IIIIII. Energy and . Energy and Matter in the Matter in the EcosystemEcosystem

Presented byPresented by

Mr. RainbeauMr. Rainbeau

A.A. Ecosystems perform Ecosystems perform two important functions:two important functions:1.1.The capture and use of energyThe capture and use of energy

2.2.Cycling of nutrients needed by Cycling of nutrients needed by organismsorganisms

B.B. Communities Communities1.1.CommunityCommunity is all of the is all of the

populations of different types populations of different types of organisms living in the same of organisms living in the same placeplace

2.2. Trophic LevelsTrophic Levels – each step – each step in the transfer of energy and in the transfer of energy and matter in a communitymatter in a community

http://www.planetpals.com/foodchain.html

a)a)ProducersProducers are the autotrophs are the autotrophs that make the food for the entire that make the food for the entire communitycommunity

b)b)ConsumersConsumers are the heterotrophs are the heterotrophs that obtain food by eating other that obtain food by eating other organismsorganisms1)1)herbivoreherbivore – primary consumers – primary consumers

that eat only plantsthat eat only plants2)2)carnivorecarnivore – animals that eat only – animals that eat only

animalsanimals3)3)detritivoredetritivore – consumers that – consumers that

feed on the tissues of dead feed on the tissues of dead organismsorganisms

4)4)omnivoresomnivores – animals that eat – animals that eat both producers and consumersboth producers and consumers

primary, secondary, and tertiary primary, secondary, and tertiary consumersconsumers

c)c)DecomposersDecomposers – an – an organism that feeds on organism that feeds on dead organic material (ex. dead organic material (ex. Bacteria and fungi)Bacteria and fungi) They transform nutrients They transform nutrients

from dead organisms back from dead organisms back into nutrients that can be into nutrients that can be used by plantsused by plants

© 2003 John Wiley and Sons Publishers

Fig 6.2 Food web of a hot spring.Fig 6.2 Food web of a hot spring.

3.3.Food chainFood chain – the sequence – the sequence of organisms through which of organisms through which food passes in a communityfood passes in a community

a)a) Example: grass Example: grass grasshopper grasshopper lizard lizard bird… bird…

producers are always the first producers are always the first link because they are the link because they are the original source of all foodoriginal source of all food

Marine benthos

mostly kelp beds,urchin herbivores

kelp urchin sea otter

plankton shellfish sea otter

b)b)Food chain is not the complete Food chain is not the complete picture bcs. most organisms picture bcs. most organisms eat more than one kind of eat more than one kind of foodfood

4.4.food webfood web is all of the is all of the interconnected food chains in interconnected food chains in an ecosystem (arrows go from an ecosystem (arrows go from energy source to the consumer)energy source to the consumer)

See page 71See page 71

http://octopus.gma.org/surfing/human/foodweb.gif

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 Fig 6.5 Food web of the harp seal.seal.

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

a)a)biomassbiomass – – the total mass of the total mass of organic matter at each trophic organic matter at each trophic level level

b)b)Only 10% of the energy is Only 10% of the energy is transferred from one level to transferred from one level to the nextthe next

Transfer of matter and energy from one trophic level to the next is not very Transfer of matter and energy from one trophic level to the next is not very efficientefficient

An Energy available at each trophic level is 90% less than the energy at the An Energy available at each trophic level is 90% less than the energy at the level belowlevel below

Energy, Biomass, and Numbers Energy, Biomass, and Numbers Pyramid (pgs. 72-73)Pyramid (pgs. 72-73)

Ocean BiologyOcean 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 reproductionmacro-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