378 ■ CHAPTER 21 Ecosystems
ECOLOGY
A
s a teenager, Daniel Boyce made extra
cash working as a deckhand on fish-
ing boats, so he was no stranger to the
ocean. Eventually, Boyce turned that interest in
marine environments into a career, and in 2007
he joined the lab of marine biologist Boris Worm
at Dalhousie University in Nova Scotia, Canada.
Several years earlier, Worm had discov-
ered that the industrialized fishing boom that
began in the 1950s had decimated predatory
fish communities. Boyce decided to follow up
on his mentor’s work by studying how that loss
of predatory fish reverberated down the food
chain. Had the disappearance of ocean pred-
ators affected plankton? Plankton, a diverse
group of free-floating organisms, are the base
of the ocean food web, supporting virtually all
marine animals. Although they are tiny, they
play a mighty role in marine environments.
When Boyce proposed this study, little did he
know that it would uncover a profound shift in
oceans around the world—a finding so shocking
that just suggesting it would plunge him and his
collaborators into a heated public controversy.Going Green
Boyce’s initial goal, similar to that of William
Ripple’s work studying wolves in Yellowstone
National Park (see Chapter 20), was to show how
the loss of a top predator affects the environ-
ment in which it lives. In Ripple’s story, a vari-
ety of species living in Yellowstone interacted
to form what we call an ecological community.
A group of communities interacting with one
another and with the physical environment they
share is an ecosystem (Figure 21.1). To say it
another way, an ecosystem is characterized by
interactions of organisms in the biotic (living)
world with each other, as well as with the abiotic
(nonliv ing) world.
An ecosystem may be small or large; a puddle
teeming with protists is an ecosystem, as is the
Atlantic Ocean. And smaller ecosystems can be
nested inside larger, more complex ecosystems.
This variety means that ecosystems do not always
have sharply defined physical boundaries. Instead,
ecologists often define an ecosystem by theFigure 21.1
Ecosystems in Nova Scotia, Canada
Overfishing has decimated fish populations in Nova Scotia, affecting the entire ecosystem in which
these fish reside. Both biotic and abiotic elements of the ecosystem have been affected.