Author Archives: johntibby

International PhD opportunity

We are seeking a high quality Quaternary/Earth Science/Geography student to undertake a joint University of Adelaide-University of Nottingham PhD project with a four year tax free scholarship.  The student will be awarded a joint University of Adelaide-University of Nottingham PhD.

 

The student will be studying the following topic:

 

The hydroclimatic history of the Australian subtropics inferred from Fraser Island lake sediments.

 

Understanding past hydroclimates are crucial in the Australian subtropics for (a) investigating the geographic expression of Pacific Ocean climate impacts; (b) constraining the full magnitude and causation of extreme droughts/floods, with relevance for future hydrological management; and (c) relating long term ecological change, including the appearance and loss of Australian animal species, to associated climate variability.

 

In this project, the student will infer past rainfall variation from lake water oxygen isotope proxies and/or the carbon isotope composition of Melaleuca quinquenervia leaves from key Fraser Island (Queensland) lakes.  The relationship between leaf carbon isotopes and rainfall is outlined in Tibby et al. (2016) and the project is discussed to some extent in this video. Oxygen isotopes would be extracted from aquatic cellulose and/or diatom and phytolith silica. This project will likely incorporate diatom and/or macrofossil analysis from these lakes.  The precise nature of the project, including the timeframe of focus will be negotiated with the successful student.

 

The student will be based in Geography at The University of Adelaide and supervised by Dr John Tibby (Geography) and Dr Jonathan Tyler (Department of Earth Sciences).  The student is expected to spend a minimum of 18 months at The University of Nottingham and it is envisaged that much of this time will be spent undertaking carbon and/or oxygen isotope analyses under the supervision of Professor Melanie Leng.

 

We are aiming to decide on a student by the end of September and thus seek expressions of interest (which in the first instance can be informal) by the 20th September to John Tibby.

 

Note that this scholarship is not available to Australian and New Zealand citizens and residents.  Please note that international students should normally have minimum qualifications of a Masters thesis or a first-authored peer-reviewed publication in an international non predatory outlet.

 

References:

Tibby J, Barr C, McInerney FA, Henderson ACG, Leng MJ, Greenway M, Marshall JC, McGregor GB, Tyler JJ and McNeil V. 2016. Carbon isotope discrimination in leaves of the broad-leaved paperbark tree, Melaleuca quinquenervia, as a tool for quantifying past tropical and subtropical rainfall. Global Change Biology 22(10): 3474–3486.

 

Please pass on  to anyone who might be interested,

John.

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Anticipated coring joy…

Having well and truly broken the first rule of blogging (blog regularly), this is my 2nd post…

Late last year my colleagues (listed below) and I were awarded an Australian Research Council grant to examine long records of environmental change from North Stradbroke Island (or “Straddie”) in south-east Queensland. We have identified some wetlands on the island which are VERY old by Australian standards (~100,000 years old). Using sediment records of stable isotopes, pollen, charcoal and other indicators we will develop, firstly, a long high resolution climate record. This can then be compared and contrasted to the pollen record (which also contains fungi found in the dung of now extinct giant animals: the megafauna) to see how much the vegetation changed as a result of megafaunal extinction, climate and the arrival of people.

To do this we are going to use optically stimulated luminescence to date sand grains in the sediments. Since Straddie is the 2nd largest (and finest) sand island in the world, there is sand in the cores, though not as much might be expected.

So…Cameron Barr and I are having a new corer built which takes wide diameter cores. This is very exciting since it is not everyday you get to commission a bespoke piece of equipment from the people who manufactured Adelaide’s “Mall’s Balls“. The corer will be ready in about 4 weeks just in time for Cameron and I to take it to Straddie and try it out.

Fingers crossed it works! Then it will be the job of Honours student Richard Lewis to painstakingly extract more than 1,000 sand grains per sample and individually load them into small pitted trays to be analysed.

To find out more about this work, our earlier Straddie papers include:

Barr, C.S., Tibby, J., Marshall, J.C., McGregor, G.B., Moss, P.T., Halverson, G.P. & Fluin, J. (2013) Combining monitoring, models and palaeolimnology to assess ecosystem response to environmental change at monthly to millennial timescales: the stability of Blue Lake, North Stradbroke Island, Australia. Freshwater Biology 58(8): 1614-1680.

Moss, P., Tibby, J., Petherick, L.M., McGowan, H.A. and Barr, C. (2013). Late Quaternary Vegetation History of North Stradbroke Island, Queensland, eastern Australia. Quaternary Science Reviews 74: 257-272.

 

The team who got the ARC grant was myself, Patrick Moss (University of Queensland: pollen), Melanie Leng (University of Nottingham: isotopes), Jeremy Shakun (Boston University: data assimilation and comparison with climate drivers) and Nigel Spooner (Adelaide: OSL dating).

The application itself was mostly the work of Cameron Barr and I.  Cameron is the post-doc employed on the project but under the ARC rules can’t be listed as an investigator.  Other key participants are our colleagues from Queensland Government Dr John Marshall and Dr Glenn McGregor and Cesca McInerney, Lee Arnold and Jon Tyler from Adelaide.

Gravity Coring with Dynamic Dredging

This sounds like a really exciting project with a great bit of kit. Looking forward to meeting Elyssa soon and hearing about her results

The Mighty Murray River

In March we conducted some gravity cores off a barge with the help of the boys from Dynamic Dredging. Conventionally this coring technique is used with deep sea vessels where a steel barrel pipe is lowered close to the sea floor with 200+kg’s of lead weights mounted on top, and then released, letting gravity ‘pile-drive’ the core barrels into the ground. A piston within the core barrel and core catcher prevent the sediment from falling out of the barrel as it’s winched up from the seafloor.

We gave this a go on the Murray at Younghusband near D.Brinkley’s Sand Supplies, at the channel margins and in the centre of the river channel. In principal it worked, however the age of our gear (from the 1960’s) prevented any deep cores, and with a 6 metre core barrel we only retrieved around 3 metres (piston basically got stuck halfway up the barrels…

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All tied up: stream monitoring in south-east South Australia

Inspired by a few colleagues, including Sophie Lewis who I met last week and writes the excellent honeybeesandhelium.com, I’ve started a blog.  I am hoping to reach a different audience, free myself (a little) from academic writing conventions and perhaps even improve my productivity.  So, here goes…

My colleague Cameron Barr and I are back from our second field trip to South Australia’s inventively named “south-east” region (the inventiveness doesn’t end there: Kingston SE is the name of one of the coastal towns, lest we confuse it with Kingston-on-Murray nearly 400 km away).

We have been collecting approx. 1 metre long lengths of rope which we had previous placed in 40 stream sites around the “south-east”.  Over the past month of so (we hope) they have been colonised by diatoms, a type of algae which form the basis of many aquatic “food chains” (see here http://tolweb.org/Diatoms/21810 for further info). We will assess whether the diatoms are being strongly influenced by nutrients (such as phosphorus) dissolved in the water of the streams.

This project, funded by the Environment Protection Authority, will hopefully help to refine South Australia’s stream water quality guidelines.  By understanding how the diatoms are influenced by nutrients, it may help the EPA to develop new nutrient thresholds in an effort to help guide efforts to improve the quality of our creeks and rivers.

Given the first set of water quality data we have been given, there is much room for improvement.  Around half of the 40 sites sampled are highly nutrient enriched while 20% are “hypereutrophic”.  Given that much of the massive drainage network that contributes these nutrients was constructed after World War II, then it is likely that we are yet to feel the full effects of these impacts.

I’ll report on the diatom results in a month or two, but for the moment I’ll sign off and leave you with a couple images from the field trip.

Here’s Cameron collecting our precious ropes…Image

and an example of the ropes themselves:  OLYMPUS DIGITAL CAMERA

Note how the ropes are frayed to maximise the habitat for colonisation by diatoms.  We got the idea from out colleague at University College London Ben Goldsmith who did his Ph.D. on diatoms in streams.

We were very impressed by scale of the windfarm near Millicent and the town’s promotion of the farm (“the largest in the Southern Hemisphere”) as a tourist attraction.  Certainly to me, the impressive windmills (some around 90 m high) enhance this landscape.Image

That’s all for now.  Next time I’ll write about our work which uses information from the past to help understand our present.