Thursday, June 29, 2006
To Exercise or Not to Excercise After a Dive?
Decompression sickness is caused by nitrogen being released from the blood too quickly, forming bubbles which may expand and injure tissue or block blood vessels. Anything that increases bubble formation will therefore increase the risk of decompression sickness.
It has previously been shown that exercising 24 hours before a dive, or during a decompression stop, significantly reduces bubble formation. Research now suggests that strenuous exercise after dive also reduces bubble formation. This is opposite to what is commonly taught.
The study - by researchers at the University of Split School of Medicine, Croatia -
was conducted on just 7 male military divers. More research is therefore needed before firm conclusions can be reached for sports divers.
The volunteer divers were in the open sea at 30 m for 30 minutes, with standard decompression. The post-dive exercise session lasted 10 minutes but was intensive.
Journal Reference: Aviat Space Environ Med, June 1, 2006; 77(6): 592-6.
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Thursday, June 22, 2006
Creature of the Month: Nudibranch, Coryphella browni
The nudibranch, or sea slug, is one of my favourite animals to spot underwater. They are often colourful little creatures, advertising their toxicity to predators.
You find nudibranchs around the world, in temperate and tropical seas, and even in the Antarctic. They are hermaphrodites: possessing both male and female organs. Some lay a single string of eggs, others produce coiled flat ribbons. These are usually white but may be red, pink, orange or other colours.
The nudibranch we're featuring today, Coryphella browni, has a translucent white body and numerous pretty coloured pointy projections (cerata), with white tips, on its back.
It feeds on hydroids, which are simple stinging-cell animals related to corals and sea anemones. It not only doesn't mind their stinging cells, it actually puts them to use. The nudibranch passes the intact
cells through its digestive tract and out to the cerata tips. Any animal taking a bite out of the cerata will cause the stinging cells to discharge, then give up and
go and eat something less painful.
Coryphella browni is up to 5 cm long and occurs around the British Isles and Northern Europe. It lays its egg masses in a wavy spiral near its hydroid food.
Further Reading:
Great British Marine Animals, by Paul Naylor, Deltor (2003)
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Labels: sealife
Wednesday, June 21, 2006
Ageing Increases Risk from Decompression Sickness
Journal Reference: Hawaii Med J, May 1, 2006; 65(5): 140-1, 153.
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Tuesday, June 13, 2006
1.5 Million for Sipadan Kidnap Victims
The order was made against Paris-based tour agent Ultramarina, which handled the tour for the three, for failing in its duty to monitor the risks in the region.
It said the company should also have realised that Western tourists would act as a magnet for a kidnap case.
The British Foreign & Commonwealth Office are currently advising: "Terrorists and criminal elements are continuing with plans to kidnap foreign tourists from the islands and coastal areas of Eastern Sabah. Boats travelling to and from offshore islands and dive sites are possible targets. If you wish to visit resorts on, and islands off, Eastern Sabah, you should exercise extreme caution." The Australian government offers similar warnings.
The Sabah Tourism Board, however, offer reassurances "Sabah is a safe destination to travel to and we wish to assure that the Malaysian Government takes security and health issues very seriously and will continue to ensure that all Malaysians and visitors alike are safe and well while on holiday in the country.".
This has been a bad couple of months for the Sabah Tourism Board as in May a barge seriously damaged an area of coral of this famous diving spot.
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Labels: SCUBA Travel
Wednesday, June 07, 2006
Review of Double Cross, a diving novel by Patrick Woodrow
Double Cross
Patrick Woodrow
Arrow, 2005
422pp. £6.99
0 0994785 9 5
Review by Andrew Reay-Robinson
An all-action novel, with plenty of diving, written by
an experienced diver. The author's diving knowledge means
that you do not have to endure the cringe-worthy diving
sequences in a lot of novels written by people with
limited if any diving experience.
The book's hero is a British underwater photographer who
accidentally kills a woman before going on the run to
protect his career. The woman's death, however, provides
him with vital clue to his inheritance and what follows
is a fast paced globetrotting adventure with plenty of
diving, drug trafficking baddies and a thrilling climax.
The book is very easy to read with simple dialogue
and is a good escapist read.
Ideal to relax with between dives on a diving holiday
or liveaboard.
Available with 20% off from amazon.co.uk at
http://www.amazon.co.uk/exec/obidos/ASIN/0099478595/1286
and from amazon.com at
http://www.amazon.com/exec/obidos/ASIN/0099478595/
For more diving book reviews, and interviews with authors, see the SCUBA Travel Bookshelf.
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Thursday, June 01, 2006
Greater Risk to Loggerhead Turtles from Longline Fishing
The study, published in the latest issue of Current Biology, says that although tbe protection of coastal areas may be attainable, the ocean-going turtles are dispersed over more than half a million square kilometers. So the largest turtles may be protected but the more numerous smaller adult turtles are at a very great risk from being caught by fisheries in the east Atlantic. Not deliberately, but as by-catch.
Previously it was thought that only juveniles foraged in the open ocean. Using satellite tracking, the new research shows that the majority of adults are also exposed to longline fisheries. The scientists conclude that fisheries in the east Atlantic will likely require complex and regionally tailored actions to protect the turtles.
Experiments over the last few years have shown that large “G”-shaped circle hooks effectively reduce turtle by-catch rates compared to smaller “J”-shaped hooks. Large circle hooks are effective without compromising commercial viability for some target species. Studies comparing small circle hooks (5.1 cm width or smaller) to smaller (4.1 cm width or smaller) J-shaped hooks found no significant difference in turtle bycatch rates. Other strategies include setting gear below the depths where turtles are in relatively high densities, using fish instead of squid for bait, single hooking fish bait versus threading the hook through the bait multiple times, timing the retrieval of line to minimize gear soak during the daytime and area and seasonal closures.
According to the WWF, some 260,000 loggerhead turtles are caught annually on longlines set for tuna, swordfish, and other fish.
Journal Source: Current Biology Volume 16, Issue 10 , 23 May 2006
Other Sources: Review of the State of Knowledge for Reducing Sea Turtle Bycatch in Pelagic Longline Gear
WWF
Photo copyright Pedrín López, http://www.seaturtle.org/
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Labels: sealife