City of Cape Town’s new protocol for cleaning tidal pools

Early in November I attended an information session at the Kalk Bay Community Centre, where the City of Cape Town announced that they will be trialling an environmentally friendly cleaning process on five of the 19 tidal pools on the 260 kilometres of Cape Town’s coastline managed by the City. This coast stretches from Silwerstroom on the West Coast to Kogel Bay on the eastern shores of False Bay.

St James tidal pool
St James tidal pool

The presentation was made by team members from the City’s Recreation and Parks department, which – among other things – is responsible for beaches, outdoor signage, ablutions, lifesaving, environmental education, and administration of Blue Flag status for the beaches and marinas that earn it. This department is also responsible for the tidal pools. (Incidentally the City’s assortment of safe seawater bathing facilities includes two of the largest tidal pools in the southern hemisphere, at Monwabisi and Strand.)

Until now, the City would use chlorine to clean the walls (top and sides) and steps in the tidal pools. The cleaning would be done after draining the pool completely. This year, a supply chain management issue meant that there was no cleaning of the tidal pools between July and November. During this time, regular swimmers (some of them members of the Sea-Change project) noticed that marine life flourished in the pools, and engaged with the City to try to find a way to keep the tidal pools safe but also to preserve the diversity of marine species that had been thriving in the pools during the cleaning hiatus. Safety, of course, is why they are cleaned: slippery, algae-covered steps are dangerous.

The tidal pool at Millers Point
The tidal pool at Millers Point

It was agreed that five of the pools – St James, Dalebrook, Wooley’s Pool, and the two pools at Kalk Bay station – would be subject to a trial of a new, environmentally friendly cleaning regimen. These pools are relatively close together in the north western corner of False Bay. The aim is still to ensure that the tops of the pool’s walls and steps are not slippery, and thus safe for bathers. But a second aim has been added by the City, which is to ensure the environmental integrity of the pools.

Under the new cleaning protocol, the following will be done:

  • the pools will be drained only when necessary, and only as far as is required to reach areas that are covered by water and in need of cleaning (for example, the steps at Dalebrook)
  • animals in harm’s way will be relocated
  • excess kelp and sea urchins will be removed from the pools
  • the tops of the walls and steps will be scraped to remove algae (the sides of the walls used to be scraped too, but this will no longer take place)
  • environmentally friendly chemicals will be used to remove the algal residue after scraping – no more chlorine and no more whitewashing!

All of the above means that the pools will be ready for use by the public immediately after cleaning, in contrast to the old protocol, which renders the pool unusable for a period after the cleaning crew has chlorined it.

I’ve asked the City for more information about the drainage procedure, and for more information about the earth-friendly chemicals that the cleaning contractor will use, but with no response so far. (If I get one I’ll obviously update this post.)

Buffels Bay tidal pool inside the Cape Point section of Table Mountain National Park
Buffels Bay tidal pool inside the Cape Point section of Table Mountain National Park

Many of the City of Cape Town’s tidal pools fall within the Table Mountain National Park Marine Protected Area, and it therefore makes perfect sense to aim to protect the animals living in them while maintaining public safety. Dr Maya Pfaff, another speaker at the information session, even suggested that some of the animals that may now thrive in the pools may actually help to keep the water clean. Mussels and feather duster worms filter the water and improve the clarity, algae take up nutrients, and limpets clean algae off the rocks.

Particularly over the festive season, the beaches and tidal pools around Cape Town are extremely busy. This is a wonderful opportunity for thousands of beach-goers to experience both safe swimming and a little bit more of what the ocean has to offer, instead of a sterile, salt-water pool devoid of healthy marine life. Bringing a snorkel and mask with you when next you go swimming will be well rewarded. To see some pictures of the amazing animals – from nudibranchs to a cuttlefish with eggs – in the St James tidal pool, check out Lisa’s instagram profile.

Do you swim regularly in any of the five pools in which the new cleaning regimen is being tested? What do you think about it? If you think that environmentally gentle cleaning of tidal pools is a good idea, what about letting the city know that you appreciate having tidal pools that are both safe and biodiverse. A short message on the City of Cape Town facebook page to say thank you and keep up the good work (and a request to extend it to the other tidal pools) is a good place to start!

You can read a news article about the new cleaning protocol here.

Shrimp news from False Bay

The University of Cape Town has announced that a further three new species of shrimp, all spotted close to shore near Millers Point in False Bay, have been described and named. All three belong to the same genus (Heteromysis), and look similar, with pale bodies marked by red spots and stripes. One of these new (to science) species lives inside octopus dens, and another lives inside the shell of certain types of hermit crab. These three shrimps join the stargazer shrimp that was discovered by and named for Guido Zsilavecz, citizen scientist and author of several books on False Bay’s marine wildlife.

Two of the new species were discovered by local film maker Craig Foster, founder of the Sea-Change project about which we read last week. These types of discoveries are very exciting and should be a great inspiration and encouragement to divers and other water users. Time in the water is rewarded. If you can’t identify something, send an email with its photo to SURG. It is possible to make significant contributions to science while holding down an entirely non-scientific day job!

Read all about the new shrimps here.

Peet’s Vulcan Rock video

Urchins, brittle stars, corals at Vulcan Rock
Urchins, brittle stars, corals at Vulcan Rock

Peet made this amazing video while diving Vulcan Rock with us. There is a huge cave with several entrances at the bottom of the reef, and he went inside to check it out.


Dive sites: Vulcan Rock

Esther exploring
Esther exploring

Vulcan Rock is a dive site just outside Hout Bay. We dived it on a day when the south easter had been blowing for a while, so the visibility was quite good. The dive site is essentially a huge stack of granite boulders, with Vulcan Rock as the highest point. The rocks are covered with sea urchins, rock lobster, corals, sea cucumbers, brittle stars, and a bit of red seaweed.

Urchins, brittle stars, corals at Vulcan Rock
Urchins, brittle stars, corals at Vulcan Rock

Esther and I stayed within the range of Open Water divers, not going deeper than 18 metres, but it is possible to go as deep as 30 metres at this site if you go for a bit of a swim. This is definitely a site to visit when the surface conditions are good and the swell is low (not that Hout Bay diving is ever great – or particularly safe – in a big swell).

Granite and kelp
Granite and kelp

I had the little Sony camera with me and took some happy snaps. Underneath all the granite is an enormous cave, with several entrances. Peet, who joined us on this dive, made a video of the cave that I will share with you later this week.

Mark bringing the boat
Mark bringing the boat

Dive date: 19 April 2015

Air temperature: 23 degrees

Water temperature:  10 degrees

Maximum depth: 15.6  metres

Visibility: 12 metres

Dive duration: 39 minutes

Article(s): Phenomena & The Verge on a sea star wasting virus

Our wedding starfish at Long Beach
Our wedding starfish at Long Beach… see, he is lying in a heart shape!

The starfish in this picture may or may not still be alive (my guess is not), but it looks very much like a starfish in the early stages of Sea Star Wasting Syndrome (SSWS), minus a few legs. (It isn’t sick – I photographed it at Long Beach a few years ago – and it is actually an invasive species on South Africa’s coast.) Sea stars on the Pacific coast of North America began sickening – suppurating and disintegrating – in mid-2013, and scientists have been scrambling to find the cause. Initially it was not clear what was causing the sea stars to die in such grisly ways: pollution, warming oceans, large storms and other possibilities were considered. The clue that told scientists that the cause was “microscopic and biological” (in the words of National Geographic Phenomena blogger Ed Yong, who covers the subject with admirable clarity) was that starfish in aquaria, who were bathed in water pumped from the ocean and filtered, were also dying.

Yong’s post explains how scientists isolated the virus (a process involving blending, filtering, and genetic sequencing), and what scientists are hoping to learn from the work they have done on this subject. Potential parallels between SSWS and viruses that periodically flare up in human populations (Ebola being a recent example) are interesting.

At The Verge, Elizabeth Lopatto writes in more detail about SSWS, its discovery, and consequences. She points out that sea stars are a “keystone species”, and that

Keystone species help maintain an ecosystem by eating quickly-reproducing prey species like urchins and mussels — keeping populations low. Without the sea stars, the urchin population explodes; bad news for the kelp forests and everything in them. Giant kelp can grow to 150 feet underwater at a speed of two feet a day, but their weaknesses are their holdfasts, which are sort of like tree roots. The holdfasts are home to brittle stars, prawns and snails, among other creatures. Urchins like to eat the kelp holdfasts. Without them, the rest of the kelp drifts off in the tides. In this way, urchins can devour forests, which, higher up, are also home to fish, including several types of commercially-important rockfish, according to the National Oceanic and Atmospheric Administration.

Lopatto’s article is an excellent read – find it here.

(As an aside, the ocean is full – full to the gills – of viruses. This was revealed to me by the Palumbis in The Extreme Life of the Sea.)

Bookshelf: The Death and Life of Monterey Bay

The Death and Life of Monterey Bay
The Death and Life of Monterey Bay

I had high hopes for The Death and Life of Monterey Bay, for reasons that will be revealed (I hope) in the course of the next few years. Monterey Bay is in California, and opens onto the Pacific Ocean. It has approximately the same surface area as False Bay but is shallower and less square. Filled with diverse marine life, it was formerly bounded by a row of sardine canneries (setting for John Steinbeck’s novel Cannery Row) which were responsible for massive pollution in the area. Tons of stinking sardine guts fouled up the bay, which had been stripped of much of its marine life by aggressive fishing practices and cascading effects in the ecosystem.

In 1892 the Hopkins Marine Station was founded, a research laboratory of Stanford University. In 1931, the area of ocean in front of the lab was designated the Hopkins Marine Life Refuge (now Reserve). The bay’s populations of abalone, sea otters, killer whales, kelp forests, whales, and other life gradually recovered, and the sea urchin barrens were overgrown and once again supported a variety of life.

In this book Palumbi and Sotka trace the decline and recovery of the bay, lingering on colourful local characters such as Monterey mayor Julia Platt, whose no-nonsense attitude ensured access to the ocean for all the residents of the area. I expected the book to be more about marine biology, with information about how the various species recovered in the ecosystem once the polluting and overfishing forces were removed, but it is definitely more of a human history, with a strong focus on Platt, John Steinbeck, and his friend Ed Ricketts, with whom he travelled to the Sea of Cortez.

The establishment of the Monterey Bay Aquarium on Cannery Row effectively redeemed an area that was the source of seemingly limitless pollution. The aquarium was opened in 1984 after years of planning. It is a sister aquarium to Cape Town’s Two Oceans Aquarium, and also has the distinction of being the first aquarium to attempt to exhibit a (juvenile) great white shark, an enterprise that (fortunately) seems doomed to failure.

There’s an excellent article on Palumbi and the book here.

Here’s Stephen Palumbi giving a TEDx talk on how Monterey Bay came back to life:


You can get the book here if you’re in South Africa, otherwise here or here.

Bookshelf: The Unnatural History of the Sea

The Unnatural History of the Sea – Callum Roberts

The Unnatural History of the Sea
The Unnatural History of the Sea

Conservation biologist Callum Roberts has spent years researching the history of the last 1,000 years’ exploitation of the sea by human beings. The result, The Unnatural History of the Sea, is a stunning and detailed illumination of the scale of destruction we have wrought on our oceans. I had been under the impression that the development of industrial-scale fishing capabilities (factory ships, flash freezing, gill nets and the like) in the mid 20th century was what prompted the most egregious overfishing practices. This, however, is an example of baseline creep, in which successive generations look back at the conditions of nature experienced by the previous generation, and mistake them for pristine.

Humans have been harvesting marine life for over 1,000 years, moving from the freshwater ecosystems of Europe’s rivers and lakes after denuding them of all significant fish life through astonishingly aggressive (and familiar-sounding) fishing practices such as stringing nets across the entire width of rivers when fish returned to spawn. Siltation of the rivers caused by deforestation on their banks, and the development of better fishing equipment, also contributed to the move to marine fishing.

Millions of sea turtles and whales used to roam the oceans. To put that in perspective, there are under 15,000 southern right whales alive today (we think they’re recovering well – haha), and approximately 200,000 breeding green sea turtles. Numerous sea turtle rookeries, where the animals return year after year to lay eggs, are now lost to memory, after their breeding populations were completely wiped out during the 16th and 17th century by explorers and settlers in the New World. Entire seal and otter populations were hunted to extinction for their pelts. Hunters and fishermen often took far more than they needed, killing for amusement, squandering the abundance and leaving carcasses to rot or tossing excess fish – already dead – back overboard. After perusing logbooks, letters, diaries and other documents, Roberts remarks that rarely did the explorers, settlers and merchants remark on any aspect of the natural beauty of the creatures they saw on their travels, and if they did it is immediately followed by instructions on how to kill and prepare the animal, and what it tastes like.

Natural marine spectacles such as the sardine run off the Eastern Cape coast of South Africa were once far less remarkable and unusual than we find them today. The migration of herring from the Arctic down to the latitudes of the United Kingdom between May and October each year drew thousands of basking sharks (now we get a news article when four are seen in one day) and other predators, and their spawning left eggs lying on the sea floor in layers up to two metres thick. Roberts says that great white sharks also feasted on this bounty of fish, and mentions that there are too many detailed reports of white sharks up to nine metres long from the 18th and 19th century to discount all of them as false. (The maximum recorded length of a white shark in modern times is approximately six metres.) Today white sharks are seen so rarely in European waters as to create a great fanfare when one of them is spotted.

The point is that the oceans used to support far, far more life and abundance than we are able to conceive of today. Herring used to be so abundant in the seas around Scandinavia that they held up shipping. Pods of dolphins didn’t number in the thousands; they numbered in the hundreds of thousands. Whales were seen in similar numbers, surrounding boats, rubbing against them, and drenching them with spray from their blowholes. Ships navigated towards land by following the sound of countless sea turtles swimming towards the beaches they laid their eggs on.

This is a crushing, shocking book. While reading it I frequently felt myself assailed with despair and regret at how long the over-exploitation of marine resources has been underway, and how much we have lost. Bottom trawling dates back to the 14th century, and already then there were complaints (to Edward III of England, in 1376) about its indiscriminate destructiveness. Scientists visiting newly-discovered (they think) sea mounts have found their once thriving slopes reduced to fields of rubble, littered with discarded trawl nets and other fishing gear debris.

The sections on fishing in the deep sea and on trawling are devastating. Roberts contends that there is no such thing as a sustainable deep sea fishery, as the target species are so long-lived and slow growing (and unknown to science), with unknown population sizes, that there is no sustainable number of fish that can be removed without risking the species’s ability to survive.

Finally, Roberts offers some solutions to arrest the awful, seemingly inevitable slide towards ocean barrens populated only with sea jellies and urchins. The steps Roberts outlines in order to save and recover the world’s fisheries are simple to state, but will be challenging to implement:

  1. reduce present fishing capacity (i.e. number of boats, level of sophistication – this is not referring to reducing quotas)
  2. eliminate risk-prone decision making (i.e. use science, and act only when you have the facts – don’t use hope or gut feel as a decision making tool)
  3. eliminate catch quotas and instead implement controls on the amount of fishing (i.e. how much effort can be expended)
  4. require people to keep what they catch
  5. require fishers to use gear modified to reduce bycatch
  6. ban or restrict the most damaging catching methods (e.g. trawl fishing)
  7. implement extensive networks of marine reserves that are off limits to fishing

He advocates the use of Marine Protected Areas (MPAs) – scientists estimate that it is necessary to protect 20-40% of the world’s oceans in order to save fisheries for the future. Strangely, to someone who lives here and doesn’t think much of our collective will and ability to police MPAs, especially when fishing is allowed in many of them, South Africa is actually a world leader and has protected a larger proportion of her territorial ocean than many other countries (the world total is about 1.2% of the oceans, with only 0.01% of the world’s oceans designated “no take” zones, according to Wikipedia). The benefits however, even of poorly policed marine parks, are significant.

I am not sure I share Roberts’s optimism that the situation can be reversed or arrested – passages from this book come to me at odd moments, leaving me nauseated at the greed, waste and ignorance that we have displayed as a species, against the life of the sea.

There’s an interview with Roberts that I found interesting, and reviews at American Scientist and the Washington Post.

You can get a copy of the book here or here, otherwise here if you’re in South Africa.

Bookshelf: The Story of Sushi

The Story of Sushi: An Unlikely Saga of Raw Fish and Rice – Trevor Corson

The Story of Sushi
The Story of Sushi

I didn’t really know what to expect from this book – I admit that I tried it out because it had a fish on the cover, and because I’d previously enjoyed Trevor Corson’s The Secret Life of Lobsters. I was pleasantly surprised. Showing the same narrative flair as he exhibits in his lobster book, Corson interweaves science and history with a present-day story with novel-like characteristics.

Formerly titled The Zen of FishThe Story of Sushi takes place at the California Sushi Academy, tracing a (real and) diverse group of students as they spend several months learning to be sushi chefs. The principal character, the weakest student in the class, is squeamish about handling raw fish, and scared of her sushi knives – one wonders if she had done any research about what being a sushi chef entails. Despite this drag on the overall mood of the classroom scenes (one can only read about someone being berated for their incompetence, or deliberately shirking tasks that they find unappealing, so many times) Corson manages to invest the reader in the lives of the chefs and students that he profiles. As the students learn about sushi, so do we.

The history parts of the book deal with the development of sushi as a cultural and culinary phenomenon, first in Japan and then spreading to the rest of the world. Corson also delves into food science, explaining why things taste the way they do, and the microbial processes that give us vinegar and other fermented foods (essential in the development and preparation of sushi), and marine biology. Make no mistake – bluefin tuna, abalone, urchins, eels and octopus play only bit parts in this book, and appear more frequently as sushi toppings than as vibrant life forms populating the world’s oceans. Corson talks about the biology of the animals only insofar as it enables development of his main – food related – themes.

I found this a surprisingly good read, and a helpful informer on the subject of an aspect of Japanese culture other than their well known penchant for whale hunting and general disingenuousness around ethical fishing practices. It has made me a more informed sushi consumer but not as regards what fish are best to eat (use SASSI for that). There is hardly a mention of whether one can ethically consume all sushi toppings with gay abandon, or whether the environmentally conscious consumer should think twice about eating certain seafoods. I do feel that I have more understanding of the construction and serving of sushi, and am able to watch the chefs at my local sushi bar with a bit more awareness.

There’s a New York Times review (and another book recommendation).

You can get a copy of the book here if you’re in South Africa, otherwise here or here.

Dive sites: Roman Rock

I’m not sure why I haven’t written about Roman Rock before. I’ve actually done four dives on the main reef, the first in 2010. The pictures in this post are from more than one of the dives – I’ll group them together, and you’ll be able to see by the water colour which dive is which.

Reef life at Roman Rock
Reef life at Roman Rock

Roman Rock reef is a very large collection of boulders separated by sand patches, centred on the Roman Rock lighthouse. Nearby reefs include Castor RockLivingstone ReefRoman’s RestWonder Reef, and Tivoli Pinnacles. The reef is comprised of granite boulders, heavily encrusted with typical Cape Town reef life – feather stars, brittle stars, nudibranchs, sea stars, urchins, sea cucumbers and ascidians – varying with the depth. If the current is strong you will find a lot of fish here, mostly roman and hottentot, enjoying the tasty bounty brought by the tide.

Part of the dive is along high walls that are reminiscent of Atlantis Reef, further south. There are deep dead-end passages in between the rocks, wide enough to swim through (or drive a car through), and the rippled sand looks like a white carpet or a runway. In the middle of nowhere you will come across a ladder; it’s been there since the first time I dived Roman Rock in 2010. Your guess is as good as mine.

Ladder in the middle of nowhere
Ladder in the middle of nowhere
Redbait at Roman Rock
Redbait at Roman Rock

The site is suitable for Open Water divers, as the maximum depth one can attain while staying adjacent to the reef is about 18 metres. There are several pinnacles and shallower plateaus that are suitable for deeper safety stops. It goes without saying that each diver must have a surface marker buoy – the site is a relatively short boat ride from False Bay Yacht Club, but offshore nonetheless and there may be boat traffic, depending on where the current takes you.

Dive date: 3 August 2013

Air temperature: 22 degrees

Water temperature: 14 degrees

Maximum depth: 16.5 metres

Visibility: 10 metres

Dive duration: 38 minutes

Dive sites (Red Sea): Barge wreck (Bluff Point, Big Gubal Island)

The barge wreck by day
The barge wreck by day

There is a barge wreck at Bluff Point on Big Gubal Island in the Red sea, where we did an amazing, fast drift dive along the side of the lagoon. During that dive we did stop in briefly at the barge wreck (its origin and identity is unknown), but it was on a night dive the previous evening that we actually spent a significant amount of time exploring the barge.

Divers exploring the barge at night
Divers exploring the barge at night

It’s supposed to be one of the best night dive sites in the Red Sea, and we were amazed by the amount of life on and around the wreckage. We saw multiple large moray eels, huge basket stars, enormous urchins, and a crazy variety of other life. We jumped off the back of our liveaboard, swam under a neighbouring liveaboard, and found the barge wreck just off its starboard side. It was teeming with divers from our boat and the other liveaboard, but there was so much to see over such a spread out area that it didn’t matter too much.

Giant basket star
Giant basket star

My favourite thing was the basket stars, of which there were many. We saw some huge ones, with diameter nearly as big as my arm span, and some small, palm-sized ones. They are not the lovely blue-grey colour of the ones we see in Cape Town, but the intricate design of their many arms is the same.

We also saw a number of moray eels. Our dive guide told us that two big ones live on the barge wreck, named George and Georgina. The ones I saw and photographed were extremely large. As with the night dive we did at the Alternatives, the water was very still and very clear, so torch light actually shone an appreciable distance. This kind of night diving is so easy and wonderful that I think it might have spoiled me for night diving in Cape Town!

Moray eels under the barge wreck
Moray eels under the barge wreck

Dive date: 21 October 2013

Air temperature: 24 degrees

Water temperature:  26 degrees

Maximum depth: 11.2 metres

Visibility:  30 metres

Dive duration: 50 minutes

Freckled hawkfish on some coral
Freckled hawkfish on some coral