Page 148 - Environment: The Science Behind the Stories

media attention on the plight of the bay, its ongoing water qual- Conclusion
ity issues, and its depleted fisheries—and spurred action.
In May 2009, President Obama directed the EPA and Thinking in terms of systems is important in understand-
other federal agencies through an executive order to establish ing Earth’s dynamics, so that we may learn how to avoid
a comprehensive plan for the restoration of the Chesapeake disrupting its processes and how to mitigate any disruptions
Bay. One year later, the EPA and the CBF announced a set- we cause. By studying the environment from a systems per-
tlement in which the EPA agreed to work with surrounding spective and by integrating scientific findings with the policy
states to provide aggressive pollution regulation in the bay. process, people who care about the Chesapeake Bay and other
In December 2010, a comprehensive “pollution budget” was waterways are working today to address dead zones around
developed and implemented with the assistance of the District the world.
of Columbia, Delaware, Maryland, New York, Pennsylvania, Earth hosts many interacting systems, and the way
Virginia, and West Virginia. one perceives them depends on the questions in which
Existing efforts to reduce nutrient and sediment inputs one is interested. Life interacts with its nonliving environ-
into the bay and to limit harvests of oysters, crabs, and fish are ment in ecosystems, systems through which energy flows
already leading to modest improvement in some aspects of the and matter is recycled. Understanding the biogeochemi-
bay’s health. For example, the CBF’s “2012 State of the Bay” cal cycles that describe the movement of nutrients within
report shows the bay’s overall health has improved 10% since and among ecosystems is crucial because human activities
2008 and cites recent studies and trends in nutrient concentra- are causing significant changes in the ways those cycles
tions that suggest pollution reduction strategies are working to function.
reduce inputs of nitrogen and phosphorus to bay waters. The Unperturbed ecosystems use renewable solar energy,
Chesapeake Bay remains highly degraded and much work is recycle nutrients, and are stabilized by negative feedback
still needed. Still, the 17 million people living in the Chesa- loops. The environmental systems we see on Earth today are
peake Bay watershed have reason to hope that the Chesapeake those that have survived the test of time. Our industrialized
Bay of tomorrow may be healthier than it is today, thanks civilization is young in comparison. These natural systems
to the collaborative efforts of concerned citizens, advocacy therefore provide us a blueprint to mimic as we move towards
organizations, and the federal and bay state governments. greater sustainability in modern society.

reviewing Objectives

you should now be able to: • Energy flows in one direction through ecosystems, whereas
matter is recycled. (pp. 128–129)
Describe the nature of environmental systems • Energy is converted to biomass, and ecosystems vary in
• Earth’s natural systems are complex, so environmental sci- their productivity. (pp. 129–130)
entists often take a holistic approach to studying environ- • Input of nutrients can boost productivity, but an excess of
mental systems. (p. 124) nutrients can alter ecosystems and cause severe ecological
• Systems are networks of interacting components that gen- and economic consequences. (pp. 129–131)
erally involve feedback loops, show dynamic equilibrium,
and result in emergent properties. (pp. 124–125) Outline the fundamentals of landscape ecology, GIS,
and ecological modeling
• Negative feedback stabilizes systems, whereas positive feed- CHAPTER 5 • Envi R onm E n TA l S y STE m S A nd E C o S y STE m E C ology
back destabilizes systems. Positive feedback often results • Landscape ecology studies how landscape structure influ-
from human disturbance of natural systems. (pp. 124–125) ences organisms. (pp. 131–132)
• Landscapes consist of patches spatially arrayed in a
• Because environmental systems interact and overlap, one’s
delineation of a system depends on the questions in which mosaic. Organisms dependent on certain types of patches
one is interested. (p. 126) may occur in metapopulations. (pp. 131–132)
• With the help of remote sensing technology and GIS, land-
• Hypoxia in the Chesapeake Bay, which results from nutri- scape ecology is being increasingly used in conservation
ent pollution in the rivers that feed it, illustrates how sys- and regional planning. (pp. 132–133)
tems are interrelated. (p. 126)
• Ecological modeling helps ecologists make sense of the
Define ecosystems and evaluate how living and non- complex systems they study. (pp. 133–134)
living entities interact in ecosystem-level ecology
Assess ecosystem services and how they benefit our lives
• Ecosystems consist of all organisms and nonliving entities
that occur and interact in a particular area at the same time. • Ecosystems provide the “goods” we know of as natural
(pp. 128–129) resources. (p. 134) 147

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