The Ocean and Its Ecosystems

Ocean is a huge body of salt water covering 71 percent of the Earth’s surface. It produces half the planet’s oxygen and regulates climate, rainfall and droughts. It is home to a vast diversity of fish, mammals and birds. It also sustains a global industry that depends on ocean resources, including shipping and trade, fishing and aquaculture, energy (sea and wind power), tourism and recreation, and freshwater production through desalination. Human activities also affect marine life and ecosystems through marine pollution, overfishing, sea level rise, and ocean acidification.

The Earth’s ocean is divided into distinct regions for geographical, historical, and cultural reasons. Oceanographers and countries traditionally recognize four named oceans: Atlantic, Pacific, Indian, and Arctic. However, due to plate tectonics and the retreat of Antarctic ice, National Geographic and other scientists are now calling for a fifth ocean – the Southern Ocean – to be recognized as the world’s most important ecosystem.

Each ocean region has different temperature, salinity, and chemistry characteristics, largely caused by the constant circulation of water through the global thermohaline circulation. This circulation is driven by solar radiation, atmospheric circulation (wind) and the Coriolis effect. The circulation of ocean waters also creates currents. Ocean currents are primarily tidal in nature, but are also driven by winds and atmospheric pressure.

The color of the ocean is determined by the presence of living and nonliving organic matter – everything from bacteria, algae, phytoplankton and other small organisms to shellfish, rocks, mineral sediments and dead plants. The most common pigment is chlorophyll. Chlorophyll reflects the amount of sunlight that the phytoplankton is receiving. The result is that the ocean appears blue in regions with high productivity and red and yellow in regions of low productivity.

Scientists use satellite imagery to monitor ocean color and other environmental factors in real time. This data is then used to develop models of the ocean’s behavior and nutrient levels. These models can help predict how the ocean may respond to changing environmental conditions, such as climate change and overfishing.

The ocean is a vital natural resource providing food, jobs and energy for billions of people around the world. It also provides recreational opportunities such as sailing, surfing and scuba diving. It also supports the world’s fishing and whaling industries, and a variety of other extractive industries such as offshore drilling and deep sea mining. It is also the source of most of our freshwater, and it absorbs carbon dioxide from the atmosphere, helping to maintain a healthy balance between greenhouse gases and other air pollutants. However, the ocean is under threat from marine pollution, overfishing, climate change and ocean acidification. As a result, the health of our oceans is deteriorating at an alarming rate. This is why it’s so important to take action now. A healthier ocean means a healthier planet.

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