Coral Bleaching event in the Vava'u Group.....

A rapid survey team assessing the reefs on Tonga reports observations of the first stages of mass coral bleaching.  The SPREP (South Pacific Regional Environmental Programme) BioRAP (Biodiversity Rapid Assessment Programme) working in the northern Tonga group of islands called “Vava’u” reports about 1-3% of corals are bleached.  Some corals are white; others partly white, and others are neon colors like light blue or yellow. 

Due to increasing water temperatures, the NOAA Coral Watch program previously announced a bleaching watch for Tonga (February 2014).  The team, recorded seawater temperatures rising in the last week to about 30.5^o C, as well as the appearance of bleached corals.  Most of the bleaching observed was between 10 meters and the surface, however individually bleached coral colonies were observed up to depths of 30 meters in some places. A range of coral species was recorded as bleaching.

Corals bleach when increased seawater temperatures occur over a period of time; the corals, which are made up of skeletons, animals and single-cell plants, are placed under stress. When the algae (zooxanthellae or plant living within the animal), which give corals not only its color but also the ability to photosynthesize and feed, are released by the coral colony, the coral becomes bright white. As the coral has lost the plant component it loses them as a food source and is under extreme stress to survive.  Corals may recover from bleaching events if seawater temperatures decrease to within the limits of coral development. Bleaching events effect many different areas of the marine ecosystem including the reef fish as well as weakened coral reefs provide little protection for shorelines.

Area of bleaching coral within the Vava'u archipelago.

Most days have been sunny, with very light winds and small waves, but February 28th was cloudy and rainy when the team departed Vava’u.  The SPREP BioRAP team was surveying reefs and terrestrial ecosystems in the Vava’u group in support of conservation planning in Tonga.  The Kingdom of Tonga is located north and slightly east of New Zealand, and east of Fiji in the Pacific, and the Vava’u group of islands is at about 18.6500^o S.

The coral reef areas identified as bleaching sites will continue to be monitored and recorded for further analysis.

The marine team was based on the Waitt Institute Scientific Platform to conduct the marine surveys of Vava’u as part of the BioRAP programme with SPREP, Ministry of Lands, Environment, Climate Change,  and Natural Resources, Waitt Foundation and VEPA.