set 1: disturbances & ocean warming

how do corals begin their lifecycle

as polyps

what is the process by which corals grow a skeleton

metamorphosis

what do coral develop to aid survival

symbiotic algae that reproduces

why is nutrient recycling important

as corals love in nutrient poor waters

what are the two types of variation

spatial and temporal

define disturbances

an event that damages or kills residents at a given site

what are the two type of disturbance durations

acute and chronic

what happens when acute disturbances occur frequently without enough recovery time

it causes chronic disturbance

why are natural disturbances important for ecosystems

play a critical role in structuring ecosystems

how do disturbances affect biodiversity

immediate levels on disturbance may promote diversity but this depends on its frequency and intensity

what are the three equilibrium hypotheses

• niche diversification hypothesis

• circular network hypothesis

• compensatory mortality hypothesis

what is the equilibrium hypothesis about community composition

• communities are usually in a state of equilibrium and recover to that state after a disturbance

• high diversity is maintained without continual species composition changes

what is the niche diversification hypothesis

• at equilibrium, each species is competitively superior in exploiting a particular subdivision of the habitat

• diversity is a function of the total range of habitats and the degree of specialisation of the species to parts of that range

what is the circular network hypothesis

at equilibrium, each species uses interference mechanisms which cause it to win over some competitors but lose to others (A>B>C but C>A)

what is the compensatory mortality hypothesis

mortality from causes unrelated to the competitive interaction falls heaviest on whichever species ranks highest in competitive ability

what is the non-equilibrium hypotheses

• the species composition of communities is seldom in a state of equilibrium

• high diversity is maintained only when the species composition is continually changing

what are the three non equilibrium hypothesis

• equal chance hypothesis

• gradual change hypothesis

• intermediate disturbance hypothesis

what is the equal chance hypothesis

• species are approximately equal in ability to colonise, exclude invaders, and resist environmental vicissitudes

• local diversity depends only on the number of species available in the geographical area and the local population density

• unlikely as it requires equal ability to resist physical extremes and recruitment to independent of local population

what is the gradual change hypothesis

• gradual environmental changes, that alter the ranking of competitive abilities, occur at a rate high enough so that the process of competitive elimination is seldom if ever completed

• not supported by organisms with long life expectancies

what is the intermediate disturbance hypothesis

• diversity is higher when disturbances are intermediate on the scales of frequency and intensity

which hypothesis is most believed

intermediate disturbance hypothesis

what are the criticisms of IDH

• empirical refutation: review of over 100 published studies find that predicted peak of diversity at intermediate diversity rarely occurs

what are the theoretical refutations of IDH

• disturbance weakens competition

• disturbances interrupt competitive exclusion

• identity of the dominant competitor changes on an intermediate timescale