ecology lecture 8 definitions Flashcards
What are the 3 major trophic levels?
producers, consumers, decomposers
trophic structure
the different feeding relationships in an ecosystem that determine the route of energy flow and nutrient cycling; plants, herbivores, carnivores. There is food chains and food webs (more realistic). plant grasshopper mouse snake hawk
producers
(autotrophs)(self-feeding); produce own food
consumers
(heterotrophs) (other-feeding); do not produce own food herbivores and carnivores
decomposers
organisms that feed on nonliving organic material (dead animals, dead plant material, fallen logs, etc.) and breakdown the material into its constituent nutrients [ release nutrients to soil,water,air for rescue by producers]
exp: bacteria, fungus,, magots, worms, vultures
primary productivity
the amount of organic matter (or fixation of energy) produced from solar energy in a given area for a given period of time by autotrophs
secondary productivity
rate at which consumers convert chemical energy of food into biomass
what are the two types of productivity
primary and secondary
keystone species
species that have a large impact on the organisms in an environment; these species often increase species diversity when they are present. Sea otter (eat sea urchins), crocodiles, wolves (eat elk) , oak trees (provide insects food)
Paine’s (1970) removal experiments
An on-going experiment Paine conducted with mussels and starfish since 1970 was ideal in demonstrating the principal of “keystone species,” which holds that certain species are critically important to the balance of an ecosystem.
Biological magnification
increase in concentration of DDT, PCBs DIOXIN, MECURY and other slowly degradable, fat-soluble chemicals in organisms tissues and organs at successively higher tropher levels of a food chain or web
bioaccumulation
increase in the concentration of DDT, PCBs, DIOXIN, MECURY and other slowly degradable, fat-soluble chemicals in organisms organs or tissues at level higher than would normally be expected
DDT
Prior to 1972 when its use was banned, DDT was a commonly used pesticide. Although it is no longer used or produced in the United States, we continue to find DDT in our environment. Other parts of the world continue to use DDT in agricultural practices and in disease-control programs. Therefore, atmospheric deposition is the current source of new DDT contamination in our Great Lakes. DDT, and its break-down products DDE and DDD, are persistent, bioacculumative, and toxic (PBT) pollutants target by EPA.
PCB
Polychlorinated biphenyls (PCBs). PCBs are either oily liquids or solids, are colorless to light yellow, and have no smell or taste. Because they do not easily burn and are good insulators, PCBs have been used widely as coolants and lubricants. \ banned in the U.S. in 1979 1920s until their ban, an estimated 1.5 billion pounds of PCBs were made microscope oils, electrical insulators, capacitors, and electric appliances such as television sets or refrigerators. PCBs were also sprayed on dirt roads to keep the dust down prior to knowing some of the unintended consequences from widespread use
Paine Part 2
Paine’s experiment showed that the population of starfish in the Tatoosh tidal zone are critical in controlling the mussel population. In test areas where Paine physically removed the starfish, mussels crowded out most other life forms. Thus, the starfish is a “keystone species” because it has a critical effect on the entire ecosystem. Without the starfish, the biodiversity in the tidal zones of Tatoosh Island would be radically different. Keystone species apply to plants and trees as well. Destruction of a certain tree or plant can also alter the characteristics of an ecosystem.
