LIFE IN THE OCEANS Plankton Nekton and Benthos

LIFE IN THE OCEANS Plankton, Nekton, and Benthos

Life in the Oceans 4 Types of Ocean Life—Plankton • Tiny marine organisms that float in ocean currents are called plankton. • Plankton range from microscopic algae and animals to organisms as large as jellyfish. • Two types of plankton are phytoplankton and zooplankton

Phytoplankton • First meal in the ocean food chain • Phytoplankton are also known as microalgae • Contain chlorophyll and require sunlight to live and grow • Preform photosynthesis and are responsible for producing around 50% of the oxygen in the atmosphere • Need nutrients such as nitrates and phosphates to survive Zooplankton • Zooplankton are typically microscopic animals that spend all or part of their lives as plankton. • Weak swimmers and usually just drift along with the currents • Can be large soft bodied animals (jellyfish) • They cannot make their own food and must eat other plankton.

Life in the Oceans 4 Nekton • Animals that can actively swim, rather than drift in the currents, are called nekton. • Swimming allows these animals to search more areas for food. • Includes mammals such as whales, dolphins, and sea lions, as well as many types of fish.

4 Benthos Life in the Oceans • Benthos are organisms that live on or in the ocean floor • Most of these animals lack a backbone and are called invertebrates. • Includes organisms such as crabs, starfish, worms, coral, sponges, seaweed and clams

OCEAN ZONES (SHORELINE TO OPEN OCEAN) Intertidal Zone Neritic Zone Oceanic Zone Benthic Zone

Intertidal Neritic Zone Continental Shelf Oceanic Zone Sunlight Benthic Zone

INTERTIDAL ZONE Intertidal Zone Continental Shelf Area between high tide line and low tide line where the ocean meets the land. Area is exposed to air for part of the day. Organisms adapted to survive exposure to air and to keep from being washed away by the waves. The benthic zone runs underneath the intertidal zone. Many benthos live here.

NERITIC ZONE Neritic Zone Continental Shelf Area over the continental shelf where the water becomes deeper and the ocean floor starts to slope downward. Water is warm and receives a lot of sunlight Area of greatest density and diversity of marine life

OCEANIC ZONE Oceanic Zone The region of the sea extending from the edge of the continental shelf, over the continental slope, and over ocean floor. Many animals such as fish, sharks, and whales are found here Some of the animals live in the very deep parts of the oceanic zone Continental Shelf

BENTHIC ZONE The Benthic Zone Ocean Floor There are shallow benthic zones and deep benthic zones The deepest parts get no sunlight and are very cold. Animals in deepest benthic zones have special adaptations for the deep dark water.

MARINE ECOSYSTEMS An ecosystem includes all of the living (biotic) things in a given area, interacting with each other, and also with their non-living (abiotic) environments. Marine ecosystems are among the largest of Earth's aquatic ecosystems. They include oceans, salt marshes, intertidal zones, estuaries, lagoons, mangroves, coral reefs, the deep sea, and the sea floor. All Ecosystems have: Producers Consumers Decomposers

PRODUCERS Producers are the organisms that can make their own food. In a marine ecosystem this role is mainly filled by phytoplankton Phytoplankton use their chloroplasts along with sunlight and carbon dioxide to perform photosynthesis. In deep water marine ecosystems where sunlight cannot penetrate the producers use a process known as chemosynthesis to make food This takes place along hydrothermal vents where organisms use chemicals that seep through to produce food

CONSUMERS Organisms that eat, or consume, producers are called consumers. Consumers get their energy from the food stored in the producers’ cells. Some also eat other consumers to get energy.

DECOMPOSERS Decomposers, such as bacteria, break down tissue and release nutrients and carbon dioxide back into the ecosystem.

OCEAN RESOURCES

EARTH’S OCEANS ARE A SOURCE OF MANY RESOURCES Earth’s oceans contain dissolved gases. Nitrogen, Oxygen and Carbon dioxide are the most plentiful dissolved gases in the ocean. Oxygen enters the ocean water from the atmosphere and is used by the animals that live in the ocean water Cold water holds more dissolved gas than warm water. Of these three gases Carbon Dioxide dissolves the easiest in the ocean.

OXYGEN FROM THE OCEAN The carbon dioxide and the sunlight are used by the phytoplankton in the surface waters of the ocean to produce oxygen. Over 50% of the Earth’s oxygen comes from phytoplankton

BIOTIC RESOURCES FROM THE OCEAN (FISHING) People have been harvesting fish from the ocean for thousands of years. Fish are the largest group of organisms taken from the ocean Fisheries today provide about 16% of the total world's protein supply with even higher percentages occurring in developing nations. With such a high human demand for fish and the importance of fishing in the economy of many countries, the potential for overfishing is great.

FISH FARMS To help alleviate overfishing many people have started to raise ocean fish in fish farms. Fish farms use a number of holding ponds to raise fish and other seafood animals to be sold for food. Huge nets line the holding ponds to keep the animals natural predators out.

FISHERIES

SEAWEED Seaweed is a species of algae Many types of seaweed are harvested from the ocean. Kelp is a type of seaweed that is used as a thickener in many different products such as ice cream and jellies Seaweed is rich in protein and is a staple of the Japanese diet.

ABIOTIC RESOURCES FROM THE OCEAN Many abiotic or nonliving resources are also harvested from the ocean These are used to provide raw materials, drinkable water and energy for Earth’s growing population. Abiotic resources from the ocean include: • Oil and natural gas These are nonrenewable resources that are found under layers of impermeable rock. Petroleum engineers must dill through layers of rock on the ocean floor to reach these resources. These have the greatest economical impact of all the oceans resources. • Sea-Floor Minerals Many minerals that mining companies crave are found in nodules on the ocean floor. These nodules are mostly manganese, which is used in making steel, but they also can contain iron, copper, nickel, and cobalt. These nodules form when dissolved substances in sea water stick to solid objects. Up to 15% of the ocean floor could covered with these nodules but mining them is difficult and expensive.

Abiotic Ocean Resources Continued: Fresh Water: Through the process of desalination the salt can be removed from sea water to make drinkable fresh water. This process is used in parts of the world were access to freshwater is limited. Energy: The energy of the moving ocean water can be harnessed to generate electricity. This can be done using the energy of the tides or tidal energy or using the energy of the waves or wave energy. Human Recreation and Tourism: Tourism is the fastest growing division of the world economy and is responsible for more than 200 million jobs all over the world

OCEAN CURRENTS AND THEIR GLOBAL IMPACT The high specific heat capacity of water allows the oceans to be the largest reservoir of heat on Earth. The heat of the ocean water drives much of the weather on earth and through the ocean currents has a major impact on global climates

SURFACE CURRENTS Powered by wind, surface currents usually move only the upper few hundred meters of seawater. Currents do not move in straight lines because of the Coriolis effect. One of the most important surface currents for sailing across the north Atlantic is the Gulf Stream. The Gulf Stream flows from Florida northeastward toward North Carolina. There it curves toward the east and becomes slower and broader.

GULF STREAM’S EFFECT ON CLIMATE Look at Iceland on the map Based on its location and its name, you might expect it to have a cold climate. However, the Gulf Stream flows past Iceland The current’s warm water heats the surrounding air and keeps Iceland’s climate mild and its harbors ice free year-round

DENSITY CURRENTS AND CLIMATE A density current forms when more dense seawater sinks beneath less dense seawater. Seawater becomes more dense when it gets colder or becomes more salty. An important density current that affects many regions of Earth’s oceans begins north of Iceland. When water freezes, dissolved salts are left behind in the unfrozen water This unfrozen water is very dense because it is cold and salty. It sinks and slowly flows along the ocean floor toward the southern Atlantic Ocean

DENSITY CURRENTS AND CLIMATE CONTINUED As the water is sinking near Iceland, warm surface water of the Gulf Stream, shown in red, moves northward from the equator to replace it. • If Earth’s temperature rose enough, ice couldn’t easily form near the polar regions. Freshwater from melting glaciers on land also could reduce the salinity of the ocean water. The density currents would weaken or stop All of Earth could experience drastic climate shifts, including changing rainfall patterns and temperatures

An upwelling is a current in the ocean that brings deep, cold water to the ocean surface. This occurs along some coasts where winds cause surface water to move away from the land. Notice that when surface water is pushed away from the coast, deep water rises to the surface to take its place This cold, deep water continually replaces the surface water that is pushed away from the coast. The cold water contains high concentrations of nutrients produced when dead organisms decayed in the deep water.

WHAT DOES UPWELLING MEAN FOR AN AREA? Areas where upwelling occurs are high in nutrients This increases the amount of phytoplankton that grows there Which will increase the number of zooplankton in the area This typically makes these areas good fishing grounds.