What's Happening at Discovery Diving

Feeding sharks for the benefit of divers is becoming more and more common, but is controversial. New research suggests that feeding in areas with several different sharks, over time, leads to one species increasing in numbers at the expense of the others. Published in PLOS ONE⁽¹⁾, the study looked at the Shark Reef Marine Reserve feeding site in Fiji from 2003 to 2012.

Eight species of shark regularly visited the site in 2003: bull shark (Carcharhinus leucas), grey reef shark (Carcharhinus amblyrhynchos), whitetip reef shark (Triaenodon obesus), blacktip reef shark (Carcharhinus melanopterus), tawny nurse shark (Nebrius ferrugineus), silvertip shark (Carcharhinus albimarginatus), sicklefin lemon shark (Negaprion acutidens), and tiger shark (Galeocerdo cuvier). By 2012, there were more individual sharks visiting, but fewer species. The winner was the bull shark. The smaller tawny nurse shark, silvertip shark and sicklefin lemon shark became very rare visitors.

At 9 foot long, not including the tail, tiger shark (Galeocerdo cuvier) Harry Lindo is not exactly on the small side.  It’s not Harry’s size that is exciting scientists and shark enthusiasts, nor a photograph taken in 2009 by Ian Card showing a shark – suspected to be Harry, trying to eat a 150 lb juvenile tiger shark off the coast of Bermuda.  Between 2009 and 2012 researchers tagged 24 tiger sharks with satellite transmitters in the Challenger Bank, which lies just off Bermuda in the Atlantic Ocean.  In study lead by James Lea (The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center) and team of international collaborators, those shark movements have been compiled and analysed.  Harry, it turns out, is one heck of an ocean wanderer.  In just over 3 years Harry swam over 44,000 kilometres – that’s more than the circumference of the Earth (just over 40,000 kilometres).  Harry’s track is the longest recorded for a tiger shark, and probably the longest ever published for any shark species.

With tentacles up to three metres long and covered with stinging cells, it’s better not to get too close to the Lion’s Mane jellyfish. It’s body can be 2 metres across, making it one of the largest species of jellyfish.

The tentacles are arranged in eight bunches, with each bunch containing over 100 tentacles. The oldest tentacles are often coloured dark red. They have a very severe sting that can produce blisters, irritation and muscular cramp and may even affect respiratory and heart function. Fragments of tentacles, left on buoy ropes for example, retain their stinging power.

The tragedy unfolded unusually slowly for an aviation catastrophe: The crew fought to control the USS Macon for more than an hour. US naval officers threw fuel canisters overboard in an attempt to reduce the weight of their vessel. The canisters imploded on their way to the ocean floor. Meanwhile, the Macon -- the largest rigid airship ever constructed in the United States -- sank inexorably downward, the safety of the Moffett Field hangar just within reach.

The Macon hit the water surface only five kilometers (three miles) off the Californian coast, along the latitude of the Point Sur lighthouse near Monterey, on Feb. 12, 1935. The zeppelin broke apart and sank into the deep water. Two of the 83 crew members died -- the low number of deaths is likely due to the fact that the Macon sank in slow motion.

Diatoms are unicellular algae that are native in many waters. They are a major component of marine phytoplankton and the food base for a large variety of marine organisms. In addition, they produce about one fifth of the oxygen in the atmosphere and are therefore a key factor for our global climate. However, these algae, which measure only a few micrometers, have yet another amazing ability: they can "smell" stones.

Jellyfish blooms are increasingly causing problems. In Korea, the number of accidents and financial losses caused by jellyfish is estimated at 300 billion won (£1.8 m) per year. To combat the jellyfish, Korean researchers led by Professor Hyeon Myeong are using a team of robots, called JEROS (Jellyfish Elimination Robotic Swarm). These slash and grind the jellyfish, killing 900 kg an hour.

Jellyfish cause the fishing industry to lose money by breaking fishing nets. They sting swimmers. They block the seawater cooling systems of power plants. In 2009, a ten-ton Japanese trawler capsized after the three man crew tried to haul up a net loaded with jellyfish.

The Mauve Stinger, or Luminescent Jellyfish, is a beautiful jellyfish. Often coloured purple, you can find it around the world in warm and temperate waters from around 12 to 30 m.

This jellyfish is the most venomous in the Mediterranean. However, its sting is usually limited to the skin surface with local pain which lasts for one to two weeks. In some cases the sting can leave scars, or pigmentation of the skin lasting for several years. Should you be stung by a jellyfish, rinse the area with vinegar for 30 minutes. If vinegar is not available use sea water: don’t use fresh water. Remove any tentacles left on the skin.

Read about dive sites and diving operators in over 90 countries, from Argentina to West Papua. All with ratings and reviews from divers: find the best places to go and companies to dive with. We're here to help you plan your next dive trip: use the SCUBA Travel diving guide.

Hermit crabs scuttle about the sea-floor using someone else’s shell for a home. They always use empty shells and never kill the original occupant.

When the crab becomes to large for its shell, it looks for another. When it finds a likely looking one it will try it on. If the shell doesn’t fit, or is too heavy, the crab returns to its old shell and continues it search.

It's that time of the year again, folks. The time where we all vow to improve ourselves — one way or another — and get a fresh start with the onset of a new year! You've heard the repeat offenders (and probably made them yourself, be honest): lose weight, quit smoking, eat healthier, save money, drink less... the list goes on. So here at Scuba Diving magazine, we decided to come up with a list of our own! You know you're a diver when...

A Diver's List of New Year's Resolutions

Human beings do not have gills, but swimming underwater as if we did has long been a basic urge. With his “amphibious respirator unit,” a prototype for what the world now calls SCUBA gear, Christian Lambertsen, Rutgers Class of 1939, made diving feasible for millions of people.

He also helped win a war.

With Cuba on the cusp, the island that time forgot; we ventured in, concerned that the Cuba now, will be changed forever with the advent of Americans ready to pour in.

Very keen to go after seeing 60 minutes program 2 yrs ago with Anderson Cooper, reveling in the ‘untouched reefs and marine life with loads of Caribbean Reef sharks’ swimming all over him, I had to go!!

After many long months of sorting out the Treasury Department documentation on the legal way to travel to Cuba. We could participate in the Ocean Conservation ‘people to people’ program legally with our marine biologist on board for diving Gardens of the Queen!

Lucky for us, Fidel Castro was an avid diver, 20 yrs ago he declared Jardines de la Reina a marine sanctuary and is highly protected today!

Nothing was easy about getting to Cuba or getting to Gardens of the Queen, it was all part of the wonderful adventure ahead of us!

With Cuba on the cusp, the island that time forgot; we ventured in, concerned that the Cuba now, will be changed forever with the advent of Americans ready to pour in.

Very keen to go after seeing 60 minutes program 2 yrs ago with Anderson Cooper, reveling in the ‘untouched reefs and marine life with loads of Caribbean Reef sharks’ swimming all over him, I had to go!!

After many long months of sorting out the Treasury Department documentation on the legal way to travel to Cuba. We could participate in the Ocean Conservation ‘people to people’ program legally with our marine biologist on board for diving Gardens of the Queen!

Lucky for us, Fidel Castro was an avid diver, 20 yrs ago he declared Jardines de la Reina a marine sanctuary and is highly protected today!

Nothing was easy about getting to Cuba or getting to Gardens of the Queen, it was all part of the wonderful adventure ahead of us!

By John Lippmann
Executive Director
DAN S.E. Asia-Pacific

Copyright: John Lippmann

During diver training, dive students are normally drilled to avoid diving beyond 130 feet / 39 meters. However this depth limit recommended by most of the training agencies is not forged in stone. Historically, it appears that it probably emerged from the U.S. Navy, possibly as a result of equipment limitations at that time, and the work restrictions imposed by the relatively short no-stop times available at greater depths.

An increasing number of divers dive beyond the 130-foot limit, some routinely and others occasionally. The advent of dive computers has negated much of the decompression penalty and dive restrictions previously associated with deep diving, and has no doubt encouraged the current trend. In addition, the increased availability of a variety of gas mixtures has enabled more divers to venture deeper and deeper.

The loss of sharks could contribute to the destruction of one of the planet’s most under-appreciated sources of carbon storage — seagrasses, according to FIU researchers. Not that sharks eat the seagrass, they don’t, but they do eat the turtles which feed in the seagrass meadows. Add this to the problems of pollution, mooring and destruction of seagrass, means this vital habitat – and the sharks – need help.

An online “citizen-science” project called “Plankton Portal” has been created by researchers at the University of Miami in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF). The Plankton Portal lets you explore the open ocean from your own home. You can dive hundreds of feet deep, and observe the unperturbed ocean and the myriad animals that inhabit the earth’s last frontier. The Plankton Portal is at http://www.planktonportal.org/.

SCUBA Travel are pleased to release their annual list of the diving best-selling books and DVDs.

Most of the books are either diving area guides – to specific locations or dives around the world – or sea life guides. One breaks the trend though: Simon Pridmore’s Scuba Confidential. This tells readers how to be a better diver.

One DVD makes the list, showing the best diving locations in world.

Here are the top ten: figures in brackets show the previous year’s position.If positions change (and some are very close) this page will update with the new best-sellers.

As you can see, many books continue to be in the top ten year after year. Coral Reef Fishes: Indo-Pacific and Caribbean has not been out of the top ten since we started publishing the list in 2002! But then, it’s a great little book.

The Okeanos is equipped with real-time broadband satellite communications that provide the ship with telepresence -- meaning the video and photos collected with underwater robots known as remotely operated vehicles, or ROVs, are shared on the internet in real time. So scientists, teachers, students, and you can watch the dives as they happen. With the ship currently exploring Papahānaumokuākea Marine National Monument in the Northwestern Hawaiian Islands and Hawaiian Islands Humpback Whale National Marine Sanctuary, there’s no time like the present to tune in and check out the action.