Florida Museum of Natural History



EDEP Program Fall 2013| Week 3-4: Ocean Currents and Pollution403860014541500Lesson TopicHow do marine biologists know how currents in the ocean work? Why is pollution so important to understand? What are scientists doing about pollution? Lesson ObjectiveAfter this week, students will be able to:Model how ocean currents work Describe the causes and the effects of Pollution.Outline various methods for combating pollution.Words to know: circulations, topographic, pollution, sediment, pesticides, pathogens, ecosystems, alien species, conservationBackground InformationOcean currents are the mass movements and circulations of water caused by various factors. They flow throughout the world connecting the oceans’ water and resources.? The patterns of these movements are determined by wind, major topographic landmarks - like the world’s largest salt flat in Bolivia, many hot springs from around the world, volcanoes found throughout the oceans, deserts, salinity, heat distribution, and the rotation of the earth.? Both surface and deep water currents are present in the movement of ocean water and are the exchange system that distributes heat, salinity, nutrients, the inhabitants of the oceans, and all other resources.Ocean currents have two different methods of moving water.? Surface currents move as a result of blowing winds and are influenced by atmospheric factors.? Deep ocean currents move as a result of the density differences that are present in the ocean.? Density is determined by both salinity and temperature; in areas such as the Poles, the water is very cold and has glaciers forming so the freshwater is taken out of the water and the remaining water becomes more saline, resulting in very dense water.? This water that is formed in the poles then moves throughout the world to mix the oceans.?Water from the equator is less dense because it’s warmer, so it moves towards the poles. The water is then used in thermohaline circulation, commonly referred to as the oceans conveyor belt. The ocean conveyor begins in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters are able to warm and rise to the surface, continuing the conveyor belt that encircles the globe.The two largest currents on earth are the Kuroshio Current which circulates near Japan, and the Antarctic Circumpolar Current which circulates around Antarctica. Other currents are: the North and South Equatorial Currents, the Gulf Stream, and the East Australian Current (many seen below). Conservation Concerns/Pollution in the OceanThe pollution of water bodies affects marine life and humans alike. Today, marine life is seriously impacted by many different sources of pollution— oil spills, garbage dumping, accumulation of toxic materials and industrial wastes in the ocean. Since oceans are the biggest natural sources of water, taking care of them and the marine life thriving in the water bodies is the responsibility of every human being and necessary to ensuring survival of the planet.Plastic bags, balloons, medical waste, soda cans, and milk cartons all find their way into the oceans of the world. These items float in the water and wash up on beaches. They often create health hazards for marine life. Ocean mammals can get entangled in old nets and drown because they cannot get to the surface for air. Birds, turtles, and fish ingest a variety of plastic items and their digestive systems become clogged. Sea turtles are especially attracted to floating plastic bags which appear to be jellyfish, one of their favorite treats. The plastic bags block the digestive system and cause a slow and painful death. Various pieces of trash can cause entanglement, starvation, drowning, and strangulation. Scientists estimate that there is one hundred million metric tons of plastic debris in the ocean. Excess nutrients result in poor water quality, leading to decreased oxygen and increased nutrients in the water (eutrophication). This can lead to enhanced algae growth on reefs, crowding out corals and significantly degrading the ecosystem. In addition, sediment deposited onto reefs smothers corals and interferes with their ability to feed and reproduce. Finally, pesticides interfere with coral reproduction and growth. Sewage discharge and runoff may also introduce pathogens into coral reef ecosystems. When the trash washes up onto beaches and into marshes and wetlands, it ruins breeding grounds and habitats. Oxygen is necessary for all life. As trash degrades in the water, it uses up oxygen. When oxygen levels are low marine life can't thrive. See the chart of the following page for more information on types of pollution that are impacting the oceans. Type of PollutionPrimary Source/CauseEffectNutrientsRunoff: approximately 50% sewage, 50% from forestry, farming, and other land use. Also airborne nitrogen oxides from power plants, cars etc.Feed algae blooms in coastal waters. Decomposing algae depletes water of oxygen, killing other marine life. Can spur algal blooms (red tides), releasing toxins that can kill fish and poison people.SedimentsErosion from mining, forestry, farming, and other land-use; coastal dredging and miningCloud water; impede photosynthesis below surface waters. Clog gills of fish. Smother and bury coastal ecosystems. Carry toxins and excess nutrients.PathogensSewage, livestock.Contaminate coastal swimming areas and seafood, spreading cholera, typhoid and other diseases.Alien SpeciesSeveral thousand per day transported in ballast water; also spread through canals linking bodies of water and fishery enhancement projects.Outcompete native species and reduce biological diversity. Introduce new marine diseases. Associated with increased incidence of red tides and other algal blooms. Problem in major ports.Persistent Toxins (PCBs, Heavy metals, DDT etc.)Industrial discharge; wastewater discharge from cities; pesticides from farms, forests, home use etc.; seepage from landfills.Poison or cause disease in coastal marine life, especially near major cities or industry. Contaminate seafood. Fat-soluble toxins that bio-accumulate in predators can cause disease and reproductive failure.Oil46% from cars, heavy machinery, industry, other land-based sources; 32% from oil tanker operations and other shipping; 13% from accidents at sea; also offshore oil drilling and natural seepage.Low level contamination can kill larvae and cause disease in marine life. Oil slicks kill marine life, especially in coastal habitats. Tar balls from coagulated oil litter beaches and coastal habitat. Oil pollution is down 60% from 1981.PlasticsFishing nets; cargo and cruise ships; beach litter; wastes from plastics industry and landfills.Discard fishing gear continues to catch fish. Other plastic debris entangles marine life or is mistaken for food. Plastics litter beaches and coasts and may persist for 200 to 400 years.Radioactive substancesDiscarded nuclear submarine and military waste; atmospheric fallout; also industrial wastes.Hot spots of radio activity. Can enter food chain and cause disease in marine life. Concentrate in top predators and shellfish, which are eaten by people.ThermalCooling water from power plants and industrial sitesKill off corals and other temperature sensitive sedentary species. Displace other marine life.NoiseSupertankers, other large vessels and machineryCan be heard thousands of kilometers away under water. May stress and disrupt marine life.Looking for SolutionsWhat can we do to help? The cornerstone of fighting pollution is going green; this is actively reducing, reusing and recycling whenever possible. Conservation is the wise use of natural resources (nutrients, minerals, water, plants, animals, etc.) and cultural resources (different groups of people from different parts of the world). It may also include protecting the large collections of resources that make up a habitat or environment. Conservation is important to make certain changes don’t happen too quickly. Rapid change can force animals, plants, places, or people to become endangered or extinct. Activities Exploring Ocean Currents 35909255270500MaterialsMilk (whole or 2%) Dinner plate Food coloring (red, yellow, green, blue) Dish-washing soap Cotton swabsProcedure418147549022000Pour enough milk in the dinner plate to completely cover the bottom and allow it to settle. Add one drop of each of the four colors of food coloring - red, yellow, blue, and green - to the milk. Keep the drops close together in the center of the plate of milk, but not close enough that they begin to mix. Find a clean cotton swab for the next part of the experiment. Have the students predict what will happen when you touch the tip of the cotton swab to the center of the milk. It's important not to stir the mix just touch it with the tip of the cotton swab. Place a drop of liquid dish soap on the tip of the cotton swab. Place the soapy end of the cotton swab back in the middle of the milk and hold it there for 10 to 15 seconds. Add another drop of soap to the tip to the cotton swab and try it again. Experiment with placing the cotton swab at different places in the milk. Be sure that the students notice that the colors in the milk continue to move even when the cotton swab is removed. The long-term effects of pollution on water MaterialsMeasuring cupTap water1-gallon (4-liter) glass jarFood coloringSpoonProcedureStudents (individually, in groups, or as a class) will start with ? cup of water in the 1-gallon jar. The activity leader will then add 2 drops of food coloring to the mixture. The activity leader will explain that this represents pollution being dispersed into the water. Students are then to add 1 cup of water a time until the color disappears. Students should find that it takes about 7 cups of water to make the color disappear. Initially, the red is visible because the molecules of red are close together (pollution starts concentrated at once source). As clean water is added, the color molecules spread evenly throughout the water (as with pollution). Eventually, the pollution molecules become far enough apart to become invisible to the naked eye. As pollution flows downstream from where it is initially dumped, it becomes mixed with more water. This does not mean that it is gone. When you drink water from the jar, you ingest a small amount of red food coloring; likewise, drinking water from the polluted water means you’re drinking a small amount of pollution. It is because of this that it is quite easy for animal life in streams miles away from the source of pollution can be affected by the pollution. Coral Reef:This week the coral reef activity is going to be placing sea life photographs and images (shown below), or drawn on their own. Coral reefs are not stagnate structures in the ocean. They are full of life and many different animals use them as shelter, for hunting, and for social interaction. Students can add it on by taping items to craft sticks/pipe cleaners and taping it onto the reef, or they could tape it to the base. However they do it, it should be how they feel most creative and inspired!The below images are merely examples and suggestions, feel free to come up with your own—even add your own drawings! GlossaryCirculations: Water current flows in a closed circular pattern within an oceanTopographic: The description of surface shapes and features of the Earth and other observable astronomical objects including planets, moons, and asteroids. Pollution: The introduction of contaminants into the natural environment that cause adverse change.Sediment: Naturally occurring material that is broken down by processes of weathering and erosion.Pesticides: Substances meant for preventing, destroying or mitigating any pest.Pathogens: A biological agent that causes disease or illness to its host.Ecosystems: A community of living organisms in conjunction with the nonliving components of their environment.Alien species: Animals and plants that are introduced accidently or deliberately into a natural environment where they are not normally found. Conservation: Protecting animals, fungi, plants and their habitats. ................
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