Coral Bleaching and the Affect of Temperature Change on Coral Reef Predator-Prey Interactions Juliann Krupa

Coral Bleaching Color in coral comes from the photosynthetic symbiotic algae that live with in the tissue of the coral Color in coral comes from the photosynthetic symbiotic algae that live with in the tissue of the coral When the sea surface temperature is raised above optimal levels, algae die and are expelled and coral dies soon after When the sea surface temperature is raised above optimal levels, algae die and are expelled and coral dies soon after The optimal temperature for corals is a small range (24-29°C) and each coral species has a specific “bleaching threshold” The optimal temperature for corals is a small range (24-29°C) and each coral species has a specific “bleaching threshold”

Coral Predators Parrotfish Damsel Fish Crown of Thorns Sea Star

Lokta-Volterra Predator-Prey Model C(t)= population (size) of coral P(t)=population of parrotfish a=growth rate of coral c=death rate of parrotfish b & d= constant of interaction between coral and fish Modified to include another parameter: Δt, degrees that SST is above bleaching threshold level

Lokta-Volterra Model Assumptions Assumptions – Interaction limited to between coral and parrotfish – Without coral, parrotfish populations proportionally decline – At its optimal temperature, coral grows at a steady rate – Temperature proportionally affects coral growth – Temperature proportionally affects parrotfish population

Δt=0

Δt=1 Δt=1.5Δt=2 Δt=.5

Sources Brown, B. E. “Coral Bleaching: Causes and Consequences”. Coral Reefs. Springer Berlin, Heidelberg. Vol. 16. June, Glynn, P.W. “Coral reef bleaching: ecological perspectives”. Coral Reefs. Springer Berlin, Heidelberg. Vol. 12. March, Hixen, Mark. “Predation, Prey Refuges and theStructure of Coral-Reef Fish Assemblages”. Ecological Monographs. Vol , Ove. Hoegh-Guldberg, Ove. “Curbing Coral Crisis”. University of Queensland, Office of Research and Post Graduate Studies. Sept 2006.