SCUBA Travel News

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 reduces bubble formation should decrease the risk of decompression sickness.

Many factors increase the chance of decompression sickness, including dehydration. Researchers from the French Navy have found that drinking 1.3 litres of a saline-glucose drink an hour and a half before the dive decreased bubble formation. This provides an easy means of reducing decompression sickness risk.

The test was carried out on eight military divers.

Journal Ref: Br. J. Sports Med., February 28, 2008


What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: decompression sickness, research

Bluefin tuna populations have declined alarmingly over the past few decades due to overfishing fuelled by an increasingly expensive industry.

A new WWF report shows that the international fleets hunting this species to extinction have twice the fishing capacity of current quotas and are netting more than three and a half times the catch levels recommended by scientists to avoid stock collapse.

"WWF's new report uncovers the absurdity of a system long out of control, where hundreds of hi-tech boats are racing to catch a handful of fish," says Dr Sergi Tudela, Head of Fisheries at WWF Mediterranean.

"It is crazy - the numerous new fleets are so modern and costly that fishermen are forced to fish illegally just to survive - and worse still they are fishing themselves out of a job," added Tudela.

To keep fishing capacity within the 2008 legal catch limits imposed by the International Commission for the Conservation of Atlantic Tunas (ICCAT), the Mediterranean fleet would need to shed 229 vessels - almost a third of the current 617-vessel fleet. Reducing fishing effort to scientifically recommended levels would require the decommissioning of 283 vessels.

WWF is calling on concerned countries to dramatically reduce capacity in this fishery as a matter of urgency ahead of the 2008 fishing season that starts at the end of April.

WWF also urges ICCAT, the body tasked with sustainably managing the fishery, to take a lead in proposing radical solutions. Until the fishery is under control and sustainably managed, WWF continues to advocate a fishing ban - and to applaud responsible retailers, restaurants, chefs and consumer groups who are boycotting Mediterranean bluefin in increasing numbers.

"The fishery is unsustainable in every way - economically, socially, and ecologically. When will the situation be brought under control? The time to act is now - while there are still bluefin tuna to save in the Mediterranean," Tudela concluded.

What can you do? If you want to buy a tin of tuna off the supermarket shelf don’t worry – you almost never find bluefin tuna in a tin. Most tinned tuna is yellowfin or skipjack. If you buy fresh tuna ask your fishmonger whether the tuna is Atlantic bluefin, and whether it comes from the Mediterranean. If it does come from the Med, don't buy it. And at the Japanese restaurant check where they source the Atlantic bluefin tuna. If it is from the Mediterranean, avoid it.

Note: the tuna caught in the Med is called "Atlantic Bluefin Tuna" (Thunnus thynnus). Don't think that because it has the word Atlantic in the name that means it was caught there.

Further Reading:
Bluefin tuna in crisis
Race for the last bluefin: Capacity of the purse seine fleet targeting bluefin tuna in the Mediterranean

-
What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: fish, Mediterranean

Is it important that global warming turns fish deaf? Yes. For coral reef fish, sound is vital for them to judge where to settle down and live.

After hatching, reef fish larvae are dispersed by ocean currents for a few weeks. The larval fish must then find their way back to a suitable reef to make their home.

It's thought that the young fish home in on high-frequency noises. Coral reefs are extremely noisy environments, with the crackle of snapping shrimps and the chatter of fish set against a backdrop of wind, rain and surf. Sound carries well underwater, and most fish have great hearing.

Global warming and more acidic oceans, though, can cause fish to be born with deformed earbones. Reasearchers at the Australian Institute of Marine Science in Townsville and the University of Edinburgh, suspected that it might be harder for these fish to pinpoint the origin of a sound, increasing the chance they would get lost in the ocean. And, indeed, their results show that this is so.

Journal References and Further Reading:
Proceedings of the Royal Society, Volume 275, Number 1634 / March 07, 2008
Animal Behaviour, doi:10.1016/j.anbehav.2007.11.004
SOUND: The essential navigation cue for young reef fishes to find their way home


--
What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: coral reef, environment, fish, marine biology, research, sealife

More than 40 percent of the world's oceans are heavily affected by human activities, and few if any areas remain untouched, according to the first global-scale study of human influence on marine ecosystems.

By overlaying maps of 17 different activities such as fishing, climate change and pollution, the researchers have produced a composite map of the toll that humans have exacted on the seas.

The work, published in Science, was conducted at the National Science Foundation (NSF)'s National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California at Santa Barbara, and involved 19 scientists from a range of universities, NGOs, and government agencies.

The study synthesized global data on human impacts to marine ecosystems such as coral reefs, seagrass beds, continental shelves and the deep ocean.

"This research is a critically needed synthesis of the impact of human activity on ocean ecosystems," said David Garrison, biological oceanography program director at NSF. "The effort is likely to be a model for assessing these effects at local and regional scales."

Past studies have focused largely on single activities or single ecosystems in isolation, and rarely at the global scale. In this study the scientists were able to look at the summed influence of human activities across the entire ocean.

"This project allows us to finally start to see the big picture of how humans are affecting the oceans." said lead scientist Ben Halpern of NCEAS. "Our results show that when these and other individual impacts are summed up, the big picture looks much worse than I imagine most people expected. It was certainly a surprise to me."

The study reports that the most heavily affected waters in the world include large areas of the North Sea, the South and East China Seas, the Caribbean Sea, the east coast of North America, the Mediterranean Sea, the Red Sea, the Persian Gulf, the Bering Sea and several regions in the western Pacific. The least affected areas are largely near the poles.

Human influence on the ocean varies dramatically across various ecosystems. The most heavily affected areas include coral reefs, rocky reefs and seamounts. The least impacted ecosystems are soft-bottom areas and open-ocean surface waters.

"My hope is that these results serve as a wake-up call to better manage and protect our oceans, rather than a reason to give up," added Halpern.
-
What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: environment, marine biology, research

The same chemicals that keep food from sticking to our frying pans and stains from setting in our carpets are damaging the livers and impairing the immune systems of loggerhead turtles - an environmental health impact that also may signal a danger for humans.

A scientific team monitoring the blood plasma of loggerhead turtles along the U.S. East Coast consistently found significant levels of perfluorinated compounds (PFCs). PFCs are used as nonstick coatings and additives in a wide variety of goods including cookware, furniture fabrics, carpets, food packaging, fire-fighting foams and cosmetics. They are very stable, persist for a long time in the environment and are known to be toxic to the liver, reproductive organs and immune systems of laboratory mammals.

PFC concentrations measured in the plasma of turtles found along the coast from Florida to North Carolina indicated that PFCs have become a major contaminant for the species. The levels of the most common PFC, perfluorooctane sulfonate (PFOS), were higher in turtles captured in the north than in the south. Data recently evaluated by NIST and College of Charleston graduate student Steven O’Connell shows that this northern trend of higher PFOS concentrations continues up into the Chesapeake Bay.

Blood chemistry analyses of PFC-contaminated loggerheads suggested damage to liver cells and the suppression of at least one immune function which could lead to a higher risk of disease. To support the “cause-effect relationship” between PFCs and illness, the researchers exposed Western fence lizards to the same PFOS levels found in loggerheads in the wild. The lizards showed significant increases in an enzyme that indicates liver toxicity. They also had signs of suppressed immune function.

These findings, Keller said, indicate that current environmental PFC exposures—at concentrations comparable to those seen in human blood samples—are putting marine species at enhanced risk of health problems from reduced immunity and may suggest a similar threat to us.

Keller reported that a recently completed study led by colleague Margie Peden-Adams of the Medical University of South Carolina that showed PFOS is toxic to the immune systems of mice at concentrations found both in loggerhead sea turtles and humans. The ability of the mouse immune system to respond to a challenge was reduced in half by PFOS—and this occurred at the lowest level of the compound ever reported for a toxic effect.

Further Reading: NIST Tech Beat
-
What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: marine biology, research, turtles

The Chevroned Butterflyfish may be at risk of extinction, scientists have warned.

The case of the Chevroned Butterflyfish is a stark example of how human pressure on the world's coral reefs is confronting certain species with 'blind alleys' from which they may be unable to escape, says Dr Morgan Pratchett of the ARC Centre of Excellence for Coral Reef Studies and James Cook University.

In a study published in the journal Behavioural Ecology and Sociobiology, Dr Pratchett and Dr Michael Berumen of Woods Hole Oceanographic Institution (USA) warn that the highly specialised nature of the feeding habits of this particular butterflyfish – the distinctively patterned Chaetodon trifascialis - make it an extinction risk as the world’s coral reefs continue to degrade due to human over-exploitation, pollution and climate change.

“The irony is that these butterflyfish are widespread around the world, and you’d have thought their chances of survival were pretty good,” Dr Pratchett said today.

“But they only eat one sort of coral – Acropora hyacinthus – and when that runs out, the fish just disappear from the reef.”

The team found it hard to believe a fish would starve rather than eat a mixed diet, so they tested C. trifascialis in tank trials on a range of different corals. The fish grew well when its favourite coral was available – but when this was removed and other sorts of corals offered, it grew thin, failed to thrive and some died.

“We call these kinds of fish obligate specialists. It means they have a very strong dietary preference for one sort of food, and when that is no longer available, they go into decline. We still don’t have a satisfactory scientific explanation for this, as it seems like rather a risky tactic in evolutionary terms – but it must confer some advantage provided enough of its preferred food is available,” Dr Pratchett says.

The A. hyacinthus coral, which the butterfly fish feeds on, is itself highly vulnerable – to attacks by plagues of crown-of-thorns starfish (thought to be triggered by humans releasing excess nutrients onto the reef as sediment, fertilizer or sewage), to storms and to the coral bleaching caused by the heating of ocean surface waters to 32 degrees or more, which is thought to be linked to global warming.

“Although extremely widespread, the Chevroned butterflyfish may be at considerable risk of extinction following ongoing degradation of coral reefs around the world, because the coral itself is exceptionally vulnerable, Dr Pratchett explains.

“It is estimated that up to 70 per cent of the world’s coral reefs are now badly degraded, which usually involves the loss of this particular coral – and, when it goes, the C. trifascialis also disappear from the reef.

“To make matters worse, butterflyfishes are one of the main families of coral reef fishes being targeted by aquarium collectors. However, the specialized coral-eaters are clearly not suitable for keeping in aquaria - and often die because they cannot obtain their main food source.”

A previous case in which a coral-dependent fish vanished occurred in the case of Gobiodon a specialized coral-dweller known only from one site, Kimbe Bay in Papua New Guinea, which was thought by scientists to have possibly become extinct after its habitat was destroyed.

Researchers consider that such extinctions are likely to occur as part of the global mass extinction of species now taking place, and that marine ecosystems may be particularly vulnerable in that small changes in habitat or water quality can have a big impact on their species.

Dr Pratchett and Dr Berumen say theirs is one of the few studies so far to consider the evolutionary and ecological basis of dietary versatility, and has implications for the fate of specialised feeders throughout the animal kingdom.

More information: ARC Centre of Excellence for Coral Reef Studies

-
What do you think of this news item? Start a discussion.
Bookmark with: del.icio.us | Digg | Newsvine | NowPublic | Reddit
|   Slashdot It! | Facebook | StumbleUpon

--
Subscribe to SCUBA News (ISSN 1476-8011) for more free news, articles, diving reports and marine life descriptions - http://www.scubatravel.co.uk/news.html

Labels: medical, research, sealife