Bookshelf: The Gulf Stream

The Gulf Stream: Tiny Plankton, Giant Bluefin, and the Amazing Story of the Powerful River in the Atlantic – Stan Ulanski

The Gulf Stream
The Gulf Stream

Stan Ulanski is an academic with a special interest in the Gulf Stream, both as an oceanographer and meteorologist, and as a keen angler. I was drawn to this book because it reminded me of a book I took out of the school library when I was twelve, also about the Gulf Stream. I remember devouring that book, and have been trying to find it again for much of my adult life. I haven’t succeeded, and this isn’t it.

The Gulf Stream is a fast flowing, warm current that runs from the Carribbean up the east coast of the United States, past Canada, and across the Atlantic Ocean. It is responsible for about ten percent (popular opinion has always held this number to be higher, but it’s not) of the warming of England’s climate, transporting heat from the tropics up into northern latitudes. At the surface, where its flow is fastest, it can move at up to 9 kilometres per hour and the water in the current may be ten degrees warmer than the water surrounding it. Oceanographer/cartographer Matthew Fontaine Maury called it a “river in the ocean”, as it is so distinct from the water surrounding it:

There is a river in the ocean. In the severest droughts it never fails, and in the mightiest floods it never overflows. Its banks and its bottom are of cold water, while its current is of warm. The Gulf of Mexico is its fountain, and its mouth is in the Arctic Sea. It is the Gulf Stream.

The Physical Geography of the Sea, 1855

Ulanski divides his book into three parts. The first section provides an oceanography lesson, as well as a history of how we came to know what we know about ocean circulation. The second section, which I felt could have been beefed up significantly, has a chapter on the plankton, sargassum weed and other small life in the current, and another dedicated to bluefin tuna. I know from Richard Ellis’s tuna book how incredible these creatures are, and I felt that Ulanski could have made more of them. (He may have felt that since tuna have been so extensively eulogised, he has nothing to add – fair enough.)

The final chapter of the second section grated my goat and I struggled to read it – it’s about fishing, a sport of which Ulanski is a keen proponent, and profoundly smug (he “feels no remorse”). I cannot understand sport fishing  (or hunting) of any kind: if you’re going to release the animal after fighting it, exhausting it, and injuring it, what have you achieved? The inflicting of a prolonged, possibly fatal wound on a creature at a significant disadvantage to you in your motorised boat with expensive fishing tackle and crafty lures? How manly. We can appreciate how marvelously put together earth’s creatures are without damaging them with our ego in the process. (I realise that other people feel differently, with equal forcefulness.)

Ulanski concludes with an examination of the history of the exploration and colonisation of the New World, both aided and impeded by the Gulf Stream. It seemed that at times he wanders far from his main subject, but it is instructive to be reminded of what was involved in crossing an ocean before the advent of GPS and the creation of detailed charts. The section on piracy is fabulous and created in me a strong urge to re-watch Pirates of the Caribbean.

While my personal preference would be for a heavier focus on the oceanography and marine biology of the Gulf Stream, Ulanski is quite right to include a comprehensive section exporing humans’ relationship to this massive current. It has shaped the settlement and economies of all the lands adjacent to it.

Here’s an incredible visualisation of ocean currents – you can see the Gulf Stream prominently in the Atlantic. What is it like to be adrift on the Gulf Stream? Find out here.

The Perfect Storm deals with the 1991 nor’easter, a storm (not uncommon in the western United States) generated by the interaction of the warm water of the Gulf Stream with atmospheric phenomena. The Gulf Stream is the “weather-maker” of the western Atlantic, according to the author, and these interactions between the current and the atmosphere will become increasingly important and explosive as the global climate changes (and let me clarify, the change has come about because of human behaviour).

If you’re in South Africa, get the book here, otherwise here or here. For an even more wide-ranging view of the Atlantic ocean (minus the marine biology), check out Simon Winchester’s Atlantic.

Video (TED): Enric Sala on pristine ocean ecosystems

Have you seen what Kingman Reef looks like? If not, today’s your lucky day. Kingman Reef is a triangular reef in the middle of nowhere (the northern Pacific Ocean). It is considered to be one of the very few practically untouched marine environments that we have left. The proliferation of coral is remarkable, and apex predators (mostly sharks) make up 75-85% of the fish biomass there.

In this TED talk, ecologist Enric Sala shows what untouched marine environments look like (turns out the accepted idea of the “normal” number of sharks for a reef is a bit on the low side), and mounts a spirited defence for no take marine reserves.

[ted id=854]

Look out for Sylvia Earle in the audience!

Google street view goes inside a ship

What will Google do next? They’ve taken their street view tool underwater, and have now taken their cameras on board the RV Falkor, a research vessel of Schmidt Ocean Institute, while she was moored in San Francisco. Click here to see the map showing the ship moored at the quay, and click on Street View at the top left corner (hover over the name of the ship in the corner of the screen if the street view block doesn’t appear) to access the interior of the ship.

The RV Falkor is a beautiful vessel – not sure how she stacks up against the SA Agulhas II or RV Mellville.  But research ships make me want to pack a bag and get on board!

GCaptain provides some background.

Series: Underwater Universe

Underwater Universe
Underwater Universe

The four episodes of this History Channel series cover waves, tides and currents, predators, and pressure – all powerful features of the ocean that can be sensationalised (some more easily than others) and presented for shock value and as imminent threats to human life. Full advantage is taken of this fact.

This very American offering doesn’t boast the measured, mellifluous tones of Benedict Cumberbatch or Steve Toussaint as narrator, but the line-up of (mostly in-studio) guest narrators is quite impressive. Bruce Parker (The Power of the Sea), Susan Casey (The Devil’s Teeth and The Wave), David Gallo (scientist presenter of the TED Talk I mentioned here), Scott Cassell (student of the Humboldt squid), Richard Ellis (writer of a number of ocean history, art and science books), and Neil Hammerschlag (shark scientist) were familiar to me, as was big wave surfer Ken Bradshaw, from this article. The strange, uncomfortable way in which the studio narrators were filmed, with silent close ups interspersed with talking, was very annoying and must have been incredibly embarrassing to shoot. Or perhaps the cameraman took the footage when the narrators didn’t realise they were being filmed.

Unlike BBC documentaries, which tend to rely purely on incredible photography and fluent narrative to convey information, the History Channel favours a CGI-heavy approach that we encountered in Treasure Quest, Deep Sea Salvage, and also in the National Geographic Shark Men series. For the subject matter of this series – particularly the sections on waves, tides and currents – it was very appropriate and informative. The first episode, devoted to tsunamis, rogue waves and “monster waves”, made good use of CGI to illustrate the concepts as they were explained. The series was produced shortly before the Japanese tsunami of 2011 (there is a hastily tacked on “thoughts and prayers” disclaimer) and features interviews with a survivor of a tsunami in Samoa. I am fascinated by rogue waves – the whole episode could have been devoted to them but they don’t make for good television – we only have indirect evidence of their existence. Also, I could have done with more footage of giant ships battling storms, but that’s what youtube is for…

The least interesting and most irritating episode was the one devoted to the ocean’s top predators, which suggested that orcas are a serious threat to humans. As evidence, the cases of captive killer whales drowning and injuring their trainers at marine theme parks were cited. No mention was made of the psychosis that these whales suffer from as a result of confinement in a small, barren, completely unnatural environment. An incident in which orcas inexplicably rammed and sank a yacht in the Pacific Ocean is also described and re-enacted. Whether the orcas did what they did because they wanted to kill the people on board is highly debatable. There is also a half-hearted attempt to paint whales as potentially vicious killers, recounting incidents when sperm whales rammed whaling boats in the 19th century. More power to the sperm whales, I say.

The other dangerous predators were (predictably) white sharks, Humboldt squid, saltwater crocodiles and Australian box jellyfish. There was a small environmental message at the end of this episode, mentioning that squid will probably end up the top predators in our oceans if current trends – fishing out large predatory fish and global warming in particular – continue.

The third episode, on the immense pressures that objects in the deep ocean are subjected to, was very interesting to Tony and me as divers. A confusing interview with a diver whose brother got DCS on a wreck dive leaves (I suspect) much out. Were they even qualified divers? Why was he surprised that his brother felt unwell and confused as to the cause after he popped to the surface from 30 metres after a 30 minute dive?

The bulk of the third episode, however, recounts a 1981 experiment called Atlantis III in which three volunteers were taken in a saturation system to a simulated depth of 686 metres while breathing Trimix 10 (70% helium, 20% nitrogen and 10% oxygen). It took 31 days for them to decompress. The chief of the experiment, Peter Bennett, was the founder and former CEO of DAN. There’s a more information about the project here – worth a read (download the pdf slowly), and a briefer account here.

The series concludes with an episode on tides and currents, including rip currents. The massive tidal range of Morecambe Bay in the United Kingdom,  is discussed at length. At low tide, up to 300 square kilometres of mudflats is exposed, and flooded again when the tide comes in. The guides who escort people out onto the mudflats when the tide is out seem like charming individuals – it is recommended not to wander around at low tide without local guidance. In 2004, the rising tide trapped and drowned 23 Chinese immigrants who were working the cockle beds – with such a large expanse of land to cover, the rising tide comes in at great speed. There is also a harrowing re-enactment of a father and his two sons getting washed out to sea in a rip current in Kauai that should make you think twice about swimming at beaches with warning signs on them.

You can get the DVDs here if you’re in South Africa. Foreigners, go here or here.

Article: Harper’s on a spill of rubber ducks

Yesterday’s review of Moby-Duck may have deterred you from seeking out the book for your own reading pleasure. You may, however, enjoy a literary approach to the topic of spilled bath toys more than I did… And for this reason I bring you an extended excerpt (possibly adapted) from the early parts of the book, by author Donovan Hohn, published at Harpers in 2007.

We know that twelve of the colorful containers stacked above deck snapped loose from their moorings and tumbled overboard. We can safely assume that the subsequent splash was terrific, like the splash a train would make were you to drive it off a seaside cliff. We know that each container measured forty feet long and eight feet wide and may have weighed as much as 58,000 pounds, depending on the cargo, and that at least one of them—perhaps when it careened into another container, perhaps when it struck the ship’s stays, perhaps as it descended to high-pressure depths—burst open. We know that when it left port, this ill-fated container had contained 7,200 little packages; that, as the water gushed in and the steel box sank, all or most of these packages came floating to the surface; that every package comprised a plastic shell and a cardboard back; that every shell housed four hollow plastic animals—a red beaver, a blue turtle, a green frog, and a yellow duck—each about three inches long; and that printed on the cardboard in multicolored lettering were the following words: FLOATEES. THE FIRST YEARS. FROM 6 MONTHS. EXPERT DEVELOPED ? PARENT PREFERRED. 100% DISHWASHER SAFE.

Read the article here.

A lesson about waves

At spring high tides, Fish Hoek beach is flooded all the way up to the barrier at the top of the beach. I’ve seen the subway flooded with waist deep water at times. One Sunday evening in September on a sunset stroll, Tony and I discovered that watching the waves roll in to the top of the beach when the tide is approaching its maximum is very soothing (if you like the sound of noisy water), and provides a nice object lesson about some aspects of wave behaviour.

Spring high tide at Fish Hoek beach
Spring high tide at Fish Hoek beach

When wave trains collide, they interfere with each other. This is mostly in evidence (from our point of view) when reading a swell forecast on MagicSeaweed. The direction of the swell that arrives at False Bay can be determined by multiple storms far out in the Southern Ocean. Waves generated by winds blowing in different directions collide – they interfere with each other – and travel to make landfall far away. The direction and height of the resulting swell arriving on the beach is derived from all the distant winds that combined to form it.

At Fish Hoek beach none of this is happening, except for swells making landfall. What does happen is that incoming waves curve in the shallower water against Jager Walk along the side of the beach. They then strike the wall in front of the subway and are deflected down the beach, perpendicular to the rest of the waves that haven’t curved because they’re still in deeper water. Where these sets of waves combine, we get to see interference at work. Here’s a video of the process. It’s like having one’s own personal wave tank to look at.


Here’s some more footage, with very expert commentary by me and Tony:


Article: Slate on ocean salinity

Phil Plait, the Bad Astronomer, writes briefly about images released in June 2011, taken by the earth-observing satellite Aquarius.

Ocean salinity as recorded by Aquarius
Ocean salinity as recorded by Aquarius

As Plait points out,

Observations like this are crucial for us to understand just how our fiendishly complex planet works. Especially now, when our climate is changing, and those changes are evident even year by year.

See the full article here.

More about the wreck of the Brunswick

I attended a talk about the Brunswick, which is wrecked off the end of Long Beach in Simon’s Town, at the Institute for Maritime Technology (IMT), in August. It was given by Jake Harding, who has just completed a thesis on the wreck for his Honours degree at the University of Cape Town. Considering that all I know about the Brunswick (even with reference to Shipwrecks and Salvage in South Africa) can be summed up in two sentences, it was extremely interesting to hear from someone who has researched the ship, and examined the wreck for further information.

The ship

The Brunswick was an East Indiaman, a merchant ship that transported goods between Britain and the East Indies. She was captured by the French vessel Marengo in 1805, and brought to Simon’s Town as a prize of war. She was captured on her sixth voyage and was in quite poor shape. Five or six voyages was considered a good lifespan for an East Indiaman. They travelled very long distances on each voyage and were away from their home ports for over a year at a time, sometimes much longer. During the time she was at anchor in Simon’s Bay, strong winds caused her anchor cables to part, and she ran aground. She was carrying a cargo of sandalwood and cotton, which was sold along with the wreck in an auction. Most of it was salvaged, although archaeologists have spotted the odd piece of sandalwood on the wreck site.

She had 30 guns, which is apparently quite a small number – warships of the time would have had hundreds of guns. At the time when the Brunswick was constructed (late 18th century), iron was used instead of hardwood for the braces or “knees” that held the hull of the ship out in its characteristic shape. She was about 40 metres long and 13 metres wide with three decks. Her hull was sheathed in copper, and the drift bolts holding the parts of the ship together are copper and iron.

The wreck

The wreck was officially discovered and identified as the Brunswick in 1993, although her rudder was found and salvaged in 1967. It can be seen in the courtyard of the Slave Lodge in central Cape Town, formerly the South African Cultural History Museum. It used to be covered with copper sheets, but those were mostly stripped off. It’s huge – over 4 metres long, but with all the original fittings it was likely over 5 metres in length.

The rudder of the Brunswick
The rudder of the Brunswick

It’s clear when you dive the site that there’s quite a lot of wreck hidden under the sand, and even in the few times we’ve dived her we’ve been able to see how the sand shifts and covers and uncovers various parts of the ship. The Simon’s Town harbour wall has led to a lot of sediment build up in the area. When the wreck was surveyed in 1994-1995 for Project Sandalwood, a survey done by IMT and the South African Cultural History Museum, they recorded pieces three metres high sticking out of the sand. There’s nothing like that today. Longshore currents also cause periodic sediment build up and removal, and the cryptic little fish called steentjies annually uncover huge areas of the wreck during their mating displays.

According to Jake, the keelson (like a keel strip), part of the copper strap attaching the rudder to the boat, and a large number of iron knees (we have only seen a couple), and one or two pieces of sandalwood are still on the wreck site. We will be looking carefully for these elements next time we dive there.

A tour of the SA Agulhas II

SA Agulhas II berthed in Cape Town
SA Agulhas II berthed in Cape Town

When the opportunity arises to go aboard a ship, we like to take it. Our most recent ship tour was of the Greenpeace Rainbow Warrior vessel. In celebration of World Oceans Day on 8 June, the Department of Environmental Affairs opened the SA Agulhas II polar research vessel to the public, and we popped down to the V&A Waterfront to see her.

The SA Agulhas II replaces the SA Agulhas, now in use as a training vessel by SAMSA. The SA Agulhas has been in service for many years, and was recently chartered by the organisers of The Coldest Journey to transport the personnel and machinery to Antarctica before the winter.

The SA Agulhas II was built in Finland at a cost of R1,3 billion, and is state of the art as far as safety features and redundancy is concerned. She has two completely separate main engines, and is capable of continuing underway if one engine room floods. The decks and outdoor staircases of the ship are heated to prevent ice build up, and her hull is capable of pushing through one metre thick ice at a speed of nearly 10 kilometres per hour. She will service Marion Island, Gough Island, and the SANAE IV base on the Antarctic continent.

Tony on the helicopter pad
Tony on the helicopter pad

The ship has room for two helicopters, with a large helipad and a hangar in which the choppers can be housed with their blades folded down. The hangar’s walls are heavily fire proofed, and look like a couch or quilt. The ship can carry 100 scientists and a crew of 45. The accommodation is lovely, with every cabin having natural light. I was ready to run away to become a polar explorer after seeing the cabins, but when we stepped out on deck into the freezing wind (remember, the ship was still at her berth in Cape Town) I changed my mind.

There are eight permanent laboratories on board, and six containerised ones which can be lifted on and off the ship depending on what experiments are to be performed. Members of the scientific personnel spoke to us about some of the work that is done on board, including sampling the carbon dioxide content of water at various depths and locations (the levels are affected by global warming), and collection of plankton in special devices that enable the scientists to measure the fecundity of a particular part of the ocean. Tony and I kind of hoped that the intern who told us that they give that information to fishing company I&J was joking or wrong, but sadly I suspect he wasn’t.

A CTD water sampler hanging over the moon pool
A CTD water sampler hanging over the moon pool

In the centre of the ship is a moon pool – just like a James Bond movie – through which instrumentation can be lowered into the ocean. It’s essentially a hole all the way through the hull, surrounded by the ship. The advantage of this is that it won’t ice over, and there is no chance of a heavy piece of machinery hung over the side of the ship causing problems of balance. There is a large door in the side of the ship through which instruments can be sent, a feature shared with the old SA Agulhas, but during long experiments it’s possible that the ship gets iced in and the instruments crushed. The device hanging over the moon pool in the photograph above is a CTD, or conductivity, temperature, depth water sampler. It measures those three variables at different depths by taking water into the cylindrical Niskin bottles that make up the array. These close at predefined depths, and the water thus obtained can be analysed on board.

The ship has thrusters and multi-directional propellors that enable her to move in almost any direction, rotate on the spot, and hold a position with incredible accuracy for hours on end, even in unfavourable sea condtions.

I was amazed by this ship, but also worried by her, half waiting for something to go wrong. We have a very sad habit in South Africa of completely dropping the ball environmentally (I’m thinking of the fisheries patrol boats gathering dust at the quay in Simon’s Town while the minister of agriculture, forestry and fisheries goes on fraudulent trips and accepts bribes), and squandering technology that could otherwise be used for great good. My hope is that the recognition from other nations that this is a special, one of a kind ship with capabilities unmatched by many other vessels will apply a form of peer pressure to keep the powers that be from wasting the SA Agulhas II’s capabilities. The scientists and crew who we spoke to on board are passionate, dedicated people. I hope they will be well served by those who set the maintenance budgets, scheduling and priorities of this special ship.

Visualising ocean surface temperatures

Here’s another beautiful sea surface temperature visualisation, this one from NOAA. It starts with the Agulhas and Benguella currents that wash South Africa’s shores, and then moves to other locations across the ocean. The dial in the bottom right hand corner of the screen shows what month of the year the data is for. I think it’s beautiful.

You can also view the video on The Atlantic website here, with a bit of a write up.