20
BY ERIKA K. CARLSON
Algae
THINGS
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DIDN’T
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98 DISCOVERMAGAZINE.COM
estimate that algae produce at least half of the oxygen
in Earth’s atmosphere by converting carbon dioxide
during photosynthesis. 11 You can thank algae for our
seafood, too. Tiny phytoplankton, found worldwide,
make up the base of aquatic food chains. 12 However,
some plankton produce toxins that build up in animals
higher up these food chains. Humans who consume
the tainted seafood could experience a range of nasty
symptoms, from vomiting and diarrhea to seizures
and memory loss. 13 Human-caused climate change
may be making toxic plankton blooms more common
and more severe as the oceans warm, conditions that
favor their rapid growth. 14 Toxic algal blooms have
hit seafood industries on the Pacific Coast hard in the
past few years. In November, a fishing trade associa-
tion sued 30 fossil fuel companies, blaming them for
economic losses. 15 Climate change might also affect
algal blooms by changing storm patterns and inten-
sifying rainfall in some parts of the world. Torrents
can wash nutrients from land fertilizers into bodies
of water, encouraging algae to multiply. 16 Fertilizer
runoff after Hurricane Irma in September 2017 might
partly explain a long-lived, catastrophic red tide that
subsequently struck Florida’s west coast, killing fish,
sea turtles and manatees. 17 Long-dead ancient algae
have a more fundamental connection to modern cli-
mate change. A lot of the fossil fuels in use today, the
main culprits of global warming, are derived from
deposits of these organisms dating back millions of
years. 18 In the early years of the 21st century, eco-
minded researchers and entrepreneurs staked claims
in a kind of gold rush — or maybe green rush — to
replace fossil fuels by using living algae in sustain-
able biofuel production. 19 The green rush has yet to
pan out. In 2017, scientists figured that algae probably
weren’t productive enough. The organisms might not
even produce enough fuel to make up for the energy
needed to grow them. 20 But here’s a productive rela-
tionship for you: Some plankton have mutually ben-
eficial partnerships with coral. The microalgae live
inside coral cells, converting sunlight into energy that
the corals can use to build reefs; in return, the plankton
get free room and board.^ D
Erika K. Carlson is an algae-eating science writer.
1 If you think algae are just plants living in water, think
again. The mostly aquatic organisms produce oxygen
through photosynthesis, though they lack many of
the other defining traits of plants, including roots and
leaves. 2 Algae can range from 100-foot-long giant
kelp to several varieties of microbes called cyanobac-
teria, also known as blue-green algae. 3 Usually asso-
ciated with dangerous algal blooms that can sicken
humans and animals, these tough little microbes can
also live in hot springs, under rocks in arid deserts
and even under Antarctic ice. 4 Cyanobacteria might
also be in your breakfast smoothie. The “superfood”
spirulina is a nontoxic cyanobacteria popular for its
nutritional profile, including proteins, vitamins, min-
erals and essential fatty acids. 5 In Chad, the Kanembu
people have been harvesting spirulina from local lakes
since at least the 1940s, way ahead of the superfood
trend. Even earlier, the Aztecs ate a different species
of the cyanobacteria, collected from the ancient Lake
Texcoco — drained during colonial times — where
Mexico City now stands. 6 Plenty of larger algae are
both nutritious and delicious. In Japan, for instance,
you might find a dozen or more varieties of seaweed
on the menu, from soups to sushi wrappers. 7 Algae
has probably found its way into your dessert, too.
The gelatinous additives agar and carrageenan,
produced from different species of red algae,
thicken and prevent separation in ice cream, jel-
lies, squishy sweets and many other processed
foods. 8 Researchers are even adding algae to
dairy cow diets. Results from a 2017 study sug-
gest that supplementing feed with seaweed might
cut down on the methane cows burp out: The algae
produces a chemical that inhibits gut microbes from
making as much of the greenhouse gas. 9 Sometimes,
in fact, algae are a little too good at reducing green-
house gases. About 445 million years ago, larger and
more complex algae became more common and
gobbled up carbon dioxide so quickly that they
disrupted the planet’s carbon cycle, according
to a 2018 Nature Geoscience study. This might
have caused the global cooling and glacia-
tion responsible for the earliest known
mass extinction. 10 Today, algae actually
help maintain the carbon cycle. Scientists
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(^3)Microalgae can be
processed into a
liquid (above) or
dried into granules
and powders after
being cultured in
petri dishes (below),
providing humans
with everything
from key vitamins
to a potential future
fuel source.
Caulerpa lentillifera, better known
as sea grapes, is an edible green
algae with a caviar-like texture.