DAN_AP_Alert_Diver_Q1_2016

The Magazine of Divers Alert Network Asia-Pacific

DAN DELIVERS IN SODWANA SPONGES TAKE OVER GETTING DIZZY WITH IT FULL FACE MASKS Quarter 1, 2016 danap.org

Contents

Image © Cormac McCreesh

ON THE COVER A school of bigeyes at Little Brother Island, Red Sea Image © Stephen Frink Settings: f/10, 1/50s, ISO 160

03 Perspectives

THE IMPORTANCE OF CONTINUED LEARNING Text by Scott Jamieson

04 DAN WAS THERE FOR ME DCS STRIKES IN SODWANA Text by DAN AP Member, Rachel

10 Incident Insight DON’T DELAY

Text by DAN AP’s John Lippmann and Scott Jamieson

Editors Brian Harper and Diana Palmer Founder, Director of Research & Chairman of the Board John Lippmann

14 Expert Opinions

General Manager Scott Jamieson

Text by Payal S. Razdan, MPH, and Neal W. Pollock, PhD

Administration Manager Sim Huber

UNDERSTANDING ALTERNOBARIC VERTIGO Image © Stephen Frink

Content Coordinator Stephen Frink

20 Gear

UNDERWATER COMMUNICATIONS SYSTEMS Text by MIchael Menduno

22 Water Planet

OVERFISHING AIDS SPONGES, HURTS CORALS Text by Joseph R. Pawlik, PhD

ALERT DIVER’S PHILOSOPHY Alert Diver is a forum for ideas and information relative to diving safety, education and practice.

Any material relating to dive safety or dive medicine or accident management is considered for publication. Ideas, comments and support are encouraged and appreciated. The views expressed by contributors are not necessarily those advocated by DAN Asia-Pacific. DAN is a neutral public service organisation which attempts to interact with all diving-related organisations or persons with equal deference. Alert Diver is published for the use of the diving public and it is not a medical journal. The use and dosage of any medication by a diver should be under the supervision of his or her physician.

Alert Diver is published as a separate, independent magazine within Scuba Diver AUSTRALASIA (SDAA) magazine. DAN AsiaPacific is not responsible for the content provided elsewhere within SDAA, and therefore this content should not be assumed to represent the views, policies or practices of DAN Asia-Pacific or Alert Diver magazine. ©Alert Diver text, illustration or photographs may not be reproduced or reprinted without the expressed consent of Divers Alert Network and its authors, artists and photographers. Many articles are reprinted with the kind permission of DAN America.

Email: info@danap.org For more information on membership, insurances and training programmes, visit our website: www.danap.org

Marketing & Communications Manager Melissa Cefai DAN AP Board of Directors John Lippmann, David Natoli, Malcolm Hill, Dr David Wilkinson, Mick Jackson, Stan Bugg, Tom Wodak, Nicholas Cheong & Dr Andrew Ng Memberships & Certifications Heidi Powell, Julie Parsonson, Cynthia Van Zyl, Mina Chivotti, Adam Lippmann, Sophie Kayne, and Diane Boyle Training John Lippmann, David Natoli and Tim Vernon-Smith Marketing Assistants Haili Mu & Adam Lippmann Accounts Anny Limbek DAN AP does not necessarily endorse the products or services of any organization or company whose advisements appear in Alert Diver

Perspectives

From DAN Asia-Pacific

THE IMPORTANCE OF CONTINUED LEARNING

Part of the DAN Asia Pacific team.

From left, Mel, Cynthia, Julie, John, Heidi, Scott, Haili, Anny, Adam, Sim

AS DIVERS, we have all been made aware of the importance of good quality training and education. The skills and knowledge we obtained during our open water course and expand upon by completing additional training, prepare us to dive safely. With this in mind, continuing to learn about diving, as well as developing our knowledge about preventing and managing diving accidents, is something all divers should do.

Fortunately, DAN AP Members have access to a broad range of resources (articles and books focused on diving health and safety issues, studies on diving health, fitness, safety and accident prevention, and more) within DAN AP’s Member-only portal and website.

Of course, within this magazine and our monthly member e-newsletters we also cover

various health and safety issues, and discuss diving incidents, enabling us to learn from the experiences of others.

DAN also provides accident management and first aid training for divers and non-divers.

The information available will not only help you stay current in an environment of constant change, but will also help you to effectively assist in the event of an emergency should you ever find yourself in that position. The ability to provide immediate, good and effective oxygen to an injured buddy may be the difference between a symptom-free outcome versus a situation requiring multiple treatments, rehabilitation and possibly residual symptoms for life.

Recently, I have dealt with two cases where prompt and effective high-concentration oxygen administration was quite likely responsible for the divers avoiding multiple hyperbaric treatments. However, in another case, if it wasn’t for the intervention of DAN and the Diving Emergency Service (DES) doctors, the diver would have received grossly sub-standard oxygen first aid, and the outcome may have been very different.

It is important that all divers continue to learn, ensuring that their skills and knowledge not only reflect current practices, but also enable them to act effectively in a time of stress.

A good diver never stops learning and DAN AP Members have access to great learning tools.

If you are not yet a DAN Member, join today at www.danap.org.

Dive safely, Scott Jamieson, DAN AP General Manager

Dive Tip Engage with DAN on Facebook for insights into various dive safety and medical issues.

Scan here or search DAN Asia Pacific.

3

Image © Cormac McCreesh

Research, Education & Medicine

DAN Was There For Me

DCI STRIKES IN SODWANA Despite being well within accepted limits, an experienced diver takes a serious hit Text by DAN AP Member, Rachel (Australia)

I am a marine biologist and for the month leading up to my incident I had been working for a local NGO in Sodwana, South Africa, diving at most six times per week, often just one dive per day. The NGO’s diving safety policy restricts all dives to a maximum depth of 18 metres with a safety stop at five metres for five minutes (under certain conditions, such as in strong current, three minutes was the minimum), with a maximum total dive time of 50 minutes.

On the day I presented with decompression illness symptoms. I led a dive to 17 metres. The dive went smoothly; visibility was approximately 15 metres and there was slight surge and 4

current. We ascended at the rate of my dive computer (a maximum nine metres per minute) and completed a five-minute safety stop at five metres. Our total dive time was 31 minutes.

Upon surfacing I jumped onto the boat and then helped pull up everyone’s weight belts, BCDs and cylinders. On the five-minute boat ride back to shore I noticed my entire left arm was feeling slightly numb. Back on shore I helped unload equipment and then went over to my partner, who works as a scuba instructor at the dive centre. I told him that my arm felt strange, he asked if I felt a tingling sensation or pain and listed off other common symptoms of decompression illness (DCI), of which I had none (DAN Note: She in fact did, as numbness is a common symptom of DCI). Based on my dive profiles we both thought I may have pinched a nerve when lifting the heavy equipment. Just in case, I kept my fluids up and was on alert for other symptoms. Although, after mentioning my numb arm to my boss from the NGO, I was

SEVERITY OF SYMPTOMS INCREASES The next morning I woke up with vertigo and I was in a confused state. I was home alone as my partner had already left for work. I tried to reach him, but he was diving, so I went back to sleep.

At this point I was too confused to understand the situation. I woke up again a couple of hours later feeling better and started getting ready for work. My partner called me and asked if I was ok; I said I was fine, but I wasn’t; the confusion had affected my judgement. Luckily, he asked more questions and realised something wasn’t right, so he had me picked up and taken to the dive centre to start breathing oxygen (O2).

My boss and the medic from the NGO were contacted and this is also when the first call to DAN was made.

After half an hour on O2 the confusion and vertigo subsided and I could feel my left arm again. This is when I realised I had DCI. Originally, the NGO medic made arrangements with DAN to get me to the nearby hospital, but we found that when I stopped breathing O2 more symptoms presented. The medic performed DAN’s neurological exam (Note: You can view the DAN Neurological Exam at www.danap. org/_pdf/neuro_test.pdf) and there were clear neurological signs. Based on this, DAN changed plans, and arranged for me to go directly to Durban Hospital, which has a hyperbaric chamber and diving doctors. From Sodwana, it was a four-hour drive to the hospital. My boss drove and the medic accompanied us to look after me. We determined this was the quickest option, as getting an ambulance to Sodwana, which is quite rural, would have resulted in further delays. Fortunately, we had enough O2 for the whole journey. DAN was in constant contact, getting updates on my condition and relaying the information to the hospital.

Based on my dive profiles we both thought I may have pinched a nerve when lifting the heavy equipment

THE WHOLE LEFT SIDE OF MY BODY WAS NUMB By the time we arrived at the hospital, the whole left side of my body was numb with pain. At

Image © Cormac McCreesh

reassured it was unlikely to be from scuba diving given my dive profile and lack of other symptoms. A colleague who had experienced DCI the previous year also didn’t think my symptom was DCI-related. That afternoon I gave a lecture, and even went to the bar and had a single beer with friends. I chose to stick to water after this as I was still a little concerned. I went to bed early as I felt tired, but no more than usual.

5

Image © Cormac McCreesh

It took me a long time to process anything and, at times, I had difficulty speaking. I then lost feeling in both my legs and it got to the point where I was unable to move them

times I didn’t know where I was or who I was, and my speech was severely affected. DAN was amazing: They arranged everything; the doctor was expecting us and diagnosed me with cerebral and spinal decompression sickness and I was in the chamber to commence my fivehour treatment not long after arriving. I was in a bad state when I went into the chamber but walked out feeling almost back to normal, just exhausted. I spent the night in hospital, although I suffered from severe pain so I was put back in the chamber for another two hours. I was discharged afterwards, as I appeared normal and passed the neurological exams, showing only slight muscle weakness on the left side of my body.

I LOST FEELING IN BOTH MY LEGS Over the next two days I experienced small amounts of sharp pain all over my body. After discussions with DAN and the diving doctor from the hospital, they recommended I breathe O2 for a full 24 hours to see if it reduced the symptoms; otherwise I would need to return to the hospital, which would involve another four-hour journey.

The O2 seemed to help but by the third day I was in a confused state again so my partner drove me back to Durban Hospital. I felt as though my mind was slipping in and out, and over the next few days everything became very foggy. It

6

took me a long time to process anything and, at times, I had difficulty speaking. I then lost feeling in both my legs and it got to the point where I was unable to move them. I was put into the chamber for another two hours, and then again the next day, and an MRI scan of my brain was taken. The doctors said I had relapsed and thought some other unknown condition had been exacerbated by the DCI, causing some of these symptoms. I was also tested to see if I have a patent foramen ovale, a hole in my heart that may increase chances of DCI, but my heart was fine. The hyperbaric chamber treatments partially helped the feeling come back into my legs and my mind felt a bit clearer. Luckily my brain scan was also clear of any lesions or tumours. The doctors said that my peripheral nervous system appeared to be damaged, which is why I felt like I had delayed reaction times for movement and speech. I didn’t undergo any further chamber treatments as the doctors thought we wouldn’t see continued improvement in my symptoms. Fortunately, they were confident I would make a full recovery over time.

LEARNING TO WALK AGAIN Two months later, after gradually learning how to walk again and gaining confidence in my balance (due to the vertigo), I finally felt good

DAN Asia-Pacific Products

Specials for Members DAN Mini Oxygen Unit

Economy Plus Unit

Only AUD$895 (Normally $955)

Only AUD $645 (Normally $695)

The DAN Mini Oxygen Unit comprises Allied Brass multi-function regulator; Pelican 1400 case; Tru-Fit Mask; Resuscitation mask; Handwheel; Demand valve hose (1.8m); non-rebreather mask; and Oxygen manual.

The DAN Economy Unit PLUS (pin-index) consists of a brass multi-function regulator with high flow and low flow outlets, demand valve, 1.5m hose, handwheel, resuscitation mask and non-rebreather mask, all housed in a small waterpoof case.

EMTR – MTV100

Resuscitation Mask

Only AUD$500 (normally $565)

Only AUD$13

Decompression Illness: A Simple Guide Only AUD$6.50

The EMT-MTV100 (with hose and mask) is a manually triggered ventilator which can be attached to a portable or central oxygen source. Importantly, it can be used as a demand valve for breathing victims or can be manually triggered for resuscitation of non-breathing victims.

The Resuscitation Mask has an oxygen inlet (and strap) for mouth-to-mouth ventilations. This mask provides additional oxygen to the non-breathing injured diver if used in conjunction with rescue breathing and constant flow oxygen.

A Resuscitation Mask should be part of every diver’s kit, and at this low price, now is the time to purchase yours!

Written by DAN AP’s John Lippmann, Decompression Illness provides practical advice on the recognition, management and prevention of DCI. Dotted with case examples, the guide highlights the diversity of diving experiences that have resulted in DCI. This guide really is a must-read for all divers.

Ready to Make an Order?

Send an email to sales@danap.org with the item/s you wish to purchase and your delivery address.

Our team will calculate the price with freight (and GST where applicable) and send you a quote.

Check out the full range of DAN Products at www.danap.org

CMYKVersion

Image © Cormac McCreesh www.cormacmccreesh.com A patent foramen ovale, or a hole in the heart, is a mostly harmless condition found in around 25 percent of people that can increase the chances of getting DCI. Rachel’s initial test did not show that she had one

If I had contacted DAN sooner and received treatment earlier, maybe I wouldn’t have suffered so much. I wish I had not been so ignorant about the fact that DCI can occur even when you are diving well within the limits 8

again. My memory was still not perfect and neither at times my speech, but the everyday person didn’t notice. I even began to lecture again for the NGO. It has been five months now since the incident and I feel almost normal. At times I struggle with fatigue, which is normal after neurological damage, and muscle pain and cramps in my legs. I know that I walk differently and compensate for any residual muscle weakness but I think it just shows how well the human body can adapt.

If I think back on the incident, I was particularly tired and stressed, and the doctors found I was slightly dehydrated. All of these factors can lead to DCI. Further, if I had contacted DAN sooner and received treatment earlier, maybe I wouldn’t have suffered so much.

I wish I had not been so ignorant about the fact that DCI can occur even when you are diving well within the limits.

I do intend to dive again. It’s something I love to do and would find it hard to live without. From now on I will always dive with nitrox and continue to stay well within the limits, and extend safety stops when possible. I will avoid repetitive dives, make sure I have slept well beforehand, and be well hydrated. Most importantly, I will continue my DAN Membership and Dive Injury Insurance.

DAN made everything easy, even though I was in a foreign country, plus the ongoing support has been great.

Safety Tip Enter DAN as a contact in your phone. Make sure you have your lifeline when you need it. Visit “Emergency” at www.danap.org. Whilst all divers can call DAN for advice, DAN can only arrange an emergency evacuation and pay for associated treatment costs for current Members (within the limits of their coverage option). Not yet a DAN AP Member? Join at www.danap.org.

Turn to page 78 for DAN’s analysis of Rachel’s incident

Image © Stephen Frink

Research, Education & Medicine

Incident Insight

DON’T DELAY Following on from Rachel’s story of her incident in South Africa (DAN Was There For Me on p4), here we analyse the details of the incident in an attempt to gain some insights Text by DAN AP’s John Lippmann and Scott Jamieson

Images are representative only; they do not feature DAN AP’s member, Rachel

10

INCIDENT DETAILS Rachel is an experienced diver. She has completed 230 lifetime dives, with the bulk undertaken within the past four years. She is also a qualified divemaster with no history of DCI but has relatively recently commenced taking medication for a thyroid condition.

As Rachel identified, she had been undertaking one to two dives per day over the past month to a maximum depth of 18 metres and averaging 15 metres.

The previous day Rachel completed two dives, with a surface interval of “a couple of hours” between dives: Dive 1: 16.7m with a 40 minute down time Dive 2: 12.7m with a 34 minute down time.

On the day of the incident Rachel completed one dive to 17.6 metres for a total dive time of 31 minutes, following a surface interval of over 20 hours. The dive was not strenuous, although there was a slight current, and the location was a site she had dived many times. Most of the dive was spent at around 15 metres and she descended to her maximum depth late in the dive, before slowly ascending to her safety stop.

SYMPTOMS The slight numbness in Rachel’s arm commenced on the short boat ride back to shore, after she had helped lift tanks and weights back onto the boat. On advising her partner and boss

Image © Stephen Frink

of the numbness in her arm, she was made to feel at ease regarding the symptom, which could be easily attributed to a muscle strain. As such, no action was taken at this time.

By morning, Rachel’s symptoms had increased in severity with feelings of vertigo and confusion. When she was able to reach her partner, his action was quick and she was picked up promptly and taken to the dive shop where O2 first aid commenced. By now she was also struggling with speech. She commenced breathing a high concentration of O2, using a non-rebreather mask, and after 30 minutes the symptoms had resolved. However, when waiting for the O2 tank to be refilled, for a period of approximately 30 minutes, the symptoms returned, as did their severity, with Rachel now struggling to walk.

Rachel’s boss at the NGO was advised of the situation and DAN Southern Africa was contacted. The NGO medic performed a neurological assessment that revealed her left arm was weak and she had a problem with co-ordination on her left side. DAN’s advice was to get Rachel to Durban Hospital. Whilst other hospitals were closer, Durban was the nearest hospital with an available chamber. Rachel was able to continue breathing O2 for the complete trip duration.

Within an hour of arriving at the hospital, Rachel was placed in the chamber for a Table 6 Treatment (five-hour duration), with a cerebralDCI diagnosis. After the treatment Rachel still

had patchy numbness on her left arm and was admitted to the neurological ward. After being reassessed the following day, the doctors decided another treatment was necessary.

Four days after the first onset of symptoms, Rachel was discharged but it wasn’t long until pain returned. The doctors advised a 24-hour period of breathing O2 at two hours on and two hours off to assist in clearing the residual symptoms. Rachel was fine whilst breathing O2 but not so in the two hours off. It was noted that Rachel had a change in personality and the neurological exam revealed jerky movement of the eyes when following a finger, she had a numb chin, bad balance whilst walking on her heels, slight amnesia, muscle weakness (unable to move her legs) and she felt extremely tired and drunk.

Rachel’s case was considered quite unique and the doctors asked that she return to the hospital to undergo a CT Scan/MRI and a neurological consult. Rachel’s partner was asked to monitor her condition, in particular for changes such as an inability to urinate and/or neurological symptoms increasing.

On returning to the hospital, Rachel underwent a further neurological exam and based on the results, leaning forward and to the right and walking on her heels, the doctors chose to admit Rachel again to complete the MRI scan of her brain. While waiting for the MRI Rachel experienced another strokelike neurological incident. DAN AP spoke to

The doctors chose to admit Rachel again to complete the MRI scan of her brain. While waiting for the MRI Rachel experienced another strokelike neurological incident

Early identification of possible DCI, and subsequent oxygen therapy can help prevent symptoms escalating

11

Image © Stephen Frink

What factors contributed to Rachel’s incident and why were her symptoms so severe?

The causes of many diving accidents are obvious, such as rapid ascent, too much time at depth, trauma, and many others. However, some are difficult to determine and there is no obvious action or incident that explains why Rachel became so ill.

It is likely that she suffered a cerebral arterial gas embolism (CAGE) as a result of a lung over-pressure injury; or, alternatively, from bubbles in the blood in her veins passing through a “shunt” (e.g., a patent foramen ovale or “PFO”) and into her arterial blood and affecting the circulation to her brain.

Rachel did report that she let go of her SMB reel and was jerked up about half a metre when she grabbed it again. However, this was at depth and was unlikely to have caused a lung over-pressure injury. She does not recall being distracted or having held her breath at any stage of the ascent.

Experienced divers diving with the limits are still at risk of developing DCI Rachel had obvious neurological complications, though the MRI did not indicate any obvious abnormalities

Dive Tip Contribute to DAN’s dive safety research. If you experience a diving incident, submit it to our Online Incident Reporting system.

Your experiences will help us continue to gather data, making diving even safer for all of us! www.danap.org/accident/ nfdir.php

12

Rachel before and after this incident and the deterioration in her condition was dramatic, with slurred speech and an inability to talk in complete sentences.

Rachel underwent two further chamber treatments (a total of four) and afterwards, aside from her slurred speech, her thinking ability was fine. The MRI did not indicate any obvious abnormalities, her speech and symptoms improved and there was no longer any numbness to her leg. She was still slightly off balance when walking on her heels. The major concern with Rachel being unable to stand on her heels was that it may suggest a possible lower lumbar injury.

Ten days after the first onset of symptoms, and following two stays in hospital, Rachel was discharged stating that she “felt like her old self again”. She was in good spirits, able to construct full sentences, and confident all the residual symptoms would resolve with time.

Rachel’s early symptoms were put down to lifting heavy equipment, an understandable assessment but one which delayed essential treatment

Image © Stephen Frink

Her dive profile, although not ideal in that she went to her maximum depth late in the dive, was nonetheless not particularly provocative and would generally be considered to be relatively safe. She had a slow, controlled ascent and did a 4.5 minute safety stop. However, as with many dives, it is likely that bubbles had formed during or after ascent. These bubbles usually don’t cause symptoms and are filtered out by the lungs over time.

Her symptoms occurred after lifting tanks and weights onto the boat. If Rachel does have a shunt, this exertion could have caused blood, and bubbles within it, to pass through and create symptoms of DCI. Rachel was tested for a PFO and one was not found. However, it is quite common for PFOs to be missed unless the appropriate test is done by someone familiar with detecting a PFO in divers.

So it is possible that Rachel has a PFO or other shunt that was missed.

Another possible cause of her symptoms was a neurological disorder (such as multiple sclerosis), unrelated to diving. Fortunately, later tests have indicated this was not the case.

Image © Stephen Frink

LESSONS LEARNED The severity of Rachel’s symptoms was unexpected given the relatively innocent dive profile but may have been a result of the delay in getting oxygen first aid initially. This goes to show that DCI should be considered whenever symptoms appear after any dive, regardless of how short or shallow. Calling a DAN hotline for advice is always a good option, and early and continued oxygen first aid is very valuable.

It was good that the organisation she was diving with had plenty of oxygen for the trip to the hospital and again when her symptoms returned after discharge. This was certainly of benefit to Rachel in managing her symptoms, and likely contributed to her eventual recovery.

Rachel’s case was a great example of the DAN community working together, with DAN Southern Africa taking an active role in assisting DAN AP to manage Rachel’s treatments.

Update To read the latest about Rachel’s case, and to find out if further testing did in fact reveal a PFO, go to www.dapap.org/rachel.php

Image © Stephen Frink

Research, Education & Medicine

Expert Opinions

UNDERSTANDING ALTERNOBARIC VERTIGO Differences in pressure between the two middle ears can result in disorientation that could be dangerous if not properly managed Text by Payal S. Razdan, MPH, and Neal W. Pollock, PhD

Alternobaric vertigo results from unequal pressurisation of the two middle ears. An inability to equalise should prompt a diver to abort the dive

14

David’s day of diving became marked by frustration after he had trouble equalising during his first dive. He was patient though, eventually reaching a maximum depth of about 27 metres (90 feet). The bottom phase of the dive continued without complications, but while ascending at a normal rate he experienced an onset of acute vertigo and disorientation. He had difficulty managing a safety stop and concluded it prematurely. Fortunately, the symptoms resolved on their own within a few minutes with no other untoward effects. The incident was unsettling; however, as he had never experienced anything like it before, it motivated him to learn more and ready himself in case it happened again.

THE PRESSURE ENVIRONMENT Learning how to equalise ear pressure is part of every diver’s basic open-water training. Whether one is breathing compressed gas or freediving, changing depth requires equalisation of middleear pressure to the ambient (surrounding) pressure. Most divers are able to equalise effectively without major difficulty, employing a variety of techniques, from jaw movement to Valsalva, usually choosing the method that minimises middle-ear stress with the least effort.

Most divers understand that a failure to equalise properly during descent or ascent can produce substantial pain and risk of injury. What many do not realise is that unequal equalisation of the two ears can produce other problems that should be appreciated. This article will focus on one in particular: alternobaric vertigo.

AIR SPACES AND THE BODY Changes in ambient pressure affect the gas volume of the air spaces within and adjacent to the body. Internal spaces include the lungs, sinuses, middle ears, gastrointestinal tract and possibly the teeth. Adjacent spaces include the mask, drysuit and sometimes the outer ear.

Some equalisation occurs automatically for healthy divers under normal conditions: The

gas volumes in the lungs and sinuses equalise during breathing, the gastrointestinal system can generally accommodate gas pressure changes, and teeth, fortunately, rarely have closed gas cavities. The gas volume in drysuits and masks is easily adjusted with auto-inflate and exhaust mechanisms and by exhaling through the nose, respectively. Gas in the ear canal under a tight hood can be eliminated by briefly pulling away the hood to allow water to displace the air.

This leaves the middle ear, which is generally actively managed to equalise the pressure on descent and passively managed to equalise the pressure on ascent. Difficulty equalising middle-ear pressure can create problems for divers.

ANATOMY AND EQUALISING EAR PRESSURE The purpose of pressure-equalising techniques is to open up the auditory tube (Eustachian tube), a duct that connects the back of the throat (nasopharynx) to the middle ear (Figure 1). The auditory tube allows gas to pass between these two spaces, balancing the pressure. On the surface, where ambient pressure changes are small, equalisation of the middle ear and the ambient pressure occurs naturally – when we yawn, swallow, laugh or chew, for example.

Equalisation of middle-ear pressure is essential to avoid damage to structures involved with hearing and balance. Functionally, sound waves (pressure waves) make their way through the outer ear canal and across the tympanic membrane (eardrum). The eardrum translates the waves into vibrations, which then pass through three small bones in the middle ear (the malleus, incus and stapes) into the inner ear.

The stapes transfers the vibrations from the middle ear through the oval window into the fluid-filled spaces of the inner ear. The oval window acts as a direct line of communication to the cochlea (sensory organ for hearing), which translates pressure stimuli into sound. However, changes in pressure can also stimulate the fluid-filled semicircular canals of the vestibular system, which interprets head motion and orientation for balance.

The inner ear is separated from the middle ear only by two delicate membranes: the oval and round windows.

The right and left cochlea can receive different sound stimuli, allowing for source localisation (distance and direction). Balance sensing is based on coordination of the semicircular canals between the two ears.

Mismatched stimulation of the vestibular system is problematic. If the difference results from a pressure imbalance, a condition known as alternobaric vertigo can result.

What many divers do not realise is that unequal equalisation of the two ears can produce other problems that should be appreciated

WHAT IS ALTERNOBARIC VERTIGO? Alternobaric vertigo (AV) is a highly descriptive term coined by Dr. Claes Lundgren in 1965.3 “Alter” means “another”, “bar” means “pressure”, “ic” means “the condition of”, and vertigo is the perception that the body or its surroundings are spinning or moving. AV arises from unequal pressure between the two middle ears, usually because the pressures are changing at different rates. Failure to equalise pressure symmetrically can cause the brain to erroneously perceive the difference as movement.

AV can occur during descent or ascent but is more commonly associated with ascent.

Figure 1:

15

Image © Stephen Frink

The challenge for divers experiencing symptoms for the first time is to avoid actions that may worsen the situation Symptoms can range from mild to severe but are typically transient, subsiding within seconds or a few minutes as pressure equilibrates.

Nystagmus (involuntary rhythmic movement of the eyes) can also occur, as can nausea and vomiting in severe cases. In addition to visual disturbances, AV events may be accompanied by the feeling of fullness, tinnitus (ringing in the ears) and muffled hearing in one or both ears.

Some divers may notice a hissing or squeaking sound, indicating poor equalisation, prior to the onset of AV. Women appear to have a greater susceptibility to the condition than men.1,2 The challenge for divers experiencing symptoms for the first time is to avoid actions that may worsen the situation. Maintaining control and a stationary position will allow the symptoms of AV to resolve naturally, with minimal risk of complication. Persistent symptoms may indicate a more serious condition (see sidebar on next page). An isolated incident of AV does not necessarily indicate future risk or more acute health concerns.

Divers experiencing AV repeatedly, however, should seek medical evaluation.

Prepare Smarter Never assume someone else is prepared to respond.

Learn the skills needed to help yourself and others in the event of a diving incident: www.danap.org/DAN_ training.php

16

PREVALENCE OF AV Cases of AV are likely to be unreported, either because no ill effects resulted or, in cases where the condition prompted a panicked response, the victim was unable to provide a report. Panic arising from unexpected disorientation can potentially lead to serious or fatal injury, if a diver bolts to the surface. A

retrospective study found 27 percent of subjects reported a history of AV associated with diving.2 A prospective study found symptoms of AV in 14 percent of subjects completing monitored dives.4 REDUCING THE RISK OF AV Effective equalisation (early, often and with the most appropriate technique for the person) and not diving when congested are simple ways to reduce the likelihood of AV. The need to exert high pressures to equalise during descent can make equalisation during ascent, which is usually a passive process, more difficult. The impact can be substantial if the soft tissues have been made swollen by overly aggressive or poorly conducted equalisation manoeuvres. If properly conducted equalisation manoeuvres fail, one should abort the dive and evaluate the situation before trying to dive later.

Some divers find it easier to equalise in a head-up position. Performing gentle, active equalisation techniques early and often during descent will help to reduce stress on ear structures. Divers that encounter frequent AV should re-evaluate their equalising techniques and possibly their buoyancy control – after being cleared to dive following medical evaluation.

Any condition that can cause inflammation and congestion of the ears and sinuses could increase the likelihood of equalisation problems such as AV. Individuals choosing to dive despite symptoms of congestion or illness may be putting themselves at risk. Diving with congestion could also lead to reverse block, a condition where

Dive Accidents Do Happen.

Don’t Let Your DAN Coverage Expire.

Four days after a Member allowed his DAN coverage to expire, he suffered a severe case of inner ear DCI. A local air ambulance was organised to get him to care quickly.

Out of Pocket Cost: $8,000 If he had Renewed his DAN Coverage: $0

www.danap.org

What If Symptoms Persist?

Image © Stephen Frink

Symptoms lasting more than a few minutes may indicate a more serious condition. Large changes in middle-ear pressure without proper equalisation can lead to middleear or inner-ear barotrauma. Poor equalisation can cause the eardrum to stretch to the point of injury.

A diver may experience a sharp pain as the eardrum ruptures, possibly followed by transiently severe vertigo driven by the rush of relatively cold water into the middle ear (caloric vertigo). These symptoms will similarly subside as the temperature difference wanes.

Treatment of mild cases may include decongestants and antibiotics.

Non-perforating injuries may heal in a few days, while ruptured eardrums can take six weeks or more. In severe cases, surgery may be required.

Inner-ear barotrauma is a pressure injury to the sensory cells of the inner ear, which may or may not involve perforation of the round or oval window. It is a much more serious condition that requires medical attention and, frequently, surgical intervention. Divers may experience prolonged severe vertigo, hearing loss and tinnitus. In any case, active equalisation should be avoided until the trauma has healed. Divers can often return to diving after an eardrum perforation, but inner-ear barotrauma may be a long-term contraindication. Innerear decompression sickness (IEDCS) can present with symptoms similar to inner-ear barotrauma. IEDCS must be treated in a hyperbaric chamber as soon as possible.

References 1. Kitajima N, SugitaKitajima A, Kitajima S. Altered Eustachian tube function in scuba divers with alternobaric vertigo.

Otol Neurotol. 2014; 35(5): 850–6.

2. Klingmann C, Knauth M, Praetorius M, Plinkert PK. Alternobaric vertigo – really a hazard? Otol Neurotol. 2006; 27(8): 1120–5.

3. Lundgren CE. Alternobaric vertigo – a diving hazard. Brit Med J. 1965; 2(5460): 511–3.

4. Uzun C, Yagiz R, Tas A, Adali MK, Inan N, Koten M, Karasalihoglu AR. Alternobaric vertigo in sport scuba divers and the risk factors. J Laryngol Otol. 2003; 117(11): 854–60.

18

gas becomes trapped in the middle ear. A diver might manage reverse block by descending slightly and then reattempting a slower ascent.

If this fails to work, however, the diver will have little choice but to risk more serious injury while continuing the ascent as slowly as possible for the circumstances. Ample gas supplies and conservative dive profiles will give the diver additional time to deal with any equalisation issues that might arise upon ascent.

Some divers may choose to rely on nasal decongestants as a solution for diving with congestion. Decongestants relieve symptoms temporarily, but they can mask issues. Using decongestants for four or five days may result in rebound congestion, making it more difficult to equalise.

IF AV OCCURS Divers who become disoriented and panic when they experience AV can face more serious problems if an uncontrolled ascent follows. It is important to remember that AV symptoms will wane as the unequal pressure resolves. A diver

should not attempt to force equalisation while experiencing AV since this could make symptoms worse or damage delicate ear structures.

If symptoms consistent with AV develop, recognition and a calm state of mind offer the best protection. Holding a depth assisted by a fixed visual reference or a physical connection to an unmoving feature (e.g., rock, rope or seafloor) can be effective while waiting for symptoms to subside.

A sudden onset of vertigo can be both a frustrating and disorienting experience for divers. If AV symptoms are experienced during the beginning of the dive, the dive should most likely be ended. If AV symptoms are experienced later in the dive, the focus should be on how to end the dive safely. In most cases, AV symptoms are self-limiting, so it is important to remain calm until symptoms resolve on their own. Divers who educate themselves on AV will be in a better position to manage the symptoms and minimise risks if an event does occur.

EXHIBITION OF THE YEAR (MPAS AWARDS 2015)

www.adex.asia

Celebrating Ocean Voices

((Photographers & Writers, Cinematographers, Videographers))

ADEX

ASIA DIVE EXPO

Get the app with everything you need for ADEX: deals, speakers, activities, lucky draw, floor plan, programme, and the ADEX Scan!

Gear

UNDERWATER COMMUNICATIONS SYSTEMS Text by Michael Menduno

In 1977, a year after I got open-water certified, Sound Wave Systems launched the Wet Phone, a voice-activated underwater communication device that promised to revolutionise sport diving, making the ocean a “silent world” no more. I added it to my wish list along with a Watergill At-Pac, the forerunner of modern-day wings, and an SAS drysuit. Sound Wave filed for bankruptcy a few years later.

SOUNDING OFF There are two kinds of underwater communication systems: hardwire and wireless – or “throughwater” – communications (comms). Hardwire systems are essentially waterproof intercoms that connect the diver to the surface; they’re used primarily by divers on umbilical cables and in some public safety applications such as very low visibility. They are not designed for sport use.

In contrast, through-water systems use ultrasound (typically 25-33 kHz) to transmit and receive signals through water in the same way that walkie-talkies or mobile phones use radio waves. The density of water, which is 784 times greater than air, makes it an excellent conductor of sound energy, a fact not lost on Nature – many marine animals, especially cetaceans, use ultrasound to communicate and navigate.

Image © David Schott

A videographer prepares to dive under more than a metre of ice in the Bering Sea. She uses a fullface mask and communications system for speaking with a tender on the surface and the talent underwater

Today – nearly 40 years later – communication systems have become standard kit for commercial, military, law enforcement, public safety, aquarium and scientific divers and for videographers, but they remain a niche product for recreational and technical divers. For many

divers the added complexity and cost of what is essentially an underwater walkie-talkie outweighs the benefits in the absence of a mission-specific need. Others say they prefer to commune in silence.

If you’re wondering whether your next diving project might benefit from vox (voice) communication, it’s worth learning a little about the technology, its implementation and use.

20

Conversely, with the exception of extremely low frequencies, radio waves do not propagate through water.

IN THE BEGINNING THERE WAS THE… WET PHONE Originally developed for the U.S. Navy in the late 1960s, early through-water comms and their spinoffs (such as the Wet Phone) used the circuitry found in AM radios to encode voice conversations (0.3–4 kHz) on an ultrasound carrier. However, amplitude modulation (AM), which transmits three simultaneous signals (a carrier and two sidebands), suffered from poor intelligibility because the signals would get out of sync as they travelled through the water and were reflected off various surfaces. Also divers had to remain nearly motionless in the water while talking, otherwise voices sounded garbled.

These issues did not help Wet Phone sales.

It wasn’t until the mid-1980s that increasingly miniaturised electronics made it possible to use sophisticated single-sideband modulation, which transmits a single ultrasonic carrier signal to eliminate the reflection and multipath problems of AM. Single-sideband quickly became the de facto standard due to its near 100-percent intelligibility under good conditions.

Today there are two vendors that build through-water comms systems for sport divers.

Products range from all-in-one, half-watt, cigarette-pack-sized sport transceivers powered by a nine-volt battery that mount on the mask strap, to more powerful five-watt, walkie-talkiesized units that can be attached to a diver’s harness and include cabling for the mic and earpiece. Most units feature dual channels and are push-to-talk like a walkie-talkie, though some offer voice-activation as an option.

Operational range varies from 45 to 450 metres for sport units to more than 800 km for professional comms, depending on sea conditions and noise levels (special military units can transmit more than five kilometres). Vendors also sell receive-only units and a variety of surface stations for surface-to-diver communication.

WHO WAS THAT MASKED MAN? If you could add comms without changing anything else, it’s likely that many more sport divers would be talking the talk. Unfortunately it’s not that simple. To talk underwater you need an air-filled space to speak into (and place a mic), and the mouth must be unencumbered.

Early sport units like the Wet Phone utilised a “mouth mask”, essentially a rubber pocket attached to the second-stage regulator and strapped over the mouth, but these proved to be largely unworkable. Instead, the community has moved to a full-face mask standard with comms, enabling divers to breathe through their nose and mouth.

Today there are a variety of full-face masks on the market along with requisite training courses. Most masks feature a built-in oronasal pocket to reduce carbon dioxide (CO2) buildup, a built-in regulator and a port to attach a comm system. In addition, the majority of masks circulate breathing gas across the faceplate to keep it from fogging.

PROS AND CONS Full-face masks offer divers a number of obvious advantages over scuba masks. They have a wider field of vision, they don’t fog up, and they are warmer and more comfortable than a bite mouthpiece. They also protect the diver’s airways in the event he or she goes unconscious underwater, which is a considerable safety benefit.

The disadvantages are subtler. Mask fit and obtaining a good seal are critical. Equalisation and mask clearing can be more difficult. With practice, gas consumption tends to be about the same with a full-face mask, but it increases considerably when you are talking, so good gasmanagement skills are required. In addition, bailout is a little trickier, particularly in cold water – the diver has to remove his mask and regulator simultaneously to use an alternative breathing source.

Full-face masks present even more challenges for tek divers. First, they complicate open-circuit gas switching: The diver must use quick disconnects and/or a gas block to switch to his decompression gas or bailout without removing his mask. Second, despite added airway safety, the use of a full-face mask with rebreathers is at best problematic for several reasons, including fogging and an increased risk of CO2 build-up.

Finally, comms gear is expensive: A full-face mask with a comms system can cost up to USD 1,000–2,000 per diver. As a result, recreational and tek divers tend to use full-face masks and comms for mission-specific applications.

Some say the uses are growing. At present, underwater comms gear may be best suited for diving in cold or dirty water, outfitting support divers who need to be able to speak with the surface, performing long decompressions or remote in-water recompression and the occasional underwater wedding. Gadget geeks also enjoy them.

Being able to talk underwater adds a layer of safety, coordination and control that may not be achieved otherwise, making underwater communications systems an indispensible tool for working divers. But given the added complexity and cost of the systems, most sport divers remain content to rely on hand and light signals to convey essential information and save their talking for after the dive.

Being able to talk underwater adds a layer of safety, coordination and control that may not be achieved otherwise, making underwater communications systems an indispensible tool for working divers

21

Water Planet

Life Aquatic

OVERFISHING AIDS SPONGES, HURTS CORALS With no predators to keep them in check, fast-growing sponges spell bad news for coral reefs Text by Joseph R. Pawlik, PhD

Sponges feed by consuming tiny particles and dissolved compounds in the seawater they pump through their bodies. Millions of flagellated cells inside sponges power this pumping, generating an outward flow from the sponges’ larger openings. A population of Caribbean giant barrel sponges can process the entire volume of seawater above a reef in as few as three to 18 days, depending on sponge abundance and depth. This unusual feeding strategy sets sponges apart from the other two primary reef occupiers, corals and seaweeds, which rely primarily or exclusively on sunlight and photosynthesis for their nutrition. Using this difference to their advantage in the struggle for available space, sponges can grow to shade and smother corals and seaweed and then steal the real estate.

THE SPONGE EATERS When my research group from the University of North Carolina Wilmington began working on sponges more than 25 years ago, the conventional wisdom was that sponges on Caribbean reefs were largely unaffected by predation. Angelfishes and hawksbill turtles had been identified as sponge predators, but it was thought that their feeding activity was evenly spread out among sponges, not causing particular harm to any one species. We discovered that several species of parrotfishes are sponge predators.

DEFENCES OR GROWTH BUT NOT BOTH Furthermore, we determined that predators avoid some sponge species because of distasteful chemical compounds in the sponges’ tissues. Over the years we have worked with 22

Image © Joe Pawlik

With brightly coloured branches, tubes, mounds, fans and barrels, sponges are dominant animals on most reefs.

Despite their quiet stillness, they are involved in an ancient and ongoing struggle with their predators and competitors – and on modern-day Caribbean reefs, sponges appear to be winning.

organic chemists to isolate and identify the chemical compounds that serve as defences for many sponge species. Some of these compounds show interesting properties that may be useful in the development of new drugs to treat human diseases. Our research found that not all sponge species on Caribbean reefs have chemical defences.

Sponge predators targeted some very common species, such as grey tube and green branching sponges, in a series of experiments we conducted on reefs in the Florida Keys. We observed that these undefended sponges grow faster than chemically defended sponge species.

This was important evidence for what ecologists call a resource trade-off: Sponge species invest

Predators avoid some sponge species because of distasteful chemical compounds in the sponges’ tissues

as Jamaica and Martinique that have been overfished using fish trapping and netting as well as locations such as the Cayman Islands, Bonaire and the southeastern Bahamas with less-fished reefs that have been mostly protected from fishing. We predicted that the removal of sponge predators on overfished reefs would allow the undefended sponge species to flourish, while these species would be held in check by sponge predators on less-fished reefs – and that’s exactly what we found.

In particular, angelfishes had a dramatic effect on the sponge species they like to eat.

Our results showed that overfishing of sponge predators altered the community of sponges in favour of faster-growing, undefended sponge species.

NO-FISH KNOCK-ON EFFECTS Overfishing of Caribbean reefs changed more than just the sponge community. Our Caribbeanwide study documented three times more

Overfishing of sponge predators altered the community of sponges in favour of faster-growing, undefended sponge species

When sponge-eating fish are overharvested, sponges can quickly overgrow and kill reefbuilding corals

Image © Joe Pawlik

their energy in either making chemical defences or growing faster, but they can’t do both.

Based on that observation, we predicted that undefended yet faster-growing sponge species would populate new reef habitats more rapidly than defended species. We were able to test this hypothesis with the sinking of the USS Spiegel Grove as an artificial reef off the coast of Key Largo, Florida, in 2002. After only four years the wreck was covered with undefended sponge species, and very few chemically defended species were present. Since then the wreck has attracted the angelfishes that eat these sponges, and on subsequent visits we have seen the relative proportion of undefended sponges decrease as the predators graze them and the chemically defended species steadily recruit and grow on the wreck.

To test our developing model of sponge ecology, a team of five of us conducted dive surveys of 69 reefs in 12 Caribbean countries over three years. We chose locations such

23

Image © Stephen Frink

Water Planet

24

sponge overgrowth of reef-building corals on overfished reefs, a direct consequence of undefended sponges growing unchecked by sponge predators. With the fast-growing sponges free from predation on overfished reefs, they were able to smother adjacent reefbuilding corals. Divers know that corals, not sponges, build the reefs we cherish. Coral reefs provide shoreline protection for reef-adjacent countries as well as millions of dollars in annual tourist revenue. For the conservation of coral, the results of our research justify the protection of sponge predators on reefs. The first course of action should be to ban fish-trapping and netting practices that indiscriminately remove fishes of all species. Sponge predators, particularly angelfishes, warrant special protection, especially from spearfishing.

Divers can help by encouraging governments to enact protective legislation and to fund management programmes and by supporting marine parks and protected areas that enforce fishing restrictions. These actions can help restore reef ecosystems that are severely out of balance.

With the fast-growing sponges free from predation on overfished reefs, they were able to smother adjacent reefbuilding corals.

Read MEMBER EXCLUSIVE

Image © Stephen Frink

OFFICIAL MEDIA PARTNER

a

ALL

Free ONLINE!

FOR

ONE, ONE

PRICE

+ 1 YEAR DAN Asia-Pacific Membership + 1 YEAR Subscription to Scuba Diver AUSTRALASIA + OCEAN PLANET for just SGD90!

a

A brand new offer from Scuba Diver AUSTRALASIA + OCEAN PLANET and DAN Asia-Pacific now lets you get your dive safety, travel, education, entertainment, lifestyle and underwater photography, in one fell swoop and for a killer price.

As part of this exciting partnership, we are offering DAN Asia-Pacific Members, anywhere in the world, FREE access to our joint publication.

Scuba Diver AUSTRALASIA, now with DAN AsiaPacific’s Alert Diver, is published four times a year and is full of fascinating content – compelling, relevant information and images from some of the world’s best underwater photographers.

If you are a DAN Asia-Pacific Member, scan the QR code and follow the instructions to receive your free issue of Scuba Diver AUSTRALASIA and Alert Diver! w w w.danap.org /join.php

FOR ALL

w w w.uw 360.asia/sdaa

Don’t miss out! Become a Member of DAN Asia-Pacific and have the world’s best dive magazine land on your doorstep eight times a year, all for the special price of just SGD90!

Option 1

GO ONLINE:

www.uw360.asia/sdaadan www.danap.org/package.php Option 2

MAIL TO: Asian Geographic Magazines Pte Ltd 20 Bedok South Road Singapore 469277 Email: support@uw360.asia Tel: +65 6298 3241 Fax: +65 6291 2068

þ YES! My name is I live in the Asia Pacific region, and I would love to get my DAN Asia-Pacific Membership and a subscription to Scuba Diver AUSTRALASIA + OCEAN PLANET, bundled together for the crazy price of just SGD90!

Here is my email address; please write to me at

@

HERE’S WHAT YOU’RE MISSING IN THIS ISSUE OF SCUBA DIVER AUSTRALASIA Scuba Diver AUSTRALASIA is one of the most well Scuba Diver respected dive magazines, full of mind-blowing images AUSTRALASIA from the world’s best photojournalists, the low-down on the newest dive equipment, the most exciting is the official stories from the world of science and media partner of destinations, conservation, and much, much more!

DAN Asia-Pacific.

FROM THE EDITOR We’ve all been there. You’re booking your next bucket-list dive trip and you get that inevitable look, the look that says, “I think you’ve got a problem”, and implies that you need some sort of intervention. And then they see you drooling over that new BCD (check out p45), and the eyebrows go up while they ask you (pointedly) how much you think diving might be taking over your life.

Some people just don’t get it.

Well, fret not; we’ve put together 61 irrefutable reasons why you really should go diving in 2016. Arm yourself with just a handful of these and not only will you be able to shut down that judgemental nonsense once and for all, but they’re soon going to be asking you for tips on where and how to get certified.

You can then casually and confidently refer them to the more than 80 enticing dive operators listed from page six… Just be sure to have your “I told you so’s” ready for when they come back with the bug!

(You’re welcome.)

www.uw360.asia/SDAA

On the cover

Give in to your diving cravings in 2016

MAR

Diveaholics

FEB

MAY

JUN

AUG

SEP

NOV

DEC

ONE OCEAN, ONE LOVE

a

ONE OCEAN, ONE LOVE a

a

Don’t miss out on the latest and greatest gear to get you under in 2016.

REASONS TO GO 06 61 DIVING IN 2016 Arm yourself with these incontrovertible justifications for going out and getting wet this year

a

a

a

a

a

ONE OCEAN, ONE LOVE

buyersguide

destinationsdirectory

26

38

icon ASIA DIVE EXPO 96 THE The region’s best dive show is all grown up...

MASKS FINS THERMAL PROTECTION REGULATORS COMPUTERS CAMERAS & HOUSINGS WATERPROOF CAMERAS VIDEO CAMERAS PHOTOGRAPHY ACCESSORIES STROBES & LIGHTS TORCHES BAGS MORE GEAR & GADGETS

ONE OCEAN, ONE LOVE

Zhang Fan

SUBSCRIBE TODAY! DAN MEMBERS PRINT SUBSCRIPTION OFFER SDAA

One year of Scuba Diver AUSTRALASIA | 4 issues

Singapore and Malaysia SGD 21 Aust/NZ/South Pacific AUD 25 Other parts of Asia USD 25 Outside Asia USD 26

SAVE UP TO 40% OFF COVER PRICE

DAN MEMBERS PRINT SUBSCRIPTION OFFER SDAA + SDOP

One year of Scuba Diver AUSTRALASIA + SD OCEAN PLANET | 8 issues

Singapore and Malaysia SGD 43 (usual price SGD 48) Aust/NZ/South Pacific AUD 49 Other parts of Asia USD 49 INCLUDES E-MAGAZINE Outside Asia USD 52 FOR FREE

Name: Address:

Email: Tel:

Payment:

VISA

MASTER

AMEX

Card No: Expiry date: CVV: Signature: Credit card payments will be processed in SGD

My Cheque/Bank Draft for SGD is enclosed, payable to: Asian Geographic Magazines Pte Ltd Bank:

Cheque No.: Only SGD cheques are accepted

Send this form to:

Asian Geographic Magazines Pte Ltd 20 Bedok South Road, Singapore 469277

DAN ASIA-PACIFIC MEMBER EXCLUSIVE READ SCUBA DIVER AUSTRALASIA FREE ONLINE!

Terms & Conditions: All promotions are valid for a limited period only and/or while stocks last. Please allow 4–6 weeks for delivery of the first issue. An acknowledgement letter will be sent to you either by email or post. All subscriptions are non-refundable upon receipt. No official receipt will be issued for payment by cheque/credit card. You will be notified if you have won a prize. Payment by cheque and/ or bank draft should be made payable to “Asian Geographic Magazines Pte Ltd” in Singapore Dollars and only Singapore (S$) cheque is acceptable. All credit card payments will be processed in Singapore Dollars (S$). For enquiries, please call our customer service at Tel: (+65) 6298 3241 or Email: sub@uw360.asia

Fax to: (+65) 6291 2068

27

APRIL 15–17, 2016

SUNTEC SINGAPORE

DEDICATED TO SEAHORSES

ADEX2016 28