Page 696 - Environment: The Science Behind the Stories

that feed on plankton-eating fish. (The left side of Figure more energy per calorie that we gain than when we eat plant
intErprEt and analyzE storiEs products.
4.9 shows these relationships in a very generalized form.)
Zebra mussels and quagga mussels, by eating both phy-
using sciEntific litEracy skills function on multiple trophic
toplankton and zooplankton,
levels. When an organism dies and sinks to the bottom, WEIGhING thE ISSUES
detritivores scavenge its tissues and decomposers recycle
its nutrients. thE FOOtPrINtS OF OUr dIEtS What proportion of your diet
Science Behind the Story features highlight how scientists develop hypotheses, test would you estimate consists of meat, milk, eggs, or other
animal products? Would you be willing to decrease this pro-
predictions, analyze and interpret data, and share findings. portion in order to reduce your ecological footprint? Describe
Energy, biomass, and numbers decrease some other ways in which you could reduce your footprint
at higher trophic levels through your food choices.

THE SCIENCE BEHINd THE STORy At each trophic level, organisms use energy in cellular respi-
ration (p. 32) to grow and maintain themselves. More energy Food webs show feeding relationships
goes toward maintenance than to building new tissues, and and energy flow
did Soap Operas most ends up being given off as heat. Only a small amount
Reduce Fertility of the energy is transferred to the next trophic level through As energy is transferred from lower trophic levels to higher
NEW! 30% of the Science
in Brazil? predation, herbivory, or parasitism. A general rule of thumb ones, it is said to pass up a food chain, a linear series of feed-
Behind the Stories are
is that each trophic level contains just 10% of the energy of ing relationships. Plant, grasshopper, rodent, and hawk make
Over the past 50 years, the South
American nation of Brazil experienced the trophic level below it (although the actual proportion can up a food chain—as do phytoplankton, zooplankton, fish, and
entirely new in the text.
the second-largest drop in fertility vary greatly). This pattern can be visualized as a pyramid fish-eating birds.
among developing nations with large (Figure 4.10). topics include:
populations—second only to China. Thinking in terms of food chains is conceptually use-
In the 1960s, the average woman in This pyramid-like pattern also tends to hold for the ful, but ecological systems are far more complex than sim-
• Tracking Fukushima’s nuclear
Brazil had six children. Today, Brazil’s numbers of organisms at each trophic level; in general,
total fertility rate is 1.9 children per legacy (Ch02) ple linear chains. A more accurate representation of the
woman, which is lower than that of the fewer organisms exist at higher trophic levels than at feeding relationships in a community is a food web—a
United States. Brazil’s drastic decrease lower ones. A grasshopper eats many plants in its lifetime, visual map of energy flow that uses arrows to show the
• Tracking Populations of
in fertility is interesting because, unlike
Hakalau’s Forest Birds (Ch03)
China, it occurred without governmen- a rodent eats many grasshoppers, and a hawk eats many many paths along which energy passes as organisms con-
tal policies that advocated controls on rodents. Thus, for every hawk in a community there must sume one another.
its citizens’ reproduction. • Does Fracking Contaminate
be many rodents, still more grasshoppers, and an immense
So how did Brazil accomplish this? brazilian soap operas, called telenovelas, are a surprising cultural force for promoting Figure 4.11 shows a food web from a temperate decidu-
A major factor was change in society’s lower fertility. Here, residents gather outside a cafe in Rio de Janeiro to watch the popu- Drinking Water? (Ch07) ous forest of eastern North America. It is greatly simplified
number of plants. Moreover, because the difference in
lar program Avenida Brasil.
view of women. It began with a civil
rights movement in the 1960s, which numbers of organisms among trophic levels tends to be and leaves out the vast majority of species and interactions that
And More!
gave females equal access to education large, the same pyramid-like relationship often holds true occur. Note, however, that even within this simplified diagram
and the opportunity to pursue careers China; the procedure is illegal except in characters, settings, and plot lines
for biomass, the collective mass of living matter in a given
outside the home. These efforts have rare circumstances. with which everyday Brazilians can we can pick out a number of food chains involving different sets
been highly successful. Women now As Brazil’s economy grew with identify. place and time. of species.
comprise 40% of the workforce in Brazil industrialization, people’s nutrition Telenovelas do not overtly
and graduate from college in greater and access to health care improved, address fertility issues, but they The pyramid pattern illustrates why eating at lower A Great Lakes food web would involve the phyto-
trophic levels—being vegan or vegetarian, for instance—
numbers than men. And in 2010, greatly reducing infant mortality rates. do promote a vision of the “ideal” plankton that photosynthesize near the water’s surface, the
Brazilians elected a woman, Dilma Families no longer needed to have Brazilian family. This family is typically
decreases a person’s ecological footprint. Each amount of
Rousseff, as their nation’s president. more children than they desired for fear middle or upper class, materialistic, zooplankton that eat them, fish that eat phytoplankton and
meat or other animal product we eat requires the input of a
Although the Brazilian government one or more would die at a young age. individualistic, and full of empow- zooplankton, larger fish that eat the smaller fish, and lam-
does not put restrictions on people’s Increasing personal wealth promoted ered women. By challenging existing preys that parasitize the fish. It would include a number of
considerably greater amount of plant material (see Figure 10.9,
reproduction, it provides family planning materialism and greater emphasis on cultural and religious values through
p. 249). Thus, when we eat animal products, we use up far
and contraception to all its citizens free career and possessions over family their characters, novelas had, and native mussels and clams and, since 1988, the zebra mus-
of charge. Eighty percent of married and children. The nation also urbanized continue to have, a profound impact sels and quagga mussels that are displacing them. It would
women of childbearing age in Brazil as people flocked to growing cities on Brazilian society. In essence, these
currently utilize contraception, a rate such as Río de Janeiro and São Paolo, programs provided a model family include diving ducks that formerly fed on native bivalves and
higher than that in the United States conveying the fertility reductions that for Brazilians to emulate—with small now prey on the mussels.
or Canada. Universal access to family occur when people leave the farm for family sizes being a key characteristic.
planning has given women control over the city. In a 2012 paper in the American 1 This food web would also show that crayfish and other
Tertiary
their desired family size and has helped It turns out, however, that Brazil Economic Journal: Applied consumers benthic (bottom-dwelling) invertebrate animals feed from the
reduce fertility across all economic had a rather unique influence affecting Economics, a team of research-
Secondary
groups, from the very rich to the very its fertility rates over the past several ers from Bocconi University in Italy, refuse of the non-native mussels. Although the mussels’ waste
poor. decades—"soap operas.” Brazilian George Washington University, and 10 promotes bacterial growth and pathogens that introduce dis-
consumers
the Inter-American Development Bank
Brazil is largely Roman Catholic, NEW! Data Analysis Q’s are
soap operas, called telenovelas or
Primary
and Roman Catholicism prohibits the novelas, are a cultural phenomenon (based in Washington, D.C.) analyzed ease to native bivalves, it also provides nutrients that nour-
and are watched religiously by people
various parameters to investigate
use of artificial methods of birth control, paired with select figures in each consumers 100 ish many benthic invertebrates. Finally, the food web would
so the high rates of contraceptive use of all ages, races, and incomes. Each statistical relationships between tel-
enovelas and fertility patterns in Brazil
novela follows the activities of several
in modern Brazil represent a significant chapter to help you develop your include underwater plants and macroscopic algae, whose
Producers
shift from traditional values. Induced fictional families, and these TV shows from 1965 to 2000. Rede Globo, the 1000 growth is enhanced as the non-native mussels filter out phyto-
abortion is not utilized in Brazil as it is in scientific literacy skills. These
are wildly popular because they have
network that has a virtual monopoly
204 questions allow you to check your Figure 4.10 Lower trophic levels generally contain more plankton, allowing sunlight to penetrate deeply into the water
column. (Jump ahead to Figure 4.15a, p. 89, for an illustration
own understanding of environ- organisms, energy content, and biomass than higher trophic of some of these effects.)
Overall, zebra and quagga mussels alter the Great Lakes
mental data as you read through levels. The tenfold ratio shown here is typical, but the shape of the food web by shifting productivity from open-water regions to
pyramid may vary greatly.
each chapter.
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Using the ratios shown in this example, let’s suppose that benthic and littoral (nearshore) regions. In so doing, the mus-
a system has 3000 grasshoppers. How many rodents sels help benthic and littoral fishes and make life harder for
82 would be expected? open-water fishes (see The Science behind The STory, pp. 86–87).
695
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