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Mercer-Golden 1 Benjy Mercer-Golden Professor Bill Durham Sophomore College 2012: “Darwin, Evolution and Galápagos” 15 October 2012 El Niño and Extinction-Level Threats to the Galápagos Penguin ABSTRACT In a fragile environment like the Galápagos, where the conservation problems that seem most alarming tend to be the more tangible issuesoverpopulation, a steadily rising touristic impact, over-fishing and illegal marine poaching, introduced species, etc.it is easy to lose sight of other significant problems that are more difficult to see with the naked eye. One such issue is that of climate change as it affects endemic species, especially those living in marine ecosystems. This paper will attempt to evaluate the evidence for a connection between anthropogenic global warming and El Niño events that are more frequent, powerful and longer lasting. It will then examine how El Niño events (in conjunction with other major threats to the species, all of them linked to human activity) have affected population trends in the Galápagos Penguin over the last 40 years. I find significant evidence for an explanatory relationship between anthropogenic global warming and the trends in El Niño events we have seen since the 1970s and for an acute impact on the Galápagos Penguin species. Examining climate-related threats in the context of the broader conservation issues affecting the Galápagos Penguin, it is clear that there is a significant (current models indicate a 30-80% likelihood) probability of extinction over the next 100 years for the species.

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Page 1: Mercer-Golden 1 Benjy Mercer-Golden Professor Bill Durham … · 2014-12-08 · Mercer-Golden 1 Benjy Mercer-Golden Professor Bill Durham Sophomore College 2012: “Darwin, Evolution

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Benjy Mercer-Golden Professor Bill Durham Sophomore College 2012: “Darwin, Evolution and Galápagos” 15 October 2012

El Niño and Extinction-Level Threats to the Galápagos Penguin

ABSTRACT

In a fragile environment like the Galápagos, where the conservation problems that

seem most alarming tend to be the more tangible issues—overpopulation, a steadily

rising touristic impact, over-fishing and illegal marine poaching, introduced species,

etc.— it is easy to lose sight of other significant problems that are more difficult to

see with the naked eye. One such issue is that of climate change as it affects endemic

species, especially those living in marine ecosystems. This paper will attempt to

evaluate the evidence for a connection between anthropogenic global warming and

El Niño events that are more frequent, powerful and longer lasting. It will then

examine how El Niño events (in conjunction with other major threats to the species,

all of them linked to human activity) have affected population trends in the

Galápagos Penguin over the last 40 years. I find significant evidence for an

explanatory relationship between anthropogenic global warming and the trends in

El Niño events we have seen since the 1970s and for an acute impact on the

Galápagos Penguin species. Examining climate-related threats in the context of the

broader conservation issues affecting the Galápagos Penguin, it is clear that there is

a significant (current models indicate a 30-80% likelihood) probability of extinction

over the next 100 years for the species.

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An adult Galápagos Penguin. Photo by Zack Gold.

INTRODUCTION

If there is one scientific concept that has reached a high degree of popular attention

over the last decade, it is climate change. Chances are that most people living in the

West of a certain age and education level have at least heard pieces of the evidence

for (or against) anthropogenic global warming, defined here and used hereafter as

the human-made warming of the earth through processes such as the production of

greenhouse gases. That said, climate change in connection with two areas of

research, El Niño events and marine species, has not received much attention in the

public sphere, and relatively few scholars have attempted a rigorous analysis of the

intersection of these research topics. My paper aims to cover both of these themes,

specifically looking at the following questions: Is there a relationship between

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anthropogenic global warming and more frequent, powerful, and longer lasting El

Niño events in the Pacific Ocean? and How significant are the threats (especially El

Niño-related threats) to the survival of the Galápagos Penguin species? I chose the

Galápagos Penguin because the species can be viewed as sentinels for the health of

the marine ecosystem as a whole. By tracking the Galápagos Penguin, we can learn a

great deal about how the earth’s oceans are changing (Boersma 2008: 597). In that

light, though my research and analysis only focuses on the Galápagos Penguin, a

similar research angle can be easily

applied towards other marine species,

as it is likely that other species may be

similarly affected by changes to ocean

environments.

BACKGROUND

El Niño Events

In a normal year in Galápagos, the

Humboldt Current flows westward

across the Pacific Ocean, bringing cold

water to the Islands. During an El Niño

year, the oceanographic event called El

Niño is combined with the atmospheric

Sea surface temperatures under three scenarios, from top to bottom: La Niña (lower average SSTs, the opposite of El Niño); normal; and El Niño. The black arrows denote the approximate geographic position of the Galápagos Islands (Latif 2009: 20578).

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event known as Southern Oscillation; together, this is defined as an El Niño Southern

Oscillation event (ENSO). Under this scenario, both the normal currents and winds

are reversed, bringing warm water from the Western Pacific Ocean to the Galápagos.

Though most commonly associated with heavy rains, the largest impact of El Niño

events on marine life is the associated rise in sea surface temperatures (SSTs) (PBS,

online). Sea surface temperatures around Gálapagos have exceeded 30° in the past

during El Niño years, which historically has been associated with catastrophic

consequences for marine life (Latif 2009: 20578).

The Galápagos Penguin

The Gálapagos penguin (spheniscus mendiculus) is the only one of the 17 penguin

species in the world that lives exclusively in an equatorial region. In response to its

environment, the species has developed various adaptive characteristics that enable

it to survive. In accordance with Bergmann’s rule that warm-blooded animals tend

to be found in larger sizes in cold environments and smaller sizes in hot

environments, it follows that the Galápagos Penguin is the second smallest of all

penguin species in the world (after the Little Penguin of southern Australia and New

Zealand), with an average body length of less than 50 cm and an average body

weight of 2.2 kg in males and 1.7 kg in females (Vargas 2009: 154-5). Behaviorally,

the Galápagos has also adapted to its environment: it nests in lava tubes, underneath

boulders or in crevices, where it can find cooler places to brood its chicks.

The upwelling from Cromwell Current, which flows eastward, provides the

cold, nutrient-rich water essential to feeding small fish in the Galápagos. Around

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95% of Galápagos Penguins inhabit the islands of Fernandina and the west coast of

Isabela, where the Cromwell Current has made sea surface temperatures lowest; the

remaining 5% are present on Santiago, Bartolome and Floreana (Vargas 2009: 156).

The species’ diet consists of small fish like sardines, anchovies, piquitangas and

mullets, which in turn feed on the zoological plankton most abundant when sea

temperatures are coldest (Boersma 1998: 249).

The red circles and arrows indicate where the Galápagos Penguin species lives; 95% of the population is located in Fernandina and the west coast of Isabela, while the remaining 5% lives on Santiago and Bartolome (Vargas 2009: 156). Picture credit: ecoadventure.com.

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HYPOTHESES

I have two core hypotheses that guide my research on this topic:

1. Anthropogenic global warming is associated with El Niño events that are

more frequent, powerful and longer lasting.

2. El Niño events pose a significant threat to the survival of the Galápagos

Penguin.

METHODS

None of the empirical data or observational analyses included in this paper are from

my own original research. Instead, I relied on the research of people like Dee

Boersma and Hernán Vargas, two experts who have studied Galápagos Penguins and

tracked their population trends for decades. For information on climate change as it

Photo by Benjy Mercer-Golden

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affects El Niño events, I too did not contribute any original research but relied on

many of the most cited papers from the last decade covering both general evidence

for and against anthropogenic global warming and its impact on El Niño events.

After I compiled all of my research, I analyzed it; my analysis is the core of this

paper. A common procedure I followed was to apply general climate change

research towards its specific impact on the Galápagos Penguin to the extent that

such an application could be conducted with intellectual integrity. For example,

whenever climate change studies made specific observations about how various

parts of the world are affected, I attempted to focus mostly on the findings applying

to the equatorial western Pacific Ocean.

FINDINGS

For the sake of clarity, there are two broad research themes that define my

findings: 1) change to oceanic conditions as a result of anthropogenic global

warming and 2) The impact of such changes on the Galápagos Penguin.

Anthropogenic global warming

There is significant evidence that the warming of the Pacific Ocean, with specific

regard to El Niño events, since the 1970s is unprecedented in human history. There

are three criteria that are essential to analyzing El Niño events: 1) How powerful is

the El Niño event? 2) How long lasting is the event? 3) How frequent are these El

Niño events? The next section of this paper will argue that the most recent El Niño

events represent a significant departure from their historical instances because they

differ according to all three categories of evidence.

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The power of El Niño events refers both to their long-term trends and their

short-term spikes of severity. Since the late 1970s, sea surface temperatures in the

Pacific Basin (which includes Ecuador and the Galápagos) have been around .8°C

(1.5° F) warmer than the historical average, a significant increase given the large

impacts of even seemingly tiny changes to oceanic temperatures (Boersma 1998:

251). This gives some indication of a shifting long-term baseline. For evidence of

short-term power or severity, the 1982-3 ENSO event was the most intense ever

recorded in the tropical Pacific Ocean, with the warming events of 1990-5 and the

1997-8 El Niño following closely behind in terms of severity (Boersma 1998: 250).

These warming events have also been lasting for longer durations than the

historical average. For example, the warm water event of 1990-5 was the longest in

recorded history since 1882 (Trenberth & Hoar 1996: 3059). Finally, there is

Photo by Benjy Mercer-Golden

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compelling evidence for a greater frequency of El Niño events in recent times than in

the earth’s previous history. Contemporary El Niño events occur 2-7 times more

frequently than they did 7,000-15,000 years ago (Riedinger et al, 2002: 1). Analysis

by climate scientists Kevin Trenberth and Timothy Hoar, starting in 1976, is that

such an increased frequency of events can be expected to happen roughly every

2000 years, making a purely statistically random occurrence highly unlikely

(Trenberth & Hoar 1996: 3059). Together, all of this evidence substantiates the

claim that the El Niño events we have witnessed over the last 40 years (the years

most impacted by anthropogenic impact) differ significantly in kind from those that

preceded them.

The question, then, is how to explain these changes. Though it is possible the

changes can be explained by natural variation over time, anthropogenic global

warming is far and away the most compelling explanation. Trenberth and Hoar

argue that it is extremely unlikely that an every-2000 years trend in El Niño events

coincidentally overlaps with a time of significant anthropogenic impact and rising

global temperatures (Trenberth & Hoar 1996: 3059). In another study, Trenberth’s

climate models indicate that the majority of global warming that scientists have

observed over the last 50 years can be attributed to human impact (Karl &

Trenberth 2003: 1720). Perhaps the most famous of all climate change analyses, the

fourth report of the United Nations’ International Panel on Climate Change (IPCC),

citing over 6,000 studies, concluded that there is an 80% probability that

anthropogenic global warming has been associated with underlying changes in the

earth’s environment (United Nations 2007: 36). Though there is no scientific

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consensus, it is highly likely that anthropogenic climate change is the chief

explanation of the unprecedented trend in El Niño events over the last 40 years.

There is, however, even less scientific consensus surrounding future predictions of

El Niño events. Some models predict a continuation or further increase in the

extreme qualities of El Niño events in the future, including the one included in the

diagram on the next page, which shows increasing mean variability in sea surface

temperature anomalies over the next 100 years (Latif 2009: 20578). Other models

predict no such change. Because of the difficulty of modeling the future (especially

given that most of these models are only based off around a century of data, and all

data before the 1970s, marking the introduction of satellite data, may be less

Photo by Zack Gold

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reliable), it is uncertain whether the current trend of more frequent, powerful, and

longer lasting El Niño events will continue.

Impact on the Galápagos Penguin

More frequent, powerful, and longer lasting El Niño events since the 1970s have had

enormous consequences for the Galápagos Penguin. The rationale for this is that

these events pose threats to at least four different aspects of the feeding and

reproductive habits of the species. In the Galápagos, small fish like anchovy,

sardines and mullets survive on plankton; increasing water temperatures likely has

led to a 70% decline in zoological plankton over the last two decades (Boersma

1998: 249). During an El Niño event, when sea surface temperatures rise, there are

This model shows increasing mean variability of sea surface temperature anomalies over the next 100 years (Latif 2009: 20582).

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less small fish present and so the main consequence of El Niño events on Galápagos

Penguins is starvation (Vargas 2009: 159). During the less powerful El Niño events,

where sea surface temperatures rise by less than 3° C, observational data has shown

that few adult penguins die, but almost no penguins can be born because the species

cannot breed successfully when water temperatures exceed 25° C (Boersma 1998:

247). In contrast, during strong El Niño events, penguin breeding is halted and there

have been examples of significant adult mortality (see chart on next page) (Vargas

2006: 110). The flooding of nests as a result of El Niño events and increased

precipitation is another problem, given that most penguin nests are usually less

than 2m above sea level (Vargas 2006: 111). Sex ratio bias is the fourth major

reason why El Niño events are so threatening to the Galápagos penguin. Research

indicates that the smaller and less physically resilient female is more likely to die

during El Niño events, leading to increasingly skewed gender ratios within the

population following each new El Niño event; from 2003 to 2005, observational

reports showed a male-biased sex ratio bias of 68%: 32%. This is crippling to

population regeneration after incidences of high adult mortality (Vargas 2006: 111).

Given the severity of the El Niño threat, it is not surprising that the

population data indicates a shrinking, at-risk population. Population estimates of

the Galápagos penguin from the latest reports in 2008 put the total number of

penguins at around 1540 individuals. In 1971, Dee Boersma estimated the

population around 3400 penguins. In that 47-year gap between 1971 and 2008, the

Galápagos Penguin population size fell by more than 50% (Vargas 2009: 159). The

strong El Nîno events have had the biggest impact on the population; the 1982-3 El

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Niño caused a 77% decrease and the 1997-8 El Niño a 65% decrease in population

(Vargas 2006: 109).

Thus far in this paper I have focused exclusively on a single threat to the

Galápagos Penguin: more frequent, powerful, and longer lasting El Niño events. It is

important to note that, though climate-related threats are the most significant to the

survival of the species, the Galápagos Penguin faces multiple other important

dangers. Disease is chief among these. Gálapagos Penguins are genetically naïve,

In this chart, Hernán Vargas measures sea surface temperature differentials against the number of penguins recorded (nota bene: this is different than population size, because not every penguin colony is tracked and so some extrapolation is used). Anything outside of the +/- .5° C green range constitutes an El Niño or La Niña event. In particular, it is important to note the devastating effects of the 1982-3 and 1997-8 El Niño events, and a slight but encouraging population growth over the last decade (Vargas 2006: 109).

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which means they have limited immune defenses against invasive diseases. In

addition, genetic studies have shown that Galápagos Penguins have limited genetic

variability as a result of a history of bottlenecks (another way of looking at the adult

mortality issue in El Niño events is that these represent population bottlenecks) and

genetic drift (a small founding population) (Vargas 2009: 160). Introduced

mosquitoes are the main disease vector with their potential to carry avian malaria,

influenza and West Nile Virus; though these diseases have not been found in

penguins, a plasmodium-type parasite (which causes malarial infections) has been

found in some individuals (Levin 2009: 3191). Predation is another significant

threat, mostly from introduced feral cats and dogs, which have been to known to kill

penguins (Vargas 2009: 159). The commercial fishery, a large and powerful industry

in Galápagos, competes with the Galápagos Penguin for food, but also poses threats

through catching penguins in nets and longlines. Finally, oil spills such as that of the

Jessica in 2001 could prove devastating to populations (Vargas 2006: 112) (Vargas

2009: 159).

CONCLUSIONS

There is considerable evidence that we have witnessed an unprecedented

trend in climate change over the last 40 years, defined by more frequent, powerful

and longer lasting El Niño events. The most likely explanation for this is

anthropogenic climate change. Nonetheless, is it essential not to view the climate

threat in isolation, but to view the survival of the Galápagos Penguin in the context

of all of the forces impacting the species. The greatest risk of extinction (an analysis

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of extinction probabilities follows shortly) comes not from one threat but from a

confluence of threats acting together in short succession.

When we examine all of the threats to the survival of the species, there is a

high degree of certainty that these are extinction-level threats. One investigation

into the future of the species in Galápagos by Hernán Vargas, collecting data from

1965 to 2004, concluded that penguins face a 30% extinction probability within the

next 100 years. This study assumes a climate future similar to the one we have seen

over the last 40 years, but does not make an assumption that El Niño events might

continue to become even more frequent, powerful, and longer lasting. When the

model accounted for the potential for such a future (by doubling the current

frequency of strong El Niño events, 5%, to 10%), the probability of extinction

reached 80% (Vargas et al 2007: 143). In that light, the threat of extinction to the

Galápagos Penguin is very real and immediate, considering this could occur within

the next 100 years.

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RECCOMENDATIONS

As countless studies consulted for this paper pointed to in their conclusions, there is

a great deal of further research that needs to be conducted on the study of

anthropogenic global warming. The next few decades of data are likely to be

essential in providing a more definitive case for the impact of anthropogenic global

warming on El Niño events. The argument that I (and many others) have made rests

mostly on the principle that climate events since the 1970s have been

This graph shows the probability of extinction over the next 100 years for the Galápagos

Penguin at various frequencies of strong El Niño events (SSTs increase by 3° or more) and weak El Niño events. The current scenario is approximately a 30% probability of extinction; if El Niño events continue to become more powerful, longer lasting and frequent in the future, then the extinction probability rises to 80% (Vargas et al 2007: 146).

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unprecedented; though there is strong evidence to defend such a claim, this still

looks at a period of only 40 years of more frequent, powerful and longer lasting El

Ñino events. We need to keep tracking climate change over the next few decades,

collecting increasingly precise and accurate data that can add clarity to the big

picture.

In addition to collecting more data, policymakers in the Galápagos should

take immediate action to protect the Galápagos Penguin species in order to reduce

the risk of extinction. There are four main responses to threats that can be

combined to form a cohesive short-term and long-term conservation strategy:

Eliminate feral cats on the islands inhabited by Galápagos Penguins (Isabela,

Fernandina, Bartolome, Santiago) or, at the very least, control their

population sizes by significant margins. Though on a considerably larger

scale, Project Isabela can serve as a model for such an undertaking. Because

feral cats pose such a significant and immediate threat to the Galápagos

Penguin species, this should be a top priority of any conservation effort.

Track and outline the common foraging ranges (mostly close to the shore) of

the Galápagos Penguin on each island it inhabits, and then prohibit net

fishing within these ranges. Increase enforcement of anti-longlining laws.

Prevent the arrival of diseases (such as influenza, avian malaria and West

Nile Virus) that pose a significant threat to the Galápagos Penguin. The center

of such an effort needs to focus on the prevention of more disease vectors,

especially mosquitoes, reaching and spreading on the islands; ships and

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planes coming from the mainland likely need to be subjected to heightened

disinsection (the use of insecticide for disease control) measures.

Respond to the broader problem of anthropogenic global warming. Even if

the above three issues are addressed, the fundamental problem associated

with more frequent, powerful and longer lasting El Niño events and

adversely affecting the Galápagos Penguin will not be tackled unless humans

make real efforts towards curbing greenhouse gas emissions and lessening

our impact on the earth. Therefore much of the fate of the Galápagos Islands

and the Galápagos Penguin is tied up with the collective fate of humanity and

its response to global warming.

All of these suggestions come with an acknowledgement that there are

significant social, political, economic, legal and enforcement constraints that have

hindered all conservation activity in Galápagos in the past and will continue to do so

in the future. These hurdles will need to be navigated by the groups enacting policy

changes.

Photo by Karina Liker

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BIBLIOGRAPHY

Boersma, P. Dee. “Penguins as Marine Sentinels.” BioScience 58.7 (July/August

2008): 597-608.

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Macdonald, D.W. “Modelling the effect of El Niño on the persistence of small

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Vargas, H., Lougheed, C. and Snell, H. “Population Size and trends of the Galápagos

Penguin Spheniscus mendiculus.” IBIS: International Journal of Avian Science

147.2 (2005): 367-374.

“Weather and the Galapagos Islands.” PBS. 2000. Web. 5 Sep. 2012.

ACKNOWLEDGEMENTS I would like to acknowledge the help of my four academic teachers and mentors for

this class, professor Bill Durham, his post-doc Carter Hunt, and the teaching

assistants, Emily Beggs and Vincent Chen. They all provided indispensable advice,

feedback and help in my research and writing pursuits on this project.