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Magic Blog

Bigtastic Brothers Islands

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Here a few snaps from a trip to the Brothers Islands in the middle of the Red Sea.

I went on a one-week liveaboard trip to research a feature for a few mags, courtesy of Oonas Divers. The very short summary is: Great diving, great conditions with a flat sea and mild current, plenty of big stuff and two excellent wrecks in the Numidia and the Aida. Good crew and great dive guides, mountains of fine food. Well worth a visit.


 

 

 

 

 

 

 

 

 

 

 

 

 

Off the top of my head memorable big stuff: A giant manta, multiple sightings of Thresher sharks, close encounters with a silky shark, oceanic white tip (also visible around the boat at night), multiple grey reef sharks (including a pregnant one), very inquisituve male and female napoleon wrasses, barracudas in the shallows,big schools of black snapper, eels a-plenty, and a gorgonian forest. Little stuff: tons of red sea anthias, goldies, the hawkfish below, a plethora of pipefish, and in the middle my favourites were squirrelfish, orangespine unicornfish, black snappers, sohail surgeonfish, masked butterflyfish, schools of fusiliers, coral and red sea groupers, and the cheeky bannerfish below.

Below: Long-nosed hawkfish in gorgonian , and giant manta and barracuda (below and behind, looks much better in hi-res)

Above - Thresher shark and silky shark

Below -  Bannerfish and grouper - Divers on the the Numidia

 

Above - a cool cornetfish and  a one of several friendly male napoleon wrasse

 

 

 

 

 

 

 

 

 

 

 

 

Above - diver over soft coral on safety stop - and over acropora corals with black snappers for company

Below: Pregnant grey reef shark - a few of the many specimens in the gorgonaian forests 

 
 

 

 

 Big Brother from the  flybridge - Pouting bannerfish - giant morayopens wide for cleaning

 
 

 

 

 

Controlling Crown-of-Thorns outbreaks

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What are crown-of-thorns?

COTSMost divers have seen the occasional brightly coloured, many-limbed, spiny rubbery-looking Crown-of-Thorns starfish (scientifically Acanthaster planci and hereinafter COTS). Like most things on a reef, they have their place in the food chain and fulfill a role in a balanced and healthy reef system. They look quite funky and can be a good subject for macro photography if there is not much else going on. But they also gang up into an extremely efficient coral killing machine. I dive from Pemba island, Zanzibar, regularly, and towards the end of a visit in late September I was told that one of the dive sites, home to leaf coral, lattice coral, and a sort of soft-looking knuckle coral was under attack from a plague of COTS.

 

Young crown-of-thorns starfish eat algae encrusted on the coral common among rocks and rubble on the reef. At about six months of age, they start to eat coral and growth rates increase, the COT going from 1cm across to 25cm in the subsequent two year -period. Crown-of-thorns starfish spend about half their time feeding. When there are few crown-of-thorns starfish, they are elusive and hide in the reef and under corals during the day. Larger starfish (more than 40 cm) usually feed during the day while smaller starfish (less than 20 cm) usually feed at night. Extrudng their stomachs onto the coral they literally suck the life out of it.

 

dead coralCrown-of-thorns starfish feed mainly on faster growing table coral species, particularly Acropora species, and may only eat a portion of the entire coral colony. As a result, the reef can recover quite rapidly from low levels of predation by crown-of-thorns starfish. Some reefs seem to support small populations of crown-of-thorns starfish for many years, with only a small reduction in coral cover. Scientists estimate that a healthy coral reef with about 40-50% coral cover can support 20-30 crown-of-thorns starfish per hectare (100 metres by 100 metres).

 

However, when starfish are in large numbers, there is intense competition for food and most types of corals will be eaten, including species such as slow-growing Porites spp. that are not usually eaten by the starfish. During a severe outbreak, the COTs can number 20 per square metre or more, piling on top of each other three or four deep at times. They can eat so much that they can kill most of the living coral in that part of the reef, reducing hard coral cover from the usual 25 - 40% of the reef surface to less than 1%. Such a reef can take over 10 years to recover.

 

What causes outbreaks of crown-of-thorns starfish?

While there have been many theories on the causes of outbreaks of the crown-of-thorns starfish, there are three theories that are supported by scientists. These theories have neither been proved nor disproved:

 

1.Fluctuations in crown-of-thorns starfish population are a natural phenomenon.

Just like any other organism, populations go up and down.

 

2. Human use of the coastal zone has increased the nutrients flowing to the sea and resulted in an increase in planktonic food for larvae of crown-of-thorns starfish. The improved survival of larvae has led to an increase in the number of adult starfish which results in outbreaks.outbreak

 

Crown-of-thorns starfish spawn over four to five months a year when water temperature is around 28C. The starfish release eggs and sperm into the water through pores on the top of their central disc and when the eggs are fertilised, they develop into larvae that drift like plankton for two to four weeks. The 1 to 2mm juveniles settle onto the reef and live among rocks and rubble on the reef remaining almost invisible until they are about six months old. First breeding when 2-3 years old, it will continue reproducing for five to seven years. Each female can spawn up to 60 million eggs during a single season. Gathering together to spawn to increase the chance of fertilisation, fertilisation rates in the field for crown-of-thorns starfish are in fact the highest measured for any invertebrate. So with even more favourable factors their proliferation could be increased considerably. However, there is little human habitation near the dive site in question, nor any rivers to bear new nutrients from further a-field.

 

3.Removal of natural predators of the crown-of-thorns starfish has allowed populations to expand.

Although crown-of-thorns starfish have few predators, one theory suggests that predators play an important role keeping starfish populations balanced. Predators of adult crown-of-thorns starfish include the giant triton snail, the napoleon or maori  wrasse, starry pufferfish and titan triggerfish.

 

The giant triton snail is highly prized and heavily collected for sale to landlubbers (and stupid divers).

However, the triton shell can consume relatively few adult COTS per week so its capacity to prevent starfish outbreaks seems limited, although it plays an important role when COTS numbers are stable. The shells for sale in tourist shops on Unguja island and at Dar-es-Salaam have come from somewhere. Humphead Maori wrasse are also reputed to be active crown-of-thorns starfish predators.

 Predation by other reef fish on juvenile starfish might also limit crown-of-thorns starfish populations. Juvenile starfish are most likely to be eaten aged around six months, when they start to feed on coral. If numbers of the predator fish were depleted by fishing activities this might allow an abnormally large number of starfish to survive to maturity. There is no substantial evidence at this time to show that commercially exploited fish eat significant numbers of juvenile COTS but there is subsistence fishing in the area, including some illegal dynamite fishing, and no notice is paid to the size or type of the fish caught. Given that there is no data available on past fish populations, it is impossible to state that their numbers are in decline, but it wouldn't be beyond the realms of possibility

Because the numbers of starfish larvae that usually survive and then settle is unknown and it is difficult to estimate feeding rates of predators required to keep them in check.

Whilst the causes are therefore impossible to define categorically, the existence of a abnormal numbers of COTS is easy. On returning in early December, armed with what I hoped to be a solution to the problem, I dropped on to the site to see what had happened over two months. Sections of the dive site, roughly 10 metres wide and 20 to 30 metres long, had been killed by the slowly creeping underwater zombie horde, leaving tracts of coral completely white and, critically, dead. The COTS were in patches, seemingly moving from the shallower sections of the reef (10m) to the edge of the wall (17m), advancing in an underwater phalanx.

Dealing with the outbreak

 buddy with syringeIn the past COTS would be removed physically from the reef and buried on land. This method has several draw backs though. Firstly, the starfish cling on to the reef and yanking them off damages the reef. Secondly, they are covered in toxic spines (the toxins come from the coral that they eat) that give very painful and sometimes dangerous stings, so they have to be handled with tongs or sharp sticks. This makes removal slow and labour-intensive. Another method tested in the past was cutting them up under water. But to do this the coral still gets damaged, there is still a considerable risk of getting stung, and COTS that have been cut in four were observed still alive two weeks later!

Research on the Great Barrier Reef discovered the solution that I was going employ. An injection of sodium bisulphate solution into the centre of the COTS kills them in a couple of days, and has no effect on other marine organisms. So I went through Ebay and found some 60ml syringes, some long needles, and ordered the cheap and readily available chemicals from a pool cleaning company, and crossed my fingers that I wouldn’t some explaining to do at Dar-es-Salaam airport. 

the resultOnce on Pemba and over the dive site, myself and two other divers mixed 200 grams of Sodium Bisulphate with a 720ml of seawater, filled up the six syringes, and dropped down. Each starfish was to be injected with 2ml, so one syringe would deal with 30. Working head down feet up most of the time, we took about 15 to 20 minutes to empty our syringes. The skin of the COTS is quick thick, but it has a sort of bumhole-like aperture in the centre of its topside, and the needles slipped in a treat. One diver collected the syringes, surfaced, refilled and came down again. In total we emptied 12 syringe-loads in less than an hour, making around 360 injections. Of course some recipients may have got a bit more than 2ml to begin with and no doubt some were done twice – spending 15 minutes head down looking at these buggers can be a bit disorientating! 

 

Over the next week we went back twice to do neighbouring patches, and went to check out the initial site. The results were pretty spectacular. After a day the COTS were starting to get flaccid, and their skins weren’t so tough (so you could tell which ones had been injected before), and a couple (that probably got an extra dose) were splitting down the middle, but still moving. After two to three days they were dead, and in various states of liquefaction. It was pretty sci-fi really. Like a melted alien or something from ghostbusters, with a patch of gooey white substance with the spines sprinkled on top. In sum, it was a pretty effective way, both in terms of time and cost, of restoring balance to the reef.

 

 

Zanzibar Magic and a bit of safari

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pembaThe spice islands of Pemba and Unguja make up the Zanizbar archipelago off the coast of Tanzania. The contrasts between the islands, Unguja has a thriving tourist industry whereas Pemba has no more than 100 tourists at peak times of the year, are numerous, as are the differences in dive sites. They are both ideally located to combine a dive trip with some of the best safari trips in the world.

 

 

Click on the links to find out more:

Diving Unguja and Pemba islands

Tanzania Safaris

 

Oceanic Garbage Soup - Trash Trawling in the Pacific

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THE SEA OF GARBAGE

 

OCEANIC GARBAGE SOUP 

 

TRASH TRAWLING IN THE NORTH PACIFICCharles Moore

 Floating on or just beneath the surface of the north Pacific Ocean over 1000 miles from any landmass lies a soup of trash; the Great Pacific Garbage Patch.  Located in the North Pacific Sub-tropical Gyre that covers approximately 10 million square miles, it covers an area the two and a half times the size of France, the largest country in Western Europe, and is 20% larger than South Africa.  Discovered in 1997 by Charles Moore, ironically an heir to a petroleum fortune, the GPGP is a mass of plastics, debris, and lost or discarded fishing nets.

Nearly 90% of all floating marine litter is plastic, a petroleum-based substance that takes decades to be broken down on land by the suns rays, and even longer in the cool seas where it is often further protected by barnacles and algae. Plastic pellets used in all sorts of packaging and plastic products are the most commonly found marine pollutant. Also known as nurdles or mermaids’ tears, 50 million tonnes are produced every year. 80% of marine rubbish comes from land via winds and rivers, with ocean currents carrying debris from the west coast of North America to the gyre in about five years, and debris from the east coast of Asia in a year or less. The remaining rubbish comes from ships with a typical 3,000-passenger cruise ship producing over eight tons of solid waste weekly, much of which ends up in the patch, alongside floats and other equipment illegally jettisoned from commercial and fishing vessels to avoid the cost of proper disposal in port. 

Then there are the contents of the estimated ten thousand cargo containers that fall overboard every year. One container can hold 10,000 running shoes, 17,000 ice hockey gloves, or a million pieces of Lego. Given the number of consignments lost and the longevity of the products, there are hundreds of thousands, if not millions, of sports shoes floating in the seas. In fact the Garbage Patch name was coined five years before Moore’s discovery by Seattle oceanographer Curtis Ebbesmeyer whilst studying a consignment of 29,000 plastic bathtub ducks lost from a container ship during a Pacific storm. Using oceanic current modelling software and plotting the positions where ducks were found, he became aware of a slow vortex into which debris was drawn.

popsicle stick and plastic bitsUnfortunately most of the trash is not brightly coloured ducks and running shoes, but mostly small plastic particles suspended at or just below the surface, making it detection by aircraft or satellite impossible. The U.N. Environment Program estimates that 46,000 pieces of plastic litter are floating on every square mile of the oceans whilst the GPGP contained at least six times more plastic matter than plankton biomass, the bottom of the food chain, when last surveyed. 

Returning from a trans-Pacific yacht race, Moore decided to try a short-cut through the virtually windless and therefore seldom crossed North Pacific Sub-tropical Gyre. Motoring through the area Moore was shocked by the contents of the sea. "Every time I came on deck, there was trash floating by," he said. "How could we have fouled such a huge area? How could this go on for a week?"

As the founder of the non-profit Algalita Marine Research Foundation he began looking into the sources of the problem and its extent. In 1999 he returned to undertake the first scientific sampling of the area he describes as two to three times the size of Texas, but that he fears could be greater than the surface area of the United States.

In June 2009, with Moore on board for his tenth mission to the area, the ORV Alguita set off on the a four-month mission to gather more data to try to gain further understanding into the wide ranging and poorly understood potential impacts of oceanic micro-plastic pollution.

The first leg of the trip concentrated on sampling the area around Hawaii providing both water samples from trawls and fish tissue samples for analysis back on land. It is believed that a significant amount of the plastic pollution currently cycling around the North Pacific passes around or through the Hawaiian islands making the area a suspect for high concentration of small particle pollution as well as large ghost net pollution. The importance of these islands, with their pristine reef ecosystems, for a myriad of species means that a full understanding of how these animals and their environment are interacting with plastic pollution is needed.

plastic ingestionThe trip home from Hawaii back to California was a key element in calculating the rate of growth of the Great Pacific Garbage Patch, included a resampling of the original 1999 gyre crossing. The 10-year gap will provide concrete figures about the rate of growth and about the seasonal changes in plastic density as the 1999 trip data will be significantly strengthened by a summer sampling of the same transects. By comparing the levels found ten years ago, and using model predictions, growth over that period can be calculated. Using trawling techniques and sampling methodology developed by the Algalita Marine Research Foundation for the 1999 sampling, amount of fish caught, with a particular interest in the family Myctophidae (lantern fish), will be compared with the data from the catch during the winter transect run in February 2008, thus for the first time assessing the load of Persistent Organic Pollutants (POPS) in their tissues.bitten plastic

The 2008 expedition discovered the widespread ingestion of plastic particles by fish that forage on plankton at night on the ocean surface. In trawls a total of 660 fish, representing six species, were captured for future study. 35 percent of these fish had ingested micro-plastic particles, the record holder having 83 fragments.

This data poses further questions that data from the 2009 expedition will shed light on. Plastics absorb Persistent Organic Pollutants (POPs) from paint chips, coolants, pesticides, and metals, so when fish eat plastic matter and then bigger fish eat them, the chemicals could be bioaccumulating. Do the micro plastic particles contain POPs, and do these harmful pollutants migrate into the tissues and organs of the fish that ingest them and subsequently enter into the human food chain? Concentrations of the most frequent POPs (PCBs, DDT, and PAH – all renowned for their effects on the human organism) on nurdles collected from Japanese coastal waters were found to be up to 1 million times higher than the levels detected in surrounding seawater, the new data from the NPSG could have far-reaching effects.

 Ingestion of plastic items kills an estimated 100,000 marine animals yearly as plastic mistaken for food fills the stomach and impedes digestion of proper nourishment. According to Pulitzer Prize-winner Kenneth Weiss’s research, young Albatrosses are killed in their hundreds of thousands, and corpses on Midway Island have been found with all sorts of plastic matter in their stomachs, including ballpoint pen lids, toy soldiers, dinosaurs, perfume bottles, highlighter pens, and disposable lighters.

More crapAlbatross are by no means the only victims. An estimated 1 million seabirds choke or become tangled in plastic nets or other debris every year. About 100,000 seals, sea lions, whales, dolphins, other marine mammals and sea turtles suffer the same fate. Furthermore, buoyant micro plastic particles ingested by small deep-sea fish may negatively impact their ability to return below and to exist in their normal habitat.

Although the actual analysis of the samples will take up to six months, visual observation comparing photos of the worst trawl in 1999 to the lightest in 2009 showed that the accumulation has not only a higher concentration of micro plastics but, according to Captain Moore, there was a record number of macro plastics. Things like parts of buoys, crates, bottles, caps, plastic popsicle sticks, umbrella handles, numerous oyster spacers, and builders’ hard hats were often found or observed floating on the surface.

On the last leg, the six crew members collected samples using a manta trawl with a rectangular opening of 0.9×0.15 m2, and a 3.5 m long, 333u net with a 30×10 cm2 collecting bag at a speed of 2.5 knots for an hour at a time, taking 52 samples. Sampling concentrated on the surface, where most of the items were found just below the surface tension with only a small part breaking the surface such as 55-gallon drums. There were items full of air like buoys and capped bottles that floated on the surface but above all location in the water column depends on sea state. If the ocean is rough, the trash is forced down deeper. When it is calm, it rises toward the surface again, although Captain Moore, the only crewmember remaining from the 1999 sampling expedition, has found plastics over 100 metres deep using a bongo trawl. Every sample came back with large quantities of plastic particulates. Though it’s difficult to quantify just how much more without the data from the samples, according to Captain Moore it appears to be significantly more. 

Researcher Bonnie Monteleone from the University of North Carolina said that the most shocking thing for her was “finding everyday house hold items like bottles and plastic containers that were half eaten or had large bite marks in them. Fish are eating the plastic. It might not be the fish that we eat that are eating the fish, but I can assure you the fish we eat are eating the fish that are eating the plastic”. ghost net

She became nauseated. “After witnessing the first few samples I thought, “Yep, that’s why I’m out here.” But after the 20th trawl, I began hoping the sample would come back free of plastic, “Shouldn’t there be just one that doesn’t have plastic in it?” But to no avail. I have to wonder if there is anywhere on this planet we haven’t polluted”.

One major difference to 1999 was that the amount of large items that were navigational hazards. Ghost nets that barely break the surface so it is difficult to see them until you are upon them. They can weigh up to 500 kilograms or more. “We managed to remove one that was around 200 lbs. If we had run into it, it could have done serious damage” said Ms Monteleone. The crew also had a near miss with a telephone pole which came within a few feet of the starboard pontoon. There was also a large item strapped to a wooden pallet that was about 3 feet square that they dared not approach too closely. The props were fouled several times with derelict fishing gear and went so far as to stop the engines in the middle of the night. Crewmember Jeff Ernst had to free dive under the boat to disentangle them. Even though there are no common shipping lanes nor cruise lines and very little if any fishing occurring near or in the GPGP, there is evidence of our negative plastic influence everywhere. 

What can be done about it? For the matter than is already in the GPGP, very little. Collecting it and disposing of it would be a monumental exercise that no government would be willing to fund, unless it were to start having tangible negative effects on human health.

The NPSG is one of five major oceanic gyres around the world, and there is mounting evidence that equivalent levels of pollution will be found there. It would appear that the only answer is to stop more plastic from getting into our oceans, but in a society ever more reliant on non-biodegradable substances, that may be a task as big as the Garbage Patch itself.

Charm Near Sharm

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Turned off by the bright lights, pseudo-palacios, and rows of Bedouin bars of Sharm yet want to explore the wonders of Ras Mohamed and the Tiran reefs? 15 minutes from the airport to the south and north of the glitzy naffness and fast food chains of Naama Bay, Sharks' Bay boasts its own jetty on site, an excellent PADI resort dive centre, and no Russians.

The warm night-time breeze was a welcome change from the wettest British August on record. Transport was awaiting us and, as a virgin visitor to Egypt, I was surprised by the small group. I had had visions of being squeezed into a large coach like the proverbial sardine, but there was room to spare in the air-conditioned minibus, and getting acquainted with my companions was easy. Of the six others, four were a non-diving female group out for some R&R; only Jean-Marie and Brendan from the People's Republic of Cork would be indulging in my wet neoprene fetish with me.

After an efficient and organised arrival, the slightly bemused porter led me to my room (as I insisted on lugging my bags up the coral ragstone steps), switched the air-con on as the bed passed my backward roll entry mattress test, and bade me good night with a worried smile.

Up with sunrise to fiddle with camera gear, I stepped onto the balcony overlooking the bay and the jetty. One of the attractions of Shark's Bay is that the boat is only a couple of hundred metres walk from the dive centre, and requires no minibus or taxi-ride before embarking.

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