Ch 9 Flashcards
(26 cards)
What is the new stable state?
Shifting from coral dominated to algae.
What is negative and positive feedback?
A cycle where to litlle grazing, reduces fish recruitment, which increases macroaglal cover, decreasing recruitment further, reducing coral cover, reducing structural complexity further reducing grazing and it keeps cycling. Positive feedback works similar but increases coral cover grazing and decreases algae cover
How do alternate stable states occur?
Once pushed into a new threshold positive feedback maintain new state
What is hysteretic?
a transition between two alternate stable states, showing two thresholds as the driver increases or decreases
What is threshold?
a pronounced threshold at
particular conditions,
Are any caribbean reefs recovering?
Jamaica’s
What is one factor responsible for the shift?
Coral mortality folloed by increased nutrients/ algae growth, Decreased herbivory
Is it a clear fact that driver act synergistically?
no, antagonism has been seen
What is changing caribbean reefs?
Acropora die-off
Why did acropora die so rapidly and before other corals?
White band disease
Why are dead acropora palmata reeds not replaced by other species?
High wave action prohibits growth of other coral growth
Acropora decline is unprecedented in which period?
Holocene
In belize what species replace acropora?
Agaricia
WHat species was strongly impacted by the bleaching event in 2005?
Montrastrea spp
Warming trends are expected to continue and depend on what?
emissions
Indo-Pacific reefs are also affected by ?
Crown of thrones
Why are crown of thrones populations increasing?
decreased predation
What species are coral reef communities changing to?
Siderestra siderea
What fish group are also declining?
corallivores ie chaetodontids
Why are herbivores decline with increased macroalgae growth?
overfishing, decreased architecture is important, juvenile grounds are being destroyed, bioerosion by parrotfish ro clionid sponges and wave action
What is the breakwater effect?
Coral reefs absorb the impact of storms
What does increased wave energy contribute too?
beach erosion
How do corals assist in beach replenishment?
As corals eroid the calcareous debri wash on shore repleniching the sand. As more corals are lost the sand will stop being replaced.
What else are reffs used for?
Building material
