Δεκέμβριος 29, 2021

Species that Matter - Latrodectus katipō

This is the species which instigated this series of articles on the special species in the dunes of our region. It is also the species that kicked off my dunes ecology habit, more than a decade ago. What's the big deal?

Firstly, almost everyone born here and many who have made this land their home, at least know what a katipō is. Most have never seen one, except in photos. In some circles, perhaps because it is the only species endemic to New Zealand which is regarded as venomous, it has achieved iconic status. The flashy markings on an adult female serve to elevate that status too. Here is one fine example:
https://inaturalist.nz/observations/103864584
Katipō males look quite diminutive beside the female, ref.
https://inaturalist.nz/calendar/arnim/2011/2/12

So you have a taste of how small spiderlings can be, ref.
https://inaturalist.nz/observations/5050491

As that observation infers, it is common for katipō spiderlings, when they break out of the eggsac, to scamper immediately to the top of the nearest tall plant to balloon away - a spectacular sight I have witnessed a few times. To get an idea of how effective spider ballooning is, read for instance
https://arxiv.org/abs/1309.4731
which is (AFAIK) the original work citing electrostatic fields as the key enabler.
The sexual dimorphism in katipō is not so extreme as with the Australian redback - that female is larger than a katipō, and the redback male is smaller than the katipō male. No wonder the redback male is lunch for the female - that is not the case with katipō.

Secondly, katipō is listed by the Department of Conservation as an 'at risk' species. It is absolutely protected under the Wildlife Act. But, it goes further than that. Quite some years ago DoC correctly decided that it could not have a programme for every species on the threatened species list. Instead signature species were nominated for varying types of ecology. Katipō was nominated for dunes environments. In my opinion, this was an excellent choice. I have observed that there's a pretty useful correlation between the katipō population in an area of dunes, and the general ecological health of those dunes, ie. there's a parallel to the coal miners' canary.

Katipō live in the dunes, and only in the dunes. If you find a look-alike spider in your backyard, I'd suggest with something greater than 99% certainty, that what you're looking at is a false katipō, (Steatoda capensis), which not only lives in more habitat types than katipō, but can look superficially like katipō too, as specimens may be very dark with a fine red-orange stripe, eg.
https://inaturalist.nz/observations/13066015

There's plenty of good material on the InterNet if you want to learn about katipō. Some I can recommend are Phil Sirvid's fine pieces for Te Papa, ref.
https://collections.tepapa.govt.nz/topic/9431
and some excellent related articles:
https://blog.tepapa.govt.nz/2009/02/10/1743/
Phil's reference in the above article is for my money, the definitive work on katipō
https://blog.tepapa.govt.nz/2009/02/13/latrodectus-love-bites/

Phil's material wasn't written recently so it doesn't include some of the things I learned in the decade I've been studying katipō. Here's some of what you won't learn from the above, or any other sources I'm aware of:

1) depending on where you're looking, katipō can produce eggsacs almost all year round. I've found new ones here, and in Hawkes Bay from August through June. Further north that may be right through the year. That doesn't say that all of them produce vast amounts of new katipō - there's a known strong correlation between katipō fecundity and temperature.

2) I had the pleasure of learning about katipō at Ocean Beach south of Cape Kidnappers, which is the only place I'm aware of where katipō of both colour morphs have been studied together. Although only 1% of those were black katipō, another 5% or so appeared to be 'hybrids' of both red and black katipō. That doesn't happen here in the dunes of the West Coast of the lower North Island, since black katipō don't find their way here. Hawkes Bay is about as far south as you can find black katipō, perhaps slightly further north on the West coast, since there is a distinct correlation to temperature for black katipo to thrive.

3) Occasionally experienced katipō viewers find katipō with a distinct brown tone to the abdomen. What is not widely known is that this is a very short phase in an adult female katipō's life, just before she produces another eggsac. The abdomen has stretched so far during this 'gravid' phase, that the light reflects differently from the abdomen. Immediately after she's laid her eggs, she's back to quite black again, and for a short period, quite wrinkly too. The second katipō observation from the top illustrates a gravid female about to add to her first eggsac.

4) Habitat loss, ie. human intervention, has doubtless been a major factor in the decline of the national population of katipō, but it is not the only reason. Earlier studies indicated that the false katipō, Steatoda capensis, which hails from South Africa, is displacing our native katipō in its ecological niche, but the story goes further. My work has included photographing instances of false katipō preying on a katipō - the colonists are killing off the natives, ref. for instance
https://inaturalist.nz/observations/102063519
The false katipō in this first case had mortally wounded the katipō, which stopped all motion a minute or two later. What makes this worse, is that false katipō and real katipō often coexist in the same web structure, from juvenile ages through adulthood, but at some point, the false katipō might turn on the native host, making a meal of it. ref. eg.
https://inaturalist.nz/observations/13065845

Further, I've fingerpointed another three exotic spider species which prey on katipō. The worst offender seems to be an Australian crab spider which in it's native Australia is not known to prey on spiders at all. Here I've observed Sidymella trapezia preying on half a dozen species of spider, including katipō and other native spider species. The following depict S.trapezia killing off a false katipō, a katipō and a native seashore wolf spider (Anoteropsis litoralis).

Sidymella eats Steatoda
a) https://inaturalist.nz/observations/6970072
Sidymella eats katipo
b) https://inaturalist.nz/observations/7152143
Sidymella eats seashore wolf spider
c) https://inaturalist.nz/observations/7152319

A third species, Australomimetus hartleyensis, colloquially known as a 'pirate spider', is well known for preying on spiders in its native Australia. These Mimetid spiders are often smaller than their prey, ie. these pirate spiders are very good at what they do. ref.
https://inaturalist.nz/observations/19039648

All three of these species are common on this coast. Any time you come across them, don't be shy. Nixing one of these is an invertebrate equivalent of bumping off a stoat. A fourth katipō-predating spider, the Australian import Nyssus coloripes, is common in Hawkes Bay, but in almost 6 years I have yet to meet it here on the West Coast.

There really is nothing to fear from katipo - they're much more afraid of you than you are of them. A male or juvenile would struggle to break your skin, and even an adult female cannot do so without real effort, so if you don't entrap an adult female, envenomation won't happen. If you get brash and provoke this, appropriate antivenin is available in hospitals, which can save you considerable discomfort for weeks. Previous generations were taught to fear the katipo, but as my friend Ruud Kleinpaste will tell you, if we educate our children to treat them with respect, then the fear gets put into perspective.

Lastly, I'm pleased to report that most of the active members of our Dune Garden team have learned how and where to find katipo in our fortnightly sessions. If you're so inclined, don't be shy about joining us. It isn't a bug, it's a feature.

Posted on Δεκέμβριος 29, 2021 0459 ΠΜ by arnim arnim | 3σχόλια | Αφήστε ένα σχόλιο

Οκτώβριος 13, 2021

Coastal Dunes - Species that Matter - Sea Spurge

While not intending to focus on the dramatic, this month I once again divert from the focus on some of the amazing and wonderful native and endemic species that we have on this coast in our dune wilderness, to focus on a different kind of problem to last month's highlighted weed [1].

Two years ago I learned about sea spurge via

https://inaturalist.nz/observations/34943019

It took my iNaturalist colleagues some weeks to settle on the identification, since at the time, this species was only known in NZ from an initial invasion in the Waikato. A DoC lady woke us up to MPI's position on this species. The participants in this process celebrated finding this plant early, before the problem became serious. If only it remained so simple. MPI's management of this species stands in stark contrast to the sorry state of our coastal dunes ecology due to coastal wattle [1] which is a far more advanced problem, in terms of destroying the native coastal dunes ecosystems. So, what's the big deal?

https://research.csiro.au/nswweeds/wp-content/uploads/sites/174/2018/11/Darby-River-landscape-14.jpg

a) Euphorbia paralias, as it is formally named, is a significant problem in Australia, where it is soaking up large sums of money to manage it.

b) Not only is the illustrated beach effectively overgrown, sea spurge can cause skin and eye irritation from the sap. This is a real deterrent for beach-oriented tourism. New South Wales is not the worst hit problem, but over 60% of beaches in NSW are affected already.

c) MPI regards this as an early-stage problem that needs to be beaten, before it starts to affect the New Zealand economy.

https://www.mpi.govt.nz/dmsdocument/3554-sea-spurge-a-serious-threat-to-new-zealands-beaches

This reflected initially in the early finds with rapid, comprehensive reactions, an ecological parallel to the government's proactive stance on Covid-19.

From the single find on the lower North Island two years ago, a recent coastal dunes survey by Kelsi Hoggard of Horizons Regional Council, had over the past month, highlighted a further three instances in our region, which were mature enough to have spawned several generations of plants, at sites west of Moana Roa Scenic Reserve south of Scott's Ferry, half way between Waitarere Beach and Hokio Beach, and half way between Kuku Beach and Waikawa Beach.[2] There has recently also been a site highlighted south of Paraparaumu Beach, as well as one on the West Coast of the South Island.

To drive the situation home, recently I came across another patch, 4km north of the Foxton Beach Surf Club, ie. right in our back yard [3].

Once again, reporting this on a Sunday caused a furore, with multiple persons from MPI chasing details, as well as our local Council and DoC contacts. This is taken seriously.

Maybe you can use this material as a guide to recognising this problem when you happen to walk in the dunes. I certainly hope so! As a starting point, if you download and read the URL on the MPI website, it will give you the necessary details to report any find of this species. That's my bottom line message - how you can help. These are our New Zealand beaches that we're working to preserve.

Consider the larger context. This is broached nicely in my article from last month[1] for coastal wattle, or you can see another 'fine' example at the well managed estuary of the Waikanae River, which at the dune front, turns into a wall of tree lupin [4]. These problems are past an easy solution, so let's not let sea spurge get like that too.

Enough banging of the drum. Start with the URL from MPI, and let's work together on this.

[1] https://inaturalist.nz/journal/arnim/55596-coastal-dunes-species-that-matter-coastal-wattle

[2a] https://inaturalist.nz/observations/93765978

[2b] https://inaturalist.nz/observations/94880736

[2c] https://inaturalist.nz/observations/94880602

[3] https://inaturalist.nz/observations/96144946

[4] https://inaturalist.nz/observations/32318247

Posted on Οκτώβριος 13, 2021 0737 ΠΜ by arnim arnim | 0σχόλια | Αφήστε ένα σχόλιο

Αύγουστος 24, 2021

Coastal Dunes - Species that Matter - Coastal Wattle

The intention is that the following is the first of a series of perspectives on species that live in our area, focusing on dunes, dune wetlands and estuaries along this west coast of the lower North Island. Often you’ll see upbeat material, covering threatened species that are doing well, or not so well, on this coast. Sometimes I’ll rant about problem species.

Because this time of year is the peak season for identifying it, I’ll start this series with a problem species. Coastal wattle, a.k.a. ''Acacia longifolia sophorae'' is the number one threat to our dunes and dune wetland environment on this coast. Here in Foxton Beach, to see this problem at scale, look at the south bank of the Manawatu River. There were formerly dunes along that shore well back in from the coast, but those dunes are all but gone, overgrown with a wide belt of coastal wattle from the plantation pine to the estuary. The native dune flora and fauna have disappeared under a coastal wattle forest:
https://inaturalist.nz/observations/92336911
We have other problem spots in the Foxton Beach area. A stalwart community team works with District Council to eliminate this from the dunes south of Foxton Beach township. On the north side of Foxton Beach at the end of Brown Terrace about one hectare of dune vegetation has gone lost to large, well established stands of coastal wattle.

To familiarise yourself with this species, as it has a characteristic flower in August/September:
https://inaturalist.nz/observations/89883519
The bright yellow flowers are identifiable from a distance this time of year.

The wattle problem is particularly obvious around Himatangi Beach:
https://inaturalist.nz/observations/89607860
The dunes are completely covered around the main beach entrance. To the north dozens of hectares of coast wattle forest have eliminated the original dune vegetation. To the south of Himatangi Beach settlement, some of the most scientifically interesting dune wetlands anywhere are under threat from encroaching coastal wattle.

This problem does not stop there, but is severe at Tangimoana, right past the Rangitikei estuary, and on to the mouth of the Whanganui River.

We have a particularly clean dune area around the north side of the Manawatu River mouth. Within the Manawatu Estuary Ramsar site[1] the dunes are free of coastal wattle, and are maintained that way by a dedicated team of volunteers. Further south than the Manawatu River, the coastal wattle problem is out of control too. The dunes are being overgrown to Waitarere Beach, and beyond. One of the finest examples of dune wetland on this coast is the 4km stretch between Kuku Beach and Waikawa Stream, but especially at the south end, the coastal wattle is running amok, over a host of native dune wetland species that deserve better.

This problem was originally created by the New Zealand Forest Service, and its predecessors, in their ambitious plans to plant New Zealand’s dunelands with pine forest[2]. With these plantations now commercialized it is difficult to push the current leaseholders of those forests to be responsible for the mess.

A retired scientist formerly associated with Landcare Research, Dr. Richard Hill, had been working for years to certify a species of invertebrate which preys on Acacia species, including coastal wattle. Whether this is a viable answer, I can’t say, but I’d like to find out more about the status of that work, as an option to consider. Our coastal dunes and their wetlands are unique, in New Zealand and wider. Dealing with this species would be a major step toward preserving them.

[1] Some pointers to the Manawatu Estuary Ramsar site:
https://www.wetlandtrust.org.nz/get-involved/ramsar-wetlands/manawatu-estuary/
https://www.metrust.org.nz/about-the-estuary
https://www.doc.govt.nz/globalassets/documents/parks-and-recreation/places-to-visit/wellington/manawatu-estuary-mgt-plan-2015-2025.pdf
https://www.horowhenua.govt.nz/Places-Events/Parks-Reserves-Recreation/Hartley-St-ReserveSunset-WalkwayManawatu-Estuary-Foxton-Beach
https://en.wikipedia.org/wiki/Manawatu_Estuary https://en.wikipedia.org/wiki/Manawatu_Estuary

[2] http://dunes.letras.ulisboa.pt/wp-content/uploads/2021/07/Dunes20drifting20in20New20Zealand2c20Sampath2c20Beattie20and20Freitas_PREPRINT.pdf

Posted on Αύγουστος 24, 2021 0929 ΠΜ by arnim arnim | 1 σχόλιο | Αφήστε ένα σχόλιο

Απρίλιος 30, 2020

killing and conservation

Brought on by a conversation, one might say, visible at
https://inaturalist.nz/flags/487426#activity_comment_4490364

My perspective, which isn't finished evolving, is that if you're not prepared to kill, then conservation work probably isn't for you. Weeding is killing, managing pest species is killing. I don't go out of my way to do either, and I don't even particularly enjoy it for its own sake, but it is part of ecosystem preservation, if we value biodiversity. If a species cannot live in the place where it evolved, where should it live?

Consequently, when I see a tree lupin or coastal wattle growing over Autetaranga or Tataraheke, it often stimulates me to action. Effects of weeds can be a great deal more subtle than that obvious example.

I have long identified four species of exotic spiders which prey on katipo. This is not published in any journal yet, but my scientific advisors have been aware of this state for more than five years. As a consequence, every time I see Sidymella trapezia, Steatoda capensis, Australomimetus hartleyensis or Nyssus coloripes, they get the squeeze. And I often reflect this information in my observations, to let others know that this is the case. If you look for it, there is hard evidence enough amongst my observations. At most I might some day update the Wikipedia article on katipo to reflect this, and address other shortcomings in that piece.

The situation is very different when native species impacts on native species. If mankind had not interceded to introduce all of these exotic species, then Mother Nature's plans would have had such native-vs-native conflicts resolved on her own terms. That's not my argument to get involved in.

Posted on Απρίλιος 30, 2020 0705 ΜΜ by arnim arnim | 4σχόλια | Αφήστε ένα σχόλιο