The third global bleaching event has been taking place over the last months. Having slowly extended across the Pacific Ocean, unusually high water temperatures emerged in Fiji in February this year. Victor Bonito of Reef Explorer Fiji Ltd. is located around 100km west of our base in Suva at the Coral Coast, and was one of the first to observe the severity of the bleaching. At this point, our sites seemed to remain unaffected which we put down to oceanic water cooling down the large lagoons we have been surveying.
Within days of the bleaching hitting Fijian reefs, Cyclone Winston took an unexpected U-turn and came ploughing straight through Fiji. When we first heard of the approaching cyclone, we hoped this may be to the reefs advantage as cyclone-induced water movement may cause cooler temperatures in the coastal waters. However, the unforeseen strength of the cyclone (which turned into a category 5 cyclone before hitting land and maintained its strength across the extent of the Fiji Islands) may have caused far more damage than the bleaching.
After waiting for some time for communities to recover from the catastrophic effects of the cyclone, I headed back out to two of our sites to investigate the effects of both events. The opportunity to investigate the effects of climate change at our sites were quite unique, as we had only just finished our initial surveys and so any differences would be solely as a consequence of the physical disturbances. Our surveys included in-depth information on benthic and fish communities, covering many factors such as herbivorous fish function, coral recruitment and turf algae dynamics, as well as many water quality measurements at each site.
This time I was unable to use SCUBA as the rest of the team has left, so instead I donned the less favourable snorkelling gear and hoped my free-diving abilities would somehow have magically improved overnight… I started the surveys in Navakavu, close to Suva. Having arrived in the village and looked at the damage from the cyclone (a couple of houses were flattened and the school roof had gone), I sat with the spokesman for the Navakavu committee, Asakaia Balawa, who’s concern was obvious as he showed pictures of bleaching he had seen in the last week on the reef. He joined on the boat for the first couple of days while we installed temperature loggers and surveyed the bleaching. The first view underwater offered a significantly altered picture to the reefs we had been working on the last six months. Though the reefs didn’t appear to have been physically damaged by the cyclone, white coral colonies glowed everywhere that you looked.
Bleaching surveys took place at our sites both at 4-6m and at 1-2m, and included both point-intercept-transects and photo-quadrats. Each time a bleached colony was encountered, the extent, severity and any mortality was recorded. Our sites here cover a water quality gradient, as well as inside/outside of protection. Closest to heavy pollution from Suva, around 70% of the corals showed at least partial bleaching, whilst at the furthest point from Suva around 40% of the corals showed signs of bleaching. The tabu/non-tabu site pair (furthest from pollution input), were not significantly different from each other, offering an interesting future opportunity to investigate differences in recovery between these two sites.
After Navakavu, I headed back to Beqa Island to see if the bleaching had extended to our sites there. After an incredibly rough ride over in a small fibreglass boat, we arrived to a very warm welcome back to Dakuibeqa Village. The following days, I resurveyed the reefs at different distances from Dakuibeqa and neighbouring Dakuni Village, and was shocked at the severity of the bleaching. Some of the previously very healthy shallow parts of the fringing reefs now had a ghostly appearance, with fields of white corals of all different species and sizes. With rough water, strong wind and heavy rain, surveys (combined with collecting Lobophora spp. leaves and sediment samples) were pretty unpleasant.
After completing the surveys and saying goodbye to the community for now, we headed back across the Beqa Channel and faced another fierce ocean. Once back, we were immediately bracing for another cyclone, and reports of severe flooding are emerging from all corners of Fiji. It seems the weather will not give these islands a break… Now I am doing the final analyses and packing, ready to finally head back to Bremen in one week!