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Why are the Orcas Disappearing?
This story begins in 1960 and ends in 2005. Assume the current year is 2050.
The year is 1960; tourists from all around the world come to the northwest Pacific coast to
view the beautiful Orcas (killer whales). Occasionally one of the tourist’s boats runs across
a pod of 30 Orcas. What a site. These beautiful, calm marine mammals can turn deadly in
a matter of seconds when devouring a 600 pound male sea lion. Only a rare few have
witnessed this awesome power first hand.
The ecosystem here is incredibly diverse. The sea lions feed on both sea urchins and surf
perch (a small ocean fish). The sea urchins feed on the many algal blooms in the
productive intertidal zone. The algae synthesize their own organic molecules and
therefore are autotrophs. Father out to sea, the surf perch are busy feeding on the krill.
Krill are a shrimp like organism that feed on the oceans primary producer phytoplankton.
Any surf perch that are found close to shore feed off of shrimp, one of the oceans tastiest
scavengers. This is a very stable ecosystem and the numbers of organisms have stayed
relatively the same for years.
Krill is utilized as a protein source for cattle food. Shrimp as we know are a food source for
humans. The human population continues to increasing rapidly. However, we are now in
1986 and we see a huge demand for beef. A new fitness craze that came out swore that
putting more protein and less carbohydrate in your diet would help one lose weight and
build muscle. Being the 1980’s, people would believe anything. Suddenly, the fishermen
were pulling krill out of the ocean by the ton. This continued for many years. Even though
people were eating less beef in the 1990’s, the human population was so large, that the
demand for beef stayed high relative to the 1960’s. We now are in 2050 and looking back
at the human population of the 1990’s and laughing a very sad laugh.
The story ends here, you will have to analyze the data given on the next page to figure out
what is happening in this ecosystem. However, first draw a food web. Be sure to include
all organisms this study.