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.”
With its spiky head plumage and intense red eyes, the southern rockhopper penguin (Eudypteschrysocome,
seen above) looks more like a slightly predatory guy at a college party
than a committed monogamous partner. But these males mate for life,
reuniting with the same female year after year during mating season.
Despite their monogamous mating patterns, however, the birds really
don’t spend much time together, according to a new study. Using GPS
trackers mounted to the penguins’ legs, scientists monitored 16 birds
from a colony in the Falkland Islands over the course of a mating
season. The data show that males arrived at the nesting site
approximately 6 days before their female counterparts and stayed about 6
days longer. However, the short mating season means the pairs are only
united for about 20 to 30 days a year. And when they were separated, it
was usually by a large distance: During the winter months, partners were separated by an average distance of about 600 km, and one pair was observed as far as 2500 km apart, the team reports online today in Biology Letters.
Despite the large spatial segregation, their habitats were quite
similar, ruling out the possibility that partners are spending the
winter months apart because of sex-based differences in habitat or food
preference. So why don’t the birds just stick together? So far it’s
still a mystery, but the team speculates that if the birds arrived at
and left the nesting site at the same time, they’d be much more likely
to spend the winter together. But because the females show up late and
leave early, the cost of finding one another after a week of dispersing
through the open ocean might not be worth it—it’s easier to just meet
back at the nesting site next year.
This Eocene Antarctic fossil penguin skull was discovered at La Meseta Formation at Seymour Island. Credit: Journal of Vertebrate PaleontologyWhen they're not being the stars of various
animated movies, penguins are playing an important role in evolutionary
studies. Penguins are unique among modern birds in that they 'fly'
through the water. Although flightless in air, penguins have a number of
adaptations which allow them glide effortlessly through the water. And
some of these adaptations are in an unlikely part of their anatomy -
their brains. Recent finds of fossil penguins from 35 million year old
sediments in Antarctica have begun to shed light on the changes in
penguin brains that accompanied their transition to water.
"Comparing multiple species (extinct and living penguins
and living birds that both fly and dive), in the way our study does,
brings us closer to the answers of two major questions about penguin
brain evolution: (1) what major morphological changes have occurred, (2)
when did these changes occur?" said lead author Claudia Tambussi. The
new finds, which are described in the latest issue of the Journal of Vertebrate Paleontology, include skulls which are so well-preserved that they could be CT-scanned to analyze their internal structure.
These scans revealed some interesting traits of these early penguins
that speak to their transitional nature. Many of these findings have to
do with the sensory abilities of these fossil species. For instance, one
area, the Wulst, which is associated with complex visual functions, is
enlarged. "The Antarctic fossils reveal that the neuroanatomy of
penguins was still evolving roughly 30 million years after the loss of
aerial flight, with trends such as the expansion of the Wulst and
reduction of the olfactory bulbs still in progress", said co-author
Daniel Ksepka.
In addition to the increase in visual complexity, and reduction in
olfaction, findings in the ear region shed light on the head position
and equilibrium-maintaining abilities of the fossil penguins. All
together, the findings show that these early penguins had many of the
adaptations of living forms, while having a few unique traits not seen
in the modern ones. Not only that, but some of these adaptations are
found in modern flying birds, attesting to penguins' unique mode of
swimming.
In this gif, one of the Antarctic Eocene skulls is featured. The virtual brain
is in blue: in red the right inner ear and carotids; in yellow the
olfactory bulbs and some nerves. Credit: Journal of Vertebrate Paleontology
Said Ksepka, "Penguins are considered flightless, but when it comes
to wing-propelled diving they are essentially practicing underwater
flight. The brain morphology reflects this as penguins retain an overall
"flight-ready" brain."
On Seymour Island emerges the La Meseta Formation, the most
prolific localities for fossil penguin remains worldwide in terms of raw
abundance. Credit: Journal of Vertebrate Paleontology
satellite image of the Galápagos Islands in 2002. Almost all of
the Galápagos penguins live along the western coasts of Isabela and
Fernandina, and two–thirds of the birds reside along the southwestern
bulge of Isabela. Credit: Imagery NASA
Shifts in trade winds and ocean currents powered a resurgence of
endangered Galápagos penguins over the past 30 years, according to a new
study. These changes enlarged a cold pool of water the penguins rely on
for food and breeding - an expansion that could continue as the climate
changes over the coming decades, the study's authors said.
The Galápagos Islands, a chain of islands 1,000 kilometers (600 miles) west of mainland Ecuador, are home to the only penguins
in the Northern Hemisphere. The 48-centimeter (19-inch) tall black and
white Galápagos penguins landed on the endangered species list in 2000
after the population plummeted to only a few hundred individuals and are
now considered the rarest penguins in the world.
Most of the penguins live on the archipelago's westernmost islands,
Isabela and Fernandina, where they feed on fish that live in a cold pool
of water on the islands' southwestern coasts. The cold pool is fed by
an ocean current,
the Equatorial Undercurrent, which flows toward the islands from the
west. When the current runs into Isabela and Fernandina, water surges
upward, bringing cold, nutrient-rich water to the surface.
New research suggests shifts in wind currents over the past three
decades, possibly due to climate change and natural variability, have
nudged the Equatorial Undercurrent north. The changing current expanded
the nutrient-rich, cold water
farther north along the coasts of the two islands, likely bolstering
algae and fish numbers in the cold pool. This allowed the penguin
population to double over the past 30 years, swelling to more than 1,000
birds by 2014, according to the new study.
Climate change could further shift wind patterns and ocean currents,
expanding cold water further north along the coasts of Isabela and
Fernandina and driving fish populations higher, according to the new
study.
Penguins, as well as other animals like fur seals and marine iguanas
that feed and reproduce near the cold waters, may increase in numbers as
the northwestern coasts of the islands become more habitable, said the
study's authors. They noted that wind and ocean currents could also
return to earlier conditions, leading to a decline in penguin
populations.
"The penguins are the innocent bystanders experiencing feast or
famine depending on what the Equatorial Undercurrent is doing from year
to year," said Kristopher Karnauskas, a climate scientist who performed
the research while at Woods Hole Oceanographic Institution in Cape Cod,
Massachusetts, and lead author of the new study recently accepted in Geophysical Research Letters, an American Geophysical Union journal.
The new findings could help inform conservation efforts to save the
endangered penguins, said the study's authors. Increasing efforts on the
northern coasts of the islands and expanding marine-protected areas
north to where the penguins are now feeding and breeding could support
population growth, the study's authors said.
Karnauskas notes that the vast majority of marine organisms will be
negatively affected by the rise in ocean temperatures and acidification
that are expected to occur across the globe as a result of climate
change.
"With climate change, there are a lot of new and increasing stresses
on ecosystems, but biology sometimes surprises us," said Karnauskas.
"There might be places—little outposts—where ecosystems might thrive
just by coincidence."
(Photo : Flickr: Aaron Logan)
Penguin population changes
The Galápagos penguin population tenuously hangs onto the islands
that so enthralled Charles Darwin during his visit in 1835. The penguins
once numbered around 2,000 individuals, but in the early 1980s a strong
El Niño - a time when sea surface temperatures in the tropical Pacific
are unusually warm - brought their numbers down to less than 500 birds.
Dogs, cats and rats introduced to the islands also stymied the penguin
population by attacking the birds, disturbing their nests, and
introducing new diseases, according to previous research.
Despite these setbacks, the penguins gradually increased in number in
the following decades, according to local bird counts. Researchers,
interested by the increase in penguins, noted that the birds remained
near the coldest stretches of water. Nearly all of the Galápagos
penguins live on the western coasts of Isabela and Fernandina, and
two-thirds of them huddled near the coldest waters at the southern tips
of the islands, according to previous research.
The study's authors wanted to know whether the growing numbers of
penguins were related to local changes in ocean temperature. They
combined previously-collected penguin population data from 1982 to 2014
with sea surface temperature data from satellites, ships and buoys for
the same time period.
They found that the cold pool, where sea surface temperatures are
below 22 degrees Celsius (71 degrees Fahrenheit), expanded 35 kilometers
(22 miles) farther north than where it was located at the beginning of
the study period. In the 1980s the cold water pocket reached only the
southern halves of the western coasts of Isabela and Fernandina. By
2014, the cold water pocket extended across the entire western coasts of
the islands.
Varying trade winds, ocean currents
A shift in trade winds and underwater ocean currents likely caused the Galápagos cold pool expansion, propose the authors.
Trade winds blow surface ocean waters from the southern side of the
equator to the northern side of the equator. As surface waters pile up
in the north, the water at the bottom of the pile is squished south,
nudging the Equatorial Undercurrent - a cold current that flows roughly
50 meters (160 feet) under the ocean surface - south of the equator.
Likely due to a combination of natural variation and human-caused
climate change, trade winds west of the Galápagos slackened during the
study period, lessening the pressure pushing the Equatorial Undercurrent
south, according to the new study. Consequently, the ocean current
gradually shifted north, increasing the amount of cold water coming to
the Galápagos Islands, according to the study's authors.
Satellite images showed that this expanded pool of cold water likely
encouraged the growth of phytoplankton, according to the new study. This
increase in ocean algae attracted fish to the area - the main entrée
for Galápagos penguins, suggest the authors. The largest pulses of cold
water reached the islands from July through December, coinciding with
the penguins' breeding season. The bountiful fish helped the birds
successfully reproduce and feed their young, according to the new study.
Models indicate trade winds will continue to abate in the future as
the climate warms, Karnauskas said. This could cause the undercurrent to
continue to move north, expanding the Galápagos cold pool and possibly
further raising penguin populations, he said. Other animal populations
like the endangered Galápagos fur seal and the marine iguana also may
profit from the prolific amount of food in the Galápagos cold pool,
according to the study's authors.
Wind and ocean currents could also possibly return to where they were
in the 1980s, compressing the cold pool and possibly leading to a
decline in penguins, Karnauskas added.
The new study shows how large-scale changes in the climate can act
locally, said Michelle L'Heureux, a climate scientist with the National
Oceanic and Atmospheric Administration's Climate Prediction Center in
College Park, Maryland, and not an author on the new paper.
"While it is important that we focus on the big picture with climate change, it's really the small scale that matters to the animals and plants that are impacted," she said.
Survival of endangered African penguin chicks
increased by 18 percent following a trial three-year fishery closure
around Robben Island in South Africa, a new study has found.
Survival of endangered African penguin
chicks increased by 18% following a trial three-year fishery closure
around Robben Island in South Africa, a new study from the University of
Exeter has found.
The results, which are published in the Royal Society Journal Biology Letters, indicate that even small 'no-take zones' can dramatically improve the survival chances of endangered species.
The African penguin population is in freefall, with adult survival
rates over the last decade desperately low. Although the ban on
commercial fishing off Robben Island has boosted chick survival, the
long term prospect for the species remains gloomy.
Dr Richard Sherley from the University of Exeter said: "One of the
major challenges of conserving a mobile species like the African penguin
is that once they leave a protected area they are subject to outside
pressures and dangers, including poor prey availability.
"Our study shows that small no-take zones can aid the survival of
African penguin chicks, but ultimately commercial fishing controls must
be combined with other management action if we are to reverse the
dramatic decline of this charismatic species."
African penguins feed on sardines and anchovies but fishing of these
species off Cape Town is considered to have contributed to a 69%
reduction in penguin numbers between 2001 and 2013.
The species' worsening conservation status led to experimental
fishing closures around four colonies between 2008 and 2014. These were
earlier found to reduce penguin foraging effort but a beneficial impact
on demographic parameters had not been demonstrated before this study
and so the benefits of the closures have been the subject of much
debate.
Although this study has shown that the fishery closure around Robben
Island has improved chick survival, if the current fishing pressure
exerted on sardine in particular continues on the west coast there will
still not be sufficient food to allow the penguin population to recover.
Seabirds will often respond to a scarcity of food by skipping or
abandoning breeding, opting not to re-lay after losing clutches of eggs,
or reducing the amount of food brought to the chicks leading to slow
growth, poor chick condition and mortality through starvation. African
penguins have shown all of these responses in recent years.
1501 nests were monitored at Robben Island between 2001 and 2013 to
determine chick survival rates and a hydro-acoustic survey was carried
out to estimate sardine and anchovy biomass.
Story Source:
The above post is reprinted from materials provided by University of Exeter. Note: Materials may be edited for content and length.
Journal Reference:
Richard B. Sherley, Henning Winker, Res Altwegg, Carl D. van der Lingen, Stephen C. Votier, Robert J. M. Crawford. Bottom-up effects of a no-take zone on endangered penguin demographics. Biology Letters, July 2015 DOI: 10.1098/rsbl.2015.0237
