the influence of Reagan administration, because governments didn’t want a bunch of self-appointed scientists from academies and so on out there. It’s no accident that it’s the Intergovernmentalpanel. Even the Saudi government has to agree. That means that when the I.P.C.C. says you’re in trouble, you’re really in trouble.”]

Perhaps Nobel laureate Gore could nuance a future statement along these lines: "Manmade global warming plays a significant and growing role in the bleaching and death of coral reefs, with devastating effects for some of the richest and most wonderful life on Earth and the human communities that depend on them. On present trends this is likely to get much worse. There are a lot of other ways in which humans damage coral reefs and these need to be managed too."

Thursday, October 04, 2007

Pipe dream

This blog is behind the curve in noting James Lovelock and Chris Rapley's letter to Nature, Ocean pipes could help the Earth to cure itself (see, for example, the BBC story here).

Responses from serious scientists and others seem to have been divided. For example, the felicitously named Quirin Schiermeier at Nature News (Mixing the oceans proposed to reduce global warming, 26 Sep, subscription only) reports a split of views on the likely net effect on atmospheric carbon dioxide concentrations:
"The concept is flawed," says Scott Doney, a marine chemist at [the Woods Hole Oceanographic Institution]. He says it neglects the fact that deeper waters with high nutrients also generally contain a lot of dissolved inorganic carbon, including dissolved CO2. Bringing these waters to the lower pressures of the surface would result in the CO2 bubbling out into the air. So contrary to the desired effect, the scheme could result in a net 'outgassing' of CO2, he warns. "There is no technological fix for this problem," he says.

Others say such a project would have no net effect on CO2 in the atmosphere. "At every meeting I've been to, when they have talked about this idea for surface ocean CO2 removal, the point has been made that you would bring up nutrients and inorganic carbon in the same ratio as you remove as biomass," says Ken Buesseler, a marine chemist at WHOI. And there are potentially many harmful impacts on sea life, he says.
In a BBC video report, Lovelock suggests that the pipes might specifically benefit coral reefs by bringing up cool water to save them. In the same clip John Shepherd, who is one of the most eminent oceanographers in the UK, says the idea may be dangerous, but he is not quoted on specifics, and I have not yet seen in any media an analysis by coral reef specialists of what they think the effects could be. Perhaps they don't think it is worth commenting on (Ove?).

One marine scientist I have talked to says:
This whole crazy scheme is proposed by people with no understanding of marine ecosystems or carbon cycles. Upwelling deep water just causes eutrophication and the algae will kill any coral reefs. Besides almost all the carbon taken up by algae is eaten, or rots, returning the CO2. Almost none is permanently buried, which is the only number that counts. This is the most inefficient possible method of carbon sequestration unless you turn the whole deep sea anoxic and kill all the fish.
P.S. 5 Oct: Oliver Morton hoists some comments from Professor Peter Williams into Nature's climate blog, including:
Even if the engineering problems could be solved, and the system made cost effective, both of which seem very doubtful, the proposal would have the reverse effect of that claimed.

Wednesday, October 03, 2007

Exploding heart

A campaign to jumpstart better protection of the Florida manatee.

Monday, October 01, 2007

Carnival of the Blue V

Shifting Baselines ("A Cure for Ocean Amnesia") has a roundup of best ocean blogging in September at Carnival of the Blue V.