Biology 121-224. September 22nd, 2010
Lecture 8-9: Ecosystems
Reading: Ch. 54: 1222-1230
Key Concepts:
1) An ecosystem has four components: (1) the abiotic environment, (2) primary producers, (3) consumers, and (4) decomposers. These components are linked by the movement of energy and nutrients.
2) The productivity of terrestrial ecosystems is limited by warmth and moisture, while nutrient availability is the key constraint in aquatic ecosystems. As energy flows from producers to consumers and decomposers, much of it is lost.
Ecosystems
An ecosystem consists of the organisms that live in an area and their physical and chemical (abiotic) environment.
An ecosystem is typically composed of multiple _______________
Chemosynthesis
Deep Sea Hydrothermal Vents aka “Black Smokers”
Ecosystem ecology includes the study of how energy flows among the components of an ecosystem; how carbon, nitrogen, and other key elements cycle through organisms, sediments, the oceans, and the atmosphere; and how humans are affecting the abiotic environment.
A. Energy Flow and Trophic Structure
An ecosystem can be thought of as an economy in which energy is the currency.
Energy flow links four components in every ecosystem:
primary producer, or autotroph is an organism that can ______________ its own food from _______________________ sources.
consumers are organisms that eat _____________________________
herbivores
carnivores
decomposers, or detritivores feed on ______________________ or the ____________________ of other organisms
The abiotic environment includes the soil, the climate, the atmosphere, and the particulate matter and solutes in water. Energy moves from the Sun or inorganic compounds to consumers, decomposers, and the abiotic environment.
1. How Does Energy Flow through an Ecosystem?
The grazing food web is composed of the network of herbivores
( _________consumers) and the organisms that eat the herbivores
( _________consumers).
The decomposer food web is made up of species that eat the dead remains of organisms.
Detritus
2. Trophic Levels, Food Chains, and Food Webs
trophic level
food chain
food web
3. Why Is Energy Lost at Each Trophic Level?
pyramid of productivity
Productivity is greatest at the _________ trophic level and declines at __________ levels.
This pattern occurs because some energy is necessarily lost in keeping an organism alive—such as the heat required for metabolism and the energy a predator needs to capture prey—at each trophic level.