This week at Macquarie Island: 15 November 2013

Royal Tasmanian Botanical Gardens (RTBG) botanist, Natalie Tapson, has been working since arriving at the end of October to increase the existing Azorella seed orchard from 9 to 54 plants. Azorella macquariensis is a cushion plant that only grows on Macquarie Island and is the major structural component of the feldmark vegetation that occurs on the windswept plateau at altitudes between 200 and 400 metres.

The species has undergone a catastrophic decline right across the island since late 2008 and as yet no definitive cause has been found for the dieback. As a result of the decline, the species is now listed at the highest level of threat under both the federal and Tasmanian threatened species acts.

A trial seed orchard established by the RTBG on Wireless Hill in 2010 was successful so it was decided to seek funding to increase the orchard to at least 50 plants to capture the genetic variability within the species. The seed will be collected for long-term storage in the RTBG seed bank and research will be undertaken to work out the germination requirements. Funding from the Mohamed bin Zayed Species Conservation Fund and the Foundation for National Parks and Wildlife have allowed the project to go ahead.

Wireless Hill is on North Head, up a steep track, in close proximity to the station. Most of the equipment for the orchard was thankfully dropped by helicopter at the site during resupply in March 2013 but some of the ingredients for the mix had to carried from the station up the hill. After a plea for help by Natalie, there was quickly a band of willing volunteers to carry backpacks full of peat and pebbles up the hill.

Much of the peat had already been autoclaved by Angela from the pest eradication (MIPEP) team in the week before L’Astrolabe arrived. With pebbles in the base for drainage and a mix of peat, perlite and gravel, most of the tubes have been filled and so far three plants have been collected from the south of the island by Peter from the MIPEP team. These have been planted as the first new additions to the seed orchard. A new tank is being installed by Josh and over the next few weeks Natalie will work with Ranger in Charge, Chris Howard, to collect more plants from across the island to add a total of 45 new plants to the seed orchard.

Natalie Tapson

Grant Hose and I arrived a few weeks ago on the L’Astrolabe. We are part of a research collaboration between the Australian Antarctic Division, University of New South Wales and Macquarie University (Sydney), looking at remediation targets following fuel spills on subantarctic and Antarctic soils. There have been a few spills to date on Macquarie Island, mostly around the power house and the fuel storage area (the “fuel farm”), but we are also looking at unimpacted areas across the isthmus (the flat area on which the station is built).

A fair bit of research has already been done the topic for warmer climates, where microbes in the soil will break down the nastier components in the fuel. However, Macca soils can be waterlogged for much of the time, which means that they can’t hold enough oxygen to support the microbes that would otherwise do this work. With very slow rates of biodegradation, these spills could be affecting the soil health (such as tiny insects, crustaceans) for decades or even centuries to come.

To help the process along, a soil rehabilitation program has been underway for several years now. It focuses on increasing microbial activity with techniques such as pumping oxygen underground (called “sparging”) and adding fertiliser to the sandy, nutrient-poor soil typical of the isthmus).

But how much rehabilitation is enough rehabilitation? This might seem like a cynical sort of question to ask, but it’s important to know what we are aiming for! That’s where our research will come in.

Since arriving we’ve been going all-out to get our work done in the short time we have here and we’ve managed to finish off the first section this week, which is fantastic. We’ve been scurrying around the isthmus taking hundreds of small soil cores, mostly from the surface, but some a bit deeper. Kate, one of researchers on the albatross project, was very confused when she walked past the perfect little circles left by our corer — what animal could possibly have dug that?!

Once we’re back in Sydney we’ll be checking the samples for things like the chemical signature, diversity and abundance of invertebrates, nutrient levels, acidity, salinity, soil type and so on. By comparing data from different sites with known histories — some part of the remediation program and some not — we hope to observe how the contamination is affecting life in the soil.

But there’s more! There is a second part to our work here that we’ve just started on this week. Last summer, Grant set up some mesocosms (special stainless steel buckets filled with a uniform mix of soil, so we can create a little system in which we know exactly what we are working with). They have been buried out in the elements for a little under a year to equilibrate with the surrounding environment.

In the coming few weeks, we’ll be digging them up, emptying them into a mixer, and spiking them with a cocktail of chemicals that resemble different intensities of fuel spill. Then next season we'll come back to see how things have developed in the buckets.

The results of our work will be useful for developing management plans for polar areas currently affected by hydrocarbon contamination, and for any future incidents.

This has been my first visit to Macca, and I feel like a kid in a lolly shop. It took me over a week to get over the dumbfounded stupor at all the amazing things going on around me. It’s been surreal, working amongst all the animals here. Where else do you take a break for a minute to watch some enormous bull elephant seals sorting the men from the boys? Or look out to sea for orcas during your daily commute (stroll) between home and the lab? And it’s just as well we got some of our samples when we did, because now that the elephant seal pups have weaned and are moving away from their mother on the beach, a few of our sites have become covered in dozens upon dozens of feisty little weaners!

Ingrid Errington, research student

This week’s Macca Gallery features the abundant wildlife that can be seen so close to station. We also have a photo of a trip to the SMA (Special Management Area) of Secluded Bay on North Head. This SMA is only accessible for a very short period — 30th September to 16th of November.