We did two short exploration dives around Ark Rock on 21 March. The first was to a small wreck roughly east of the rock itself, and the second one was to check out a pair of boilers lying on the sand s short distance apart. There’s nothing else around except for some rocky reef, which Tony and I explored for a while after we were done with the boiler.
View over the boiler
The boiler looks quite imposing – for the technicalities on fire boxes and things visit the Wikivoyage page for Ark Rock, but it’s solitary and impressive. There are no other bits of wreckage lying around. Most of the boiler is very overgrown, and we found a huge roman hiding in one of the holes in the boiler.
Front of the boiler with holes at the bottom
The rocky reef close to the boiler is covered with sea cucumbers, Stephens codium, brittle stars and feather stars.
Stephens codium and sea star
Tony and I were fascinated with the sea pens sticking out of the sand, and I spent quite a while watching a warty pleurobranch trying to walk over a brittle star (who fought back).
Warty pleurobranch walking over a brittle star
We took a slow swim around the reef and back to the boiler and the shot line, which was on the sand nearby. The water was very green, but the visibility was fairly respectable!
The idea for this post was prompted by a two recent dives. One we did at Partridge Point, where the life on the rocks is so prolific that in places it seemed to be stacked on top of itself for want of space. The other we did one evening at Long Beach, and on the way out at the end of the dive, in the first two metres of water off the beach, I spotted two tiny long-siphoned whelks, clearly juveniles. One was hitching a ride on the back of a hermit crab!
Baby long-siphoned whelk riding a hermit crab
Returning the favour, here’s a close-up of part of the shell of a simply enormous long-siphoned whelk (probably over 30 centimetres long) at Partridge Point. He’s got a variety of creatures on his shell, most noticeably a bright red-chested sea cucumber!
Whelk with red chested sea cucumbers hitching a ride
Many of the brittle stars I’ve seen lately have been covered with very photogenic little crustaceans called ornate amphipods, looking a bit like wood lice in full party dress. They are common, but not often seen by divers as we tend to focus on the big stuff! They are scavengers and feed on whatever they can find as they travel over reefs (and, in this case, other marine life)!
Ornate amphipods riding on a brittle star
Even though sea squirts don’t have thoughts or emotions as such, I was amused by this cluster of red bait that I saw at Long Beach. It’s been covered by another kind of colonial ascidian (the greyish blue mass with white siphons), leaving just the large siphons of the red bait visible.
Red bait under a colonial ascidian
Something similar has happened here:
Encrusted red bait
Some of the hitch hikers we see aren’t entirely benign. I’ve already posted a picture of a puffadder shyshark with a copepod parasite sticking out of his gill covers – these parasites don’t cause the fish any noticeable discomfort, but they’re not without impact. Here’s another unfortunate shyshark we found at Long Beach early in February.
Shyshark with parasite in its gill cover
Fish lice tend to attach themselves just above the eye of fransmadam, hottentot and similar fish. The lice essentially drink the blood of their host fish – they’re horrible creatures and we’ve noticed that many of the fish affected by them tend to hang around divers and to swim very sluggishly. Guido of SURG has pulled off a louse before, from a very docile fish, and there was a big seeping hole in the fish’s head underneath where the louse was attached.
Fransmadam with fish louse at Fisherman's Beach
Tony and I have seen very small fish with lice attached, almost a quarter of their size, and fish with more than one fish louse in residence. Here’s a maasbanker, one of a school that followed us around for a couple of dives at Long Beach in March.
Juvenile maasbanker with fish louse
In the picture below, the fish second from left towards the top of the photo has a large louse on his head.
Hottentot at Sunny Cove
After all that depressing parasite stuff, here’s a picture I find absolutely hilarious. The starfish isn’t going anywhere fast, but looks as though he’s reclining in a plushy couch formed by his fellow marine creatures. He is begging to have a smile photoshopped on!
Shoo, we love this show! It’s a documentary-style reality show about crab fishermen in Alaska. It’s back-breaking, dangerous work conducted in short bursts on the Bering Sea near the top of the world (the sea Sarah Palin looks across from her front porch in order to spy on Russia). The crab fishing (in this season at least) is done derby-style: the government opens the season on a particular date, and then based on how much is caught, closes it a few days thereafter.
The men work almost 24 hours a day, knowing that their available time to take advantage of the crab bounty is short. The captains engage in the strategising and planning – they have to decide where to lay their crab traps (called pots) and when to collect them again, hopefully bursting with crab. For the deckhands, it’s cold, wet, dangerous (lots of moving parts) and repetitive. They put the crab pots overboard, each weighing several hundred kilograms. When they collect a string of pots, one man throws a grapple hook to land between two buoys floating above the pot, and the crane then winches the even heavier full pot onto the boat. Its contents are transferred to a sorting table where female (in the case of king crabs), small and dirty (barnacle-encrusted) crabs are thrown back into the sea. The live crab are transferred to water-filled holding tanks on the boat, and at the end of the season they are offloaded directly to a processing plant.
I’ve always had a little obsession with fishing boats, and Tony’s not-so-secret desire is to spend a day on one of the little boats that goes out of Kalk Bay harbour to see what goes on… This is almost as good as being on one yourself. The sea is fierce, huge and beautiful, and the two seasons take place in October (king crab) and January (opilio crab) so the winter weather is harsh. There’s freezing spray, howling winds, huge waves and icy water. To fall overboard without a survival suit on amounts to almost certain death.
Despite the dangers, the competition is fierce. Crab are valuable – the larger king crab were selling for nearly $30 each when this season was filmed (2005) and men make fortunes in a few days doing this work.
I’ve been holding off on this post chiefly because hermit crabs are devilishly difficult to photograph. They look really cool, beetling around on the sand, but getting the camera to an angle that captures their little hairy legs and beady eyes is tricky. Plus, at the first hint of interference, they disappear into their shells.
Large hermit crab at Long Beach
Most of our local dive sites are overrun with hermit crabs. I mean it – I spend a fair amount of time lying on the sand waiting for Tony to finish skills with his students, and these little guys are ubiquitous.
Hermit crab on shell patch
There are patches of shells at Long Beach that look kind of deserted, but if you watch for a while you can see ten or twenty hermit crabs crawling over each other. I wonder whether this isn’t the equivalent of a used car lot for them: hermit crabs use empty shells from other molluscs as their homes. When they outgrow the shell, they must find a new one, and quick as a flash crawl out of the old shell and into the new. There is a high degree of competition for good shells. More than once we’ve seen two of these little guys tussling over real estate.
When out of their shells, these little crabs apparently look more like lobsters, with a soft tail part (hence the need for a shell). We get a couple of different kinds in the Cape, but most of them have pink hairy legs and bad attitude. They are hugely entertaining if you just lie and watch them, but as soon as you pick them up they retreat into their shells (justifiably so) and wait to be released.
Overbalancing - shell too large?
As the crabs grow, they must find larger and larger shells as homes. The competition is fierce. Sometimes we see absolutely huge, venerable granddaddies like the one below, with a forest of sea lettuce on his shell.
Hermit crab with decorations
We see them on day as well as night dives, and they seem to be quite active at night. Here’s one I found in the shallows one evneing at Long Beach.
Hermit crab at night
They can be quite fierce – every evening the starfish are removed from the Touch Pool at the Two Oceans Aquarium because otherwise, while unsupervised, the hermit crabs nip on their limbs.
We have had a lot of lousy weather lately resulting in the boat diving being cancelled almost every week since the beginning of the year. With a Deep Specialty in progress this has been a huge setback. With the prospects of a deep boat dive diminishing we decided to do a deep dive in the quarry.
Blue Rock Quarry
Blue Rock Quarry is situated just outside of Somerset West and is so named for the blue rock harvested there years ago. When it fell into disuse, it was filled up with water and now plays host to a range of watersports and recreational activities.
Blue Rock Quarry - looks inviting, yes?
We chose a spot that had a depth of close to 50 metres as we were looking for a maximum depth of 40 metres. The water looks clean and inviting from the surface and in fact the visibility is very good despite the total darkness that surrounds you from around 30 metres.
Buoy line dropping to 25 metres
Cecil, Clare and I entered the water here, where a line goes down the wall to a ledge at about 25 metres. The water is clear providing you do not rub a fin, finger or bubble on the walls as this results in a cascade of silt and fine rock rubble which takes a fair amount of time to clear.
Rocky slope
We had planned to stop at 20 and again at 30 metres on the way down but due to the poor visiblity we stopped a few more times just for me to make sure Clare and Cecil were still above me on the line.
Cecil descending down the buoy line
At 30 metres we encountered a tree. The branches sticking out in all directions are a huge hazard in low visibility as entanglement is a real possibility. We moved away from the tree and picked up another cable that I reckon runs down to nearly 50 metres.
Dark diving in the quarry
At 34 metres the water was very dark, and visibility was reduced to almost zero due to the silt dislodged by us on the cable. I stopped at 34 metres and shone my light down; directly below me was another tree.
The walls of Blue Rock quarry
We could move away from the line and descend further or turn the dive here. We did the skills required for the dive at this depth and started our ascent. Ascending was slow and deliberate, with planned stops at 20, 10 and 5 metres.
Tree stump at 5 metres
We did not see any life except for one small freshwater crab spotted by Clare. You don’t do this dive to sightsee!
Cecil doing his safety stop
Things to remember for a fresh water dive: weighting is critical, and you must remove weight for this dive. A good dive light, a back-up and cyalumes or strobes are also required plus a detailed dive plan. The quarry is also used for wake boarding and cable water skiing and a circular raised cable drags the skiiers around the perimeter so an ascent off the line is out of the question.
Dive date: 26 March 2011
Air temperature: 25 degrees
Water temperature: 12 degrees (much warmer on the surface, over 20 degrees)
Maximum depth: 34.4 metres (33.6 metres according to the dive computer, adjusted by 2.5% for fresh water)
Visibility: 4 metres
Dive duration: 23 minutes
As a facility for training the quarry is an option but having dived many quarries in my life I would much rather choose an angry dirty ocean to a quarry.
We visited it again recently, but my camera battery had given out after too much diving and photography for one little camera for one day. We returned to the artificial reef on Saturday 19 March, after it had spent 119 days in the water (4 months).
Algae-encrusted PVC pipe disappearing into the sand
The reef itself is now so covered with sea lettuce that we almost swam right past it. The PVC pipes are almost completely buried in the sand, and algae encrusts almost every surface except for the cable ties. Feather stars seem to have taken a particular liking to the sponges, which have retained their shape (if not their colour) remarkably well.
Sign (left) and sponges (right) covered with feather stars, ascidians and hermit crabs
The reef is populated by lots of (shy) klipfish, many of whom take cover in the sea lettuce. One, however, was very friendly and I almost got left behind playing with him on the sand.
Friendly klipfishKlipfish and warty pleurobranch
We found a very fat pipefish, and a whole bed of hermit crabs going about their business. At least one warty pleurobranch was in residence, sitting on the wooden box.
Fat pipefish on the reefMask box covered with algae
The sign requesting divers not to mess with the reef is completely encrusted with sea squirts of various sizes and descriptions – larger ones as well as the smaller colonical ascidians. It’s not legible any more!
Sign overgrown with ascidians
We were amazed by how thoroughly the sea has taken over the various items we laid down four months ago. What was originally quite an ugly collection of pipes and other random objects has become a thriving little oasis on the sand. We purposely placed the artificial reef away from other rocky outcrops or detritus that housed copious marine life – out on the sand, we’d be able to see who passed by, and know that the reef was seeded from scratch and not from an adjacent underwater feature.
For a before and after comparison, I’d recommend you go and check out what the reef looked like in these prior posts:
Ten metre tall kelp plants at Shark Alley near Pyramid Rock
The South African west coast is characterised by the tall, beautiful brownish green sea plants called kelp. These plants thrive in cold (below 20 degrees celcius), nutrient-rich, highly aerated water, and the strong wave action of the Atlantic is thus a feature of their ideal habitat.
Sea bamboo at Long Beach
Much of the water at the Two Oceans Aquarium is filtered through the kelp forest exhibit before being transferred to other tanks in the facility. The kelp plants do a remarkable job of cleaning the water of ammonia and other waste products. The fact that there is a kelp forest exhibit in the TOA is remarkable – it’s a non-trivial undertaking to grow live kelp plants successfully in a confined environment. Read more about it here.
Lush kelp in the Atlantic
Three main species of kelp dominate the South African coast: sea bamboo (which is what we see mostly in Cape Town), split-fan kelp, and bladder kelp. Kelp plants are made up of a holdfast (which looks like a tangle of roots, but actually just clings to the rocks), a long stipe or stalk reaching upwards towards the surface, and the fronds, leaves or (most accurately) blades, which absorb nutrients from the water.
Sevengill cowshark disappears into the kelp at Shark Alley
Kelp plants like rocky surfaces to anchor onto, so the dive sites that feature kelp forests are often rocky reefs and outcrops such as Fisherman’s Beach, Shark Alley, and most of the Atlantic sites. Sandy bottoms are no good for kelp – nothing to grip onto – which is why there’s not much of it at Long Beach.
Kelp growing at Long Beach
At low tide you can often see the tips of the kelp stems sticking just out of the water. There are small air-filled floatation devices called pneumatocysts attached to each kelp plant, which keeps the blades close to the surface of the water where they can take advantage of the sunlight. Some species (like sea bamboo, which is in most of the photos I have here) have a single large pneumatocyst at the end of each stipe, and others have one at the base of each blade.
Kelp at Long Beach
Kelp forests provide a habitat for countless creatures, from the fish that shelter among their blades, to the kelp limpets that are specially shaped to fit snugly against the kelp stipes, to the crabs that love to hide in the waving forests. Abalone feed on kelp, and sea urchins use drifting pieces of kelp blades as hats to shelter from the sun.
Kelp limpet at Fisherman's Beach
During our training at the Two Oceans Aquarium, we dissected a kelp holdfast, and the number of creatures that live in that tightly-packed root system is astonishing. We found tiny brittle stars, kelp crabs the size of your fingernail, hundreds of worms, isopods, mussels, and tiny limpets. There’s a whole ecosystem that subsists entirely within the holdfast.
Cape rock crab in the kelp at Long Beach
There are also many creatures that call the higher-up portions of kelp plants their homes. Cape rock crabs often shelter in the fronds, and orange-clubbednudibranchs feed on the bryzoans (moss animals) that form pretty lacy patterns on the kelp leaves.
Orange clubbed nudibranch feeding on bryzoans
Top shells (there are a couple of varieties) live and feed on the kelp fronds. They’re really hard to photograph (and they’re SO pretty) because the movement of the kelp in the water confuses my camera (and the photographer).
Tony shows me a top shell
The kelp stipes themselves are a habitat for other creatures. Coraline algae encrusts them, and tiny barnacles, hydroids and sea plants form beautiful, detailed colonies that reward close examination.
Coraline algae on kelp stems at Fisherman's Beach
These photos were taken at Fisherman’s Beach, which boasts particularly gorgeous kelp stems. Inside broken stipes, we’ve found isopods, sea lice and other creatures that shelter inside the hollow tubes.
The Silver Fox diving behind an encrusted kelp stem at Fisherman's Beach
Diving in a kelp forest for the first time can be scary – I was terrified I’d get wrapped in the kelp and be stuck there forever. In fact, if you move slowly, it’s very easy, and it’s REALLY hard to get anything wrapped around you to the extent that your movement is hindered. Kelp blades are smooth and just stroke over you gently. There’s no sinister thrashing or wrapping like a giant squid grasping you in its tentacles. Kelp is your friend!
In surgy conditions, kelp is useful to hang onto (this may not be good advice). The holdfasts attach to the rock unbelievably firmly, in order to withstand the buffeting that the kelp gets from the waves, so the stems can generally support 65 kilograms of diver as well!
I demonstrate how useful kelp is in surgy conditions, at A Frame
Kelp is hugely useful to humans – it’s used in the production of plant fertilisers (mmm – breathe in the smell!). Alginate, a substance derived from kelp, is used to thicken custard, toothpaste, salad dressings, mayonnaise, ice cream and jelly. Kelp grows incredibly fast, so it’s an ideal crop. Sometimes you can see strips carved out of the kelp forests between Kommetjie and Misty Cliffs – that’s where one of the kelp product manufacturers has been harvesting. They move down the coast taking a strip at a time, and by the time they get back to the beginning the forest has recovered.
Tony has dived North Paw before (while I sat, sick with jealousy, in front of an Excel spreadsheet at work). This time I went with him and some students, and we were to explore an unmapped pinnacle to the north of the site, which seems to be quite extensive. It rises to within 10-12 metres of the surface, and doesn’t actually have a name yet…
Tony and Cecil on the surface
Grant’s best suggestion (which some on the boat were keen to override) is “Bokkie’s Rump” – the idea being that the lion (Lion’s head) has its two paws (North Lion’s Paw and South Lion’s Paw) resting on a little springbok that he’s caught. The bokkie’s rump (ahem) sticks out beyond the northern paw.
DC relaxing with North Paw rocks in the background and Grant's boat approaching
Grant put the shot on top of the pinnacle, which according to Peter Southwood, is about 8 by 10 metres. We descended next to it – a lovely sheer wall – down to the sand at about 20 metres. There are rock lobsters galore, and rich invertebrate life.
Rock lobsters at North Paw
Georgina pointed out a large cuttlefish, well camouflaged on the reef. When he moved, he changed colour to match his new background. Tony also found four tiny cuttlefish – fingernail-sized – lined up as if for a race. When he turned to call me with the camera, they scattered, invisibly, on the sand.
Cuttlefish at North PawSame cuttlefish, different colour
I found a few different nudibranchs – black, gas flame and crowned – and Tony also found one for me, much to his delight. He claims to have been having a “nudibranch drought” lately!
Gas flame nudibranch under some coralBlack nudibranch at North Paw
The site is rocky with lots of crevices for rock lobster to hide in. We saw some large ones, but, Gerard assured me, no HUGE ones. He should know! We were highly amused to see one big guy eating a sea jelly – the ocean floor was littered with a few dead (or incapacitated) ones, and apparently rock lobsters enjoy that kind of treat. I also saw a large rock lobster carefully carrying a cluster of mussels!
Hungry rock lobster eating a night light sea jelly
At the safety stop I saw no fewer than four different kinds of sea jelly – the largest being a night light sea jelly that was almost as long as Tony, with a huge purple bell. He obligingly swam behind it to give some perspective to the photo but I carried on photographing the jelly as it swam off into the distance.
Night light sea jelly
Gerard had gotten low on air earlier, and returned to the boat… While he was waiting for a pick-up, something bumped his leg hard, and he was convinced it was a shark. Instead, it was one of the friendly seals that had visited us during our dive. His comments on the subject are unprintable – suffice it to say he got a bit of a fright!
Brittle stars on a sponge
When the rest of us surfaced we got to chill for a while, looking at the magnificent scenery, because we’d come quite far from the original pinnacle. We had drifted with the current, roughly towards the Atlantic seaboard. It must be – as I announced when the boat arrived – the most beautiful place in the world to surface. The diving’s pretty good too!
Many of Tony’s students come to him with extensive skin diving experience. Living in Cape Town, it’s almost obligatory to enjoy at least one lobster braai during the season (and often many more). Sometimes the veteran lobster-divers struggle at first with breathing through a regulator – their instinct while under water is to hold their breath (it’s illegal to take lobster when you’re on scuba). But their comfort in the water (and being used to the cold) stands them in good stead, once Tony’s tapped them on the regulator a few times to remind them to inhale!
Lobster on a wreck at Long Beach
We see West Coast rock lobster (not crayfish – those are freshwater creatures) in both False Bay and on the Atlantic side. They are gregarious, and can often be found sheltering in cracks and under overhangs, in quite large groups.
West coast rock lobster on the BOS 400 wreck
It’s a pleasure to do a deep wreck dive such as on the Maori and on the BOS 400, and see hordes of good-sized rock lobster teeming all over the wreck. Some of the shallower sites are definitely over-fished, and we only see really big specimens when we dive beyond the range of your average skin diving lobster hunter. On Gerard’s first deep wreck dive in Smitswinkel Bay, we hadn’t been on the wreck for three minutes when I turned around to see him excitedly waving a MASSIVE lobster at me, the biggest either of us had ever seen. Some finger waggling and head shaking convinced him to replace Mr Lobster in his home, but I think Gerard was heartbroken.
Small rock lobster at Long Beach
Rock lobster are almost impossible to farm. At the Two Oceans Aquarium on our crash course in marine biology we learned that there are 13 larval stages, during which time the creature drifts hundreds of kilometres offshore through a huge variety of water conditions that it would be impossible to replicate in a mariculture setting. The larval phases can last up to two years. Lobsters grow very, very slowly and can live to the age of 50. There’s some nice detail on the Two Oceans Aquarium website.
Rock lobsters on the Maori
They eat crabs, abalone, starfish, snails and sea urchins – this latter fact makes them quite important in the ecosystem as a whole. I’ve mentioned before that juvenile abalone shelter among sea urchins. If there are too many lobsters, they eat too many urchins (and too many abalone) and this leads to a decline in the population of abalone. It’s a fine balance.
Rock lobster at Long Beach
Lobsters are incredibly sensitive to the level of oxygen in the water, which sometimes leads to what look like mass walkouts onto the beach when there’s a red tide or similar event leading to (near-)anoxic conditions on our coastline. What actually happens is that they move away from the de-oxygenated water where the red tide has died, and get stranded on the beach by a retreating tide. Once when Tony was landing a dive boat at Miller’s Point, he was waiting for a chance to use the slipway next to a fishing boat that was packed to the gills with lobster. The captain said they’d found a spot where thousands of lobster were strolling together in orderly formation across the ocean floor, and he’d just scooped them up. (He would not share where this magical location was, but the lobster were probably moving to more highly oxygenated waters.) Having substantially exceeded his quota, the fisherman was somewhat twitchy about being pulled over by the authorities!
Rock lobster on the move on the Maori
Poaching of rock lobster is a big problem in South Africa. They’re a very valuable commodity – you just need to go and have a seafood platter at a Camps Bay restaurant to see what damage it can do to your wallet – and easily accessible to anyone who can hold their breath and is prepared to do a bit of rock scrambling. The government Department of Environmental Affairs tries to manage stocks by implementing a closed season, catch and size limits.
Currently, you may only take lobster that measure greater than 8 centimetres from the front of their head to the end of their carapace (NOT to the tip of their tails, as I used to think – fortunately I’m not a lobster fisherman!);
You must have a MPA permit to take lobster (same form at the post office as the scuba diving one);
The season runs from November to April (the dates vary by year);
You may only take lobster during the day – between sunrise and sunset;
You’re not allowed to sell them;
You are not allowed to take females in berry (with eggs), or lobsters with soft shells that have just moulted;
There are also regulations about the number of rock lobster you may transport at once, or have in your possession.
I struggled with this book – I wanted it to be something other than what it is. I was expecting a litany of gorgeous new marine life. What the book is, is a brief and awkwardly written (but we can overlook this) outline of the different ocean habitats, a summary of the rationale for the Census of Marine Life, a description of some of the projects that fell under the auspices of the Census (a bewildering array of acronyms), and an all too brief description of the experimental techniques used by the census takers.
This latter part was by far the most interesting to me – the transponderes, tagging systems and other ways in which the census gathered its data are cutting edge and remarkable. I was particularly taken with the use of acoustic technology to determine the size and composition of schools of fish. Apparently different fish give off different signals when sound waves are propagated through their schools, enabling the researchers to non-invasively count and identify the fish in different ocean regions. There’s also a slightly sad-looking sea lion with a tag on its head, the size of a match box. These tags can record all manner of information about the creature’s travels in the sea, water temperature, how deep it dives, and so on. Since technology enables us to make things smaller every day, the tags just get better and more useful.
The book is interspersed with photographs of cool new marine life, but not that many. My favourite by far was the adorable yeti crab.
Yeti crab
There are also photos of census takers at work. Tony was particularly impressed with himself when I showed him one of the ways in which the census takers audited reef life: they deposited PVC containers with little holes in on the reefs, left them there for a year or two, and then retrieved them to see what life had moved in. Much like our artificial reef project, only more scientific!
At the end of each chapter is several pages of referenced papers, which enables you to go and look up in far more detail anything that caught your fancy.
The French documentary Oceans, which I reviewed previously, was part of the Census project. There is a bit of information about how some of the material was filmed (something which interested me and Tony when we watched it) – turns out they used towed cameras and cameras on poles to track some of the fast moving marine life. The shots were steadier than a dude on scuba could ever achieve!
