When water rises above a certain temperature, coral bleaching may occur. The coral expels Zooxanthellae algae living in its tissues, leaving the coral a white colour. The graph shows how the water temperature is changing in the coral reefs surrounding the Cayman Islands.
Key: sea surface temperature in September ----- coral bleaching threshold
State the trend in temperatures from 1982 to 2018.
[1]- "Overall" water temperature increasing
- OR the range of fluctuations increases
NoteDo not accept the trend is fluctuating
Deduce the effect of bleaching on corals.
[4]a. the coral and the algae have a symbiotic/mutualistic relationship OR two different organisms live together and depend on each other 1 mark
b. algae expelled from coral/relationship broken 1 mark
c. coral produces carbon dioxide from respiration 1 mark
d. the algae use the carbon dioxide to carry out photosynthesis/produce nutrients 1 mark
e. without the nutrients from the algae the coral are liable to starve 1 mark
f. coral dies/is susceptible to disease 1 mark
NoteDo not accept effects on species other than coral
