As part of a national-scale review of the endemic biodiversity values in Great Artesian Basin springs (for the background see this previous post) we are reviewing the current knowledge about what kinds of species are where, what we know about them, and what parts of the basin seem to be home to the most species.
In each of these updates I will:
- List the species and evolutionarily distinct units we now think we should recognise and how this has changed in recent years
- Describe the patterns of biodiversity across the basin
- Discuss their current conservation status & threats
First stop, the snails (surprise!?).
To help myself understand what is going on with the snails in springs, I have made a handy Google Earth folder. You can download it here. If you have Google Earth (or you can download it for free) you can go on a little adventure around the springs yourself.
The file includes the following:
- Every spring complex that is fed by the GAB and some basic statistics about each one – just click on the little ‘dot’. Some of these complexes have completely dried up, they are displayed as a crossed circle. If you zoom in this dot may not be on the actual springs – they represent ‘centroids’ (i.e. a point in between all the springs in the complex)
- Every species of endemic spring snail currently recognised, split into genetically distinct clades if they exist. If you click on a teardrop you can also see some basic information about each snail. Make sure you click places because in some spots LOTS of species are all stacked on top of each other (e.g. Pelican Creek)
- Current mines and mining-related prospecting areas that are likely to threaten or impinge on springs.
Please feel free to download and explore! Let me know if you find any glitches.
# species: 37
# families: 3
Highest diversity family
By far the Tateinae (prev. Hydrobiidae) – there are representatives of this family in almost every spring with snails in it. They’ve diversified the most over long periods of time (approx. since the late Miocene); currently four genera, but there are about to be some big taxonomic changes in this group.
Highest diversity complex
– 1st place –
By miles is the Pelican Creek complex (Barcaldine Supergroup) with 12 species. Edgbaston also holds higher family-level diversity than any other complex.
– 2nd place –
A number of complexes in the Lake Eyre Supergroup in South Australia – 11 of which have five species (CES, CHS, CJS, EFN, EFS, FFS, NBP, NFS, NOS, NTM, NTF).
Points of interest
The Pelican Creek complex, which is composed of the springs on Edgbaston as well as neighbouring property to the south Myross, is a phenomenal place. Unlike South Australia, where there is a large number of species spread over a relatively large area, the diversity of endemic snails in Queensland is centred on Pelican Creek. You can see how distinctive this is in the figure above on the left – there are many complexes with no species, quite a few with between 1-5 species BUT only one with 12 species. These twelve species only occupy this one tiny spec of Queensland, meaning if anything were to happen to that one area they would all disappear.
Of interest at Pelican Creek is also the fact that it is the only complex where numerous families of endemic species are represented – take a look at South Australia, all their diversity is composed of one family. This is shown in the central figure above – its the only place that has THREE families and the Barcaldine complex overall is the only complex with more than one family. This means that Edgbaston is not only diverse in terms of the numbers of species, but also in the “taxonomic distinctiveness” of those species as well – i.e. they’re not all close relatives of one another.
In contrast, the species from South Australia are spread over a much greater area; the biggest span between populations is ~300km for F. zeidleri, which is about 30 times the distance between individual populations at Edgbaston. Some of these disjunct pockets of springs are on their own ‘evolutionary path’ – populations start differentiating from each other enough that they are distinctly different when we assess their genes. You can see this in the far right figure above – species with large distances between populations have larger numbers of distinct genetic units. This is the kind of process that, with enough time a bit of luck and some special circumstances, makes new species. This also gives some of these species in South Australia a bit of a ‘back up’ if a single complex disappears – loosing complexes is still bad because it decreases the genetic diversity within the species but it won’t lead to an all out extinction like it will at Pelican Creek.
What’s so cool about snails in springs?
Most of these species have ancestors that LOVE clean, fresh, permanent and cool water – the kind of stuff that flows through rainforest and coastal streams. This is not the kind of water body that exists in the majority of the arid center where ‘boom and bust’ water cycles usually mean floods, then stagnant pools that slowly dry until there is nothing left. There are organisms that are well adapted to this kind of situation – for example Artemia ‘fairy shrimps’ have eggs that can last in the dry cracked soil and wait for the next rain.
These snails do not have such talents. Most of them die within a few hours of being out of moisture, they cannot walk across the hot dry land that is between springs and they are pretty sensitive even to some of the conditions within their own springs (i.e. springs can get pretty salty). This means that they NEED springs. The reason they still exist in the outback, the reason why we have so many species and the reason that these species are all so evolutionarily special is because of the springs. Remove the springs, you loose it all.
There is no other group of animals in springs that are as diverse as the snails. There is something about springs that ‘breeds’ species (I’ve speculated about some of these here). In some cases, there has been huge divergence in the way species look and the conditions they can withstand, in other cases snails essentially look the same but are very different species. This can be pretty confusing, but thanks to some amazing efforts by taxonomists (like Winston Ponder) we’ve got most of them figured out.
- Taxonomists currently urge that we consider not only species level diversity but also the diversity of ‘evolutionary distinct units’ within springs like those we see in the South Australian species like F. zeidleri. We have integrated these into the new database and I’ve marked them on the map for you to see if you so desire .
- Recent taxonomic changes have meant the boundaries of where some species are found have changed a little in the South Australian complexes.
What needs to be done?
This overview is a great starting point, but we are no where near done yet. Reviewing the literature around these species has highlighted some of the key things we need to focus on if we want to preserve this diverse and evolutionarily interesting group of animals.
#1 – Inconsistency in conservation status & protection
Despite most of these species facing similar threats, the conservation listing of endemic spring snails is inconsistent at best. Whilst some species have been thoroughly assessed (mostly Tateinae e.g. Fonscochlea aquatic above) many of the newer species are yet to be assessed or lack enough data to be assessed under the IUCN (e.g. Glyraulus edgbastonensis and Gabbia fontana above), and those that are considered at high threat are not integrated into the Australian conservation legislation at national (the EPBC) or state-levels. This reduces the power to protect these species, particularly in places where they are at direct threat (i.e. at the Doongmabulla complex which will disappear with the Carmichael coal mine). Most of them are currently integrated into a ‘blanket’ listing for all animals and plants dependant on springs, but such legislation makes activities such as offsetting and risky species translocations a viable option for mines that wish to compromise a single complex (e.g. Carmichael again).
#2 – Describe the rest
Many species remain undescribed. Winston Ponder is on to the Tateinae but there are also other species that require taxonomic attention – for example the Glyptophysa of Edgbaston. We have found other Glyptophysa in other complexes that, with lessons about cryptic species learned from elsewhere, may mean we could still be underestimating diversity within Queensland.
#3 – Fill the gaps
There’s a lot of information about the species of snails that live in Lake Eyre, but very little about those in Queensland. Despite Pelican Creek being a ‘hot spot’ of diversity in such a small area, we lack the level of knowledge about population dynamics and migration that we possess for South Australian species. We still don’t know how much within-species diversity exists in the species of Pelican creek.
#4 – Understanding threats
Unlike some of the other animals like the fishes, we have very little idea about how snails respond to potential changes in springs environments caused by humans. In many complexes introduced species that can and do eat endemic snails exist (e.g. at Pelican Creek there are both Gambusia and Cane Toads, both of which have been shown to eat endemic snails). Introduced plants like Bamboo and Prickly Acacia can choke springs, sucking up available water and drying up spring pools. Pigs and cows churn up springs, digging up vegetation and causing nutrient enrichment.
I’de like to thank Mark Kennard and Rod Fensham for supporting this work as well as the Great Artesian Basin Co-ordinating Committee for funding my PhD as a whole. I would also like to thank Bush Heritage Australia for letting me work in the amazing paradise of Edgbaston – summarising this work only re-enforces how phenomenal it is. This work would not have been possible without the tireless efforts of Rod Fensham, Russ Fairfax, Jen Silcock and Boris Laffineur who visited, checked and collated every spring location used here. I would also like to thank Winston Ponder, as well as Donald Colgan, Robert Herschler, Jessica Worthington-Wilmer, Nick Murphy, Travis Gotch and Kathryn Perez for their dedication to these amazing animals. Reviewing their work was a pleasure.
- Ponder, W.F., and Clark, G.A. (1990) A radiation of hydrobiid Snails in threatened artesian springs in western Queensland Records of the Australian Museum 42(3), 301-363 (get it here) and Ponder, W.F., Hershler, R., and Jenkins, B. (1989) An endemic radiation of Hydrobiid snails from Artesian Springs in Northern South Australia – their taxonomy, physiology, distribution and anatomy. Malacologia 31(1), 1-140. (get it here).
- Read up about the basics here, or some academic contributions from springs by Nick Murphy such as: Murphy, N.P., Adams, M., Guzik, M.T., and Austin, A.D. (2013) Extraordinary micro-endemism in Australian desert spring amphipods. Molecular Phylogenetics and Evolution 66(3), 645-653. (get it here)