Diving Thoughts

Dense superswarms of krill form in the Southern Ocean and some can stretch for tens of kilometres. Krill are shrimp-like crustaceans such as the Antarctic krill (Euphausia superba).

Scientists have discovered that there are two main types of swarms. The smaller ones may be  up to 50 metres long  and 4 metres deep, with an average density of 10 krill per cubic metre.  These are usually made up of adult krill, which are negatively buoyant. This means they have to swim to keep afloat, which takes up energy and means they need to eat more. But while a swarm offers some protection against predators, it means they are also competing for food, which could be why these adult swarms are not larger or more dense.

The second type of swarms are much bigger and also much denser. These tend to be formed of juvenile krill which are buoyant and so need less energy.

One worrying aspect is the possible impact of overfishing, if most krill in the Southern Ocean are gathered in a few very large superswarms. Fishing fleets can effectively locate these superswarms and by fishing them out could remove the majority of krill living in the ocean, which would have a dramatic effect on other species and the environment.

The next thing scientists may have to look at is why the largest swarms form at night, when the animals would typically be feeding and people had expected them to disperse.

The above photo comes from an article on the BBC’s website.

President Mohamed Nasheed (pictured) of the Maldives and 11 of his ministers held the world’s first underwater cabinet meeting. They were all in diving gear at a depth of 4 metres. It was a PR stunt to raise awareness of global warming which could result in sea level changes that could flood the Maldives and make it uninhabitable. The immediate target is to focus attention on trying to get a better deal at the upcoming climate summit in Copenhagen.

The ministers sat around a horseshoe shaped table at 10am surrounded by fish, and signed an “SOS”  agreement, calling for carbon emission cuts.

The president, already a keen diver, told the BBC that “What do we hope to achieve? We hope not to die. I hope I can live in the Maldives and raise my grandchildren here,”

There is a video of the meeting and an article on the BBC’s website.

Scientists from Diversitas, an international programme of biodiversity science, have warned of an alarming increase of animal extinctions as a result of threats to biodiversity and ecosystems. In a blog they seem particularly concerned about freshwater species.

At the 6th Conference of Parties to the UN Convention on Biological Diversity in April 2003,  123 world ministers committed to “achieve, by 2010, a significant reduction of the current rate of biodiversity loss at the local, national and regional levels, as a contribution to poverty alleviation and to the benefit of all life on Earth.”  Georgina Mace of Imperial College, London, and Vice-Chair of the international DIVERSITAS programme says that ““We will certainly miss the target for reducing the rate of biodiversity loss by 2010 and therefore also miss the 2015 environmental targets within the U.N. Millennium Development Goals to improve health and livelihoods for the world’s poorest and most vulnerable people”.

The Diversitas programme is organising its second Open Science Conference in Capetown on Oct. 13-16 with 600 experts from around the world.

You can read more here.

In an attempt to highlight the threat of climate change, the government of the Maldives will hold a cabinet meeting underwater. On 17th October, all the cabinet ministers bar one (who has a health problem that precludes diving) will hold a meeting at which they will sign a document calling for global cuts in carbon emissions.

President Nasheed, who is already a diver, will also hold a press conference in the water, although presumably not underwater which might make him a little difficult to hear. Although some might argue that would be a good thing for a politician.

The ministers are being trained at a military base in the Maldives and for the underwater meeting will each be accompanied by an instructor and military escorts.

It certainly sounds an interesting way to highlight the effects of global warming, which are likely to hit the island nation very hard, since the Maldives is on average only 2.3 metres above sea level.

President Nasheed sounds to be a bit of a character. Shortly after his election he made headlines when he talked about creating a sovereign wealth fund to buy up land with a view to relocating the entire country.

You can read more about the underwater cabinet meeting on the BBC’s website, from where the above photo came.

On Thursday evening the Royal Geographical Society – Hong Kong are presenting a lecture by Dr. Gavin Schmidt on NASA’s research into the nature of global warming and consequent climate change. The lecture is apparently going to combine scientific analysis with stunning photography illustrating the effects of climate change.

The talk is at 3F, British Council, 3 Supreme Court Road (this venue is next to Pacific Place, 5 minutes from Admiralty MTR) on Thursday 8th October. There will be a Drinks Reception at 6.30 pm followed by the Lecture at 7.30 pm.

There is more information on the RGS-HK website.

Scientists working in the Galapagos have found 3 new species of coral and one that had been thought to be extinct. The area they were researching was near Wolf and Darwin islands, which are in the north-east of the island archipelago. This area has apparently not been studied in detail since the 1970s.

The three new coral species are from the genera Hydrozoanthus, Parazoanthus and Antipathozoanthus. In addition, Honeycomb coral (Gardineroseris planulata) had been thought to have been wiped out in 1997/98 by the last major El Nino event but several colonies were found.

El Nino events raise sea water temperatures around the Galapagos up to say 30C., which can lead to the coral polyps ejecting the symbiotic algae that live within them. This leads to the  coral dying and the resulting bleached reefs are very obvious. This recent research suggests that the algae may be adapting to warmer temperatures, which could be a small piece of good news for reefs everywhere.

The above picture is from the Guardian, and you can read more from their website.

On Thursday the Royal Geographical Society of Hong Kong is presenting a lecture by Dr. Alan Knight, who has spent nearly 20 years in sustainable development in the fields of retail, global finance and advising government. He specialises in working with business and policy makers to ensure they can still be profitable while also being sustainable from a perspective of the planet. So not anti-business, foaming at the mouth type of environmentalist.

The talk will be at the Pacific Place Conference Centre, 5/F, One Pacific Place, Admiralty, with drinks from 6:30pm and the lecture starting at 7:30pm. It will cost HKD 100  for members and HKD 150 for non-members. There is more information on the RGS Hong Kong website.

The Guardian has got an interactive map of 10 coral reefs around the world, with a brief description of them and the pressures they are facing as a result of climate change. They reckon you should go and see them before they die.

The map is here.

There’s more on the Arctic methane story in this article from New Scientist.

Methane is a powerful greenhouse gas, so if large quantities of it are released into the atmosphere it could make climate change even worse.That may be starting to happen as researchers have found 250 plumes of methane bubbles that are rising from the sea bed off Norway.

Vast quantities of methane are trapped as methane hydrate in sediment under the Arctic seabed. Methane hydrate is a frozen substance made up of water and methane, which is stable under high pressure and low temperature. But as temperatures rise, the hydrate is starting to break down which can result in the methane being released.

The lower the temperature is, the less pressure is required to keep the methane hydrate stable.  Data collected over 30 years shows that it used to be stable at a depth of 360 metres, but recent evidence shows that it is now stable at depths of over 400 metres.  This is probably because this area of the ocean is now 1 C. warmer than it used to be.

Researchers have found that most of the methane is dissolving into the seawater and they have not yet detected any evidence that the gas is breaking the surface and getting into the atmosphere, although they emphasise that this doesn’t mean that it isn’t doing. But even if it’s not getting into the atmosphere, it is making the ocean more acidic, as it is combining with oxygen in the water to form CO2, which in sea water forms carbonic acid.

The full BBC story can be found on their website.

The BBC has an interesting article on whether jellyfish help to stir up the oceans, helping to distribute heat, nutrients and chemicals. They draw their material from a recent article in Nature where researchers used a green dye to see the effects caused by swimming jellyfish.

Over 50 years ago Charles Darwin (no, not that one – his grandson) identified that animals contribute to marine turbulence and the influence of this “biogenic” mixing in comparison to wind and tides has been debated ever since. This recent research has shown that small creatures as well as very large ones contribute. The researchers studied jellyfish because they were relatively easy to study, but they feel that crusteceans like krill are more likely to be more significant since there are so many of them.

The principle is to do with aerodynamics. That a creature at depth will carry colder, deeper water up with it as it migrates upwards. The effect is likely to be largest in specific areas where there is a high concentration of life.

For more information, go to the BBC’s website.

Given all the press recently about the serious decline of blue fin tuna worldwide, should we be eating  tuna? Well, it seems to depend on what type of tuna it is and which tuna “stock” it comes from. There are seven species which are divided into 23 stocks. Research shows that six of these stocks are overfished, six are fully utilised, two have not been assessed and nine are not yet fully utilised. So leaving aside blue fin tuna, the largest and most highly prized species, it sounds as though things could be a lot worse. However there is an over-capacity of tuna fishing boats, and there are no controls to prevent new boats from entering fisheries.

Tuna migrate long distances and may well pass through fishing zones of several countries as well as international waters. This makes their conservation that bit more problematic, as they suffer from the tragedy of the commons, meaning everyone has an incentive to take as much as possible of a resource  because if they don’t then other people will. Now would seem to be a good time  for countries to look at working together to try and preserve tuna while their numbers are in relatively good shape.

There is a good article on this on the New Scientist’s website.