Cape Town’s visible shipwrecks: Commodore II finds a home

Commodore II by the Milnerton lagoon
Commodore II by the Milnerton lagoon

I am happy to report that the Commodore II has finally been paid the attention she deserves, and moved to a permanent position on the shore of Milnerton lagoon. SAHRA began a process in late 2016 (when the wreck still lay on the beach close to the lagoon mouth) that has finally concluded with the wreck being moved on Friday 23 November. There are some pictures of that endeavour here and here.

View towards Lagoon Beach hotel
View towards Lagoon Beach hotel

We first wrote about the Commodore II in 2015, and I was amazed that a wreck with such a fascinating and high-profile history could have practically disappeared into obscurity. There appeared to be no desire from the keepers of our maritime heritage to protect her, and when she washed up the Milnerton lagoon during a storm in late 2017, it seemed that she would be carted away piecemeal for firewood before anyone realised what was being lost.

View of the Commodore II
View of the Commodore II

Late last year, an enterprising local resident secured the wreck to the banks of the lagoon off Esplanade road, at his personal expense, to prevent it from washing around inside the lagoon and injuring paddlers or damaging the historic bridge further up. We wrote about his efforts here.

The Commodore II's sturdy construction
The Commodore II’s sturdy construction

The new, and hopefully final location of the wreck is just next to the small parking area outside the Lagoon Beach hotel and Wang Thai restaurant. It’s entirely accessible at all hours of the day and night, and there are promises of interpretive signage to share the wreck’s history with passers by.

Tube worms cover the lower portion of the wreck
Tube worms cover the lower portion of the wreck

I went to visit the wreck a week after she was moved. Dried pond weed still covers some of the planking, and thousands of tiny tube worms cover the lower part of the structure that was submerged (I can’t tell what kind – most likely Ficopomatus enigmatus, the estuarine tube worm that thrives in brackish water).

It’s great that the Commodore II is now firmly on the radar as one of Cape Town’s historic shipwrecks, worthy of preservation. I’ll be updating my ebook to reflect her new location before year-end. Meanwhile, read about her chequered history here.

Newsletter: Better than nothing

Hi divers

Weekend dive plans

Saturday and/or Sunday: Boat dives in False Bay

The forecast today is a little better for the weekend than it was earlier this week. There is some wind and some odd swell and swell direction changes but I believe it should be worth diving both Saturday and Sunday. Sunday will most likely be a little better. I have students on the boat on both days so there is not much space, however, if you are quick you can reserve a spot!

Zandvlei Nature Reserve
Zandvlei Nature Reserve

Things to do

It’s not as if one needs to actively seek out extra commitments at this time of year, but in case you’re at a loose end check out Wavescape’s Slide Night happening on Monday (you need to book in advance for this). You can get some adult education at UCT’s annual Summer School in January, and there’s something for you whether your interest is sharks or shipwrecks.


Tony Lindeque
076 817 1099

Diving is addictive!

To subscribe to receive this newsletter by email, use the form on this page!

What causes the brown water at Muizenberg beach?

Capetonians are familiar with the tea-coloured water that runs in our mountain streams. Most people know that the brown colour comes from tannins, leached naturally from the indigenous fynbos vegetation. Perhaps less well known is the reason for the brown water that is sometimes seen in the surf zone along Muizenberg beach, stretching all the way to Strandfontein, Monwabisi and beyond.

Tea-coloured water at Muizenberg
Tea-coloured water at Muizenberg

The most frequent explanations that are offered on social media are, of course, pollution, “raw sewage”, and the like. This is not the reason for the brown water, and it does not necessarily impact the water’s safety or healthfulness for humans to swim in.

Like False Bay’s famous colour fronts, the reason for the brown waves at Muizenberg beach turns out to have much to do with the topography of False Bay, particularly of the kilometres-long beach at its head (Muizenberg-Strandfontein-Macassar-Monwabisi), and something called a diatom.

View of Muizenberg showing patches of brown water
View of Muizenberg showing patches of brown water


Diatoms are a type of phytoplankton (plant plankton or microalgae). They are single celled, usually symmetrically shaped organisms that multiply by dividing in half at a constant rate. Their cell walls are made of silica, SiO2. Chicken keepers and gardeners may be familiar with diatomaceous earth – this is made up of the fossilised shells of ancient diatoms.

Diatoms are what are called primary producers or autotrophs, meaning that they generate organic material from carbon dioxide and other inorganic nutrients (for example nitrates and phosphates), through the process of photosynthesis, which uses light as an energy source. Primary producers sit at the base of the food chain and all life relies on them, directly or indirectly. Everything else produces organic material from other organic material (such as diatoms).

I am telling you all about diatoms because the brown water at Muizenberg contains an accumulation of a diatom that you can call Anaulus australis Drebes et Schultz the first time you mention it, but usually just Anaulus australis, or Anaulus for short. There are several members of the genus Anaulus, but usually just one tends to be dominant at each beach where these accumulations occur, and Anaulus australis is the main species found along the South African coast.

Analaus are pillow-shaped diatoms. If you wanted to see what an individual Anaulus diatom looked like, you’d use a microscope, but when enough of them are in one place, they can be seen to change the colour of the water. There’s a picture of them under a microscope at the bottom of this webpage (they also occur in Brazil). They occur at beaches with particular topograhical characteristics, which explains why you haven’t seen them at Camps Bay, Kogel Bay, or Scarborough.

At hospitable beaches, the diatoms are always there, spending much of the time lying dormant in the sand behind the surf zone. A proportion of the diatom population is able to survive for relatively long periods (estimated to be more than two months) like this, in the dark on the seabed, not photosynthesising or dividing, until the correct meteorological conditions arise for an accumulation. But first – what sorts of beaches are hospitable to Anaulus?

Brown water in the surf zone at Muizenberg
Brown water in the surf zone at Muizenberg

Topographical conditions

There are five physical features of coasts that are prone to diatom accumulations. They are:

  1. a high-energy sandy – not rocky – shore
  2. a long beach, more than 4 kilometres in extent
  3. the presence of rip currents
  4. a surf zone at least 150 metres wide
  5. a nutrient source close to the surf zone (often an unconfined aquifer overlaid by a dune field)

Muizenberg and Strandfontein beach tick all these boxes. The beach stretches from Surfers Corner all the way across the top of False Bay to Monwabisi, a distance of over 20 kilometres. It is a high energy beach, meaning that it is exposed to large waves and strong winds, and is not protected by any offshore features such as sandbars or headlands that might reduce the force of the waves. Rip currents do occur at the beach, and both these and the exceptionally wide surf zone – wider during south easterly winds in summer – can be observed from the mountainside on Boyes Drive. (A rip current is like a hidden river flowing out to sea from the beach. The Sydney Morning Herald has an excellent visual explainer of rip currents here.)

The head of False Bay where Muizenberg is situated is incredibly nutrient-rich, much of it thanks to urbanisation. The canalised Zandvlei estuary – the only vaguely functional one on False Bay’s coast – is situated a short distance down the beach, and supplies nitrates, phosphates and other nutrients to the surf zone. Many of these nutrients are technically pollutants, added to the river further upstream. The Cape Flats Waste Water Treatment plant at Strandfontein also discharges 200 million litres of treated water per day (under normal, non-drought circumstances) via a canal onto Strandfontein beach. This is essentially an artificial estuary for Zeekoevlei. This waste water has spent some time working its way through the settlement ponds at Strandfontein, but is nevertheless rich in ammonia and other nutrients, and Anaulus accumulations are a very common sight in the surf around this discharge point. The dunes that run along Baden Powell drive overlay a high water table, and groundwater seepage – specially during times of heavy rainfall – may also leach nutrients out of the ground and into the surf zone.

Meteorological conditions

The meteorological conditions required for an Anaulus accumulation involve strong wind and a large swell. These act together to create rough sea conditions, which stir up the dormant diatoms from the ocean floor. The diatoms adhere to air bubbles in the surf zone, staying suspended in the water column, which is when you would notice the water turning brown. Exposed to light, they awaken from their dormant state and start to photosynthesise, take up nutrients, divide and multiply. The presence of rip currents creates an onshore-offshore flow all along the beach. This forms a semi-closed ecosystem, and the diatoms are essentially trapped in gyres in the waves. Longshore currents that run parallel to the beach transport Anaulus cells out of the surf zone at one end, and bring fresh (sea)water in at the other end of the beach.

It may seem surprising that anything manages to accumulate in the waves of a beach, but the surf zone is actually quite retentive, meaning that things that end up there often tend to stay there. (Incidentally, this is why it’s a terrible idea to discharge the byproduct of reverse osmosis seawater desalination –  a super-salty brine – into the surf zone. It must be discharged offshore so that it can disperse and mix with the surrounding water.)

Diatoms in the surf zone at Muizenberg
Diatoms in the surf zone at Muizenberg

You’ll notice that, contrary to what you may have seen when large amounts of plankton are under discussion, I’ve been using the word “accumulation” instead of “bloom” to talk about Anaulus. This is deliberate, because of the constant presence and constant rate of division of the diatoms. When the water goes brown, it doesn’t mean that Anaulus is suddenly multiplying faster than usual. It means that it’s all been gathered together in patches, is exposed to light and therefore photosynthesising (at its usual steady rate), and is thus more visible than it was when it was lying on the ocean floor.

Anaulus at Muizenberg in November 2017
Anaulus at Muizenberg in November 2017

The human factor

You may also be thinking that everything I’ve said about the nutrients that Anaulus requires to survive and thrive points to the fact that humans – and pollution – are ultimately responsible for these brown-water plankton accumulations at Muizenberg. Well yes, in a way. But accumulations of Anaulus australis and related species have been observed and documented for well over 100 years at suitable beaches around the world, and are a natural phenomenon.

Yes, we are providing more nutrients to the False Bay diatom population than they would otherwise have received without human settlement in the greater Cape Town area, but these accumulations would likely occur regardless. They are certainly more intense now than they would have been in the past, but estuaries are nutrient-rich locations even when not surrounded by a large city. Furthermore, the water table is high on the Cape Flats, which would supply nutrients to the surf zone regardless of whether humans lived nearby.

Anaulus is in fact performing a vital and useful function by mopping up the excess nutrients that the city discharges in the ocean. The mass of diatoms – primary producers – also provides a food source to bivalves such as mussels, and other invertebrates. We can be grateful that the excess nutrients that urbanisation directs towards the ocean at the head of False Bay leads only to accumulations of harmless diatoms, rather than to frequent occurrences of harmful algal blooms that can kill marine life and exacerbate respiratory problems in humans.

Muizenberg during a diatom aggregation
Muizenberg during a diatom aggregation


Most of the original scientific study on surf zone diatoms in South Africa was done by a group of researchers (primarily M Talbot, Eileen Campbell and Guy Bate) from the University of Port Elizabeth, working at the Sundays River Beach in the Eastern Cape. I did quite a bit of reading to research this post, but you can start with this paper for a description of the topographical characteristics of beaches where surf zone diatoms accumulate. The first few chapters of this Masters thesis also provide a good overall survey of what is known about surf zone diatoms.

Putting knowledge into practice

Not every instance of brown, foamy water at the beach will be an Anaulus accumulation. On the west coast of South Africa, for example, there are no beaches where Anaulus occurs, but you may see brownish foam that is the result of heavy wave action frothing up organic matter in the surf (nothing sinister – there is a lot of organic material in the ocean). A clue to help you distinguish diatom accumulations from other brown-water phenomena – apart from running through the checklist of required beach characteristics above – is that an Anaulus accumulation doesn’t stretch much beyond the back of the surf zone. If the brown water stretches beyond the furthest row of waves, it’s probably something else. (And this seems like an apposite time to remind you that sewage looks whitish-grey, not brown, when it’s pumped out into the ocean.)

The number of beaches worldwide where surf zone diatom accumulations occur is so small – less than 100 – that Odebrecht et al could enumerate them in a 2013 paper. I hope this helps to convince you that the brown water at Muizenberg beach (and beyond) is something special and interesting, not to be feared. Go surfing!

Bookshelf: Life’s a Beach

Life’s a Beach: Your Round-The-Coast Guide To South African Beaches – Ann Gadd

Compliments of the season. If you’re contemplating which beach to head to for tomorrow’s traditional Boxing Day beach outing, a venerable South African institution, I have just the book for you. The product of a mammoth investment of time (which couldn’t have been all bad) and distance travelled, Life’s a Beach is a handy guide to (possibly, probably, almost) every single beach along South Africa’s coastline.

Life's a Beach
Life’s a Beach

Each pair of facing pages covers a stretch of coast, and beaches are rated for surfing, alongside information about swimming, kiteboarding, wake boarding, kayaking and canoeing, diving, fishing and hiking. The scuba diving information for the sites around the Cape Peninsula, with which I am familiar, is reasonable, but of necessity very abbreviated owing to the book’s format and primary focus. It goes without saying that you should seek out some local knowledge before diving in an area you haven’t visited before.

Unique experiences and best kept secrets (no longer – haha!) are highlighted, as well as the presence of braai and picnic facilities. Tips on where to go for sundowners are also included. Child friendly activities are mentioned where applicable, too.

Access tips, as well as warnings about rips, pollution, sharks (thank you Shark Spotters!) and whether a beach has Blue Flag status round off the comprehensive information that is provided in a handily concise manner. This book will be extremely useful when you’re visiting an unfamiliar stretch of South Africa’s coastline, and particularly invaluable when it’s a little known and less popular beach.

Get a copy of the book here, or here if you’re outside South Africa.

And if you’re going to the beach in Cape Town tomorrow, make sure you’ve downloaded the free Shark Spotters smartphone app. Get it here for your iPhone, and here for Android.

Cape Town’s visible shipwrecks: Update on the Commodore II

Until recently, the last time I specifically went looking for the wreck of the Commodore II was in December last year, when I went to Milnerton lagoon beach to show visiting family the beautiful view of Table Mountain. At that time tides and waves had moved the wreck further away from the lagoon mouth, and she was lying on the sand at a spot that would be partially submerged at high tide.

There has been some community discussion about the future of the wreck since late last year, but nothing changed until winter arrived.

Commodore II in December 2016
Commodore II in December 2016

Next time I went to look for the wreck, just after the Cape storm of 7 June this year, I couldn’t find it. A waiter at the Wang Thai restaurant on the beach told me he’d seen it all the way up at the old Wood Bridge at Woodbridge Island, and that people were removing pieces of the wreck and carrying them away. The storm surge had actually lodged the wreck partially under the old Wood Bridge (a sensitive National Monument constructed in 1901), and there was the potential for it to cause damage. There’s a picture of the wreck in this position on page 28 of this document (pdf).

Commodore II, secure for now
Commodore II, secure for now

A few weeks ago Gerhard Beukes, a Milnerton resident, messaged me to say that he had secured the wreck about half way down the lagoon. It had been winched free of the Wood Bridge by Koos Retief, Area Biodiversity Manager at Table Bay Nature Reserve, and had floated back down the lagoon to settle on a sandbank near Gerhard’s home.

Gerhard estimates that the wreck weighs about 25 tons, and with considerable personal effort and some financial outlay he has attached it to the lagoon bank, resting on the sandy bottom in shallow water, with chains and heavy lifting straps. The chain is secured to bolts attached to metal pipes sunk deep into the bank.

The Commodore II in Milnerton
The Commodore II in Milnerton

The arrangement will prevent the wreck from washing around inside the lagoon and potentially injuring kayakers and other water users. It will also prevent it from washing out into Table Bay and becoming a semi-submerged shipping hazard, potentially lethal to vessels (something like the Seli 1 is when her buoy goes missing).

View towards Woodbridge Island
View towards Woodbridge Island

It’s also quite visible: if you walk or drive down Esplanade Street in Milnerton with Lagoon Beach behind you, you’ll come across the remains of the Commodore II next to the bank of the lagoon on your left. The wreck is over 60 years old, which means that under South African law it is protected and removing pieces of it is an offence. I hope that having many local residents’ eyes on the wreck will ensure it some measure of safety, even in the absence of any enforcement of the relevant laws.

How can you help?

To make sure the wreck does not come loose next time a large volume of water washes down the river and into the lagoon after heavy rains, it needs some further reinforcing in its current location. This could be done with a further 5 metre length of heavy duty chain, or (preferably) two loading slings, 25mm steel cable with rings or eyes on both ends. The harness needs to be capable of holding 25 tons of wood in place even under strain, and are necessary to completely stabilise the wreck.

If you have such items lying around unused at home, or are sufficiently moved and interested by the wonderful history of the Commodore II to make a donation, please comment on this post or use the contact form here, and I’ll connect you with Gerhard, the current guardian of the Commodore II.

Are you interested in shipwrecks that you can visit without going underwater? Read more about Cape Town’s visible shipwrecks here.

Say yes to 22 new Marine Protected Areas for South Africa

Twenty two new marine protected areas have been proposed for South Africa. The benefits of MPAs are well known, so this is excellent news for the future of our marine environment. The public is invited to comment on the proposal, and as a responsible ocean loving individual, sending an email to comment would be one of the ways you can save the ocean. Read on to find out the details.

Proposed new MPAs for South Africa (existing ones in navy blue)
Proposed new MPAs for South Africa (existing ones in navy blue)

Included in the proposed new Marine Protected Areas are South Africa’s first offshore MPAs. The press release from the Department of Environmental Affairs states that:

Many of these new MPAs aim to protect offshore ecosystems and species, ranging from deep areas along the Namibian border to a more than tenfold expansion of iSimangaliso Wetland Park in the KwaZulu-Natal Province. They include charismatic features, such as, fossilised yellow wood forest at a depth of 120m off Port Nolloth, a deep cold-water coral reef standing 30m high off the seabed near Port Elizabeth and a world famous diving destination where seven shark species aggregate, at Protea Banks in KwaZulu-Natal. These MPAs also include undersea mountains, canyons, sandy plains, deep and shallow muds and diverse gravel habitats with unique fauna.

What good will these MPAs do? According to the press release:

The new MPAs will secure protection of marine habitats like reefs, mangroves and coastal wetlands which are required to help protect coastal communities from the results of storm surges, rising sea-levels and extreme weather. Offshore, these MPAs will protect vulnerable habitats and secure spawning grounds for various marine species, therefore helping to sustain fisheries and ensure long-term benefits important to food and job security.

The new MPAs will increase the protected portion of South Africa’s territorial waters from less than 0.5%, to 5%. The government has undertaken to get this figure to 10% by 2019.

What does this mean for you?

Scuba diving

If you’re a scuba diver, you probably know that diving in a Marine Protected Area – particularly in a no-take zone – is an extra special experience because of the abundant fish and other marine life. The prospect of richer, more diverse dive sites to explore is an exciting one, but there are more benefits to this proposal than just enhanced eco-tourism opportunities.

Scuba diving businesses will have to acquire permits from the Department of Environmental Affairs (for about R500 per year) to operate in the Marine Protected Areas. (This has been in force for some time, and ethical dive operators in Cape Town who take clients diving in any of the existing MPAs should be in possession of a permit already.) There are also the permits issued to individual scuba divers (for about R100 per year, obtainable at the post office) to dive in an MPA – you will see this mentioned in Tony’s newsletter now and then, as a reminder.

Environmental protection

Some of the new MPAs are in offshore regions that would otherwise be at risk from destructive trawl fishing and other exploitative activities such as mineral, oil and gas extraction from the seabed.

Many of these MPAs will, like the Tsitsikamma MPA, serve as nurseries for fish stocks. Recreational and commercial fisheries will benefit from allowing the fish to spawn unmolested in protected areas along the coast. Holding ourselves back from fishing everywhere, at every opportunity, shows long-term thinking, and will have short-term benefits as well as for future generations.

Undesirable activities

Not all of the MPAs will be closed to fishing – those of you familiar with the network of protected areas around the Cape Peninsula will be familiar with this idea. For example, a number of pelagic game- and baitfish species may be caught within the Controlled Pelagic Zones of the Amathole, iSimangaliso, Protea and Aliwal Shoal Marine Protected Areas. Commercial fishing permits may also be issued for use in the MPAs.

Existing discharges of effluent are permitted to continue – specifically into the Aliwal Shoal MPA.  This means that SAPPI may continue to pump wood-pulp effluent onto the dive sites there.

What to do?

If you would like to show your support for the proposal – and who doesn’t love a well-chosen MPA? – send an email to You have until 2 May 2016 to do so, and you can include any other relevant comments about the MPA proposal in your missive.

You can download the full document detailing the proposed new MPAs complete with maps, management regulations and co-ordinates (a 336 page pdf) here.

Tony and I are looking forward to passing over some of the new MPAs on the Agulhas Bank (maybe numbers 11 and 12 on the map above) next year – without getting wet. You can come too! (But you may have to impersonate a twitcher.)

Who to thank?

This project has been spearheaded by a team at SANBI (the South African National Biodiversity Institute) led by Dr Kerry Sink. Dr Sink has been awarded a prestigious Pew Fellowship in Marine Conservation for 2016, and her fellowship work encompasses a range of projects aimed at strengthening and expanding South Africa’s network of Marine Protected Areas.


We are extraordinarily fortunate to have a scientist and conservationist of Dr Sink’s calibre as a champion for MPAs in South Africa. So you can thank her!

Bookshelf: The Coastal Guide of South Africa

The Coastal Guide of South Africa – Lynne Matthews

The Coastal Guide of South Africa
The Coastal Guide of South Africa

This is a slim guidebook that will be useful to anyone living at the coast or enjoying a holiday there. Covering all of South Africa’s almost 3,000 kilometres of coastline, this book has sections on all the flora and fauna found between the dunes and the ocean. It is by no means exhaustive, and a local guide will always have more information on a particular locale, but for scratching the surface or beginning to learn about coastal life forms, this is an excellent start.

When I was younger we had giant Reader’s Digest guidebooks to help with road trips and visits to the shore, and this is a super scaled-down little cousin of those faithful hardback volumes. The introductory section deals with tides, currents, and the different zones along our coastline. There are sections on plants, birds, fish, invertebrates, reptiles and mammals. The species identification information is good, with distribution, size and the main identifying features provided, at a minimum.

There is also a section on fishing regulations. I’m not a fisherman so I can’t comment on whether it’s even worth putting these in a book – are they static, or subject to frequent change at the whim of DAFF? There is also a section on SASSI – how to eat seafood sustainably. If I had to add a section, I’d ask for something on ocean safety – rip currents, drinking and swimming, not wearing sunscreen, boating foolishly, scuba diving in boat traffic without a buoy – all the things that keep the NSRI and lifesavers busy over the festive season. One can’t be reminded often enough.

The book is mainly illustrated with line drawings and paintings, as well as several maps. If you have space in your bag for a larger format book, I’d recommend Southern African Sea Life: A Guide for Young Explorers over The Coastal Guide of South Africa because it’s more practical and detailed, but if you don’t have children you might feel shy whipping that one out while on the beach!

You can get a copy of this book here.

Newsletter: Cry of the fish eagle

Hi divers

We are back from a few days of houseboating on the Knysna lagoon. At high tide the water was clean and 17 -18 degrees. The lagoon is a vibrant and healthy ecosystem and the bird life is amazing. During the early evenings we sat on anchor with a torch and a bucket and caught a multitude of small creatures for a look see and a photo and then returned them to the flowing water. The birdlife highlight of the trip was a pair of resident fish eagles.

Fish eagle pair on the Knysna lagoon
Fish eagle pair on the Knysna lagoon

Dive reports from last weekend were sketchy at best with rumours of 15 metre visibility yet very very little comment on the usual media sites. I have therefore no idea on what the diving was like. I believe yesterday was somewhat better on the far reefs but shore entries apparently had 3 metre viz.

Sunset on the Knysna lagoon
Sunset on the Knysna lagoon

The wind today has been in the right direction to clean the bay but along with the wind and rain is a 6 metre swell. There is some south easterly wind but the temperature in the Atlantic today was 16 degrees, False Bay is 12 degrees, so I doubt it is going to get much better for the weekend. The swell is mostly gone on Sunday but its unlikely (my opinion only) that False Bay will be good after the swell.

Egyptian geese in formation
Egyptian geese in formation

So my plan is to spend Saturday training in the pool and Sunday, well let’s see what things look like late Saturday. (The swell may not peak at 6 metres and may end sooner than forecast.)


Don’t forget about our Durban dive trip from 17-21 June, and our Red Sea trip in October. If you’d like more details on either of these, give me a shout.


Tony Lindeque
076 817 1099

Diving is addictive!


Article: Wired on the Salton Sea

Did you know that there is a 24 by 56 kilometre (approximately) body of water in southern California that was created in an accidental flood in 1905? Nor did I. It’s called the Salton Sea, and I learned about it from an article on (and some supplementary googling).

The Salton Sea lies about 70 metres below sea level. Its maximum depth is 16 metres. The sea was created as a result of an engineering accident during efforts to divert part of the Colorado River into canals that fed arid areas. The new body of water achieved some success in the 1950s as a leisure venue where watersports and sport fishing took place, but it is as a bird and wildlife habitat that the Salton Sea is most renowned. Over 400 species have been documented there, and many migratory birds pause their journeys at the sea.

Very little water flows into the sea, and none flows out. This has caused increasing salinity of its water, which is currently 50% saltier than the Pacific Ocean. Surprisingly, a fish called tilapia (I think we might have seen a type of tilapia while diving at Marico Oog) thrives there, despite the stresses of an increasingly salty environment, algal blooms owing to fertiliser runoff into the sea, and extremes of temperature in summer and winter. Bacteria consuming the summer algal blooms deplete the oxygen in the water and suffocate the fish, which die suddenly and in startlingly large numbers.

The area undergoes massive and rapid changes, flip flopping from one unstable state to another. In a sense, this is all natural – there has been little human interference in the Salton Sea’s ecosystem (apart from the fertiliser runoff that occasionally enters the water) and the rapid transitions speak of the sensitivity of the ecosystem rather than rampant human-caused destruction. Despite the gruesomeness and the resulting stench, the mass fish mortalities have their use – their decomposing bodies add to the nutrients in the sea and support other forms of life.

With almost no inflow, the water in the Salton Sea is gradually evaporating, adding to its salinity and exposing areas of land which are saturated with a century’s worth of agricultural chemicals. The chemical-infused grit becomes airborne when the wind blows, and cause respiratory and other health problems among the residents of the surrounding areas. Left alone, this by-product of the drying Salton Sea will only increase in volume and severity.

There have been various plans and attempts to “save” the Salton Sea, all of them wildly expensive. Some proposals have been to construct canals to the Gulf of California or to the Pacific, to establish water circulation into the sea. Others propose desalination plants on the sea shore. The Salton Sea Authority aims to preserve the Salton Sea and stabilise it, with current preferred method being the creation of a large seawater dam covering much of the current Salton Sea area. Here is a link to a full analysis and proposed restoration plan. None of the proposals are simple or cheap – a massive engineering feat is required, whatever solution is ultimately pursued.

Looking beyond the complexities of its management and the expensive decisions required about its future, the Salton Sea is a strikingly beautiful and curious place. There are some amazing photos here and some others here, and a National Geographic article about the sea here.

The Salton Sea is a fascinating case study of how complicated the outcomes can be when human constructs (deliberate or – as in this case – accidental) interact with natural processes. River estuaries are an example of an existing habitat or structure that can be irreparably altered by relatively small actions such as closing part of the river mouth. It is too difficult to predict the consequences of such changes to places that have formed naturally over thousands of years, and usually almost impossible to reverse these. Beach erosion and sand dune build up or movement may be the result of the construction of a jetty or tidal pool, diverting the power of the waves to another, unforseen location. The speed at which the Salton Sea has evolved is fascinating, and the apocalyptic natural events that mark its history – colossal algal blooms, rampant fish and avian deaths, and catastrophic evaporation – are salutory warnings of how violently unpredictable nature can be.

The full article from Wired is here.

Bookshelf: Under the Sea-Wind

Under the Sea-Wind – Rachel Carson

Under the Sea Wind
Under the Sea Wind

Under the Sea-Wind is the first book in a loose trilogy of books about the ocean, completed by The Sea Around Us and The Edge of the Sea. In typical fashion I read the books out of order, but it hardly matters. While The Sea Around Us is concerned with grand, overarching themes of history and oceanography as they relate to the ocean, Under the Sea-Wind describes a year in the life of sea birds, eels, and mackerel. “Sea-Wind” is Carson’s shorthand for the ecosystem encompassing the ocean, rivers, and all life. It is written almost like a story-book, and I think would be enjoyed by a child for the plot elements and drama as much as by an adult for the vivid writing and naturalistic details that Carson includes.

What I loved was that the creatures that Carson writes about – the eel, the mackerel – all encounter man’s work and activity in their realm. Fishermen (purse seine, trawlers and simple artisanal ones) and ships are threats to the mackerel and other fish, and harbours provide a varied, sheltered environment for coming of age. There is no hint, however, of the environmental catastrophes of global warming and overfishing that were beginning even in 1941 when this book was published.

This is an unusual book – like the love child of a nature book and a novel – but a beautiful and fulfilling read. I think you should read The Sea Around Us first, decide if you like Carson’s writing, and then try Under the Sea-Wind.

But how can you not love this writing?

To stand at the edge of the sea, to sense the ebb and flow of the tides, to feel the breath of a mist moving over a great salt marsh, to watch the flight of shore birds that have swept up and down the surf lines of the continents for untold thousands of years, to see the running of the old eels and the young shad to the sea, is to have knowledge of things that are as nearly eternal as any earthly life can be. These things were before ever man stood on the shore of the ocean and looked out upon it with wonder; they continue year in, year out, through the centuries and the ages, while man’s kingdoms rise and fall.

Under the Sea-Wind, Rachel Carson – Foreword, page 3

You can buy the book here if you’re in South Africa, otherwise here. Kindle users can go here and here.