Energy Flow In Ecosystems Notes Producers Consumers Feeding Relationships Ecological Pyramids

Producers ▪Sunlight is the main source of energy for life on Earth ▪Organisms that capture energy from sunlight or chemicals and use that energy to produce food are called autotrophs. –They make their own food ▪Also called producers.

Producers ▪Plants use photosynthesis to produce food from the energy they capture from the sun. ▪Land - best autotrophs are plants ▪Freshwater - best autotrophs are algae. ▪Tidal Flats/Salt Marshes - Cyanobacteria (photosynthetic bacteria)

Producers ▪Some autotrophs produce energy without light ▪Chemosynthesis: process where organisms use chemical energy to produce carbohydrates. ▪Performed by several types of bacteria –Volcanic vents in ocean –Hot springs –Tidal Marshes

Consumers ▪Many organisms - animals, fungi, and many bacteria - can only acquire energy from other organisms. ▪These animals are called heterotrophs. ▪Also called consumers.

Types of consumers

Feeding Relationships ▪Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)

Food Chains ▪Food Chain: a series of steps in which organisms transfer energy by eating and being eaten. ▪Most ecosystems are complex, too complex to be represented in a food chain.

Food Webs ▪To represent the complex feeding relationship in an ecosystem, food webs are used. ▪Food webs link all food chains in an ecosystem together.

Food Webs ▪Trophic Levels: each step in a food chain or food web. –Producers make up the first level –Consumers make up the second (secondary), third (tertiary), or higher levels.

Ecological Pyramids ▪Amount of energy or matter in an ecosystem can be represented by an ecological pyramid. ▪Ecological pyramid: diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. ▪Three types: –Energy pyramids –Biomass pyramids –Pyramids of Numbers

Energy Pyramids ▪Theoretically - no limit on the number of trophic levels in an ecosystem. ▪The Hitch - only about 10% of the energy available with one trophic level is transferred to organisms at the next trophic level. ▪Summary - the more levels, the less energy that remains from the original

Biomass Pyramids ▪Biomass: the total amount of living tissue in a given trophic level. –Represented in grams of organic matter per unit area ▪Shows potential food available for each trophic level.

Pyramids of Numbers ▪Based on the number of individual organisms at each trophic level. ▪Not the case for a forest ecosystem –In most forests, there are fewer producers than there are consumers. –Ex: Many insects live in one tree.