Coral bleaching in Oahu

Coral bleaching in Oahu has been on the rise since 1996, when Hawaii's first major coral bleaching occurred in Kaneohe Bay, followed by major bleaching events in the Northwest islands in 2002 and 2004. In 2014, biologists from the University of Queensland observed the first mass bleaching event, and attributed it to The Blob.

Coral bleaching turns the coral white, but it does not kill it right away. Depending factors like what type of coral is it, and temperature of the water in that specific area, decide on how long the coral has. Coral bleaching effects in Hawaii are primarily caused by water temperature increases due to climate change. A rise in the water temperature is a stressor to the coral. When stressed, the coral releases algae that lives in their tissues, so when released they lose all of their color, turning them white.

Areas impacted by coral bleaching
The amount of bleached coral is increasing around the island of Oahu. As of November 2019, two secluded beaches on the island, Yokohama bay and Makua beach have had reports of coral bleaching. Also including around Daniel K. Inouye International Airport, these areas have 75% or more of coral bleached. The main cause of this mass bleaching event is by the rise in the water temperature of as small as two to three degrees Fahrenheit. The types of corals include the two most popular corals of Hawaii, the Rose or Cauliflower coral. These corals are 10 - 20 in in diameter.

Kaneohe Bay reef
The Kāneʻohe Bay reef is 8 mi in length and 2.7 mi in width. A second barrier reef covers 27 mi off the coast of Molokaʻi island in the archipelago. About 40 years ago there were raw sewage dumps in Kaneohe Bay, killing some coral. The sewage gave the advantage to a growing benthic algae species. The green algae Dictyosphaeria cavernosa, formed mat like structures covering and killing some of the coral. And the corals that the algae did not reach, the sewage and the low water quality had weaken them over time. The corals reproduction cycle was slowed and more likely to contract a disease.