1. Individual Assignment: Case-In-Point Analysis

Select one Case-In-Point presented in Ch. 3??”5 of Environment.
Write a 700- to 900-word analysis of the selected case. In your analysis, include the following:

o Identify any unintended consequences of humankind’s activities that have led to environmental problems.
o Describe how scientific or technological activities are exacerbating or improving the existing situation.
o Discuss how a proper application of the scientific method could have helped the problem.
o Address any alternative solutions beyond the scientific method.
• Format your analysis consistent with APA guidelines.

• Flow of Energy Through Ecosystems 59
o
• C ASE IN POINT
o
• HOW HUMANS HAVE AFFECTED THE ANTARCTIC FOOD WEB
o
• Although the icy waters around Antarctica may seem an inhospitable environment, a
• complex food web is found there. The base of the food web consists of microscopic,
• photosynthetic algae present in vast numbers in the well-lit, nutrient-rich water. A huge
• population of herbivores??”tiny shrimplike krill??”eat these marine algae (Figure 3.11).
• Krill, in turn, support a variety of larger animals. A major consumer of krill is the baleen
• whale, which filters krill out of the frigid water. Baleen whales include blue whales,
• humpback whales, and right whales. Squid and fishes also consume krill in great quantities.
• These, in turn, are eaten by other carnivores: toothed whales such as the sperm
• whale, elephant seals and leopard seals, king penguins and emperor penguins, and birds
• such as the albatross and the petrel.
• Humans have had an impact on the Antarctic food web as they have had on most
• other ecosystems. Before the advent of whaling, baleen whales consumed huge quantities
• of krill. Until a global ban on hunting large whales was enacted in 1986, whaling
• steadily reduced the number of large baleen whales in Antarctic waters. As a result
• of fewer whales eating krill, more krill became available for
• other krill-eating animals, whose populations increased.
• Now that commercial whaling is regulated, it is hoped that
• the number of large baleen whales will slowly increase, and that
• appears to be the case for some species. However, the populations
• of most baleen whales in the Southern Hemisphere are still
• a fraction of their pre-whaling levels. It is not known whether
• baleen whales will return to their former position of dominance
• in terms of krill consumption in the food web. Biologists will
• monitor changes in the Antarctic food web as the whale populations
• recover.
• Thinning of the ozone layer in the stratospheric region of the
• atmosphere over Antarctica has the potential to cause long-term
• effects on the entire Antarctic food web. Ozone thinning allows
• more of the sun’s ultraviolet radiation to penetrate to Earth’s surface.
• Ultraviolet radiation contains more energy than visible light
• and can break the chemical bonds of some biologically important molecules, such as
• deoxyribonucleic acid (DNA). Scientists are concerned that ozone thinning over Antarctica
• may damage the algae that form the base of the food web in the Southern Ocean. Increased
• ultraviolet radiation is penetrating the surface waters around Antarctica, and algal productivity
• has declined, probably as a result of increased exposure to ultraviolet radiation.
• (The problem of stratospheric ozone depletion is discussed in detail in Chapter 20.)
• Another human-induced change that may be responsible for declines in certain
• Antarctic populations is global climate change. As the water has warmed in recent
• decades around Antarctica, less pack ice has formed during winter months. Large
• numbers of marine algae are found in and around the pack ice, providing a critical
• supply of food for the krill, which reproduce in the area. Years with below-average pack
• ice cover mean fewer algae, which mean fewer krill reproducing. Scientists have demonstrated
• that low krill abundance coincides with unsuccessful breeding seasons for penguins
• and fur seals, which struggle to find food during warmer winters. Scientists are
• concerned that climate change will continue to decrease the amount of pack ice, which
• will reverberate through the food web. (Global climate change, including the effect on
• Adélie penguins in Antarctica, is discussed in Chapter 21.)
• To complicate matters, some commercial fishermen have started to harvest krill
• to make fishmeal for aquaculture industries (discussed in Chapter 19). Scientists worry
• that the human harvest of krill may endanger the many marine animals that depend
• on krill for food. ?