Food webs Flashcards
Autotrophs
Organisms that get energy from non-living environment to produce organic matter
Photoautotrophs
Use solar energy
Chemoautotrophs
Use energy from chemical compounds
Heterotrophs
Feed on organic matter produced by autotrophs
Primary producers
Autotrophs
Consumers
heterotrophs
Food chain
transfer of energy among primary producers and consumers
Trophic level
each level in the foos chain
Food webs
Complex trophic structures that include several primary producers, consumers that eat more than one kind of food, changes in diet with development
How much energy is transferred to one level to the other in the trophic pyramid?
10%
What is DOM?
Dissolved Organic Matter: waste organic matter dissolved in water
What is the function of decomposers?
Decompose DOM or detritus to reintroduce it into the food web
Nutrient regeneration
Reintroduction of DOM in food web
What is the succession of species in microbial loop?
Phytoplankton, DOM, bacteria, protozoans, zooplankton
What is detritus?
Non-living organic matter in solid form (dead organisms, etc.)
What are detritivores?
Organisms that feed on DOM or detritus
What are types of food webs?
Connectedness web
Energy flow web
Functional web
Connectedness web
Shows feeding relationships among organisms
Energy flow web
Connections quantified as energy fluxes
Functional web
Describes influence of a population on the growth of another population
Describe estuarine foodweb
Detritus-based, few herbivores, birds are very important, surplus of detritus outflows
Describe seagrass community foodweb
Detritus based
Rocky shore community food web
Herbivors and predation
Describe coral reef community food web
Efficient nutrient recycling
Highest fixation of nitrogen
Zooxanthellae and turf algae most important primary producers
Many organisms feed on corals, their eggs or mucus
Describe epipelagic food web
Complex and long
Efficient energy transfer
Size-structured
Feed on different trophic levels
What is hydrotermal vents foodweb characterized by?
Chemosynthesis
Describe arctic food web
Key role of zooplankton
Describe antarctic food web
Krill has key role
What is top-down control?
Control of predators in highest trophic level
Increase of these causes a decrease in the next trophic level, and a consequent increase in the trophic level after that
What is bottom-up control?
Producers regulate food web
Increase of production results in increased productivity for all higher trophic levels
What is a trophic cascade?
Change in primary producers population or lower trophic level as a result of change in consumers’ population
What is a regime shift in trophic cascades?
Large scale transition between alternative states in ecosystems
What is the most common method to assess food webs?
Stable-isotope analysis or, less, gut content analysis
What does stable isotope analysis study?
Trophic relations and energy flows, trophic levels, source of nutrients
What is stable isotope analysis?
Composition of a stable isotope is studied in the consumers tissue, and the difference between that and the prey’s tissue, as a result of fractionation, is assessed. Based on the fact that heavier isotopes are conserved during chemical reactions
What are problems with stable isotope analysis?
Sampling is done extensively
Individuals are sacrificed for studying
What does analysis of gut content define?
Feeding behaviour
Trophic level
Predator-prey relationship
What are problems of analysis of gut content?
Intensive work
Different digestion times
Large sample size required
What is the aim of lipids and fatty acids assessment?
1) they serve as tracers of trophic relations
2) reliable indicators of long-term diet
