Ecosystems and Energy Transfer

Ecosystem Ecology Basics We know Earth is a system, in which energy flows and matter cycles in Ecosystems and Ecosystems are composed of biotic and abiotic factors and form the Biosphere. What are ecosystems? What are biotic and abiotic factors? How can we model ecosystem interactions and the flow of energy and nutrients?

Energy Flow in Ecosystems can be modeled in Food Chains & Food Webs Food Chains Show 1 feeding relationship from producer  consumers Food Webs Interconnected food chains They show all of the feeding relationships in an ecosystem

Ultimate source of energy  Sun

Producers Organisms that produce their own energy are producers. Most producers utilize photosynthesis, but not all…. Autotrophs: self-feeding Producers also use cellular respiration to convert chemical energy of food into a different form of chemical energy, ATP Any energy unused by the producer or released as heat/waste is available to other organisms C 6 H 12 O 6 + 6O 2  6H 2 O + 6CO 2 + ATP

Consumers Heterotrophs- “other feeders” Primary (1 st order) consumers eat producers; Herbivores; Trophic Level 2 Secondary (2 nd order) consumers eat primary consumers; Omnivores or carnivores; Trophic Level 3 Tertiary (3 rd order) consumers eat secondary consumers; Typically carnivores; Trophic level 4

Decomposers- Breakdown (no mouth parts) organic matter and return the nutrients to the soil Ex. Fungi and Bacteria Detritivores- Eat (mouth parts) organic matter and help return nutrients to the soil Ex. earthworms Scavengers- Eat carcasses- they like a “free lunch”; Keep disease at bay in ecosystems Ex. Turkey Vultures, Hyena Other Heterotrophs…

Black bear Rabbit Grass Hawk Blueberries Squirrel Acorns (Oak Tree) Construct a food web using the following organisms:

Example Food Web Blueberries Grass Acorns (oak) RabbitSquirrel Black BearHawk

Can you identify… Autotrophs & Heterotrophs? Which organism(s) are producers? Which organism(s) is an omnivore? Which organism(s) is a carnivore? Do any organisms occupy more than one trophic level? What heterotrophs are missing?

Example Food Web Blueberries Grass Acorns (oak) RabbitSquirrel Black BearHawk TL 1 Producers TL 2 1° Consumers Omnivores TL 3 2° Consumers Omnivores or Carnivores TL 2/3 1° /2 ° Consumers Omnivore

12 The transfer of energy from producer to primary consumer then to higher order consumers. One linear feeding relationship. Food Chains- One line of Energy Transfer in an Ecosystem

13 More Food Chain Examples

Food Webs- Interconnected food chains They show all of the feeding relationships in an ecosystem

15 How Many Chains are in this web?

16 Identify the Producers, Consumers, & Decomposers: Count the Food Chains!

Energy in an Ecosystem Energy FLOWS through ecosystems Only 10% of the energy is available to organisms in the next trophic level; 10% rule. 90% of the energy is unavailable due to maintaining life functions, respiration, and heat energy transferred to the atmosphere. So, more energy is stored in producers than available to top-level consumers.

10% rule in action What trophic level should the bulk of the biomass be in an ecosystem? Producers Example- The Savanna of Africa – 100 km 2 of grasses (10 km x 10 km) – Herd of 450 wildebeests – Pride of 20 lions The higher up the food chain, the less available energy  less top-level consumers 4 th or 5 th level consumers are rare in nature

19 Energy Pyramids Show Amount of available energy decreases for higher consumersAmount of available energy decreases for higher consumers Amount of available energy decreases down the food chainAmount of available energy decreases down the food chain It takes a large number of producers to support a small number of primary consumersIt takes a large number of producers to support a small number of primary consumers It takes a large number of primary consumers to support a small number of secondary consumersIt takes a large number of primary consumers to support a small number of secondary consumers

100% 10% 1% 0.1% Trophic Levels indicate feeding position in ecosystems TL 4 TL 3 TL 2 TL 1

21 Identify 1 st, 2 nd, 3 rd and 4 th level consumers in this food web.

Vultures TED Talks The significance of scavengers: love_vultures.html