SCUBA Travel News

Researchers at Portsmouth University and the US Coast Guard are working together to develop a computer model that will predict how long someone will survive when lost at sea.

The Search and Rescue Survival Model has been designed to take the pressure off rescuers making difficult decisions about when a search and rescue mission should be stopped.

“Using this new computer model will take pressure off humans making very emotional and sensitive decisions about when to end a search,” said Professor Mike Tipton, human and applied physiologist, from the University of Portsmouth.

“When the model predicts that a victim can no longer survive, the search and rescue team can stop or redeploy the search.

“It will ensure that Coast Guard personnel are not exposed to the high risks associated with search and rescue operations any longer than necessary and will also help to save time and resources,” he said.

The US Coast Guard currently uses a software system known as SAROPS (Search and Rescue Optimal Planning System) to calculate how far a person will have drifted and how large the search area should be.

Data such as wind speed, sea state and water temperature is entered into SAROPS along with information about the victim’s sex, height, weight and what they were wearing to determine exactly how the search should be conducted.

“Calculating survival time will add another layer to SAROPS; it will be able to predict not only where a search should be conducted but when it should be stopped,” said Professor Tipton.

“The University of Portsmouth has been able to tap into and analyze data held by the Institute of Naval Medicine and the Royal National Lifeboats Institution, both critical to the development of this survival model. To our knowledge no other similar repository of this information exists - even in the US.

“The development of this technology is very exciting. It will be trialled in American waters in late 2009 and once thoroughly tested, the aim is to roll it out to the whole of the US,” he said.

Labels: America, research, SCUBA diving, USA

Sea snakes may slither in saltwater, but they sip the sweet stuff.

So concludes a University of Florida zoologist in a paper appearing this month in the online edition of the November/December issue of the journal Physiological and Biochemical Zoology.

Harvey Lillywhite says it has been the “long-standing dogma” that the roughly 60 species of venomous sea snakes worldwide satisfy their drinking needs by drinking seawater, with internal salt glands filtering and excreting the salt. Experiments with three species of captive sea kraits captured near Taiwan, however, found that the snakes refused to drink saltwater even if thirsty — and then would drink only freshwater or heavily diluted saltwater.

“Our experiments demonstrate they actually dehydrate in sea water, and they’ll only drink freshwater, or highly diluted brackish water with small concentrations of saltwater — 10 to 20 percent,” Lilywhite said.

Harold Heatwole, a professor of zoology at North Carolina State University and expert on sea snakes, termed Lillywhite’s conclusion “a very significant finding.”

“This result probably holds the key to understanding the geographic distribution of sea snakes,” Heatwole said.

The research may help explain why sea snakes tend to have patchy distributions and are most common in regions with abundant rainfall, Lillywhite said. Because global climate change tends to accentuate droughts in tropical regions, the findings also suggest that at least some species of sea snakes could be threatened now or in the future, he added.

“There may be places where sea snakes are barely getting enough water now,” he said. “If the rainfall is reduced just a bit, they’ll either die out or have to move.”

Sea snakes are members of the elapid family of snakes that also includes cobras, mambas and coral snakes. They are thought to have originated as land-dwelling snakes that later evolved to live in oceans. Most spend all, or nearly all, of their lives in seawater, including giving birth to live young while swimming. A minority, including the kraits that Lillywhite studied, lay eggs and spend at least a small part of their lives on land.

Lillywhite believes the sea snakes that spend their lives in the open ocean drink water from the “lens” of freshwater that sits atop saltwater during and after rainfall, before the two have had a chance to mix. That would explain why some seawater lagoons, where the waters are calmer due to protection from reefs, are home to dense populations of sea snakes — the freshwater lens persists for longer periods before mixing into saltwater.

Rather than helping sea snakes gain water, the snakes’ salt gland may help the snakes with ion balance — moving excess salts from the bloodstream, Lillywhite said.

Some sea snake species living in dry regions may already be suffering as a result of climate change. Lillywhite said a colleague in Australia, which is in the midst of a historic drought, has observed declines and possible extinctions in some species at Ashmore Reef, home to the most diverse and abundant population of sea snakes in the world.

“We are trying to look at rainfall in that region and see if there is a correlation,” Lillywhite said.

He added that his findings also raise questions about the accepted wisdom that other marine reptiles, including sea turtles, satisfy their freshwater needs by drinking saltwater.

Labels: environment, marine biology, research

Ecologists and oceanographers are attempting to predict the future impacts of climate change by reconstructing the past behavior of Arctic climate and ocean circulation.

In a November special issue of the journal Ecology, a group of scientists report that if current patterns of change in the Arctic and North Atlantic Oceans continue, alterations of ocean circulation could occur on a global scale, with potentially dramatic implications for the world's climate and biosphere.

Over 65 million years, the Earth has undergone several major warming and cooling episodes, which were largely mitigated by the expansion and contraction of sea ice in the Arctic.

"When the Arctic cools and ice sheets and sea ice expand, the increased ice cover increases albedo, or reflectance of the sun's rays by the ice," says Greene, the lead author on the paper. "When more of the sun is reflected rather than absorbed, this leads to global cooling."
Likewise, when ice sheets and sea ice contract and expose the darker-colored land or ocean underneath, heat is absorbed, accelerating climate warming.

Currently, the Earth is in the midst of an interglacial period, characterized by retracted ice sheets and warmer temperatures.

In the past three decades, changes in Arctic climate and ice cover have led to several reorganizations of northern ocean circulation patterns.

Since 1989, a species of plankton native to the Pacific Ocean has been colonizing the North Atlantic Ocean, a feat that hasn't occurred in more than 800 thousand years. These plankton were carried across the Arctic Ocean by Pacific waters that made their way to the North Atlantic.

Continued exposure to freshwater forcing in the Arctic could disrupt global ocean circulation during the next century and lead to very abrupt changes in climate, similar to those that occurred at the onset of the last ice age.

Further Reading: National Science Foundation

Labels: environment

A million tonnes of fish and other sea creatures caught in the North Sea are thrown overboard every year, according to a new report from WWF-Germany.

The study, Sea Creatures Are Not Rubbish, shows that one-third of North Sea catch is discarded and calls for a gradual ban on the practice of discarding in the European Union.

This practice occurs when boats decide to dispose of fish which they catch but cannot land or derive income from, or when they have caught more fish than they are allowed to land, or they discard the less valuable fish in order to make more space for more valuable fish.

For example, the report cites the situation with Dover sole, for which six kilos of sea creatures are caught incidentally and discarded for every kilo found in the fishmonger. Similarly, catching one kilo of Norwegian lobster or scampi results in five kilos of bycatch.

The European Union recently declared that 88 per cent of the fisheries stocks of the EU are overfished, compared with 25 per cent on average globally. Bycatch is a major contributor to overfishing, and this unsustainable and illogical practice should be addressed.

WWF is calling for a European-wide discard ban and a bycatch action package. In the future every fish caught should be landed and allocated to the catch quota.

At the same time fishermen should be obliged to use better catch technologies and in this way the bycatch in some fisheries could be reduced by up to 90 per cent.

A legislative initiative against discard practice, announced by the European Commission, was only recently torpedoed by the powerful fishery lobby of some member countries.

You can download the report from the WWF site at http://assets.panda.org/downloads/studie___meerestiere_sind_kein_muell_.pdf

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Labels: fish, UK