Dr Gregg‘s frustration with the “woo” surrounding dolphins is palpable as he attempts to demolish the facade of pseudo-science and fantasy that dolphins seem to attract. Secretly I think that many people want to believe that there is something magical about dolphins, even without subscribing to the fact that they can heal at a distance or communicate with aliens. For that reason (I think), I found this a fairly uncomfortable and negative read. Predictably the book caused a bit of a media storm upon its release. It’s a short read, but requires careful scrutiny in order not to miss the subtleties and brutalise the message.
This book is perhaps less about dolphins than you might expect, and more about the difficulties in studying animal cognition and intelligence. It is enlightening, for someone who isn’t a scientist, to gain an understanding of the challenges involved – not just in studying, but in actually first defining the terms of reference.
If you’re interested in animal intelligence and (dare I say it) emotions, let me recommend Carl Safina’s latest book, Beyond Words: What Animals Think and Feel. If you’re particularly into dolphins, I suggest Susan Casey’s Voices in the Ocean for a broad layman’s overview with a focus that is not purely scientific, and Dolphin Confidential by Maddalena Bearzi for the field scientist’s perspective.
Voices in the Ocean: A Journey into the Wild and Haunting World of Dolphins – Susan Casey
It is clear from the first pages of Voices in the Ocean that Susan Casey is enchanted by dolphins, and her book does not shy away from the mysticism and wild attributions of almost supernatural powers that dog our toothed marine mammal friends. She is author of The Wave and The Devil’s Teeth, and favours an immersive and almost obsessive style of engagement with her subject. This makes for good reading.
Despite the persistent thread of woo running through the entire book, Casey manages to expose important and awful aspects of humans’ relationship with dolphins. Some of these are often overlooked. She visits dolphins in theme parks, goes to the cove at Taiji in Japan (location of a famous dolphin hunt), and – in what I view as the most important section of the book because the topic is so under-reported – the Solomon Islands.
Casey concludes with a study of the Minoan culture on Crete, a hopeful note after a trip into the hellish depths of depravity that seem to occur more often than not at the human-dolphin interface. You can read more about Voices in the Oceanat Outside Magazine, the Guardian, and the New York Times.
You can get a copy of the book here (South Africa), here or here.
Today we took a load of surfers out to Dungeons. Amongst them were a few first timers at Dungeons and the happy cheers and bear hugs when they caught their first serious Dungeons roller was a sight worth seeing. Dungeons is a spectacular sight so if you haven’t been there do so at least once in your life.
Back to diving… We dived the Atlantic last weekend. Maori Bay was cold and clean-ish. Visibility was around 10 metres but then the temperature was also in the single digits. Die Josie was a lot cleaner and just as cold.
On Sunday we dived in False Bay – doing Search and Recovery for an Advanced course in 2 m visibility makes it a little more realistic!
Well… There is swell and wind in the forecast. The swell was not all that noticeable in False Bay today but was very surf-worthy at Dungeons and Muizenberg today. The wind is forecast at around 30 km/h for both days and for students doing their first boat dives I think it’s not that good an idea. So I have no launches planned for this weekend.
John Dabiri and his team injected dye into the water around a moon jelly as it swam. Like Gandalf’s smoke rings, the jellies created rings of water behind them, moving down their tentacles as they swam.
The team later showed that the moon jellyfish actually produces two vortex rings for every beat of its bell. While the first one travels backwards, a second one rolls back into the bell itself, speeding up as it goes, and sucking water into the center of the jellyfish. This allows the animal to recapture some of the energy it spends on each swimming “stroke,” and pick up speed even when it’s making no effort. For that reason, the moon jellyfish is the most efficient swimmer in the ocean.
The ground floor of the Cape Agulhas lighthouse is devoted to a lighthouse museum and curio shop/tourist information centre. The museum is small, but well worth investigation if you’re a lighthouse buff.
There is a large number of posters on display, covering the history of the Agulhas light and the surrounding area, as well as lighthouses around the world. There is also a selection of lenses and other historical lighthouse and rescue equipment.
This will be a quick newsletter as we are downwind of a raging vegetation fire and the smoke is unbelievably thick. Even our tortoises are going to spend the night indoors. Firefighters, many of whom are volunteers, have been have a rough time of late and I admire their endurance, skills and management of these situations.
We had really good conditions in Hout Bay last weekend with clean and cold being the main factor. 8 degrees celcius is chilly but the viz was easy 15 metres.
The south easter has humped all week long and False Bay is a little messy. The visibility in the yacht basin today was actually very good but I think the rest of False Bay would have been messy. The yacht basin is protected from the south easter by the naval harbour.
The forecast leads me to believe that Hout Bay will be good on Saturday and False Bay on Sunday. I would also like to slip in a night dive on Saturday if the conditions permit.
Much of my recent Arctic obsession has been historical, with a related interest in the hostile environment that has stymied (and killed) so many explorers over the centuries. Bruce Parry is a British documentarian (didn’t know that was a thing, but it seems fun) who seems to be dearly loved and some kind of national institution to the Brits. After watching this five-episode BBC series on the Arctic and its people, we could understand his charm.
Parry visits people living in Siberia, Greenland, northern Canada, Alaska, and the far north of Norway. He throws himself into their activities – whether rounding up reindeer, hunting for seals on the ice, fishing in Alaska (I had some serious lifestyle envy at this point), or racing up mountains. He is sensitive and respectful, and seems to forge genuine bonds with the families he visits.
The common thread that marks the lives of many of the tribes and peoples’ that Parry visits is that climate change, and the encroaching changes wrought by the pace of modern life, are challenging their traditions and lifestyles. Having lived sustainably off the land for generations, these people’s movements, traditions and futures are now circumscribed by all sorts of interventions from modern society. Not least of these is a lack of understanding of and respect for how they live.
Tony and I found much to discuss – for example, after the episode covering a traditional whale hunt in Alaska. Is there a difference between Japanese industrial whaling and an Inuit community’s subsistence hunting for a couple of whales a year, done with reverence, prayers, and gratitude for the whale, whose bones will be scraped clean by polar bears after the entire carcass has been distributed in the village? Is it possible to kill an animal as large as a whale, humanely? Is all whaling wrong? These are difficult questions but it is worth grappling with them. As my friend Tami has exhorted me in the words of Rilke (in a different context, admittedly), “live the questions!”
The series was filmed over the course of a summer, during which time much of the usual ice that marks the Arctic landscape was absent. The look of the landscape initially puzzled (and disappointed) me – without the icy covering, everything looks quite barren and gravelly!
You can get the dvd here (South Africa), otherwise here or here.
Rescue Warriors: The US Coastguard, America’s Forgotten Heroes – David Helvarg
Much of this book reads like one of the Reader’s Digest “drama in real life” stories that I used to devour from the magazines that my granny brought us when she came to visit. (She’d also bring a packet of Sparkles or Cadbury Eclairs.)
Journalist, activist and former war correspondent David Helvarg (who also wrote Saved by the Sea and 50 Ways to Save the Ocean) spent two years embedded with various branches of the US Coastguard in order to experience their work.
I was wrong. The mandate of the US Coastguard is to enforce maritime law (this is its primary difference from the NSRI) as well as to perform search and rescue operations. Viewers of the Deadliest Catch series will be familiar with the rescue work of the Coastguard in extremely challenging conditions. As a result of its law-enforcement mission, the Coastguard uses weapons and provides a lot more military-style training than you’d expect from a pure rescue operation. The Coastguard falls under the department of homeland security and operates cutters (with guns), icebreakers, small boats, helicopters, and other aircraft.
Helvarg’s conservationist tendencies shine through in several parts of Rescue Warriors, and he does not shy away from confronting the aspects of the Coastguard that he finds problematic. His contention is that the Coastguard receives far less publicity than it deserves. This book goes some way towards bringing attention to the individuals who have saved tens of thousands of people during Hurricane Katrina, via water evacuation during the September 11 attacks, and in countless other less well-known emergency situations.
This is a gripping read which I thoroughly enjoyed. I was amazed by the amount of funding and equipment that the Coastguard has at its disposal compared to the NSRI, even though the organisation is actually badly underfunded, especially when considered relative to the rest of the United States war machine. I was also impressed by the egalitarian approach that draws many women to join the Coastguard and enables them to rise in its ranks. The Coastguard made all its jobs available to women in 1977, something which other branches of the military have not yet done.
You can get a copy of the book here (South Africa), here or here.
Perhaps you have wondered what causes the patterns of strange coloured water in False Bay during the summer months. Perhaps you have dived in it, and wondered why sometimes you can’t see your hand in front of your face! Wonder no more – I am here to help.
Frequent visitors to and residents of the shores of False Bay will observe that at certain times of the year, the ocean is marked by bands and arcs of sharply contrasting coloured water. This phenomenon is known as a colour front. In oceanography, a front is the interface or boundary between two separate masses of water. In this case, the water masses are easy to discern, because they are of different colours. There are usually other characteristics of the water on each side of the front that differ, too. Fronts are either convergent (the water masses are moving towards each other) or divergent. The presence of marine debris (like pieces of kelp) at the front boundary suggests that it is convergent.
Causes of colour fronts in False Bay
Prior to 2005, there was much conjecture about the causes of these fronts (including the usual pollution bugbear), but little evidence to support any of the theories. By sampling, the fronts were found not to be caused by pollution, or by plankton blooms in the surf zone. It was known that a colour front was most likely to occur in False Bay after a period of southerly or south easterly wind lasting a few days. October and November seem to be prime months for the phenomenon.
When a large, obvious colour front arose near Simon’s Town in November 2005 with milky green water on one side, and darker blue-green water on the other, researchers from UCT and IMT sprang into action, sampling the water on each side of the boundary so that they could measure its characteristics. Speed is of the essence in these situations; colour fronts can disappear quickly. The one in the picture below is busy decaying – notice the smudged boundary.
Measurements revealed that the milky green water overlaid the clearer, bluer water, down to a depth of 11-12 metres (this will vary from front to front). The milky water did not extend to the ocean floor. Scuba divers around the Cape Peninsula will be familiar with the experience of diving through two or more layers of water, with varying turbidity (clarity) and temperature! (Here is picture of Tony and Christo diving near Oudekraal in the Atlantic that shows what the boundary between two layers of water can look like.)
The researchers found that the milky coloured greenish water was full of fine, almost neutrally buoyant particles of calcium-rich sediment. The green-blue water contained much less calcium, but relatively more silicon, which would suggest the presence of diatoms (a kind of phytoplankton – you can think of them as teeny tiny plant-like organisms) or sand in the water. The origins of the calcium-enriched sediment in the milky water are interesting: one source is from the shallows (less than 30 metres deep) of north western corner of False Bay, where the ocean floor is made up of rocks that are rich in calcium carbonate (such calcrete and limestone), some areas covered by a thin layer of sand.
The second probable origin for the particles of calcium-rich material is the interface between the sea and the land at the northern end of False Bay. The cliffs at Wolfgat/Swartklip at the head of the bay are made of calcrete, and at Swartklip the beach narrows to the extent that the cliffs erode directly into the water when the sea is high. Strong southerly winds create a wide (of the order of one kilometre) surf zone at Muizenberg and Strandfontein; a spring tide also adds to ideal conditions for the generation of a colour front.
The temperature of the milky water was found to be slightly (0.4 degrees Celcius) higher than the green-blue water. This measurement will also vary from front to front. The researchers speculate that the temperature difference could be because the milky water originated in the surf zone, which is shallower and therefore warmer, or because the high concentration of suspended particles in the milky water caused greater absorption of heat from the sun.
Here’s the tl;dr: strong southerly and/or south easterly winds, perhaps coupled with spring tide conditions, set up a very wide surf zone along the northern end of False Bay, which disturbs the sediment on the ocean bottom and drives the waves further up the beach than usual. Particles of buoyant calcium carbonate from the sea floor and eroded from the cliffs at Swartklip are lifted up into the water column, changing its colour to a milky-green shade. Wind-driven circulation patterns in the bay push the front from its original location in a southerly direction, towards Simon’s Town.
What to do?
Contrary to what your friends on social media may claim, not all colour changes in the ocean around Cape Town can be attributed to a giant sewerage plume. Hardly any of them can, in fact. In summer, the reason for the ocean looking green, red or even brown is likely to do with a plankton bloom of some description, or related to suspended sediments (as in this case) or other naturally arising material in the water. Instead of using this as an opportunity to become hysterical on the internet, how about celebrating the incredibly dynamic system that we can observe, living near the ocean? Drive up a mountain next to the ocean and take in the spectacle from on high. Dip your face in the water and see what it does to the viz. Take some pictures for posterity. And – if you don’t know what’s causing it – try to find and question someone who does know, like a scientist, or consult a good non-fiction book, to find out some facts.