Monday, October 3, 2016

Spending time with Antarctic penguins

Emperor penguins and chicks at Cape Crozier colony.
Antarctica NZ
Emperor penguins and chicks at Cape Crozier colony. 
Most of Antarctica New Zealand's upcoming science season concerns climate change, but some lucky researchers get to spend time with penguins. WILL HARVIE reports.
Kiwis have been studying penguins as long as Kiwis have been going to Antarctica.
This summer, Antarctica New Zealand is planning three penguin research projects.

Adelie penguins on a newly formed ice floe in the northern Ross Sea in 2007-2008.
John Mitchell/Antarctica NZ
Adelie penguins on a newly formed ice floe in the northern Ross Sea in 2007-2008. 
Probably the most ambitious will be a return trip to Cape Adare, site of the largest adelie penguin colony in the world. That expedition is being led by Antarctica NZ's chief science adviser Gary Wilson.
He and colleagues visited the remote cape, 750 kilometres north of Scott Base, last summer and Morgan Coleman of Landcare Research attached geolocator  tags to 78 adelies.
This year's mission is to retrieve as many of those tags as possible. That's a task because there are almost a million adelies at Cape Adare, according to a 2015 census and finding 78 specific animals is needle in haystack stuff. Fortunately, says Wilson, adelies usually return to their traditional nesting sites.

Michael Armstrong gathers adelie penguin chicks.
Jason Edwards/Antarctica NZ
Michael Armstrong gathers adelie penguin chicks.

The tags store the data and must be retrieved to be useful. They give latitude and longitude positions twice a day and the data will tell scientists where the birds have been over the last 12 months.

It is known adelies must have access to open water – that's where the food is – and they probably follow the ice-sheet edge as it expands over winter. The birds then return to breeding colonies on land in spring as the sea-ice breaks up.

But exactly where the Cape Adare adelies go in winter isn't known and the tags will clear that up, if enough can be retrieved. Wilson hopes to retrieve all of the tags but is realistically expecting to lose a third to half of them.

If the study proves successful, scientists could use more sophisticated tags that record temperature, the salinity of sea water and how deep the Cape Adare adelies dive in search of food in winter. Again this isn't well known.

There's a bigger point to the Cape Adare project, Wilson says. It concerns climate change.
It's hard to know if change is caused by global warming or expected variability from year to year, or regional differences, he says.

By tracking a predator like penguins and expanding to other species and measures, Wilson and colleagues hope to get a much fuller picture of what's happening at Cape Adare, for example.
"If you can integrate all of the trends ... you'll get a long-term ecological tool" that makes predicting the effects of future climate change sharper, he says.

Adelie penguins at Cape Adare are in a "key location close to the confluence of the Southern Ocean and the Antarctic Continental Shelf, so impacts on Antarctica from the Southern Ocean and from Antarctica on the Southern Ocean should be able to be disentangled".

Meanwhile, Phil Lyver of Landcare Research and colleagues will assess mercury contamination in emperor and adelie penguins on Ross Island.

Mercury is a naturally occurring element, but it is also released by human activities such as fossil fuel-fired electricity generation, mining and waste incineration. It is transported in the atmosphere to polar regions where it is deposited in to the ocean and on to snow and ice, Lyver says.

It is taken up by microorganisms and travels up the food chain to krill, squid, fish and predators such as penguins.

A small number of penguins from the Ross Sea region recently showed low concentrations of mercury (about 1 part per million of mercury). "Anything above 5ppm is of concern," Lyver says.

This study will provide a better benchmark of mercury in penguins for the Ross Sea, but will also assess how it varies according to species, age and sex.

The birds are restrained using a specially adapted crook or net and then bagged, weighed, measured and observed. Feather samples are taken and these will be analysed for mercury at the University of Canterbury by MSc student Natalie Pilcher.

Emperor penguins, the largest of the penguins, weighing up to 30kg, can be a handful. Even the smaller adelies, at 4kg to 6kg, are fierce and have "absolutely" left Lyver and colleagues with scars and bruises.

The researchers expect emperor penguins to have more mercury in their feathers than adelies because the assumption is that emperors feed higher in the food web.

Lyver has been to Antarctica almost every season since 2004 and has a 10-year backlog of penguin feathers for the University of Canterbury team to analyse.
"We're expecting a low result," he says.

Meanwhile, Fiona Shanhun  of Antarctica NZ picks up responsibility for an annual penguin census in the Ross Island region, home of Scott Base. The first census was taken in the 1981-82 season and has been done almost every year since.

The technique hasn't changed much. A photographer leans out of a plane door and shoots colonies as the pilot flies a grid pattern. Back in the lab, the photos are stitched together. In the old days, a technician discerned birds from rocks and the count was manual.

These days software does the counting – with oversight by humans.

The good news is that some penguin colonies in the Ross Sea have basically doubled in size since 2001.
Lyver, who used to oversee the census, hypothesises that expanding sea ice – and a longer sea-ice season – have "provided a great platform for foraging".

Climate change does not cause uniform change across the southern continent. Sea-ice extent and penguin populations are both dropping precipitously on the Antarctic Peninsula south of Chile. Penguin census data are available to all at a Nasa-funded database,

None of the penguin projects take a great deal of time.

Gary Wilson expects to be based at Cape Hallett for two weeks and get four days at Cape Adare, travelling between them by chopper. The census takes place over a couple of weeks in late November and early December.

Fiona Shanhun will be among the team going to Cape Adare. She'll be on the Ice for 76 days this summer, including a stint at Scott Base as part of the leadership team.

 - Stuff


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