Human Impact on Oceans
Mrs. Morgan (sample)
How do humans efffect the world's oceans?
Marine Sanctuaries
Sanctuary waters may provide a secure habitat for endangered species. Sanctuaries may also protect shipwrecks and historic artifacts. They serve as outdoor classrooms for schoolchildren and laboratories for researchers who want to better understand and protect the ocean environment. Sanctuaries also protect economically important fisheries.
Marine sanctuaries often have different zones, which allow different activities. A permit system usually regulates these activities, such as fishing or recreational water sports. Only a certain number of permits are issued every year. The permits allow the MPA to prevent overfishing or pollution due to boats or other personal watercraft.
Oxygen Production
Gases in the atmosphere like carbon, nitrogen, sulfur and oxygen are dissolved through the water cycle. The gases that are now crucial to all ecosystems and biological processes originally came from the inside layers of the earth during the period when the earth was first formed. The rate of flow for oxygen as well as other gases is controlled by biological processes, especially metabolism of organisms like prokaryotes and bacteria. Prokaryotes have been around since the beginning of the Earth, have evolved to be able to use chemical energy to create organic matter and are capable of both reducing and oxidizing inorganic compounds. Bacteria that can reduce inorganic compounds are anaerobic and those that oxidize inorganic compounds are aerobic. Aerobic bacteria release oxygen as a by-product of photosynthesis.
Approximately two billion years ago, aerobic bacteria began producing oxygen which gradually filled up all of the oxygen reservoirs in the environment. Once these “sinks” were filled, molecular oxygen began to build in the atmosphere, creating an environment favorable for other life to inhabit the Earth. Sinks included reduced iron ions and hydrogen sulfide gas. Evidence of this process can be found in the banded iron formations created when iron minerals were precipitated. The oxygen started to fill the atmosphere up and new bacteria evolved that could use oxygen to oxidize both inorganic and organic compounds. Bacteria that were accustomed to an oxygen-poor atmosphere only survived in anaerobic environments like sewage, swamps, and in the sediments of both marine and freshwater areas.
Phytoplankton account for possibly 90% of the world's oxygen production because water covers about 70% of the Earth and phytoplankton are abundant in the photic zone of the surface layers. Some of the oxygen produced by phytoplankton is absorbed by the ocean, but most flows into the atmosphere where it becomes available for oxygen dependent life forms.