Bookshelf: The Edge of the Sea

The Edge of the Sea – Rachel Carson

The Edge of the Sea
The Edge of the Sea

The Edge of the Sea completes the trilogy begun by Under the Sea-Wind and The Sea Around Us. Its focus is on the coastline, the meeting point between land and ocean where one is most conscious of the passage of time and the cycles of nature. Rachel Carson was an American writer, and lived and worked on the east coast of the United States. The northern reaches of this coast are similar to the Cape Town coastline, in that there are kelp forests and much invertebrate life in the cool water. Its southern reaches in the Florida Keys, however, are characterised by coral reefs and mangrove forests, more reminiscent of Sodwana Bay in KwaZulu Natal, on South Africa’s north western coast.

This is a more conventional piece of nature writing than Under the Sea-Wind, and its scope is far narrower than The Sea Around Us. It is fascinating, however, to delve into the secret lives of crabs, sand fleas, limpets, urchins, sea stars, clams and a large number of their neighbours. While – for the most part – we don’t find the exact same creatures on our side of the Atlantic, their adaptations to life in the intertidal zone are similar, and their behaviour and diet is too.

The section on the coral reefs and mangroves of Florida was interesting to me because that kind of coastline is relatively unfamiliar – I’ve only visited coral reefs three times (Zanzibar, Sodwana twice) and don’t know nearly as much about how those ecosystems work. It was the first time someone articulated for me a point that – in retrospect – is probably completely obvious to everyone else on earth, but for me was a lightbulb moment. Coral reefs only occur on east-facing coasts (think about the location of the Florida Keys, the Great Barrier reef in Australia, the east African coral reefs), as the western coasts of continents are typically subject to upwelling driven by wind and the direction of the earth’s rotation.

Rather than being an active participant in the life of the shore, man is portrayed here as an observer, unable to influence the tidal and seasonal rhythms that drive all behaviour here. The book is illustrated with beautiful line drawings and one or two maps, and I’d recommend it highly. There’s a comprehensive glossary with full species names at the back.

You can buy the book here, or for Kindle get it here.

Bookshelf: The Living Shores of Southern Africa

The Living Shores of Southern Africa – George & Margo Branch

The Living Shores of Southern Africa
The Living Shores of Southern Africa

It took me a while to get my hands on a copy of this classic volume by Margo and George Branch, with photography by Anthony Bannister. It was a staple in the classroom of every biology teacher I ever had, and occupies pride of place behind the microscope display at the Two Oceans Aquarium, where it has helped countless nonplussed volunteers answer sticky questions about jellyfish reproduction or the eating habits of limpets. It was first published in 1983 and is long out of print.

The first half of the book deals with habitats – the rocky shore, beaches, estuaries, the open ocean, coral reefs, and kelp forests. The authors manage to sneak in quite a lot of physical oceanography without one noticing, as it obviously impacts the flora and fauna that can colonise a particular area. Prof Branch has a special interest in limpets, and I was amazed to discover the intricate adaptations that these unassuming little creatures have to life in the highly competitive, high stress intertidal zone. The section on kelp forests was also wonderful to me, as a regular diver in these parts! I found the chapter on estuaries somewhat dispiriting, given that it was written thirty years ago and it seems unlikely that matters have changed since then. Prof Branch used the Richard’s Bay estuary of the Mhlathuze River as an example of how human interference turned a thriving, sensitive ecosystem into a muddy wasteland in a matter of a couple of years. I have not visited Richard’s Bay, and indeed had not heard anything about this particular estuary before encountering it in this book, so I will have to do some research to find out whether it’s still in such a parlous state.

I found the sections on sharks, seals and whales – under the chapter on man and the sea – puzzling and upsetting, but perhaps they are just a reflection on where scientific understanding of ecosystems was in the early 1980s. I would be interested to hear Prof Branch’s views on these three types of animal today.


On sharks, the authors mention that the Natal Anti-Shark Measures Board (now renamed to something less obviously brutal, but still with the same ultimate aim of killing sharks) killed 11,700 large sharks in eleven years (presumably the decade to 1980). The authors state that it is not known what the effect of removing so many top predators will be on the ecosystem, but do note that there were an estimated extra 2.8 million dusky sharks – a smaller species that has thrived in the absence of tiger and bull sharks – at the end of the eleven year period in question. I was immediately reminded of the fairly recent shark bite that occurred on a baited dive on Aliwal Shoal a few months ago. The culprit was a dusky shark.

What I found unsettling was that very little concern was expressed about the impact of killing so many sharks – highly migratory creatures, in many cases – along a small region of the coastline. The authors do mention the case of Tasmania, which after a few years of shark nets experienced a population explosion of octopus (traditional shark food), who destroyed the local rock lobster population and the profitable local lobster fishing industry. I know that the authors’ focus has been more on coastal species, but their apparent lack of recognition of the role of sharks in a healthy ocean was strange to me given their obvious awareness of how vital is every link of the food web on the rocky shore (urchins, abalone, kelp, sea otters, rock lobster, etc.).


The authors describe the economic value of the seal cull (which in the 1980s was a grim reality of South African life, and in Namibia still is the case). Baby seals were (are) valued for their soft pelts and the oil in their bodies, and mature seals just for the oil – their pelts were deemed to be too battle-scarred to make into a fur coat. The method of killing baby seals with a blow to their heads was sanctioned as humane by the NSPCA because their little skulls are still soft when they are young (and, in a happy coincidence, it doesn’t damage the pelts).

Apart from the economic rationale for killing seals, the authors state that seal colonies “attract sharks” – as if this is a reason to destroy them. I found this extremely confusing – why is one creature more important or desirable than another? The fact that fish, limpets, seals and sharks exist in the ocean means that they all have a role to play, and that somehow these populations lived in balance before human intervention.

Another reason provided for the annual seal cull (which at one point left 35 seals on Seal Island, in contrast to the current population of over 75,000 seals) was that their numbers were increasing “unchecked” and threatening the nesting sites of seabirds on the island. Nowhere do the authors acknowledge that the reason for the seal population explosion could be that their natural predator, the white shark, was fished to the brink of disappearance off the South African coast by testosterone-fueled trophy hunters. Fortunately today shark and seal eco-tourism is big business, and I don’t think (I stand to be corrected) that any seals are legally killed in South Africa any more.


Whaling was an entrenched part of the South African economy from the early 1800s, but was comprehensively banned in 1979, shortly before this book was published. In Blue Water White Death the whaling station in Durban was shown, and whale carcasses were used by the filmmakers to attract sharks. The authors provide a synopsis of the state of whaling in the world’s oceans at the time of writing (depressing – what is the validity of “scientific whaling” when it is conducted by a country that feeds whale meat to school children?) and the population status of various types of whale.

They suggest that, because the small Minke whale competes with blue whales for food, Minke whales should continue to be hunted in order to give blue whales a chance at increasing their numbers. My (admittedly uninformed) view of it is that – what with the population explosion of krill that whaling engendered in the Southern Ocean, the blue whales aren’t even going to notice a few small Minkes dining at the lunch bar with them. Whale populations have been reduced to such a tiny fraction of what they used to be that – for a long time still, everything else being equal – competition for food isn’t going to feature in their population dynamics. My feeling on the matter is that if a Minke whale ever even SEES a blue whale, let alone has the opportunity to argue over a ball of krill with it, it should count itself a lucky little whale and move right along.

The second half of the book deals with specific organisms, their life cycle (beautifully illustrated by Margo Branch), and their habits. The authors focus on invertebrates, as (they say) fishes are extensively dealt with in other volumes. The accompanying photographs were taken by Anthony Bannister, and have not dated at all in terms of quality – they are vivid, clear, and beautiful.

Some of what I learned

I learned a huge amount from this book. It’s clearly provided source material for almost every other South African marine flora and fauna book that has been written, and sentences – that I’ve seen in other books and presentations – kept ringing bells with me (I tend to use my fish ID books quite hard, trying to wring out every last fact from the one-paragraph descriptions accompanying the photos). The authors in fact collaborated on the handy Two Oceans guide, which keeps getting better with each new edition and is indispensible for the travelling South African diver.

  • I learned that the presence of plough shells on a beach generally indicates that it is safe for swimming – these little snails surf in the waves using their large feet as a sail, and if there were rip currents they would be drawn offshore and lost. Their activities on fish Hoek beach are shown to great effect in the BBC’s The Blue Planet series.
  • I loved learning how Rocky Bank protects the western side of False Bay to some extent, slowing down the swells as they enter the bay and causing them to focus their power somewhere near the Steenbras River mouth on the opposite side of the bay.
  • I loved learning about limpets’ “home scars” – the spot on the rock that fits their shell perfectly, and that they somehow return to over and over after foraging for food – and how some species tend little gardens of algae, encouraging its growth by mowing paths in it (and getting fed at the same time). Simple things like the effects of strong or harsh wave action on the slope and sand type of a beach, and as a result the type of life that thrives there, were also fascinating.
  • I learned that 30 years ago (when this book was published) overfishing was already a serious, serious problem.

You can obtain a copy by scouring secondhand book stores,, and

Sodwana rockpools

At the corner of Sodwana Bay is Jesser’s Point, where the dive operator we use in Sodwana, Coral Divers, has a gazebo and launch spot. There’s a little reef here that is completely covered at high tide, but at low tide is exposed with some beautiful rockpools inhabited by many juvenile fish, urchins and crabs.


Clare went exploring here between dives, taking advantage of the fact that she was wearing a wetsuit to kneel down in the pools with her underwater camera. I soon followed her with my video camera, and the footage above was all shot in water less than a metre deep. It’s warm and crystal clear. Look out for Clare in a red shirt, floppy hat and half a wetsuit.