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.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Baboons on the beach

Baboon on the beach Baboon on the beach

A recent low tide visit to the beach at Platboom near Cape Point, on the Atlantic coast of the peninsula, enabled us to watch a troop of Chacma baboons (Papio ursinus)  foraging for limpets, mussels and other marine snacks on the rocks at low tide. The baboons bite the tops off the limpets with their formidable incisors, or pry them from the rocks intact to get at the protein-rich flesh. They also eat mussels.

Baboons foraging for seafood at Platboom Baboons foraging for seafood at Platboom

This foraging behaviour is extremely rare among primates. In baboons, it is only observed on the Cape Peninsula and in one other species in Somalia. Matthew Lewis studied this troop of baboons as they foraged around the Cape Point nature reserve, and his thesis makes for fascinating reading. (Wild Card Magazine also featured Matthew’s research.)

Baboon on the beach Baboon on the beach

The amount of time the baboons are able to spend foraging on the shore is largely determined by the height of the tide, and by weather conditions. As a result, the amount of time the baboons spend seeking marine food sources is small compared with the time they spend looking for roots, bulbs, insects, berries, and small animals.

Low tide at Platboom Low tide at Platboom

These baboons are part of the Kanonkop troop which ranges freely in the Cape of Good Hope section of Table Mountain National Park and whose home range does not bring them into conflict with humans (or, as a rule, allow them access to any anthropogenic food sources). They were completely uninterested in us and our vehicle, unlike the baboons we see further up the peninsula around Millers Point, for example.

Concentrating baboon Concentrating baboon

Newsletter: Diversnight ahoy

Hi divers

Weekend dive plans

Saturday: Night dive at Long Beach – meet at 7.00pm

I took a look at Hout Bay as well as False Bay today, and neither look all that great. There has been big swell and strong winds this week so it’s a little messy. Saturday is a calm, quiet day with neither swell nor wind, so this should help settle the ocean enough for a decent night dive on Saturday evening. It is not inconceivable that very early boat dives could work on Sunday, however that’s a decision that can only be made late on Saturday.

Biscuit skate at night
Biscuit skate at night

Diversnight

Diversnight is this Saturday, 3 November. We plan to meet at Long Beach (the tide is against us for a jetty dive) at 7.00 pm. My plan is to start the dive just on 8.00 pm. There are several groups and clubs doing dives for Diversnight so there will be several shore-based people around to keep an eye on the cars.

If you are joining us please let me know sooner rather than later (it makes cake baking easier), and if you require any gear!

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Newsletter: Three strikes

Hi divers

Weekend dive plans

No diving

Neither the wind strength and direction, or the swell size, period and direction translate into anything close to great diving conditions. I won’t be diving but you may get lucky with some visibility in the cold Atlantic.

Succulents in Lamberts Bay
Succulents in Lamberts Bay

Reminders

I mentioned these last week, but here we go again:

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Newsletter: Direction dependent

Hi divers

Weekend dive plans

Saturday: Boat dives from False Bay Yacht Club, conditions permitting

Karoo windmill
Karoo windmill

Saturday looks like the better diving option wind-wise, however Friday’s odd swell direction may trash the conditions, if it’s as southerly as the forecast says. I plan to launch on Saturday, weather permitting, but will make the call tomorrow afternoon. Let me know if you want to dive.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Newsletter: Clean bay

Hi divers

Weekend dive plans

Sunday: Boat dives from False Bay Yacht Club, conditions dependent

View of the Atlantic from the top of the tower
View of the Atlantic from the top of the Kommetjie lighthouse

The wind direction has been great and False Bay is very clean, if a little cold. The weekend has some southeasterly wind forecast and we will still feel the effects of the current 6-7 metre swell. Luckily the swell is westerly so it won’t be that harsh.

I have a dry day planned for Saturday, but will launch on Sunday if the weather behaves. I will have limited access to my phone tomorrow and Saturday so please let me know sooner rather than later if you want to dive.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Newsletter: Signs of winter

Hi divers

Weekend dive plans

No launches planned – diving on Tuesday and Wednesday next week!

The weekend has typical winter conditions. A long period swell of around 5-6 metres with 30 – 40 kilometre/hour winds means really rough and bumpy surface conditions, not the kind of conditions I enjoy diving in. We have no planned launches. Go flower hunting instead. (The flower in the picture, Hessea cinnamomea, only blooms the winter after a fire, and then goes dormant, sometimes for decades, until the next burn.)

Hessea cinnamomea at Cape Point
Hessea cinnamomea at Cape Point

The visibility is decent and that won’t change too soon. Tuesday and Wednesday have less swell and very little wind so we will launch then. Download a leave form and complete it, and send it in to whoever will miss you if you don’t turn up at work… And join us for some aquatic therapy.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Goose barnacles on the beach

A (lovely, rain-bringing) onshore wind left great rafts of kelp all over Noordhoek beach one weekend in mid May. Finding anything of substance on this beach is unusual; it’s on an exposed piece of coastline and all but the most robust objects are dashed to pieces before they arrive on the sand. Seeing all the washed up kelp also reminded me that frequenting the beaches inside False Bay, that are daily cleaned of washed up kelp by the City of Cape Town, is liable to give one a skewed idea of just how much kelp naturally washes up on the sand.

Kelp stipe covered in goose barnacles
Kelp stipe covered in goose barnacles

This time, there was kelp, and lots of it. Several of the pieces of kelp had been colonised by goose barnacles. There are several species of goose barnacle that occur off South Africa’s coast, but these ones are Lepas testudinata. They are incredibly strange looking animals, and some of them were still alive and writhing slowly in the drying sun.

In parts of the world (I’m looking at you, Iberian peninsula), goose barnacles are an expensive delicacy. I have nothing to say about that.

Goose barnacles, with my paw for scale
Goose barnacles, with my paw for scale

Lepas testudinata larvae most often attach to free-floating pieces of kelp (Ecklonia maxima) and plastic debris, which is why you have probably never seen these mesmerisingly gross-looking creatures while on a dive. In the picture below, you can see that they’re attached to the bottom of a kelp holdfast, where it would ordinarily attach to the rock. This shows that they attached after the kelp broke off.

A kelp holdfast encrusted with goose barnacles
A kelp holdfast encrusted with goose barnacles

Each barnacle is possessed of a long fleshy peduncle, or stalk, which attaches to the kelp holdfast, stipe or fronds. On the end of the peduncle is a carapace (shell) made up of five separate pieces. The large part of the barnacle on the end of the peduncle (what you’d think of as its body), covered by the carapace, is called the capitulum. The apparatus that the barnacle uses for feeding – essentially six pairs of hairy legs – reside inside the carapace, along with the mouth. There’s some more detail and a nice diagram at this link. If you are familiar with other kinds of barnacles – the volcano-shaped ones that live on rocks, ships, whales and piers for example, then most of this (except the peduncle) should sound familiar to you.

Lepas testudinata goose barnacles
Lepas testudinata goose barnacles

Research done around South Africa’s coast (published here) by Otto Whitehead, Aiden Biccard and Charles Griffiths, identified the marked preference of Lepas testudinata for attaching to kelp. The researchers surveyed a selection of beaches around South Africa’s coast, from the west coast of the Cape Peninsula up to northern KwaZulu Natal, between June and October 2009. When they found goose barnacles washed up, they recorded the species of barnacle, the type of material they were attached to, the dimensions of the object, and its location. They also estimated the number of barnacles in each colony they found.

Lepas testudinata was the species they found most commonly, of the six species in total that they identified along the area of coast that was surveyed. (There’s a nice picture of the six species in their paper, which I used to identify the ones I found.)  This species of goose barnacle was found to prefer kelp, as mentioned, and also tended to colonise large objects compared to the other species (this could, of course, be because pieces of kelp are usually larger than items such as bits of plastic, glass, feathers, and shells that some other species prefer).

Kelp fronds with goose barnacles
Kelp fronds with goose barnacles

Lepas testudinata was the only species of goose barnacle that the researchers regularly found to form colonies comprising more than 1,000 individuals. It is also the only species of goose barnacle recorded by the survey that is only found in temperate (cooler) waters, which happens to be where kelp is found, too.

The researchers note that the goose barnacles of the Lepas testudinata species that they found on kelp seemed to have exceptionally long peduncles, some more than 25 centimetres long, and that this seems to differ from what has been previously known about them (which is that they have “short, spiny” peduncles). They suggest that perhaps the variety of Lepas testudinata that colonises kelp may even be a separate species from the one previously described (more research obviously required to ascertain this). You can see from my photographs that the peduncles of the washed up Noordhoek beach goose barnacle colonies are also quite long, some easily 20 centimetres in length.

Clusters of goose barnacles on a kelp stipe
Clusters of goose barnacles on a kelp stipe

They also found that the increasing prevalence of long-lasting and buoyant plastic marine debris and other anthropogenic objects around our coastline, which some species of goose barnacles preferentially attach to, gives these weird little creatures increased opportunities to form colonies, and to spread to new places. This is one of those interesting phenomena to keep in mind, as humans inexorably alter the environment. Some creatures will benefit in strange ways from warming oceans, and others will find new homes in the garbage we leave lying around.

Newsletter: Just swell

Hi divers

Weekend dive plans

No diving​

False Bay has been magical all week with exceptional visibility. The weekend looks a little iffy. The first real winter swell arrives tonight: the forecast says around 8 metres at 16 seconds. It thunders through tomorrow, meaning that Dungeons will be cooking… For the brave and top-class surfers. It tapers off during the weekend but Saturday’s wind is forecast to be around 50 km/h. Sunday’s wind is a lot less, however still more than our size boat is suitable for. Sadly a dry weekend for us.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

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Newsletter: Seasonal changes

Hi divers

Weekend dive plans

Staying dry

Both days this weekend have swell, and wind blowing from the wrong direction, and the current dark colour of False Bay means we are definitely staying dry. The weather does look better on Monday and Tuesday for those that have a flexible work schedule – if you’re one such, get in touch.

The Shark Spotters centre at Muizenberg
The Shark Spotters centre at Muizenberg

Binoculars for Shark Spotters

The Shark Spotters team are running a crowd funding campaign to raise money for new, high powered binoculars for the spotters. I can tell you that the right pair of binoculars makes all the difference. Cape Town’s Shark Spotters program is an international model for a beach safety solution that protects both sharks and people. They are very deserving of your support – please consider contributing to the campaign at this link.

Citizen Science Day

I promised to remind you again about the SANBI Citizen Science day, and it’s rolling around this weekend. There’s a full program of short lectures from representatives of various projects on Saturday, free of charge, in the conference venue at Kirstenbosch Gardens. There’s more detail at this facebook event link, and a list of the talks here.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

Diving is addictive!

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