LATE QUARTERLY EDITION

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ALIENS

NEAG AND TOADNUTS TALK WETLANDS WITH MAYOR DAN PLATO

Mayor Dan Plato came to show his interest in the Noordhoek wetlands (and toads too of course). He understands the immense value wetlands provide by cleaning stormwater and recharging our aquifers. He also acknowledged that wetlands need protection.

It’s good to know that the DA listens to the concerns of its residents and that the environment is being given proper consideration at last. Seen in the picture – Dr Rob Anderson, Dep Mayor Nielson, Andrea Marais-Potgieter, Alderman Purchase, Simon Liell-Cock, Alison Faraday, Mayor Plato and Glenn Ashton. Out of the picture JP Smith and Suzie J’Kul

Decolonising Our Home & Garden – Encounters With Vespula Germanica Written by: Liz Smith

VespulaG-tunnel entrance

"THE 'WASPS MUST FALL' CAMPAIGN BEGAN"

Until a couple of months ago I regarded our ageing wooden windows as a natural asset. They attract a pair of olive woodpeckers who from time to time come knocking on the frames in search of bugs, affording us the rare opportunity to observe these shy birds from the ‘hide’ of my study. The birdbath nearby draws many small birds, once resulting in a 4-day visit from a beautiful 1.5m boomslang, draped elegantly over a flowering Indigofera jucunda while she digested a ‘bulge’ under our watchful gaze. Our philosophy of ‘live and let live’ has given us many wonderful experiences, including a surprise midnight encounter in the bathroom with a ring-tailed genet, an African goshawk we twice had to usher out of the kitchen, and an over-curious squirrel we had to extricate from our fireplace after he fell down the chimney. The joys of living in Noordhoek. But, I have discovered, there are limits.

 

On a warm February evening, I was watering the garden from the rainwater tank when a flying missile hit me on the chin with a painful sting. Swiping wildly at the ‘thing’ I ran to the nearest doorway, yelling for help, with a loud buzzing pursuing me. It finally caught up in the kitchen and stung me again on my back. Luckily my husband’s approach scared it off, and once we’d established it wasn’t a bee and doctored my stings, we went looking. What we found was an innocuous little hole at the base of our (admittedly very vrot) window frame on the sunny side of the house, in and out of which were flying stout, black-and-yellow striped wasps. We’d seen them in England and France – ‘yellow jackets’ our American friends call them – but here in the South? This was a first and it set alarm bells ringing.

 

Vespula Germanica, as I have since identified them from the three-minute black spots on the nose, is a European wasp invasive to South Africa, particularly around Cape Town, which holds NEMBA 1b status, i.e. ‘invasive species that require control by means of an invasive species management programme’.[1]

Unlike our own laid-back paper wasps who don’t put up much of a fight if you knock their nests down from your eaves, these guys are highly aggressive carnivores. They are also uncannily strategic and persevering when overcoming pesky problems like finding the entrance of their home covered with clay (chew a new hole through the window frame into the wall cavity) or getting the mole-sized entrance of their underground cavern filled with an inverted Doom fogger (burrow up and emerge Terminator style from the sand to start a new home a few meters away.)

VespulaG-1

They are described as ‘social wasps’, a euphemism for the fact that a single queen, having found a dark hole to make a nest in an attic, a wall cavity or underground, can produce a colony of over 6000 highly efficient omnivorous foragers and 1500 breeding wasps in one summer. This is in their ‘home country’ where winters are severe and nests die off completely due to the cold.[2] It’s another story in a Mediterranean climate like ours. Colonies in Australia produce over 17,000 wasps in a summer season, many of which survive the winter[3] leading to colonies that are well…. enormous!

 

It was time to get serious. The “Wasps Must Fall” campaign began.

 

Strategies we considered included calling pest control companies (“We don’t do wasps,”) and pouring petrol down the wall cavity and lighting a match (vetoed to remain on good terms with our insurers.), Accessing my inner assassin, I settled for the combination strategy of stealing out in the dead of night, (being Germanic, the wasps work late and rise early) armed with a tin or two of the natural pyrethrum, Avispray, to spray down the hole, (Doom doesn’t work – after a shake or two they get up and fly off) a spade to quickly cover the hole in the case of underground nests, and a tub of clay to smear over the pitted window frame in the case of the two wall nests. We then rose at dawn to open the underground nests, spraying as we went to ward off stragglers, and reluctantly but necessarily poured 3 or 4 litres of diesel down the tunnel to subdue the determined hordes that swam towards us out of the football-sized cavern. Finally, we destroyed the nest with the spade and buried the whole messy business.

 

 

Wall nests are more of a challenge. With exterior exits sealed and plenty of pyrethrum applied, all can be quiet for days… then suddenly an ominous buzz emanates from the window sill as a newly hatched crowd of wasps squeeze their way out of any crevice and crack, filling the room angrily. Luckily our large stock of Avispray quickly overcomes them. So all-consuming has this campaign become that I find myself greedily counting corpses or staring at a small hole, spray nozzle at the ready, waiting for black antennae to appear. The longer-term effects of leaping for the spray can at the slightest buzz and listening intently to walls and windowsills are equally worrying. Just when I think the end is in sight a lone wasp dances through the door flying figure eights in search of a small dark hole to start the whole cycle over again…

 

Perhaps I should have gone for the petrol-and-match option as the preferred “invasive species management plan” after all.

 

[1] https://www.invasives.org.za/legislation/item/571-german-wasp-vespula-germanica

[2] Archer, M.E. (2014). The Vespoid Wasps (Tiphiidae, Mutillidae, Sapygidae, Scoliidae and Vespidae) of the British Isles. London: Royal Entomological Society. p. 61.

[3] Kasper, Marta (2008). “Colony characteristics of Vespula germanica in a Mediterranean climate”. Australian Journal of Entomology47 (4): 265–274. 

Aliens IN the SEA - Written by Dr. Rob Anderson

deveopingkel

A mussel clump developing on a kelp head

Look at any rocky shore in the Western Cape at low tide and you’ll be looking at aliens: species that are not indigenous to our seas, but have arrived in the last few decades. The chances are you’ll see sheets of nice healthy mussels, and higher up the shore a zone of barnacles. The mussels are almost certainly Mytilus galloprovincialis, the Mediterranean (or blue) mussel, which arrived in Saldanha Bay almost 40 years ago and have since spread over 2 000 km of coast, only stopping at the warm-water barrier of KZN. They’ve been good news for oystercatchers, but have displaced indigenous mussels and other intertidal life such as limpets and seaweeds. The barnacles could well be Balanus glandula (the Pacific barnacle), which arrived about 25 years ago and now dominate the barnacle zone along about 500 km of shoreline, especially in False Bay. These are only the most noticeable of almost 90 alien species that have been recorded on our shores, among which more than 50 are “invasive” (steadily spreading from their point of introduction). 

 

Should we worry about these aliens? After all, one mussel or barnacle looks much like another. The answer is not simple. Some aliens have the potential to transform a shore and how it functions: to reduce productivity and diversity and cause a ripple that runs thought the whole ecosystem. Others may have negligible ecological effects, or may even benefit certain local species. The problem is that we only find out after things happen, and sometimes the unexpected does.

A few years back, when we first noticed big clumps of mussels growing on our local kelp in False Bay (sea bamboo Ecklonia maxima), we became curious. The mussel clumps were so big on some of the older kelp plants that their normally buoyant heads had sunk to the bottom, where large starfish were feeding on the mussels. At UCT, Prof Charles Griffiths and I recruited an MSc student, Colleen Lindberg, to help examine this phenomenon in some detail.

 

After some enjoyable field work (diving, measuring and collecting) and less enjoyable lab work (sorting, identifying, weighing, stats/calculations and writing up: mostly by Colleen), a picture emerged with an alien on centre stage: the Mediterranean mussel.

It turns out that this normally intertidal species settles on a small percentage of the kelp heads near the outer edges of the kelp beds, avoiding the calmer inner reaches (they prefer rougher water). Occasionally the mussels settle on the kelp stipes (stems) where they can also grow to masses of several kilograms. So far, fewer than 10% of our kelp plants are affected, the loss of kelp is slight, and the mussel masses are providing a wonderful habitat for all sorts of tiny animals (and a few seaweeds). But there is a downside: some of these animals are also aliens with the potential to become invasive. And as kelp plants break loose in storms and can float hundreds of kilometres, they can spread these little passengers widely along the coast.

 

Colleen and Charles identified 80 species of small animals in the mussel clumps we sampled, including known aliens and even a species of kelp-boring crustacean that is new to science! On the positive side, the increased diversity and biomass of small animals within the kelp bed could benefit fish and crustaceans.

 

It remains to be seen if the Mediterranean mussels will spread onto more kelp plants or move east or west of False Bay. If they do, they could cause problems for commercial kelp-harvesters. Controlled harvesting of kelp provides feed for South Africa’s lucrative abalone farms and is the basis of a thriving business that makes agricultural plant-growth stimulants from kelp. Meanwhile, we wait and watch.

 

Sources

Branch G and Branch M. 2018. Living Shores. Struik Nature, Cape Town. 336 pages.

Lindberg C, Griffiths C L, Anderson RJ. Alien mussels colonize a South African kelp bed canopy: Quantification and ecological implications of a novel bioinvasion. (Paper submitted to the African Journal of Marine Science, Feb 2018).

oldkelp stripe
An old kelp stipe with mussels and other life
musselladen
A mussel-laden kelp head on its way to the bottom!

Top ALIENS in Cape Town


ROOIKRANS


BLACK WATTLE


PORT JACKSON


SILKY HAKEA


LONG-LEAFED WATTLE


STINKBEAN


AUSTRALIAN MYRTLE


SPIDER GUM


CLUSTER PINE


BLACKWOOD

WHAT WAS NEAG UP TO SO FAR IN 2019?

MONTHLY BEACH CLEAN-UPS

Caileen Swiegers has taken the lead of the beach clean-ups. She noticed that most of the rubbish is situated around Kakapo and has therefore been focussing on that area. We welcome Ceileen to the NEAG team!

COLLABORATION WITH PROJECT NOORDHOEKED

The Project Noordhoeked team has been helping NEAG clean the beach and we are very grateful for the extra help we get from them.

WETLAND EDUCATION

NEAG had a visit from city officials and we used the opportunity to educate them about the value of wetlands and the risks of collapse.

CURATOR OF STELLENBOSCH BOTANICAL GARDENS

Dr. Donovan Kirkwood gave an interesting talk at the NEAG AGM. We found his insights around soil and the usage of compost interesting!

GROWING ENVIRONMENTALISM

NEAG welcomed two new members to our group: Gwen Hewett and Andy Mills. We are very happy that our green family keeps growing #fortheloveofnature

NEED FOR A FUNDRAISER

NEAG is actively looking for an individual that can help us with fundraising. We often have to employ experts to help us with environmental assessments and this costs moola. If you know of anybody interested, please get in touch with us!

THE ALIENS VERSUS THE ENDEMIC Written by: Robyn Mason, Cape Dutch Nursery

Port Jackson taking over our beloved Chappies
Port Jackson taking over our beloved Chappies

We have the privilege of living in the Cape Floral Kingdom, the smallest of the six floral kingdoms in the world. Although this area occupies less than 0.4% of dry land, it has more species than all other kingdoms combined.

The World Heritage Council declared the Cape a world heritage site in 2004 due to the rich and diverse flora that flourishes in it. Two thirds of the region’s 9000 plant species are found nowhere else on earth.

BUT… more than 1700 types of fynbos in our area are either ‘critically endangered’, ‘endangered’ or ‘vulnerable’.

 

Alien species invasion is a huge threat to their survival. Besides taking valuable water and space from our indigenous plants, they also make the natural fires hotter than our fire-adapted fynbos can tolerate, and these severe infernos can not only kill fynbos seeds but also change the soil so it is no longer suitable for fynbos.

 

Besides the endemic flora, a vast population of endemic insect species found only in the fynbos biome are threatened too. Insects are of enormous importance to the functioning of natural ecosystems and to the lives of humans, yet are overlooked as they are, quite literally, at the bottom of most food chains, yet critically important as pollinators. And six of our endemic birds are also important fynbos pollinators, including the Cape sugarbird and the orange-breasted sunbird.

Among the aliens causing trouble in our area are the Port Jackson, rooikrans, black wattle, stinkbean and silky hakea, as well as smaller invaders such as the Madeira vine which is highly invasive and capable of smothering indigenous vegetation.

 

After the fires in 2015, Cape Dutch supported an initiative to tackle the proliferation of Port Jackson on the patch of TMNP as you ascend Chapmans Peak after the pine grove to the left of the road. We are proud that this area is now alien free and thick with native species including Kiggelaria africana (Wild Peach), Metalasia muricata (blombos), Helichrysum cymosum (gold carpet), Athanasia dentata (geel blombos), Searsia crenata (dune crowberry, and Chrysanthemoides monilefra (now renamed Osteospermum monilefrum).

 

As the local retail nursery, Cape Dutch Gardens plays an important role in influencing the vegetation in our private gardens. We need to encourage more wild endemic gardens as safe havens for reptiles, birds, bees, butterflies and other insects, allowing natural systems to interact while minimising the need for maintenance and watering.

 

Wouldn’t it be great if all landowners in the valley participated in clearing all invasive aliens from their properties and verges, and took an active role in conserving our unique flora?

Another suffocation by Madeira Vine - Chappies
Another suffocation by Madeira Vine - Chappies

Destructive shot hole borer beetle sighted in Somerset West - By City of Cape Town

The City of Cape Town can confirm that the invasive polyphagous shot hole Borer beetle (PSHB) has been sighted in Somerset West. The City is in the process of appointing an experienced invasive plant removal team to remove the infected trees.

The PSBH infestation was discovered in Oldenland Road in Somerset West by passionate gardeners and environmentalists who noted that a London plane tree in their garden was ailing and exhibited signs of a PSHB beetle invasion.

The City’s Invasive Species Unit was contacted last month and a student with a Master’s of Science degree (MSc) from Stellenbosch University who is currently working on the PSHB beetle for his thesis, collected samples from the infested sweetgum (Liquidambar styraciflua) and London plane trees in Oldenland Road for laboratory analyses.

On 3 April 2019 after extensive DNA testing the results of the positive PSHB identification were released in a statement by academic experts from the Stellenbosch University’s Department of Conservation Ecology and Entomology and the Forestry and Agricultural Biotechnology Institute at the University of Pretoria.

The City can as such confirm that a limited number of trees in Oldenland Road in Somerset West, namely London planes and sweetgums, are infested with shot hole borer beetles.

The City is working on a plan to remove the trees. It is critical that the PSHB beetles are not spread during the removal project. An experienced invasive plant removal team trained in the dangers of vector pathways and cleaning equipment will be appointed to assist the City. The wood will be chipped on site and carefully removed to a different site for solarisation or burning. 
 
Report PSHB beetle sightings online

The City is encouraging residents to report any suspected sightings of a PSHB invasion or fusarium dieback online by visiting the Invasive Species Unit’s shot hole borer reporting tool on www.capetowninvasives.org.za.

  • Click on ‘Report a PSHB sighting’ to give your details and the location of the infected tree. Residents can also upload images of the tree and entrance tunnels as this will assist the City to do a speedy identification.
  • Officials from the City’s Invasive Species Unit and an arborist at the City Parks and Recreation Department will conduct an investigation.

The website has an extensive database of information about PSHB where residents can learn more about this destructive beetle.

More about the PSHB beetle

  • The beetle is the size of a sesame seed and is approximately two millimetres in length. Its symbiont fungal partner are threatened trees across South Africa
  • It is an ambrosia beetle native to Southeast Asia
  • It was first discovered in South Africa in 2017 on London plane trees in KwaZulu-Natal’s National Botanical Gardens in Pietermaritzburg
  • The beetle is invading and poses a threat to exotic and indigenous trees across South Africa
  • The beetle’s most likely pathway or vector is through the movement of infested wood, originating from dead or dying PSHB infested trees, including wood intended to be used for cooking or heating

Lifecycle of the PSHB beetle

  • The female beetle carries with her three species of fungi, including the pathogen, Fusarium euwallaceae
  • The adult females burrow into trees to establish brood galleries where they lay their eggs. They introduce the fungus which colonises gallery walls, becoming a food source for developing larvae and adult beetles. The fungus kills the water conducting tissues of the tree and can lead to branch dieback and eventually causes the tree to die

What trees are invaded?

  • Alien trees infested to date include London plane trees, sweetgums, Japanese maples, Chinese maples, pin oaks, and English oaks
  • Indigenous trees invaded to date include the coast coral tree, the forest bush willow and the Cape willow

What to do

  • Burning of the infected wood is the preferred method
  • Chipping of the wood into small pieces for compost is also recommended as the heat build-up in the composting process will kill the beetle
  • Once the tree has been felled the debris should be cleared as soon as possible and if required, the area should be sanitised
  • Infested plant material can be placed in refuse bags and sealed. The bags must be put in direct sunlight for solarisation as the heat from the sun helps to kill the beetle and its larvae

 
End

Published by: 
City of Cape Town, Media Office

WINTER IS COMING

It is nearly time for the BIG MIGRATION of the Endangered Western Leopard Toad in Noordhoek. If you would like to help save this species from extinction please consider volunteering during Toad season. You can contact ToadNUTs – Alison (082-771-6232) or Suzie (082-476-1016). Be part of the power team saving this species one toad at a time.

BAN SINGLE USE PLASTICS

Karoline Hanks (a Noordhoek local and NEAG member) founded SUPA (Single-Use Plastic Alternatives two years ago. She produces a range of SUP alternative products from reusable fabric bowl covers, fresh produce bags, a carry-all shweshwe pouch for reusable shopping bags and wax-infused sandwich wraps. Her FB page often carries up-to-date articles on the war against SUPs, as well as news on her product range. To order or chat about anything related to reducing your household plastic footprint, call Karoline on 083 745 3060 or visit the SUPA FB page.

https://www.facebook.com/SUPAlternatives/

DISCLAIMER: Views expressed in our newsletter articles are those of the contributors and where applicable, those of the authors of the original source material

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