Ecosystems and the Environment

Ecosystems and the Environment Unit 10

Ecosystems: What is an Ecosystem? And Energy Flow in Ecosystems Chapter 16.1 and 16.2 Benagh2013

Interactions of Organisms and Their Environments • We are part of the environment along with all of Earth’s other organisms. • Ecology: the study of the interactions of living organisms with one another and with their physical environment. Benagh 2013

Ecology • Habitat: The place where a particular population of a species lives • The range of tolerance an organism possesses determines where it can live. • Community: the many different species that live together in a habitat • Ecosystem: a community and the physical aspects of its habitat (soil, water, weather) • Abiotic Factors: the physical aspects of a habitat • Biotic Factors: the organisms in a habitat Benagh2013

Diverse Communities in Ecosystems • Biodiversity: the variety of organisms, their genetic differences, and the communities and ecosystems in which they occur. • Biodiversity can be impacted by limiting factors, which can control the number of organisms in an ecosystem. Examples: nutrients, water, shelter, etc. Benagh2013

Change of Ecosystems Over Time • The physical boundaries between ecosystems are not always obvious. • Additionally, ecosystems do not remain static (the same). • For example a volcano, a receding glacier, or fire can destroy vegetation and create new habitat. • The first organisms to live in these newly formed habitats are often small, fast-growing plants called pioneer species. Benagh 2013

Succession • Once new species start moving into this newly formed habitat, they go through process called succession. • Ecological Succession: a somewhat regular progression of species replacement • Primary Succession: succession that occurs where life has not existed before • Volcanic island • Secondary Succession: succession that occurs in areas where there has been previous growth • Abandoned field Benagh2013

Glacier Bay: An Example of Succession • An example of primary succession is a receding glacier because land is continually being exposed as the face of the glacier moves back. • The soil is poor in nitrogen at first. • Pioneer species (the first species to colonize a new area) move in. • Alder seeds blow in, their roots fix nitrogen (make it usable for plants) and add nutrients to the soil. • Nitrogen Fixation: the process by which gaseous nitrogen is converted into ammonia, a compound that organisms can use to make amino acids Benagh2013

Glacier Bay: An Example of Succession • New trees are able to move in. • Eventually, the area is filled with dense thickets of trees. • The ecosystem has finally become a climax community: a community that has reached a steady state through ecological succession. Benagh2013

Primary Energy Source • Everything that we do requires energy, and this energy flows from organism to organism. • Most life on Earth depends on photosynthetic organisms. • Primary Productivity: the rate at which organic material is produced by photosynthetic organisms in an ecosystem. • This determines the amount of energy available in an ecosystem. • Producers: organisms that capture energy in photosynthesis including plants, algae, and some bacteria • Consumers: organisms that consume plants of other organisms to obtain the energy necessary to build their molecules. Benagh2013

Trophic Levels • Trophic Level: one of the steps in a food chain or pyramid. • First Level (lowest level): producers which perform photosynthesis and sometimes absorb nitrogen gas with the help of nitrogen-fixing bacteria. • Second Level: Herbivores, which eat primary producers. Use microorganisms to help digest plant materials in their guts. • Third Level: Secondary consumers; animals that eat other animals. • Fourth Level: Tertiary Consumers; carnivores that eat other carnivores • Detritivores: organisms that obtain their energy from the organic wastes produced at all trophic levels. • Decomposers: Bacteria and fungi are decomposers because they cause decay. • Decay is very important because it allows for the recycling of nutrients. Benagh2013

Aquatic Food Chains • Food Chain: the path of energy through trophic levels. Benagh2013

Aquatic Food Web • Food Web: a complicated, interconnected group of food chains. • In most ecosystems, energy does not follow simple straight paths seen in simplified food chains. Benagh2013

Energy Transfer • During every transfer of energy within an ecosystem, energy is lost as heat. • Thus, the amount of useful energy decreases and energy passes through an ecosystem. • This is why there are more producers and primary consumers than secondary and tertiary consumers. • Only about 10% of energy is passed up trophic levels. • Sometimes energy is not the only thing transferred between trophic levels: • Biological Magnification: the accumulation of increasingly large amounts of toxic substances within each successive link of the food chain. Benagh2013

The Pyramid of Energy • Ecologists often illustrate the flow of energy through an ecosystem using an energy pyramid. • Energy Pyramid: a diagram in which each Trophic level is represented by blocks stacked one another. • The width of the block indicates how much energy is stored at each trophic level. • Only about 1/10 of the energy in a trophic level is found in the next trophic level, so it takes a pyramid shape. Benagh2013

Limitations of Trophic Levels • Most ecosystems only involve three or four trophic levels because too much energy is lost to support more. • Biomass may sometimes be a better indicator of energy than organism number. • Biomass: the dry weigh of tissue an other organic matter found in a specific ecosystem. Each higher level contains only 10% of the biomass found in the trophic level below it. Benagh2013

04/03/13 DOL: For each statement below, identify the relevant ecological term. • The LIVING part of an ecosystem. • The type of succession that occurs where life has not existed before. • Organisms that capture energy in photosynthesis including plants, algae, and some bacteria. • Organisms that cause decay. • The amount of energy that passes to the next trophic level.

Cycling of Materials in Ecosystems Chapter 16.3 Benagh2013

Biogeochemical Cycles • Nature does not throw away raw materials! • The physical parts of the ecosystems cycle constantly in various nutrient cycles! • Carbon atoms are passed from one organism to another. • Producers are eaten by herbivores, which are eaten by carnivores, which are eaten by top carnivores, which eventually die and are decayed by decomposers. Eventually their carbon atoms become part the soil to feed the producers and start the process over! • The four biogeochemical cycles we will talk about are the water, carbon, phosphorus, and nitrogen cycles. • Biogeochemical cycle: the circulation of substances through living organisms from or to the environment. • Substances cycle between livingand non-living reservoirs. Benagh2013

The Water Cycle • Of all nonliving components of an ecosystem, water has the greatest impact on the inhabitants: • Precipitation (rain and snow) • Ground water (water stored under ground) • Ultimately the water cycle is caused by heating by the sun leading to evaporation. Benagh2013

The Water Cycle • Living Components: • Water is taken up by the roots of plants. • Water moves back into the atmosphere by evaporating from leaves in transpiration (which is also ultimately caused by the sun). • Water is very important to aquatic ecosystems such as lakes, rivers, oceans, estuaries, and wetlands. Benagh2013

The Carbon Cycle • Carbon cycles between the nonliving environment and living organisms. • The nutrient cycling of carbon is very closely related to the cycling of Oxygen (O2). • Carbon dioxide (CO2) in the air/water is used by plants, algae, or bacteria in photosynthesis to make new organic nutrients (sugars). Carbon atoms can return to the pool of CO2 in the air and water in three ways: • Respiration • Combustion • Erosion Benagh2013

The Carbon Cycle • Respiration: Oxygen (O2) is used to oxidize organic molecules in cellular respiration and CO2 is released as a byproduct. Benagh2013

The Carbon Cycle • Combustion: Carbon returns to the atmosphere through burning. • Carbon in wood can stay there for many years, and is released when the wood is burned. • In fossil fuels (oil, natural gas, coal) the carbon has been stored underground for millions of years! • Burning releases CO2 which is necessary for plant growth but can potentially cause global warming if too much carbon is released! Benagh2013

The Carbon Cycle • Erosion: Marine organisms use carbon dioxide dissolved in the sea water to make calcium carbonate shells. • Shells of dead organisms eventually form sediments such as limestone. • As limestone is exposed and erodes, carbon is again available to different organisms. Benagh2013

The Phosphorus Cycle • Phosphorus is an essential part of our bodies. • Essential for ATP and DNA creation. • Phosphorous is usually stored in soil and rock as calcium phosphate. • It dissolves in water to form phosphate ions, PO43-. • This phosphate is absorbed by the roots of plants and used to build organic molecules. • Animals eat the plants and reuse the organic phosphorus. • Excessive amounts of nutrients such as phosphorus entering waterways causes too many algae to grow and hurts the aquatic system. Benagh2013

Benagh2013 The Nitrogen Cycle • The atmosphere is 78 percent nitrogen gas, N2. • In spite of how much nitrogen is around us, most organisms cannot use it in that form because of the strong bonds between the two N atoms. • Some bacteria can break the bond and make ammonia, NH3 in a process called Nitrogen Fixation. • Nitrogen Fixation: the process by which gaseous nitrogen is converted into ammonia, a compound that organisms can use to make amino acids. • Nitrogen fixation is performed by bacteria that live in the soil and root nodules (swellings) of plants like alder trees.

The Four Stages of the Nitrogen Cycle • Assimilation: the absorption and incorporation of nitrogen into organic compounds by plants. • Ammonification: the production of ammonia (NH3) by bacteria during the decay of organic matter. • Nitrification: the production of nitrate from ammonia. • Denitrification: the conversion of nitrate to nitrogen gas. Benagh2013

04/05/13 DOL: For each statement below, identify the relevant biogeochemical cycle. • Includes the process of combustion • Includes the processes of transpiration. • The main reservoir (storage area) for this nutrient is the atmosphere, but most organisms cannot utilize it in this form. • Usually stored in soil and rocks. • Includes the process of assimilation, or incorporation into our proteins.

The Environment Chapter 18 Benagh2013

Acid Rain • Coal-burning power plants make smoke with lots of sulfur, because the coal contained lots of sulfur. • Sulfur introduced into the atmosphere combines with water vapor to form sulfuric acid. • Sulfuric acid carried back to Earth’s surface in precipitation (rain or snow) is called Acid Rain. • Lowering the pH of water (making it more acidic) can cause death of organisms such as lake animals, tree root fungi, and plant death. Benagh2013

The Ozone Layer • Remember, we need that protective layer of Ozone (O3) created by early photosynthetic cyanobacteria. • The Ozone layer protects us from dangerous Ultraviolet (UV) light. • In 1985, Scientists noticed that there was an Ozone hole over Antarctica. Every year, the hole gets worse, allowing more UV light to get to Earth’s surface. • Increased exposure to UV light can cause skin cancer, cataracts, etc. Benagh2013

Ozone Destruction • The ozone is being destroyed primarily by a class of chemicals called Chlorofluorocarbons (CFCs). CFCs are normally stable. • CFCs are used as coolants in refrigerators and air conditions, as propellants in aerosol spray cans, and foaming agents in plastic-foam creation. • It turns out, high in the atmosphere where we find the ozone layer, CFCs are not so stable. • They lose a chlorine atom, which enters into a series of reactions that destroy the Ozone (O3) and turn it into regular Oxygen (O2). • CFCS are now banned as aerosol can propellants in the U.S. Benagh2013

Global Temperature • Since the 1950s, the global temperatures have been increasing. • In Earth’s history, there have been many periods of Global Warming, which are often followed by periods of cold. • Scientists hypothesize that human activity may be significantly contributing to the modern global warming we see today. Benagh2013

The Greenhouse Effect • Our planet would be cold except that we have a layer of Greenhouse Gases containing water vapor, carbon dioxide (CO2), methane, and nitrous oxide keeping it warm because the bonds between these atoms absorbs solar energy as heat radiates from earth. This is called the Greenhouse Effect. • Greenhouse Effect: heat is trapped within the atmosphere of the Earth in the same way that glass traps heat in a greenhouse. • Due to the burning of fossil fuels, we have increased the carbon dioxide in the atmosphere. Benagh2013

Global Warming • The figure below shows the average change in global temperature since 1960 compared to the concentration of carbon dioxide in the atmosphere. • There is a strong correlation between the two, which has convinced many scientists that temperature and carbon dioxide levels are related. • However, correlation is not causation. Benagh2013

Chemical Pollution • The environment can not absorb any amount of pollution. Too much pollution can cause problems in ecosystems and to humans. • Chemical pollution is a major environmental problem. • Examples of chemical pollution: • Oil spills • Toxic materials • Carcinogenic (cancer-causing) materials • Agricultural chemicals such as pesticides (which are often toxic) Benagh2013

Types of Chemical Pollution • Modern agriculture often introduces large amounts of chemicals, including: pesticides, herbicides, and fertilizers. • Molecules of chlorinated hydrocarbons including the pesticides DDT, chlordane, lindane, and dieldrin are slow to break down in the environment. • These chemicals are also stored in the fat of animals. • As these molecules move up trophic levels, they become increasingly concentrated. Benagh2013

Types of Chemical Pollution • Biological Magnification: the accumulation of increasingly large amounts of toxic substances within each successive link of the food chain. • In birds, DDT causes eggs to be thin, and fragile—these eggs often break. • This was the worst in predatory birds because they are high in the food chain and occupy a high trophic level. • As such, the numbers of predatory birds dwindled. • In 1972 the use of DDT was restricted in the U.S. Benagh2013

Loss of Resources • We are damaging ecosystems in many ways, including consuming or destroying resources that we cannot replace. • There are three kinds of nonrenewable resources being consumed or destroyed far too quickly: • Extinction of Species: we have destroyed 50% of the worlds rainforest in 50 years, taking many species with them. 10% of well known species are endangered, and there are likely many more unknown species at risk. • Loss of Topsoil: fertile soil for agriculture is being depleted because of poor land management that washes away rich topsoil (the fertile part of soil that allows plants to grow) • Groundwater Pollution and Depletion Benagh2013

3. Ground-Water Pollution and Depletion • Finally, we cannot replace ground water. • Much of our water is stored underground in aquifers (rock reservoirs for water). • Water seeps into aquifers too slowly to replace, and we are removing too much of the water. • In the U.S., most areas are not concerned with conserving ground water—we waste water on lawns, washing cars, and flushing toilets. Benagh2013

Growth of Human Population • Birth rates are high across the world, and death rates are decreasing. This leads to an increase in population size. • Population growth is fastest in the developing countries of Asia, Africa, and Latin America. • We reached 6 billion in 1999. There are now 7 billion people on the planet. • There are concerns that we may be reaching our carrying capacity. Benagh2013

04/09/13 DOL: For each statement below, identify the environmental problem described. • Sulfur in the atmosphere leads to lowered pH of water. • The breakdown of this atmospheric structure is caused by CFCs and can lead to increased rates of skin cancer. • Human-caused increase of Earth’s average temperature caused by the excessive release of greenhouse gases. • The accumulation of increasingly large amounts of toxic substances within each successive link of the food chain. • Size of human population.

04/11/2013 Journal Entry In the journal section of your binder, address the following questions in paragraph form. At the end of 5 minutes, you should have written 4-5 complete sentences. • What is symbiosis? • What was the relationship described in the video? • How has each species changed to help the other species?

How Organisms Interact in Communities and how Competition Shapes Communities Chapter 17.1 and 17.2

Evolution in Communities • Ecosystem’s inhabitants are a web of interactions between organisms. • Some interactions among species are the result of a long evolutionary history where the organisms adjust to one another. • Natural selection has often matched characteristics of flowers to a pollinator. • Coevolution: back-and-forth evolutionary adjustments between interacting members of a community.

Predators and Prey Coevolve • Predation: the act of one organism killing another for food. • Lions eating zebras • Parasitism: one organism feeds on and usually lives on or in another, typically larger organism. Parasites do not usually kill their prey (known as their host). • External parasites: feed on the host’s outside • Lice, fleas on dogs • Internal parasites: live entirely within the host’body • Hookworm

Plant Defenses Against Herbivores • Predation is also a problem for plants, which are rooted to the ground. • Plants have thorns, spines, prickles, and chemical compounds that discourage herbivores. • Secondary Compounds: defensive chemicals found in plants; often the primary means of defense. • Certain herbivores can feed on and be protected by the chemicals.

Symbiotic Species • Symbiosis: two or more species living together in a close, long-term association. • Can be: • Beneficial to both organisms • Benefit one organism and leave the other harmed or unaffected • Parasitism: one type of symbiotic relationship that is detrimental to the host organism.

Mutualism and Commensalism • Mutualism: a symbiotic relationship in which both participating species benefit. • Ants and Aphids: aphids suck sap from plants which they alter and secrete—ants use this as food and “milk” the aphids. The ants protect the aphids, so they are both helped by the relationship. • Commensalism: a symbiotic relationship in which one species benefits and the other is neither harmed nor helped. • Clown Fish and Sea Anemones: anemones have stinging tentacles, but the clown fish can live among the tentacles for protection. Anemones are not harmed by the relationship.

Ecosystems and the Environment