From hendee@aoml.noaa.gov Tue Dec 12 09:10:45 2000 Date: Tue, 11 Apr 2000 07:09:07 -0400 (EDT) From: Jim Hendee To: coral Subject: Re: Fiji bleaching event (fwd) [ The following text is in the "X-UNKNOWN" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] ---------- Forwarded message ---------- Date: Tue, 11 Apr 2000 07:26:23 +1200 (FJT) From: "Biological Consultants (Fiji)" To: coral-list@aoml.noaa.gov Subject: Re: Fiji bleaching event Dear Coral-Listers, In addition to Bruce Carlsons reports, the following is a more general appraisal of the coral bleaching event now developing in Fiji. March/April Coral Bleaching Event in Fiji April 10, 2000 A coral a bleaching event is well underway in Fiji with 30-31C temperatures being experienced along the southern areas of Fiji's main islands of Viti Levu and Vanua Levu. Considering the time-line of this warm water event, the first reports of minor bleaching were reported in late April. An observation (Feb. 20, 2000) of some minor bleaching at the entrance to Suva Harbour was interpreted as due to heavy rain. I conducted a Reef Check at the Fijian Resort (27/2/00) at the western end of the Coral Coast, S. Viti Levu and saw only minor, "possible" bleaching in a few colonies of Acropora. It was determined then that no bleaching was occurring. A recent call to the Fijian Resort Dive operation confirmed that the bleaching has occurred in the area of survey within the first week of March. Austin Bowden-Kerby commenting the reef flat environment gave the following report. "The Cuvu reefs (Fijian Resort) are pretty severely bleached, it started over a month ago, but has spread. The interesting thing is what has not bleached; most of the larger colonies appear completely unaffected, adapted to the heat, regardless of species. Also smaller Seriatopora and some Pocillopora are resistant as well as many of the staghorn Acroporas. There has been some death, but lots of extremely bleached corals seem to be holding their own so far, many Stylophora look like they might die though." By contrast, it is the larger colonies that appear to be affected in the subtidal areas of the reef slope. The bleaching of large plate and corymbose Acropora colonies are evident. A trip to Frigate Pass in the Beqa Lagoon (12/3/00) revealed extensive bleaching, or should, I say bluing or yellowing. The effect was dramatic with sprawling colonies of Acropora monticulosa and A. humilis appearing bright blue due to the absence of the zooxanthellae. A. nana also exhibited a blue appearance. A. hyacinthus, A. clathrata, A. nasuta, a sprawling zoanthid and many soft corals took on a yellow appearance. Some became very white. Light green was a common color for Gonioporas. Regardless of color, it often appears luminescent. It is estimated that there is 50% bleaching with >65% in some areas. Up to 30% of those affected were blue. Montastrea curta and Platygyra sinensis were affected. A. muricata was bleaching white. Pocillopora eydouxi is common and showed no bleaching. The presence of the bleaching was patchy with some areas not particularly affected. This observation was probably two weeks into the event. Now a little more than a month the beginning of the event, a dive on the local Suva reefs near the harbour entrance, and Rattail Passage (2/4/00) revealed extensive bleaching with an estimate 75% of the hard and soft coral affected. Most of these were bleached white though many still had blue, pink or yellow coloration. Unfortunately, an estimated 15% of colonies had algae beginning to grow on their surfaces, indicating that these were the colonies affected early in the episode (~1 month) and have died. Many of the colonies were ½ bleached indicating a progressive effect with some portions covered by algae. The water temperature was 31.5C at the Suva Harbour entrance and 31C at Rattail passage. Interestingly, some species that were bleached totally, have colonies of the same species nearby that appear to be totally unaffected. The bleaching was evident at depth and in underhangs and crevice areas. A listing of the species that have bleached is extensive, with many Acroporas and notably colonies of Lobophyllia sp. and Diploastrea sp. All of the Montiporas seemed affected. Some Acroporas like were completely unbleached. Unlike the earlier observations at the Fijian Resort, the Seriatopora and Pocillopora are bleaching to varying degrees. Large tabulate colonies have been affected often progressively. In some cases algae has began to settle on one portion of the colony which is bleached white in the center but will still exhibit natural coloration on a portion. Among the bleached colonies, there are colonies that are not bleached and appear healthy. Other observations have come from the Cousteau Resort near Savusavu, Vanua Levu which report high percentages of coral bleaching (65%) (11/3/00). Reports of from helicopter trip along the southern coast of Viti Levu revealed the bleaching to be occurring all along the coast. Two things have surprised me about this event. One is the vivid colour of many of the corals (pinks, blues and yellows) which are evident after the expulsion of the their zooxanthellae. It also seems that the symptom of coloration is more characteristics of the offshore, clearer waters. In the inshore areas, the bleaching white is more apparent, but many exceptions. The second is the rapid nature of the effect. One week all is well and the next week, there is apparent widespread bleaching. We are now in the sixth week with high water temperatures. NOAA's hotspot website seems to be very informative in showing the progressive warming. Of interest, the warm water didn't migrate from somewhere else. It originated at these latitudes, largely south of Fiji extending east. Thankfully, according to the website, it seems to be breaking up, at least near Fiji. Temperature reports from some areas confirm that the inshore temperatures still remain high (~31C). A call to Ha'atafu, Tongatapu, Tonga and the report of the widespread bluing of coral is the same. As with Fiji, lots of blue and yellow coloration is characterizing the coral areas. A trip 10 miles north of Tongatapu to some isolated barrier reefs revealed the same phenomenon. Bleaching has been reported from the Ha'apai group, central Tonga. Though further north and outside of the hotspot area, bleaching of the large Acropora plates, particularly evident at depth (~15m), has been reported from Guadalcanal, Solomon Islands. The extent is uncertain but is occurring. Apparently less so in the shallow waters. Best regards, Ed Lovell Biological Consultants, Fiji Suva Edward R. Lovell