Chapter 19 Oceanography

Section 1 – The Seafloor Ocean basins – low areas of Earth filled with water Continental shelf – gradually sloping end of the continent that extends under the ocean Continental slope – steeper slope that extends from the outer edge of the continental shelf down to the ocean floor Abyssal plains – flat seafloor areas from 4,000 m to 6,000 m below the ocean surface

Section 1 – The Seafloor… Continued As crustal plates move, the ocean floor changes Mid-ocean ridge – new ocean floor is formed. Eruption of magma from Earth’s interior Process called seafloor spreading Trenches – long, narrow, steep-sided depressions Form at subduction zones where one crustal plate sinks beneath another Example: Mariana Trench

Section 1 – The Seafloor… Continued Many mineral resources can be found in the ocean. Petroleum, natural gas, phosphorite, limestone, sand gravel – examples of continental shelf deposits Economically important - can be mined Placer deposits – can form where rivers enter oceans Sulfur, iron, copper, zinc, silver –examples of deep-water deposits Too difficult and expensive to mine Manganese nodules – deposits that form from seawater

Section 2 – Life in the Ocean Ocean organisms carry out life processes every day. Photosynthesis – marine plants and algae use energy from the Sun to make food. Producers – organisms that undergo photosynthesis Consumers – organisms that feed on producers Chemosynthesis – the process of using sulfur or nitrogen compounds as energy to produce food Energy is passed from one organism to another organism in a food chain Complex feeding system of overlapping food chains – food webs

Section 2 – Life in the Ocean… Continued Varieties of ocean life Plankton – marine organisms that drift with the current Phytoplankton – producers Zooplankton – feed on phytoplankton Nekton – animals that actively swim rather than drift in the current Can control their buoyancy Some deep-dwelling nekton produce their own light Benthos – plants and animals living on or in the seafloor

Section 2 – Life in the Ocean… Continued Habitats along the near-shore areas of the continental shelf – ocean margin habitats Beach – dwelling organisms are adapted to a constantly changing environment. Tide pools formed in rocky shore areas contain food and provide protection. Estuaries provide a lower salt environment with many nutrients. A coral reef forms in clear, warm water an provides a habitat for many species

Section 3 – Ocean Pollution Pollution – introduction of harmful waste products, chemicals, and other substances not native to an environment Sewage – pollutant that acts like a fertilizer Creates algal blooms Uses up oxygen so other organisms die Chemicals – wastes from industrial and agricultural products Oil – from tankers and land runoff

Section 3 – Ocean Pollution… Continued Solid wastes – debris washed up on beaches that kill or create hazards for animals Silt – sediment from erosion that can cover coral reefs or fill marshes Pollution effects – ocean environments are drastically changing Pollution control – international organizations and treaties work to reduce ocean pollution.

Section 3 – Ocean Pollution… Continued No international agreement exists to control land based activities that affect the oceans. Everyone’s cooperation is needed Continue to learn about marine pollution