III. Energy and Matter in the Ecosystem Presented by Mr. Rainbeau

A. Ecosystems perform two important functions: 1. The capture and use of energy 2. Cycling of nutrients needed by organisms

B. Communities 1. Community is all of the populations of different types of organisms living in the same place

2. Trophic Levels – each step in the transfer of energy and matter in a community

a) Producers are the autotrophs that make the food for the entire community

b)Consumers are the heterotrophs that obtain food by eating other organisms 1)herbivore – primary consumers that eat only plants 2)carnivore – animals that eat only animals 3)detritivore – consumers that feed on the tissues of dead organisms 4)omnivores – animals that eat both producers and consumers

 primary, secondary, and tertiary consumers

c) Decomposers – an organism that feeds on dead organic material (ex. Bacteria and fungi)  They transform nutrients from dead organisms back into nutrients that can be used by plants

© 2003 John Wiley and Sons Publishers Fig 6.2 Food web of a hot spring.

3. Food chain – the sequence of organisms through which food passes in a community a)Example: grass  grasshopper  lizard  bird… producers are always the first link because they are the original source of all food producers are always the first link because they are the original source of all food

Marine benthos mostly kelp beds, urchin herbivores

kelp  urchin  sea otter plankton  shellfish  sea otter

b)Food chain is not the complete picture bcs. most organisms eat more than one kind of food 4. food web is all of the interconnected food chains in an ecosystem (arrows go from energy source to the consumer) See page 71 See page 71

vs. Carpenter and Kitchell 1993 Martinez 1997 Two views of nature: food chains vs. food webs

© 2003 John Wiley and Sons Publishers Fig 6.5 Food web of the harp seal.

5.Energy (ecological) pyramid: diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web.

a) biomass – the total mass of organic matter at each trophic level b) Only 10% of the energy is transferred from one level to the next Transfer of matter and energy from one trophic level to the next is not very efficient Transfer of matter and energy from one trophic level to the next is not very efficient An Energy available at each trophic level is 90% less than the energy at the level below An Energy available at each trophic level is 90% less than the energy at the level below Energy, Biomass, and Numbers Pyramid (pgs )

Ocean Biology Ocean Plants - restricted to surface waters where there is enough light for photosynthesis (the euphotic zone). Phytoplankton - microscopic single celled plants, account for >95% of total photosynthesis, some form chains of cells. Macroscopic Plants - seaweeds, kelp, mangroves, larger plants in the oceans, <5% of ocean photosynthesis. Bacteria - found throughout the oceans Account for most remineralization - breakdown of organic matter (zooplankton also contribute substantially). Some bacteria are part of the phytoplankton, capable of photosynthesis. (photo-autotrophs). Some bacteria associated with the hydrothermal vents are chemo-autotrophs, obtaining energy from chemical reactions, rather than from sunlight.

Ocean Biology Ocean Animals Zooplankton - account for most grazing of phytoplankton, typically divided into two broad size classes: micro-zooplankton - small diverse group of grazers, some single celled protists, fast reproduction macro-zooplankton - larger zooplankton, slow reproduction Small Fish - eat mainly zooplankton and some larger phytoplankton, provide food for higher trophic levels. Higher Trophic Levels - big fish, birds, dolphins, seals, whales, sharks, humans, etc... Important for ecology, marine resources for humans, negligible impact on global biogeochemical cycles