OCEAN 320 Lecture Notes - Lecture 2: Organochloride, Keystone Species
Unit 1B: The Human Ocean
20th Century Changes
• Population
o Over the last half a century, human population has more than doubled
o 7.5 billion people alive, 1.5 billion starving
o Advancements in fishing technology lead to a global feeding frenzy, which was
sustainable on the 2 billion population it started on, but will be completely
depleted in the case of the tuna fish for example by 2050
• Petrochemicals & Waste
o Petrochemicals (petroleum-based chemicals) were developed and introduced to
the environment specifically to eradicate pests, but these chemicals affected all
life; birds, farm animals, etc die from exposure and tainted resources (food, water,
etc)
o Ex: DDT (a chlorinated hydrocarbon) banned from US in 70’s, but still remains in
the soil and oceans, and more is released elsewhere, where it is not banned
▪ Ban was controversial because DDT could save human lives by
eradicating malaria, but in the long run hurts the human species and
inevitably destroys the environment
o Ex 2: plastic is found in every ocean, mimics plankton, and is consumed,
becoming a part of the food chain
• Systems Understanding
o Modern science has a much better grasp of the oceans many systems and how
immense they are
▪ Ex: plankton! are! so! important! but up until the 1990’s no one knew that
an extremely important species of plankton (called bacterial plankton)
even existed and contributed so heavily to their ecosystem
o All works codependently; humans are just as much a part of the system as they
are reliant on it
o Must watch our development and use of petroleum, petrochemicals, and plastics
so as not to create an irreversible problem
o We are in a precarious environmental state
▪ Hydrocarbon consumption is dramatically changing the character of our
atmosphere
▪ Oceans are dissolving more CO2 and thereby becoming more acidic
▪ Oceans also absorbing heat
▪ System is being strained, and if we lose keystone species, the whole
ecosystem will collapse; notably, the ocean’s resources (food chain!) are
being messed with, which could result in an ocean-wide system collapse
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