Trophic Levels and Food Chains Quaternary consumers Food Chain: set of food (energy) transfer from trophic level to trophic level Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Carnivore Primary consumers Herbivore Zooplankton Producers Plant Phytoplankton Figure 19.21 A terrestrial food chain A marine food chain

Herbivores: eat plants, algae, or autotrophic bacteria, are the primary consumers of an ecosystem Carnivores, which eat the consumers from the levels below Secondary consumers include many small mammals, such as rodents, and small fishes that eat zooplankton Tertiary consumers, such as snakes, eat mice and other secondary consumers Quaternary consumers include hawks and killer whales.

Decomposers: What is a decomposer and what do they do? What trophic level would you put them at? Derive their energy from the dead material left by all trophic levels Are often left off of most food chain diagrams Figure 19.22

Figure 19.23 Quaternary, tertiary, and secondary consumers Secondary and primary consumers Primary consumers Producers (plants) Figure 19.23

Energy Pyramids When energy flows as organic matter through the trophic levels of an ecosystem, much of it is lost at each link in a food chain. Why? When you burn energy to run down the mile in gym what happens to most of the energy you are using?

Plant material eaten by caterpillar Does all the energy this caterpillar eats get passed to the bird who eats him? Plant material eaten by caterpillar 100 kilocalories (kcal) 35 kcal Cellular respiration 50 kcal Feces 15 kcal Growth Figure 19.25

Energy pyramid Is a diagram that represents the cumulative loss of energy from a food chain

What happens to energy as you go up trophic levels? Why? Tertiary consumers 10 kcal Secondary consumers 100 kcal Primary consumers 1,000 kcal Producers 10,000 kcal Figure 19.26

CHEMICAL CYCLING IN ECOSYSTEMS Depend on a recycling of chemical elements What gets recycled in our ecosystem? Energy?? NOOO Water Carbon Phosphorus

Generalized scheme for biogeochemical cycles Consumers Producers Detritivores Nutrients available to producers Abiotic reservoir Geologic processes Figure 19.28

Higher-level consumers The carbon cycle CO2 in atmosphere Photosynthesis Burning Producers Wood and fossil fuels Cellular respiration Higher-level consumers Primary consumers Decomposition Detritivores Detritus What do we eat that has carbon? (a) The carbon cycle Figure 19.29a

Producers: Plants take in CO2 and make sugar by photosynthesis. Carbon Cycle Producers: Plants take in CO2 and make sugar by photosynthesis. Consumers: Animals eat plants to get energy (respiration) from sugar and make proteins from the carbon. Breath out CO2 as a waste product of respiration. Animals die and dentritus (decomposers) break down the carbon and other elements back into the soil and air for plants to use again.

The nitrogen cycle Detritus Nitrates (NO3– ) Decomposition Nitrogen (N2) in atmosphere Detritus Amino acids and proteins in plants and animals Denitrifying bacteria Detritivores Assimilation by plants Nitrogen-fixing bacteria in root nodules of legumes Nitrates (NO3– ) Decomposition Nitrogen fixation Nitrogen-fixing bacteria in soil Ammonium (NH4+ ) Nitrifying bacteria (b) The nitrogen cycle Figure 19.29b

Nitrogen Fixation by bacteria Plants need nitrogen but cannot take it in from the air. Bacteria in the soil on the roots of plants take in nitrogen (N2) and make ammonia (NH4) which plants can then use to get nitrogen.

Precipitated (solid) phosphates Phosphates in solution The phosphorous cycle Uplifting of rock Phosphates in rock Weathering of rock Phosphates in organic compounds Consumers Producers Detritus Rock Phosphates in soil (inorganic) Precipitated (solid) phosphates Phosphates in solution Detritivores in soil What part of you has phosphate? (c) The phosphorus cycle Figure 19.29c

The water cycle Net movement of water vapor by wind (36) Solar heat Water vapor over the land Water vapor over the sea Precipitation over the land (95) Evaporation and transpiration (59) Precipitation over the sea (283) Evaporation from the sea (319) Surface water and groundwater Flow of water from land to sea (36) Oceans (d) The water cycle Figure 19.29d