13. Biotic And Abiotic Interactions Flashcards
What are the main physical conditions that may effect distribution?
Temperature, geology
Where might different mesohabitats be found in a stream?
Mud, river channel, snags
What are the two forms of competition?
Inter specific and intraspecifc
What is exploitation competition?
Where food or space are limited?
What is interference competition?
Aggressive interactions between competitor species individuals
How can competition be reduced?
Resource partitioning
How does hydropstchidae avaoid competition
Different species live in different areas of the stream
Where can microhabitat partitioning take place?
Ok or around rocks and boulders , different points of the rock can harbour different species
What happened when glossoma was reduced?
Baetis increased
What do the relative numbers of herbivores depend on?
The success of others, competition
Name a net spinning caddis?
Hydropsychae
How did fish use resource partitioning in the Mississippi?
Areas with vegetation and depth impacted where most species lived
What are the main aquatic predators?
Fish
What insects can be predators
Dragon flies, stone flies, choronomidae. Basically lots of flies
How do predators select their prey?
Size, activity, visibility
What are the 2 main prey mechanisms to avoid predation?
Capture and encounter
Where might prey hide in a stream
Creveses in the rocks, move into the hyporeheic zone
How do prey reduce captive rates?
Detect and flee- precontact, armour, aggressive traits, playing dead-post contact
What do daphnia produce to reduce predation by fish?
Helmet horns
Which insect uses fast swimming to escape predation?
Baetis
What is a common adaption to reduce predation in stream organisms?
Camouflage, a lot of insects are the colour of their environment
What is Aposematism
The use of extreme colour to warn predators, colour can be linked to foul taste or chemicals
Which garden insect can taste unpleasant and can release a toxic substance?
Lady birds
How does the water strider vary spatially?
Only in vegetation when fish are present and only out in the open when there are no fish
What animals can change their development rate so that they emerge smaller when more fish are present?
Mayfly
What is training bias?
When fish only feed on one species of insect as they know this one is safe
What has been said about control in the trophic system?
Areas of top down control, animals at the top control those at the bottom
What Does herbivory do to peripyton?
Reduces it
What else does herbivory do?
Influences community composition, opening up areas for other species
What happens to algae with grazing pressure?
Their photosynthetic rate increases with pressure
What is the harsh benign concept?
A gradient in streams
What does harsh mean according to peckarsky?
Few competition predation effects
According to peckersky?
What does benign mean?
Environments allow for well developed competition
What is disterbance?
Relatively discrete event in time that removed organisms and opens up space that can be colonised by individuals
What is an example of a common disaster in a stream?
Flood
What is the intermediate disturbance hypothesis?
We expect to find the highest level of diversity in middle levels of disturbance
What is the patch dynamic concept?
Disturbance opens up patches for new colonisers
What is another name for fugitive species?
Ruderal species
What species will be dominated by good competitors?
Stable systems like large rainforest rivers
What systems do fugitive species dominate?
Small flashy unreliable habitats
How can patches be created though biological activity?
Salmon redds
How can nuphar lutea create more habitats
Reducing flow, deposition of sediments
What effect can crayfish have on systems?
Clean gravel, larger supply of FPOM
How much can blackflies reduce flow in water?
75%less flow after 60mm
How do hydropsyche make room for mayflies?
The reduction of flow
What are reciprocal subsidies?
When one environment is benefiting the other
Why does it take longer for salmon to move into newly formed streams?
They normally only go back to the stream where they were born
When happens do adult salmon when they go back up stream?
They die, massive release of nutrients
How is the salmon carcus used?
Different parts of the salmon used by different animals, bears eat the heads
What caddis fly can expand to huge numbers to feed on salmon carcass?
Ecclisomyia
What happens after the bears are finished with the fish?
Leave bits of the carcass or defecate out
How can tree rings link to salmon abundance?
The more salmon the thinker faster growing the tree is
How many insects are there in summer streams per meter squared?
250mg
When are terrerestrial invertebrates more important?
The summer
When do most fish feed?
The afternoon
What is Allen’s paradox?
Trout consumed 30x more biomass than what was available in the stream, in the summer 60% can be invertebrates
What else can eat stoneflies
Ground beetles, 80% of diet
What impact does predation by beetles have on the river system?
Less egg laying, control of the environment
What is Thanotaxis?
Playing dead
What is another name for a micro habitat?
Meso habitats
Who came up with the patch dynamics theory?
Townsend
What is patch dynamics?
Disturbances continually opening up patches that are colonised
