Ecology Ch. 3 – The Biosphere

3.1 - What is Ecology? It is the scientific study of interaction among organisms and between organisms and their environment

What is the Biosphere? The biosphere is the combined portions of the entire planet where life exists.

Levels of Organization To understand relationships within the biosphere ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere

Levels (con’t.) Species: a group of organisms so similar to one another that they can breed and produce fertile offspring. Populations: a group of individuals that belong to the same species and live in the same area. Communities: different populations that live together in a defined area.

Levels (con’t.) Ecosystems: all the organisms that live in a particular place, together with their nonliving or physical environment. Biomes: a group of ecosystems that have the same climate and dominant communities.

Levels of Organization

Biotic and Abiotic Factors Biotic Factors – Any living part of the environment with which an organism might interact Ex. – animals, plants, mushrooms & bacteria Abiotic Factors – Any nonliving part of the environment Ex. – sunlight, heat, water, soil, etc.

Biotic and Abiotic Factors Together The differences between biotic and abiotic factors are not always clear and simple Many physical factors can be strongly influenced by the activities of organisms Ex. – pond “muck” is a combination of soil (abiotic) and leaf mold & decomposing plant material (biotic)

Biotic and Abiotic Factors

Ecological Methods Scientists use three basic approaches to conduct ecological research. They are: Observing Experimenting Modeling

3-2 Energy, Producers, and Consumers What happens if your car runs out of gas? What do you need before you can play in a soccer game or run for 5 miles? Living systems need a constant input of Energy.

Primary Producers Autotrophs Organisms that use energy from the environment to make complex organic compounds Also known as producers. Why? Two types Photosynthesis - Energy from the Sun Chemosynthesis - Life without Light

Primary Producers Primary Producers The first producers of energy-rich compounds that are later used by other organisms Energy from the Sun Capturing light energy and using it to convert CO2 & H2O into O2 & Carbohydrates Energy without Light Using chemical energy to make Carbohydrates

Sources of Energy

Consumers Heterotrophs Rely on other organisms for their energy and food supply. Also known as consumers Why?

Consumers Types of Consumers Herbivores Carnivores – Omnivores Obtain energy and nutrients by eating plant materials Carnivores – Kill and eat other animals Omnivores Eat both plants and animals Scavengers Consume the carcasses of dead animals Detritivores Feed on dead and decaying plant and animal remains Decomposers Chemically break down matter

Beyond Consumer Categories These simple categories often don’t express the real complexities of nature. Examples: Hyenas (carnivores) will scavenge if they get a chance Aquatic animals will eat a mixture of algae, bits of animal carcasses, and detritus

3.3 Energy Flow in Ecosystems Energy flows through the ecosystem in one direction.

Energy Flow in Ecosystems

Food Chain A series of steps in which organisms transfer energy by eating and being eaten.

Food Web A network of many feeding interactions

Food Web

Food Webs and Disturbance Relationships in Food Webs are not simple. Disturbances do happen and their effects can be dramatic. Example - Marine Food Web / Krill

Antarctic Food Web

Trophic Levels and Ecological Pyramids Each level in a food chain or food web is a trophic level. Each trophic level depends on the level below it for energy.

What is a Trophic Level?

Ecological Pyramids Can be used to represent energy, matter or number of individuals at each trophic level

Energy Pyramid Only 10% of the energy available at one trophic level makes it to the next level When one organism eats another, energy is lost. Where does this energy go?

Energy Pyramid

Biomass Pyramid Represents all the living tissue (food) at each trophic level.

Biomass Pyramid

Pyramid of Numbers The number of individual organisms at each trophic level usually decreases as you go up the pyramid of numbers.

Pyramid of Numbers

3-4 Cycles of Matter Unlike the one-way flow of energy, matter is recycled in the biosphere. Where does your body get the materials, such as Carbon, it needs to function? __________ Elements , chemical compounds and other forms of matter are passed from one organism to another through biogeochemical cycles. Bio - ______ Geo - ______ Chemical - ______

Water Cycle

Other Biogeochemical Cycles Carbon Cycle - carbon is especially important because it is the key ingredient in all living organisms. Carbon is found in oceans, the air, and certain types of rock.

Carbon Cycle

Nitrogen Cycle - All organisms require nitrogen to make amino acids which are used to build proteins.

Nitrogen Cycle

Phosphorus Cycle - Unlike carbon nitrogen and oxygen, phosphorous does not enter the air, it remains mostly in rock, soil minerals, and ocean sediments. Phosphorous is of great biological importance for molecules like DNA and RNA.

Phosphorous Cycle

Nutrient Limitation Primary Productivity: the rate at which organic matter is created by a producer. Controlled by the availability of nutrients in the environment How can a nutrient be a limiting factor for an ecosystem? If even a single essential nutrient is in short supply, primary productivity will be limited

Nutrient Limitation Limiting Nutrient the nutrient whose supply limits productivity Ex. - If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients.

Nutrient Limitation In Soil In Aquatic Ecosystems Growth of crop plants is limited by one or more nutrients that must be taken up by plants through their roots That’s why farmers use fertilizers! In Aquatic Ecosystems Sometimes receive large amounts of a limiting nutrient (runoff from fertilized fields) The result can be an Algal Bloom which can cover the water’s surface and disrupt the ecosystem