May 30, 2017

Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai‘i

Ku‘ulei S. Rodgers, Keisha D. Bahr, Paul L. Jokiel, Angela Richards Donà
  • Determines the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O‘ahu, Hawai‘i
  • Conducts surveys at HBNP in October 2015 and January 2016 that reveal extensive bleaching (47%) and high levels of coral mortality (9.8%)
  • Finds that bleaching ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH)
  • Finds that the highest levels of bleaching occurred in two sectors with different circulation patterns:
    • KH experienced comparatively low circulation velocity and a low temperature increase
    • Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase
  • Results show that high coral mortality occurred despite the lack of local factors that can lead to decline such as high fishing pressure or sedimentation
  • In spite of visitor impacts being strikingly different in WB versus BD/KH, mortality rates were similar
  • Concludes that elevated temperature was more influential in coral bleaching and the associated mortality than high circulation or visitor use