Adélie Penguins struggle to reach their nesting sites if there’s too much ice in the way.
Jane Younger, Author provided
Author:Jane Younger
Postdoctoral research fellow, University of Tasmania
Disclosure statement
Jane Younger receives funding from the Australian
Antarctic Division, the ANZ Trustees Holsworth Wildlife Research
Endowment, the Sea World Research and Rescue Foundation, and the
National Science Foundation.
Penguin numbers exploded in East Antarctica at the end of the last ice age, according to research
published today in BMC Evolutionary Biology. Despite their image as
cold-loving creatures, the increase in Adélie penguin numbers seems to
be closely linked to shrinking glaciers, raising the possibility the
these penguins could be winners from current climate change.
Adélie penguins are one of only two penguin species that live on the
Antarctic continent. Their cousins, emperor penguins, may be the movie stars,
but it is the Adélies that are the bigger players in the Southern
Ocean. They outnumber emperors by more than ten to one, with a
population of over 7.5 million breeding adults and counting.
Given the abundance of Adélie penguins and their crucial role in
Southern Ocean ecosystems, there has been a great deal of interest in
understanding how the species is likely to respond to future climate
change. There are more then 7 million of these guys in Antarctica.Jane Younger, Author provided
Sensitivity to sea ice
Breeding colonies have been monitored for decades to determine the effects of a changing environment on the penguins. A common finding of many of these studies is that Adélies are highly sensitive to sea ice conditions.
Unlike emperor penguins, Adélies do not nest on the sea ice, but they must cross it to reach their nests on land. As everyone knows, penguins are not the most efficient walkers, and in years with a lot of sea ice their journeys to and from the ocean to feed their chicks can become lengthy. With a longer wait between meals chicks are less likely to survive.
In an extreme case, extensive sea ice at one breeding colony had a devastating impact in 2014, and not a single chick survived.
Based on these observations over years and decades, there has been concern that changing sea ice conditions, including increases in certain parts of Antarctica, could have a serious impact on Adélie penguin numbers in the future.
Short-term vs long-term climate change
However, the climate change that is taking place now is not a decadal trend. Rather, the shrinking glaciers and ice sheets, changing sea ice conditions, and shifting currents and weather patterns represent a global change to a new climate.
We therefore set out to understand how Adélie penguins in East Antarctica were affected by the last big shift to a different climate: the ending of the last ice age.
Following similar methods to our previous study on emperor penguins, we used genetic data to uncover the trend of the Adélie population in East Antarctica over the past 22,000 years. Researchers have been investigating penguins to see how they might respond to climate change.Laura Morrissey, Author provided
The end of the ice age
We found that, as for the emperor penguins, Adélies were far less common during the ice age. This is not at all surprising since most of their nesting sites would have been covered with glaciers and their feeding grounds encased in sea ice that never melted.
Following the end of the ice age 20,000 years ago, temperatures increased slowly, and after a few thousand years of warming the glaciers and ice sheets began to shrink. Fast forward to 10,000 years ago and the annual sea ice melting cycle that we see today was established.
Given the sensitivity of Adélie penguins to sea ice changes today, we predicted that Adélie numbers would remain very small until 10,000 years ago when sea ice conditions became similar to what they are now.
However, the penguins surprised us again. We found that the number of Adélies exploded by around 135-fold, but the expansion pre-dated the sea ice change by at least 3000 years. Penguin numbers exploded at the end of the last ice age.Jane Younger, Author provided
Shrinking glaciers
The proliferation of Adélie penguins in East Antarctica began during a period of ice sheet and glacier retreat, which would have increased the amount of ice-free ground available for nesting.
A study of Adélie penguins at the Scotia Arc, on the opposite side of the continent, found that numbers in this region rose 17,000 years ago. That expansion was several thousand years before the growth of the East Antarctic population, but coincided with the shrinking of glaciers in the Scotia Arc. This lends further support to our conclusion that it was glacier retreat, rather than changing sea ice conditions, that caused the hike in Adélie penguin numbers after the last ice age.
This is an important finding, as it suggests that the effects of climate change on a species over thousands of years can be quite different to the effects over years or decades. Given the long-term nature of contemporary climate change, we suggest that it is critical to consider millennial-scale trends alongside decadal ecological studies when predicting the effects of climate change on a species.
Could penguins benefit from future climate change?
Glaciers and ice sheets in Antarctica will continue to shrink. As this happens, ground that was previously covered in ice will become suitable for Adélie penguin nesting. In regions with adequate food supplies and where sea ice conditions remain favourable, Adélie penguin numbers may continue to grow.
A recent study using satellite images showed that one breeding colony in the Ross Sea grew by 84% between 1983 and 2010, as a direct result of a glacier shrinking by 543 m and uncovering new nesting sites.
While it seems that East Antarctic Adélie penguins might come out on top as climate change winners, it is important to keep in mind that for penguins to flourish their food supplies must be plentiful enough to meet the demands of a growing population. Whether this will be the case in the future remains to be seen, as Adélie penguin prey species, such as Antarctic krill, are threatened by both climate change and commercial fisheries.
In the 19th century, Darwin's most vocal scientific
advocate was Thomas Henry Huxley, who is also remembered as a pioneer of
the hypotheses that birds are living dinosaurs. He noticed several
similarities of the skeleton of living birds and extinct dinosaurs,
among them, a pointed portion of the anklebone projecting upwards onto
the shank bone (aka drumstick). This "ascending process" is well known
to specialists as a unique trait of dinosaurs. However, until the late
20th century, many scientists were doubtful about the dinosaur-bird
link. Some pointed out that the ascending process in most birds was a
projection of the neighbouring heel bone, rather than the anklebone. If
so, it would not be comparable, and would not support the dinosaur-bird
link.
Like modern amphibians, the remote ancestors
of birds once had three bones in their upper ankle. When these evolved
into landegg-laying animals, only two bones were present in this region.
In dinosaurs, one of these, the anklebone, presents a pointed upward
projection, the "ascending process". This trait is also present in
birds, which are living dinosaurs. A new detailed embryological study in
birds reveals that their ankle has re-evolved an amphibian-like
developmental pattern, with three separate elements, one of which
becomes the dinosaurian ascending process
Credit: Image courtesy of Universidad de Chile
In the 19th century, Darwin's most vocal
scientific advocate was Thomas Henry Huxley, who is also remembered as a
pioneer of the hypotheses that birds are living dinosaurs. He noticed
several similarities of the skeleton of living birds and extinct
dinosaurs, among them, a pointed portion of the anklebone projecting
upwards onto the shank bone (aka drumstick). This "ascending process" is
well known to specialists as a unique trait of dinosaurs. However,
until the late 20th century, many scientists were doubtful about the
dinosaur-bird link. Some pointed out that the ascending process in most
birds was a projection of the neighbouring heel bone, rather than the
anklebone. If so, it would not be comparable, and would not support the
dinosaur-bird link.
Some argued that in bird embryos, the ascending process develops from
the anklebone in dinosaur-like fashion, while others considered that
its development in birds is unique and different from dinosaurs.
Nowadays, the dinosaur-bird link is mainstream science, thanks to new
methods of data analysis, and a dense series of intermediate fossils
(including feathered dinosaurs). However, the disagreements about the
composition and embryology of the avian ankle were never clarified
fully. A new study in Nature Communications by Luis Ossa, Jorge
Mpodozis and Alexander Vargas, from the University of Chile, provides a
careful re-examination of ankle development in 6 different major groups
of birds, selected specifically to clarify conditions in their last
common ancestor. It also utilizes new techniques that allow
three-dimensional analysis of fluorescent embryonic skeletons, using
advanced spin-disc confocal microscopy and software.
This work has revealed that the ascending process does not develop
from either the heel bone or the ankle bone, but from a third element,
the intermedium. In the ancient lineage of paleognath birds (such as
tinamous, ostriches and kiwis) the intermedium comes closer to the
anklebone, producing a dinosaur-like pattern. However, in the other
major avian branch (neognaths), which includes most species of living
birds, it comes closer to the heel bone; that creates the impression it
is a different structure, when it is actually the same. "It puts the
final nail in the anti-dinosaur coffin" says Jacques Gauthier, a
vertebrate paleontologist and professor at Yale University "The
dinosaurian ascending process is retained in all birds, though it has
changed its association from ankle to heel bones in neognath birds."
More remarkably, however, this finding reveals an unexpected
evolutionary transformation in birds. In embryos of the landegg-laying
animals, the amniotes (which include crocodilians, lizards, turtles, and
mammals, who secondarily evolved live birth) the intermedium fuses to
the anklebone shortly after it forms, disappearing as a separate
element. This does not occur in the bird ankle, which develops more like
their very distant relatives that still lay their eggs in water, the
amphibians. Since birds clearly belong within landegg-laying animals,
their ankles have somehow resurrected a long-lost developmental pathway,
still retained in the amphibians of today -- a surprising case of
evolutionary reversal. The study also presented fossil evidence from
juvenile specimens of toothed birds from the Cretaceous period. These
show that, at this early stage of bird evolution, the ascending process
already developed separately.
Evolutionary reversions have always generated much discussion among
scientists, because ancient traits can occasionally re-appear in a
highly transformed context. A recent paper in BMC Evolutionary Biology
(Diaz and Trainor, 2015) has revealed that chameleons also re-evolved an
independent intermedium, in the specialized functional context of a
climbing reptile. The reappearance of this long-lost developmental
pattern in highly evolved organisms like birds and chameleons could be
compared to finding primitive clockwork gears inside your latest
smartphone. These intriguing discoveries are bound to renew discussion
about the interplay between the evolution of new functions and the
resurrection of old developmental patterns.
Story Source:
The above post is reprinted from materials provided by Universidad de Chile. Note: Materials may be edited for content and length.
Journal Reference:
Luis Ossa-Fuentes, Jorge Mpodozis, Alexander O Vargas. Bird embryos uncover homology and evolution of the dinosaur ankle. Nature Communications, 2015; 6: 8902 DOI: 10.1038/ncomms9902
Seabirds are being severely threatened by fisheries, pollution and
invasive species. Scientist and conservationalist Ross Wanless explains
to DW why the birds of the sea could be pivotal for survival of the
planet.
The African-Eurasian Waterbird Agreement (AEWA) met in Bonn, Germany,
November 9 through 13 to discuss conservation of seabirds. In addition
to aiming for an agreement from AEWA member countries on changing
fishery management to benefit migratory seabirds, researchers and
conservationists also worked together on managing other seabird threats.
DW caught up with Ross Wanless of BirdLife International toward the end of the conference in Bonn.
DW: What is the state of seabirds globally?
Ross Wanless: Seabirds are among the most threatened group of birds in
the world, in fact their conservation status has decreased faster than
any equivalent group of birds, so they are really not in good shape.
What is the biggest threat to seabirds?
There are two main threats, one is fisheries and a whole range of things
within that - so accidental mortality and overfishing - and the other
is invasive species on islands.
About 30 years ago, people discovered that when they counted up the
number of birds that had been caught up in tuna longline fishing hooks
and extrapolated that to the whole fishery, they realized that one or
two birds on each boat every day translated into tens of thousands of
albatrosses. That broke open a huge issue that we have been battling
with ever since: how to stop birds from being caught on longlines.
Solving the problems of seabird conservation, Wanless says, is not an easy job
What, if any, solution exists to address the impact of fisheries on sea birds?
There are many solutions, some of them are quite simple and
straightforward, don't cost a lot and allow fishing to continue really
essentially unchanged. Like just minor modifications to their gear, or
how fishers work.
There are other, probably more problematic solutions, such as reduction
in fishing and area closures to fishing. There is a whole suite of
things that can be done.
If we focus on your home country, South Africa, what would you say is needed there to help seabirds?
BirdLife South Africa has done some amazing work in preventing bycatch,
or the incidental catching of seabirds in our fisheries, and our
fisheries are some of the best in the world in terms of having solved
these enormous problems almost completely.
But, we're really grappling with the problem of the lack of food and the
role that fisheries play in causing the collapse of, for example,
African penguin populations. So, while we have been good at solving some
problems, we are still really coming to grips with some of the other
problems.
Through your work, you have initiated some large-scale conservation
programs to help the African penguin and other seabirds at risk of low
trophic level fisheries impacts, what has that entailed?
Low trophic level fisheries, or forage fisheries, are fisheries that
target the small things in the sea, like krill, or sardine or anchovy.
They tend to be at the base of the ecosystem, the base of the food
chain, so if you overfish those stocks, everything else that feeds on
them - the whales, the dolphins, the seals, the seabirds, the other fish
that are also commercially exploited - all take strain. It's a real
problem and that's the kind of fishing we have to manage very carefully,
and that is what we think is behind some of the African penguin
collapse.
We need to look at seabirds to understand how other marine life are faring, says Wanless
There is no question that overfishing happened in our waters in the
1960s. The stocks of fish have changed dramatically, and the penguin
numbers collapsed along with that.
How can people live harmoniously with seabirds?
I think to many people, there is a false dichotomy. It's not seabirds or
fisheries - actually, fisheries should be using seabirds. We believe
that penguins, for example in the southwestern part of Africa, are a
real sentinel: They are a signal that the marine system is under stress
and that if we don't pay attention, the fisheries could collapse.
What we are trying to convince people is: Use the penguins, the
information they are telling you is valuable, and you should maybe think
seriously about changing your fishing practices.
Pitting penguins or other seabirds against fisheries is really the wrong
way to look at it. When the penguins recover, you will probably have a
healthy ecosystem again.
I challenge you to answer the question "how many fish are in the sea"
with any degree of accuracy - but I can tell you exactly how many
penguins there are in southern Africa. We have really good data that we
can use, and if we could just change our mindset about that, I think
everyone would be in a better space.
The average person may possibly say "seabirds don't concern me" - why should we care about them?
Seabirds in many respects are an important tool for helping manage our
impact on the marine environment. The interconnectedness of the ocean is
dynamic and different from terrestrial environments, and we don't
really have a good understanding or ability to mange it. If we let the
seabirds go, if we forget about them and say we don't care, we can live
without them - maybe we are right, maybe we are wrong. If we are wrong,
have we lost something we can never recover, and everyone suffers at the
end of the day? We are playing a high-risk game by ignoring critical
components of ecosystems such as seabirds.
If we destroy those species, future generations will never forgive us - we have a responsibility to look after those things.
Fishers, government and individuals need to work together to ensure seabird survival, Wanless tells DW
What recent developments have been made to protect seabirds?
Seabirds are probably the most international birds of all birds, because
the high seas occupy about 60 percent of the surface of the Earth. No
one owns the high seas, so they are not in any one country's waters for
much of their lives. So we have to be joined up and work collaboratively
to protect them.
We have created the World Seabird Union, which brings together 90
percent of seabird
conversationalists and researchers, and that gives us
a united voice where we can discuss and plan around issues and hold
conferences. This allows us to pull things together in a joint way that
is so much more powerful than people or countries working individually.
What has come out of the Bonn conference?
The conference has really shown the willingness of countries to grapple
with issues and to find effective, efficient ways of addressing problems
- not duplicating existing initiatives or existing programs - and that
is really encouraging.
That means we are not throwing money at problems. Everyone is really
conscious of finding ways where an agreement can be used to do things
that no one else is doing, and we don't need to bother with where others
are doing them - that, to me, is a really encouraging sign.
Dr. Ross Wanless is the Africa Coordinator for the BirdLife
International Marine Programme, and the Seabird Conservation Programme
manager for BirdLife South Africa.
In a finding that could change the way scientists
think about bird evolution, researchers have found that the shape of
bird wings is influenced more by how closely related species are to one
another than by flight style.The research challenges scientific beliefs
that assume the way a bird species flies -- whether it primarily dives,
glides or flaps, for instance -- plays the primary role in the evolution
of its wing shape.
Samples of the dorsal (middle column) and
ventral (left column) sides of wings from bird specimens analyzed by the
researchers. The right column depicts a consensus wing shape generated
by analyzing the wing shape of 105 bird taxon (figure f), a figure
depicting how various wing shapes differed from the consensus wing
(figure g), and the magnitude of variation across different parts of the
consensus wing ( figure h). Credit: Xia Wang.
In a finding that could change the way
scientists think about bird evolution, researchers have found that the
shape of bird wings is influenced more by how closely related species
are to one another than by flight style.
The research challenges scientific beliefs that assume the way a bird
species flies--whether it primarily dives, glides or flaps, for
instance--plays the primary role in the evolution of its wing shape. It
also indicates that it may be more difficult than previously thought to
infer flying behaviors of early birds and the first flying dinosaurs
from fossils alone.
Julia Clarke, an associate professor in the Department of Geological
Sciences at The University of Texas Jackson School of Geosciences,
conducted the work with Xia Wang, a post-doctoral researcher who led the
study. Their research was published in the journal Proceedings of the Royal Society B: Biological Sciences in October.
Bird wings, unlike stiff airplane wings, are flexible and change
shape during flight. So, their geometry and wing outline may not tell
the whole story of a particular flight style or environment, Clarke
said. "We've taken a lot for granted. Birds are not airplanes," Clarke said.
By comparing geometry across species and clades -- groups of
organisms that evolved from a common ancestor -- the researchers found
that birds that are closely related evolutionarily have similar wing
structures, even if the birds show very different flight styles. For
example, albatrosses, penguins and loons, despite looking very different
from one another, all belong to the clade Aequornithes and have a wing
shape that is very similar.
The study is the first to analyze wing geometry across all major
groups of birds. Researchers
analyzed over 100 photographs of wings from
different bird species.
In general, the analysis of species from across nine major avian
clades showed that wing shape became more varied as different clades
diverged from early ancestors, Clarke said. The researchers found an
interesting exception to this trend in the wings of Passerines --a clade
that includes songbirds. Instead of a wing shape that resembles more
closely related relatives, their shape resembles that of Galliformes, a
distantly related order that includes birds, such as chickens and
turkeys, whose direct ancestors were among the first birds on the
planet. "Those little songbirds share aspects of wing geometry, especially
the relative length of the covert feathers, with some of early bird
species but have very different body sizes, ecologies and flight
styles," Clarke said.
Clarke and Wang also studied covert feathers in these birds. They
found that across clades these feathers, which cover the base of the
flight feathers, are about the same length whether they are on the top
or underside of a wing. The similarity of covert feathers both on a
single wing and across clades, brings into question their function,
Clarke said.
It's been proposed that some of the upper coverts may play a sensory
role, and the lower or underwing coverts, a role in aerodynamics. But
the similarity in the distribution and organization of covert feathers
on both sides of the wings suggests that such distinct roles may not be
the case, Clarke said. "There's no existing hypothesis to explain that pattern," Clarke
said. "So a question now is why the length of these feathers tends to be
similar and why they show similar trends across birds. We could be
looking for a developmental explanation or a functional one."
Story Source:
The above post is reprinted from materials provided by University of Texas at Austin. Note: Materials may be edited for content and length.
Journal Reference:
Xia Wang, Julia A. Clarke. The evolution of avian wing shape and previously unrecognized trends in covert feathering. Proceedings of the Royal Society B: Biological Sciences, 2015; 282 (1816): 20151935 DOI: 10.1098/rspb.2015.1935
Dramatic changes in climate force birds to swim more than 80 miles further in search of fish
Between 1992 and 2010, researchers fitted king penguins with trackers
This allowed them to track their movements in the Indian Ocean
A climate anomaly of just 1°C (34°F) can shift the limit of the polar front
This increases how far birds swim to find fish by up to 83 miles (130km)
By
Victoria Woollaston for MailOnline
Published:
28 October 2015
Weather
forecasters have been warning us to prepare for a 'monster' El Niño
this winter and now experts believe it could also have a devastating
effect on penguin numbers.
By
tracking a group of king penguins, researchers have discovered that a
climate anomaly of just 1°C (34°F) can increase how far they have to
swim in search of fish by up to 83 miles (130km).
During
the last major El Niño event in 1997, penguin populations fell by a
third and this year's event threatens to be similarly harmful.
Over a 16-year period researchers
discovered that a climate anomaly of just 1°C (34°F) can increase how
far king penguins (pictured) have to swim in search for fish by up to 83
miles (130km). During the last major El Niño event in 1997, penguin
populations fell by a third and this year's event could be similarly
devastating
Between
1992 and 2010, a group of 15 breeding penguins from the king penguin
colony of the Baie du Marin, Possession Island, Crozet were fitted with
satellite transmitters.
During summer, these penguins were tracked swimming from the Crozet Islands to forage for fish in the Antarctic polar front.
A polar front is an area where cold polar air meets warm tropical air and this boundary can measure thousands of miles long.
King
penguins, as well as other predators, get the majority of their food
from this region because the conditions are suitable for high
concentrations of zooplankton and fish.
The penguins were tracked swimming
from the Crozet Islands (represented by the orange dot) to forage for
fish in the Antarctic polar front (marked by the green lines). This
distance remained relatively stable until 1997, the year of the
strongest El Niño on record, when the southern limit shifted
dramatically
During this year, sea surface
temperatures (pictured) in the southern Indian Ocean rose 1°C (34°F)
above average and this caused the polar front to shift by around 83
miles (130 km)
The Crozet penguins (pictured) were each fitted with satellite transmitters
The
southern limit of this front can shift in response to changes in
climate, and significant climatic events such as El Niño can cause it to
move significantly.
By
following the penguins' movements, the researchers obtained a total of
124 tracks they could use to analyse climate changes and foraging
distances.
Each track corresponded to the 'at-sea movements' of a penguin during one foraging trip off the colony.
Each year, over the 16-year tracking period, the penguins were seen leaving the Crozet Islands and typically heading south.
This distance remained relatively stable until 1997, the year of the strongest El Niño on record.
During
this year, sea surface temperatures in the southern Indian Ocean rose
1°C (34°F) above average and this caused the southern limit of the polar
front to shift by around 83 miles (130 km).
This doubled the length of time the penguins were at sea and away from the safety of the group.
'During
a climatically-extreme year, a strong southward shift of the polar
front produced a doubling of the mean distance that penguins travelled
on foraging trips, coinciding with a 34 per cent decline in the
archipelago’s breeding population the following year,' explained the
researchers.
'Future
climatic scenarios predict that the polar front may shift even further
southwards, posing a potentially serious threat to the persistence of
diving predators in the region.'
El Niño is caused by a shift in the
distribution of warm water in the Pacific Ocean around the equator. The
National Oceanic Atmospheric Administration recently issued its official
winter forecast and said 'the driver of this winter's outlook is El
Niño'. It warned this year's event (right) is likely to equal the event
of 1997 (left)
The shift in the polar front was found
to double the length of time the penguins (pictured) were at sea and
away from the safety of the group. Predictions suggest that the polar
front may shift even further southwards in the future, which would pose a
potentially serious threat to the colonies in the region
WHAT IS EL NIÑO
El Niño is caused by a shift in the distribution of warm water in the Pacific Ocean around the equator.
Usually
the wind blows strongly from east to west, due to the rotation of the
Earth, causing water to pile up in the west of the Pacific.
This pulls up colder water from the deep ocean in the eastern Pacific.
However, in an El Niño, the winds pushing the water get weaker and cause the warmer water to shift back towards the east.
This causes the eastern Pacific to get warmer.
But
as the ocean temperature is linked to the wind currents, this causes
the winds to grow weaker still and so the ocean grows warmer, meaning
the El Niño grows.
This
change in air and ocean currents around the equator can have a major
impact on the weather patterns around the globe by creating pressure
anomalies in the atmosphere.
El Niño is caused by a shift in the distribution of warm water in the Pacific Ocean around the equator.
Usually
the wind blows strongly from east to west, due to the rotation of the
Earth, causing water to pile up in the western part of the Pacific.
This pulls up colder water from the deep ocean in the eastern Pacific.
However, in an El Niño the winds pushing the water get weaker and cause the warmer water to shift back towards the east.
This causes the eastern Pacific to get warmer.
But
as the ocean temperature is linked to the wind currents, this causes
the winds to grow weaker still and so the ocean grows warmer, meaning
the El Niño grows.
This
change in air and ocean currents around the equator can have a major
impact on the weather patterns around the globe by creating pressure
anomalies in the atmosphere.
The
National Oceanic Atmospheric Administration recently issued its
official winter forecast and said 'the driver of this winter's outlook
is El Nino.'
It warned that this year's El Niño is already strong and appears likely to equal the event of 1997 and 1998.
Seabirds
are considered to be useful and practical indicators of the state of
marine ecosystems because they integrate across changes in the lower
trophic levels and the physical environment. Signals from this key group
of species can indicate broad scale impacts or response to
environmental change. Recent studies of penguin populations, the most
commonly abundant Antarctic seabirds in the west Antarctic Peninsula and
western Ross Sea, have demonstrated that physical changes in Antarctic
marine environments have profound effects on biota at high trophic
levels. Large populations of the circumpolar-breeding Adélie penguin
occur in East Antarctica, but direct, standardized population data
across much of this vast coastline have been more limited than in other
Antarctic regions. We combine extensive new population survey data, new
population estimation methods, and re-interpreted historical survey data
to assess decadal-scale change in East Antarctic Adélie penguin
breeding populations. We show that, in contrast to the west Antarctic
Peninsula and western Ross Sea where breeding populations have decreased
or shown variable trends over the last 30 years, East Antarctic
regional populations have almost doubled in abundance since the 1980’s
and have been increasing since the earliest counts in the 1960’s. The
population changes are associated with five-year lagged changes in the
physical environment, suggesting that the changing environment impacts
primarily on the pre-breeding age classes. East Antarctic marine
ecosystems have been subject to a number of changes over the last 50
years which may have influenced Adélie penguin population growth,
including decadal-scale climate variation, an inferred mid-20th century
sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.
New research projects a doubling of surface
melting of Antarctic ice shelves by 2050 and that by 2100 melting may
surpass intensities associated with ice shelf collapse, if greenhouse
gas emissions from fossil fuel consumption continue at the present rate.
The study's lead author, Luke
Trusel, standing in front of sea ice covered in melt ponds in December
2010 outside of McMurdo Station, Antarctica.
Credit: Photo courtesy of Luke Trusel
New research published today projects a
doubling of surface melting of Antarctic ice shelves by 2050 and that
by 2100 melting may surpass intensities associated with ice shelf
collapse, if greenhouse gas emissions from fossil fuel consumption
continue at the present rate.
Ice shelves are the floating extensions of the continent's massive
land-based ice sheets. While the melting or breakup of floating ice
shelves does not directly raise sea level, ice shelves do have a "door
stop" effect: They slow the flow of ice from glaciers and ice sheets
into the ocean, where it melts and raises sea levels.
"Our results illustrate just how rapidly melting in Antarctica can
intensify in a warming climate," said Luke Trusel, lead author and
postdoctoral scholar at Woods Hole Oceanographic Institution (WHOI).
"This has already occurred in places like the Antarctic Peninsula where
we've observed warming and abrupt ice shelf collapses in the last few
decades. Our model projections show that similar levels of melt may
occur across coastal Antarctica near the end of this century, raising
concerns about future ice shelf stability."
The study, published Oct. 12, 2015, in Nature Geoscience,
was conducted by Trusel, Clark University Associate Professor of
Geography Karen Frey, WHOI scientists Sarah Das and Kristopher
Karnauskas, Peter Kuipers Munneke and Michiel R. van den Broeke of the
Institute for Marine and Atmospheric Research Utrecht University, and
Erik van Meijgaard of the Royal Netherlands Meteorological Institute.
To study how melting evolves over time and to predict future ice
sheet melting along the entire Antarctic coastline, the scientists
combined satellite observations of ice surface melting with climate
model simulations under scenarios of intermediate and high levels of
greenhouse gas emissions until the year 2100.
The results indicate a strong potential for the doubling of
Antarctica-wide ice sheet surface melting by 2050, under either
emissions scenario. However, between 2050 and 2100, the models reveal a
significant divergence between the two scenarios. Under the
high-emissions climate scenario, by 2100 ice sheet surface melting
approaches or exceeds intensities associated with ice shelf collapse in
the past. Under the reduced-emissions scenario, there is relatively
little increase in ice sheet melting after the doubling in 2050.
"The data presented in this study clearly show that climate policy,
and therefore the trajectory of greenhouse gas emissions over the coming
century, have an enormous control over the future fate of surface
melting of Antarctic ice shelves, which we must consider when assessing
their long-term stability and potential indirect contributions to sea
level rise," said Frey.
Funding for the research was provided by NASA, the Doherty
Postdoctoral Scholarship Program at WHOI, the Netherlands Earth System
Science Centre, the Polar Program of the Netherlands Organization of
Scientific Research, and the Dutch Ministry of Infrastructure and the
Environment.
Luke D. Trusel, Karen E. Frey, Sarah B. Das, Kristopher B.
Karnauskas, Peter Kuipers Munneke, Erik van Meijgaard & Michiel R.
van den Broeke. Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios. Nature Geoscience, 2015 DOI: 10.1038/ngeo2563
A world-first global analysis of marine responses to
climbing human carbon dioxide emissions has painted a grim picture of
future fisheries and ocean ecosystems.
A world-first global analysis of marine responses to climbing human CO2 emissions has painted a grim picture of future fisheries and ocean ecosystems.
Published today in the journal Proceedings of the National Academy of Sciences (PNAS),
marine ecologists from the University of Adelaide say the expected
ocean acidification and warming is likely to produce a reduction in
diversity and numbers of various key species that underpin marine
ecosystems around the world.
"This 'simplification' of our oceans will have profound consequences
for our current way of life, particularly for coastal populations and
those that rely on oceans for food and trade," says Associate Professor
Ivan Nagelkerken, Australian Research Council (ARC) Future Fellow with
the University's Environment Institute.
Associate Professor Nagelkerken and fellow University of Adelaide
marine ecologist Professor Sean Connell have conducted a 'meta-analysis'
of the data from 632 published experiments covering tropical to artic
waters, and a range of ecosystems from coral reefs, through kelp forests
to open oceans.
"We know relatively little about how climate change will affect the
marine environment," says Professor Connell. "Until now, there has been
almost total reliance on qualitative reviews and perspectives of
potential global change. Where quantitative assessments exist, they
typically focus on single stressors, single ecosystems or single
species.
"This analysis combines the results of all these experiments to study
the combined effects of multiple stressors on whole communities,
including species interactions and different measures of responses to
climate change."
The researchers found that there would be "limited scope" for
acclimation to warmer waters and acidification. Very few species will
escape the negative effects of increasing CO2, with an
expected large reduction in species diversity and abundance across the
globe. One exception will be microorganisms, which are expected to
increase in number and diversity.
From a total food web point of view, primary production from the
smallest plankton is expected to increase in the warmer waters but this
often doesn't translate into secondary production (the zooplankton and
smaller fish) which shows decreased productivity under ocean
acidification.
"With higher metabolic rates in the warmer water, and therefore a
greater demand for food, there is a mismatch with less food available
for carnivores ─ the bigger fish that fisheries industries are based
around," says Associate Professor Nagelkerken. "There will be a species
collapse from the top of the food chain down."
The analysis also showed that with warmer waters or increased
acidification or both, there would be deleterious impacts on
habitat-forming species for example coral, oysters and mussels. Any
slight change in the health of habitats would have a broad impact on a
wide range of species these reefs harbour.
Another finding was that acidification would lead to a decline in
dimethylsulfide gas (DMS) production by ocean plankton which helps cloud
formation and therefore in controlling Earth's heat exchange.
Story Source:
The above post is reprinted from materials provided by University of Adelaide. Note: Materials may be edited for content and length.
Journal Reference:
Ivan Nagelkerken and Sean D. Connell. Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions. PNAS, October 12, 2015 DOI: 10.1073/pnas.1510856112
There
are many advantages to being alive today, but there is one
disadvantage—we missed out on seeing the best animal ever. Thirty-seven
million years ago, the oceans and land were patrolled by a 6’8” penguin.
Today,
Antarctic penguins are struggling. Thirty-seven million years ago, life
was good. The coast of the continent was home to many different species
of penguin, some of which would look familiar to us today. Others, not
so much.
One penguin in particular would make us look twice—and possibly run. Palaeeudyptes klekowskii was sized up as the result of two differentfinds.
Neither was a complete skeleton, but both provided multiple wing bones
and foot bones that allowed scientists to estimate the penguin’s size.
Assuming it had the same proportions as modern penguins, this extinct megapenguin was a little over six-and-a-half feet tall. Before the discovery, the largest penguin species to ever have existed was thought to be only about five feet tall, just a foot taller than the Emperor penguin. Palaeeudyptes klekowskii
would have stood out, even among the other penguins waddling around
with it in its own time. It also would have dived down lower than other
penguins, or at least stayed underwater longer.
A larger body means a
larger lung capacity, so these penguins would probably have been able to
stay under water for 40 minutes between breaths. Imagine a
basketball-player-sized penguin coming at you from out of the darkness.
Who doesn’t enjoy waking to a pleasant smell wafting past?
Unfortunately for them, the penguins in a recent study woke up not to
pancakes frying nearby, but to less appetizing aromas—for example, feces
on a stick. But scientists promise the experiment taught them valuable
lessons about a penguin’s capabilities. Besides, they let the birds go
right back to sleep.
“Research into the sense of smell in birds has a bit of a dubious history,” says Gregory Cunningham,
a biologist at St. John Fisher College. In recent decades, scientists
have begun to get a better grasp on what birds can smell, but there’s
still a lot to learn.
With king penguins (Aptenodytes patagonicus), researchers
have focused more on sound than smell. The birds form monogamous pairs
to breed; parents take turns caring for the egg or chick and foraging
for food. When a penguin returns from the sea, it uses the sound of its
partner’s squawk to find it among the huge breeding colony.
Penguins seem to use their sense of smell to help them hunt for fish,
so it’s possible the birds also use smell to find each other. Maybe
they can sniff out the colony when they’re getting close; maybe they can
even recognize the individual scent of a partner. The first step toward
finding out is to see how penguins react to the smell of other
penguins. Do they notice the smell of penguin feces or feathers?
Cunningham and his coauthor, Francesco Bonadonna, studied a king
penguin colony in the Kerguelen Islands. (Coincidentally, the scientists
shared a beach with some other researchers you may have read about
here, who were studying whether penguins find each other’s beaks sexy.)
To test the birds’ sensitivity to smells, Cunningham and
Bonadonna would use a very simple test: could the smell wake a sleeping
penguin?
The researchers wrapped duct tape around the ends of metal dowels,
sticky side out. Then they rolled the tape in one of three materials:
ordinary sand, recently molted penguin feathers, or fresh penguin poop.
Cunningham says the feathers and feces were both easily detectable to a
human nose. (The feces “did not smell very good,” he notes, while the
feathers had a more subtle, “perhaps musky” odor.)
On the beach, they looked for penguins that were asleep, standing
with their beaks tucked under one wing. They tested 108 sleeping birds.
Each time, a researcher crept up to the penguin and held one of the odor
sticks about an inch beneath its beak. After 15 seconds, they scored
the bird’s reaction. A penguin got a score of zero if it kept dozing, 1
if it moved its head a little or clacked its beak, 2 if it twitched, and
3 if it woke up outright.
It may not be shocking that an animal can smell a blob of poop. But
Cunningham says this preliminary experiment will eventually help us
understand how penguins use scent to get around. He’s shown that the
birds can detect the smell of other penguins; the next step will be to
learn whether they use these smells to rendezvous with their colonies or
partners.
“We’re taking a species that has long been thought to use primarily
acoustic cues to identify each other,” Cunningham says, “and adding
another layer of complexity to their umwelt, their sensory
world.” Meanwhile, the animals probably wish the scientists would add a
layer of something between those poop sticks and their beaks.
ELIZABETH FIEDLER It’s an early August morning on a nearly deserted beach in southern Brazil, and 23 Magellanic penguins (Spheniscus magellanicus)
are tottering toward the water. These penguins are survivors. About two
months ago, birds that should have been swimming and feeding offshore
started washing up on the beaches of the Brazilian state of Santa
Catarina, primarily near the city of Florianopolis. More than 120 have
come ashore this year, but most were too weak to survive. The birds now
heading toward the Atlantic waves lapping Moçambique Beach were
rehabilitated by a group of veterinarians and volunteers who stand
gathered on the shore, watching their avian charges disappear into the
water.
Each year around April, as the Southern Hemisphere winter approaches,
the Magellanic penguins, also known as Patagonian penguins, leave their
breeding grounds in southern Argentina. They migrate northward to
wintering grounds in the coastal waters of northern Argentina, Uruguay,
and southern Brazil in search of food. (Some southernmost breeders also
head along Chile’s Pacific shores, but that route is less well studied.)
It’s a monumental journey: a round-trip of up to 4,000 kilometers that
coincides with the seasonal spawning of anchovies, a staple of the
penguins’ diets. The birds face many challenges along the way, and some
run out of strength, winding up on Brazil’s beaches in serious need of
help.
Birds like these appear every year, while others continue their travels
even farther north. Researchers are still trying to understand exactly
why some birds end up farther from home than ever before.
These temperate penguin species demonstrate that new challenges are confronting their populations.—P. Dee Boersma,
University of Washington
Cristiane Kolesnikovas
is a veterinarian with Associação R3 Animal, an NGO that does wildlife
rehabilitation for the Santa Catarina State government. Sitting in her
office at Parque Estadual do Rio Vermelho, the state park where the
penguins are rehabilitated, Kolesnikovas says each year the penguins
swim north until they find sufficient food. Most of the birds that show
up here are not injured—just weak.
“Most of them are juveniles that we think cannot eat as well as the
adults, so they beach,” she says. “And some are caught by nets.” But for
the most part, the circumstances that lead to the penguins’ arrival on
Brazilian beaches are still mysterious.
Recent years have been tough for Magellanic penguins along the Atlantic
coast of South America. In 2008, more than 3,000 birds were found
stranded along the coast of Brazil—almost all of them juveniles. Nearly
15 percent of the birds were smothered in oil, and about a third were
dead.
Pablo García Borboroglu,
a researcher at Argentina’s National Research Council and president of
the Global Penguin Society, and collaborators studied what happened with
the penguins in 2008 and reported their findings in a 2010 Marine Pollution Bulletin
article: the penguins had strayed far north of their normal winter
migration path (60:1652-57). A few nearly reached the Equator. Most of
the birds that went as far as northern Brazil were juveniles. Many were
dehydrated, anemic, hypothermic, and emaciated, García Borboroglu says.
He notes one factor that may have contributed to the anomalous migration
is that year’s unusually cold sea-surface temperatures around the time
that the anchovy were spawning, which may have depleted the penguins’
key prey base. PENGUIN
KINDERGARTEN: Veterinarian Cristiane Kolesnikovas checks on juvenile
Magellanic penguins at the Parque Estadual do Rio Vermelho the day
before some of them would be released into the wild.ELIZABETH FIEDLER
García
Borboroglu is tracking the birds to better understand the challenges
they face. He’s used satellite trackers attached to their backs and
bands on their feet, but he says he is still searching for a system that
can withstand months in salt water and has a suitably long battery
life.
García Borboroglu says he believes climate change is causing the birds
to modify their migration route, but it is difficult to know for
certain. He adds that most climate–change models predict increased
anomalies, such as swings in temperature, throughout Earth’s oceans.
P. Dee Boersma,
a collaborator of García Borboroglu who heads the University of
Washington’s Center for Penguins as Ocean Sentinels, says that
temperate-zone penguins, even while pairs are incubating eggs and taking
turns feeding at sea, are swimming 60 km farther north from their nests
than they did a decade ago. This change likely reflects “shifts in prey
in response to climate change and reductions in prey abundance caused
by commercial fishing,” she says. “These temperate penguin species,
marine sentinels for southern oceans, demonstrate that new challenges
are confronting their populations.”
Knowing what is going on with penguins could prove useful for
understanding the changing nature of marine ecosystems in a broader
sense. Those changes include increases in precipitation and reductions
in sea ice associated with climate warming. In a 2008 BioScience
article, Boersma wrote that as “ocean samplers, penguins provide
insights into patterns of regional ocean productivity and long-term
climate variation” (58: 597-607). Boersma says that after more than 30
years of studying temperate penguins, her research suggests that marine
systems now face “a new era of unprecedented challenges.”
