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Climate Change Biology:
Dr. Anne Todgham,
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an assistant biology professor at SF State,
finds fascination in purple sea urchins–
plum-colored, hedgehog-like marine invertebrates. Todgham describes the animals as
“ecosystem engineers” because their voracious
grazing can remodel the kelp beds in a reef ecosystem. Although the urchins are themselves
highly prized delicacies in Japan, Todgham’s
interest is far from culinary: She has studied
the spiny animals and their tiny larvae as bellweathers of global climate change.
Stress
On Ocean Organisms
by Robert Hausman
As CO2 dissolves in the ocean, the pH of seawater
drops and it’s becoming more acidic for the animals that live there.
A new faculty member beginning in
2009, Todgham has been busy applying for
research grants, outfitting her laboratory in
Hensill Hall, getting her research program
off the ground, and designing new courses.
She currently is involving graduate and
undergraduate students in her important
research on environmentally-induced stress
in sea urchins and other marine life. Her
goal, she explains, is to understand “the
physiological mechanisms animals have in
place to tolerate the rapid pace of climate
change we are now experiencing.”
Purple urchins live up and down the
northern Pacific coast, says Todgham, and
she chose to study this particular spe-
cies because other researchers had already
sequenced its complete genome. Animals
experience a series of subtle cellular changes
in response to environmental stress, she explains. By knowing the entire genetic code,
biologists can “monitor changes in the types
of proteins in the animal’s cells at any given
time.” Such a detailed understanding of an
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Photo: Tim Crombie
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1) Early development of purple
sea urchins (left to right):
2-cell, 4-cell, blastula,
gastrula, late prism and
early 4-arm pluteus stages.
At 15°C it takes approximately
72h to reach the early 4-arm
pluteus stage.
2) Late gastrula stage of the
painted sea urchin, Lytechinus
pictus. The larval skeleton is
beginning to form on the right
side of the urchin.
2
Photo: Paul Matson
3
Photo: Paul Matson
4
Photo: Tim Crombie
3) Late prism stage of the
painted sea urchin, Lytechinus
pictus. At the prism stage,
the larval skeleton is clearly
visible. Rearing larvae in CO2acidified seawater predicted by
ocean acidification scenarios
causes a change in the shape
and size of this skeleton.
4) Eight-arm stage of the
painted sea urchin, Lytechinus
pictus. This larval urchin is
almost ready to metamorphoses into a juvenile urchin that
looks much more similar to the
spiny adults.
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animal’s stress response to climate change
will then allow biologists to make predictions about their survival for the next 90
years if average global temperatures continue
to rise dramatically.
“In 90 years,” Todgham says, “we
expect the temperature to be 2 degrees
warmer, in a conservative scenario, or,
maybe 4 degrees warmer in a business-asusual scenario.” If we do nothing to prevent
global warming, in other words, “it’s predicted that our temperature will be about 4
degrees warmer by 2100, than it is today.”
The figures she cites come from a 2007
report by a group called the Intergovernmental Panel on Climate Change, or IPCC.
In her postdoctoral research on purple sea
urchins, Todgham applied these projected
conditions, focusing specifically on the
organism’s juvenile larval stage. “A number
of people in climate change biology think
it’s really important that we not only look
at adult animals, but we look at juveniles as
well, because maybe the juveniles are more
vulnerable, or sensitive to environmental
change than adults.” If the larvae are unable
to tolerate rising temperatures or increasing acid levels in seawater, then they could
have a poor chance of maturing into resilient
adults.
Ocean acidification has been one important focus of climate change research. As
atmospheric carbon dioxide levels rise and
additional CO2 dissolves in ocean water,
Todgham says, it creates an environment
that is “more acidic for the animals that
live there.” So far, much of the research has
centered on marine animals that “calcify,” or
build a calcium carbonate shell or exoskeleton, including snails, mussels, oysters, and
reef-building corals. “Under high carbon
dioxide conditions in the oceans,” Todgham
says, “corals, and other calcareous, or calcifying, animals, are not able to make their
hard parts as effectively.” The hard parts
they do build “are actually disintegrating, as
well, in these acidic waters.”
Todgham earned her PhD from the
University of British Columbia in 2005,
and that same year, began a postdoctoral
fellowship at UC Santa Barbara. There, she
studied—among other things—the effects of
CO2-driven seawater acidification on larval
development of sea urchins. In the laboratory, she recreated a futuristic ocean environment, based on the acidity levels predicted
90 years hence. She bubbled seawater with
carbon dioxide gas, to simulate what the
oceans might look like in 2100. Then, she
and colleagues would “take the larvae that
we spawned in the lab, and raised them in
these conditions.”
To understand the purple sea urchin
larva’s response to climate change at the
molecular level, Todgham chose about 1,100
genes important to stress tolerance, biomineralization, development, and metabolism
from its total of approximately 23,000
genes. Next, she applied DNA microarray
Anne Todgham, Assistant Professor of Biology
“In 90 years,” Todgham says,
“we expect the temperature
to be 2 degrees warmer, in a
conservative scenario, or, maybe
4 degrees warmer in a businessas-usual scenario.”
chips to measure changes in gene expression. Todgham describes the microarray chip
as an instrument resembling a microscope
slide that can detect changes in the levels of
messenger RNA (mRNA) from thousands
of genes at a time in response to environmental change. Todgham put all 1,100 of
the selected genes on a microarray chip to
monitor how they responded to changes in
seawater pH. Todgham was able to measure
changes in the larvae’s gene expression in
response to the increased CO2, in particular,
monitoring gene expression pathways for
metabolism and stress response. Her team
found that genes and proteins responsible
for building the urchin’s exoskeleton were
turned down. She as also able to confirm
this through direct observation: Under
a microscope, larvae exposed to elevated
CO2 and therefore lower pH levels formed
smaller exoskeletons. “We were some of the
first to show that a number of genes that
were responsible for building the skeleton
were turned down,” says Todgham.
Todgham’s passion for biology shows
whenever she describes her research. This
enthusiasm apparently began at an early
age and remained as she followed the long
academic pathway that eventually led her
to SF State. From the start, she recalls, “I
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“This is an exciting time for students to get involved
was a naturalist.” Every summer Todgham’s
family vacationed in Maine, where she and
her dad would spend four or five hours at a
time tidepooling in the intertidal zone. “You
swim in the ocean and you don’t really see
much, but then you go into these tidepools and they’re teeming with life,” says
Todgham.
Her love of biology stayed strong all
the way through high school, including the
day representatives came from the University of Guelph in Ontario. “I got swept
off my feet by the university spokespeople
that came over to my high school,” she says.
“They talked about the fact that, strangely,
being a landlocked university, it had the
top marine biology program in Canada.”
She eventually enrolled at the University of
Guelph, and found that many of the professors were comparative animal physiologists.
Experts in that field, Todgham says, “seek to
understand how animals living in different
environments might have similar solutions
to common environmental problems.” They
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Photo: Nann Fangue
Photo: Dave Hurt
in biology,” Todgham says, “because we’re in a time where we
have a lot to contribute in understanding how our marine ecosystems are going to fare in the face of climate change.”
Top:
Undergraduate student, Audrey Nickles (left), and graduate students Lina Ceballos (middle)
and Brittany Bjelde (right) collecting limpets during low tide at Fort Ross, CA.
Bottom:
Rocky intertidal shoreline of the coast north of Point Conception, CA. Large rock in the foreground is prime habitat for the territorial owl limpet, Lottia gigantea.
to common environmental problems.” They
also seek to explain “how animals of the
same environment might have evolved different solutions to common problems.”
As an undergraduate, Todgham immersed herself in comparative animal physiology, and as a junior, got the opportunity
to work with a doctoral candidate who had
collected tropical plankton samples from
the Caribbean. Todgham helped categorize
hundreds of samples into groups of different
animals and plants. She learned that she
liked the camaraderie and activity of the
laboratory—but that tropical plankton ecology did not hold her interest.
Her undergraduate years at Guelph
presented Todgham with more opportunities to actively study comparative animal
physiology and expand her understanding
of marine biology. One project focused
on the effects of thyroid hormones on the
metabolism of the Arctic char, a fish in
the salmon family. Next, she studied and
published a paper on how exercise affected
nitrogen metabolism in rainbow trout in a
small swim flume. Her work helped document the phenomenon—little known at
the time—that while fish mainly excrete
the nitrogenous waste product ammonia,
they can “also excrete urea, like we do, as
mammals,” Todgham says. Her senior thesis
examined the effect of wave exposure on the
distribution of limpet species prevalent from
the rocky coasts of British Columbia south
to California.
With such diverse experiences as an
undergraduate, Todgham had a difficult
time choosing where to focus her future
studies. To her relief, a professor shared
some valuable advice: “You don’t have to
choose, just relax, start doing a Master’s
project, and if it’s what you love and you
find that you’re really inspired by
it, you can continue with doing
your PhD.”
Todgham enrolled for
graduate work at the University of British Columbia and
selected a project on Vancouver’s west coast. Her subject
was inducible stress tolerance in
intertidal fish. In the intertidal
zone such as along Vancouver’s
rock coast, she explains, environmental
stress may include a temperature increase
of as much as 10 degrees in a given day. In
addition, oxygen levels in the tide pools can
drop to nearly zero at night as the abundant plants and animals consume much of
the oxygen produced by plants during the
daytime.
During her doctoral work under
advisors Trish Schulte and George Iwama,
Todgham learned the molecular biology
techniques that would later shape her
research career. ”Instead of looking at
hormonal changes like cortisol and glucose”
in the stressed fish species, she says, “I had
a chance to look at some changes in levels
of gene expression, which are the effects
of stress on molecular and cellular mechanisms.” Todgham chose to examine so-called
heat shock proteins. “They’re called heat
shock proteins because they were first
discovered in response to heat shock. We
now know that they are actually induced in
response to a wide range of environmental
stressors,” she says. “Working at the molecular level, measuring how gene expression changes in response to environmental
changes really set in motion the kind of
research that I did in both my post-doc, and
now, here at San Francisco State.”
In 2005, with her new PhD from the
University of British Columbia, Todgham
moved on to postdoctoral work at UC
Santa Barbara, where she continued to look
at stress tolerance at the molecular level.
As mentioned earlier, she looked at how
seawater acidification affects sea urchin
larvae. She also studied the stress tolerance
of Antarctic fishes. “These Antarctic fishes
thrive at temperatures right at the freezing
point of the sea water,” she explains, “yet
they don’t freeze.” Living organisms are “all
very similar in the types of genes that we
have and in the sequence of these genes.
What amazes me is that different animals
have taken advantage of different aspects
of their genome to allow them to thrive in
different environments, and in stressful environments.” Todgham is still interested in
environmentally-induced stress. “It led me
into the research I do now,” she says, in climate change biology, including whether animals can “flex” their physiology in response
to rapidly changing conditions.
Her position at SF State allows
Todgham to pursue both research and teaching. “I really like that San Francisco State
University puts a lot of pride into being an
institution that provides this nice balance:
a strong teaching environment, a scholastic
environment for students, and I’m hoping
to have a strong research program that will
involve both graduate and undergraduate
students,” she says.
As a new professor, Todgham spends a
lot of time preparing her lectures. Recently,
she designed a course in environmental
physiology. “It allows me to talk about all of
the weird and wonderful creatures we have
on this planet and how they’re uniquely
designed to deal with harsh environments,”
she explains. Much of her scientific writing,
she adds, involves applying for research
grants. When she is not writing lectures
or grant proposals, Todgham reads current
literature on climate change biology. She
plans to collaborate with Dr. Jonathon Stillman, a marine biology professor at Romberg
Tiburon Center, SF State’s marine station
on the Bay, and is outfitting her lab with
research equipment to conduct environmental physiology research.
“This is an exciting time for students
to get involved in biology,” Todgham says,
“because we’re in a time where we have a lot
to contribute in understanding how our marine ecosystems are going to fare in the face
of climate change.” We need more research
aimed at identifying which populations are
vulnerable to ocean acidification, she adds.
“We also need a clear understanding of the
costs associated with the synergistic interactions of ocean acidification and ocean warming.” Although environmental issues depress
and concern many students, Todgham closes
with a word of hope: “There’s a place at the
table for us in this challenge that we face as
a globe. While it’s a daunting task, it’s an
exciting time, as well.” v
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