A first look at coral reefs in the Vatu-i-Ra Seascape

Assessing coral reefs for cyclone damage and coral bleaching
March 11, 2016
Diving Nigali Passage in Gau
March 16, 2016

BY: Sangeeta Mangubhai

Our first dives were in and around the Vatu-i-Ra Conservation Park, which has been proposed as a conservation area by local communities from Nakorotubu District, as part of a unique partnership with local dive tourism operators and the Ra Provincial Office, supported by the Wildlife Conservation Society. We knew the eye Cyclone Winston passed over Ra, destroying up to 90 percent of people’s homes throughout the province, while churning up the sea in its path – so we were expecting some damage to the reefs.

As we headed out to our first dive site we saw Vatu-i-Ra in the distance, an island of cultural and historical importance to the village of Nasau, and home to nine species of breeding seabirds. With more than 20,000 pairs of breeding Black Noddies (Anous tenuirostris), the island is recognised as an Important Bird and Biodiversity Area. What was apparent, even at a distance was that almost all of the trees on Vatu-i-Ra Island seemed to be stripped of their leaves and very few seabirds could be seen. Without the leaves for cover, aboreal nests or chicks will not survive. We will know more next month when BirdLife International, NatureFiji-MareqetiViti and the Wildlife Conservation Society partner up, to do detailed assessments of the island and surrounding reefs.

As I rolled back off the skiff into the water for my first dive, I was dreading what was below the surface. As I opened my eyes and descended down to 20 meters, I was surprised by the condition of the reef. While there were broken branching and plating corals, and larger coral heads that had fallen over in the storm surge, the majority of the reef, for most part, was intact. Hard corals which are critical for building coral reefs and for providing a home and shelter for small fish and invertebrates, were still abundant at all depths including in the shallows. In fact the cyclone seemed to have churned up the water, and fish schools with thriving on abundance of plankton (small microscopic animals) in the water column.

What was missing though, were the beautiful colourful soft corals and sea fans that Fiji is well-known for, and for which divers travel across the world to visit. Wind and wave action had uprooted both soft coral and sea fans, leaving behind bare scoured rock surfaces. Within two weeks of the cyclone, these areas were already covered in a fine layer of green turf algae.

However, as long as there are enough herbivorous fish in the water, over time this layer of turf algae will be mown down (eaten) by these fish, and the hard and soft corals that survived will spawn and produce larvae that will settle and recruit back onto the reefs. Disturbances such as cyclones can actually be good for reefs, as it opens up spaces and can allow new species to settle, provided the damage is not catastrophic. I am relieved to see that the damage to the Vatu-i-Ra Conservation Park and surrounding reefs is not catastrophic, and those reefs will continue to thrive and remaining productive. If well protected, the conservation park may provide a refuge for coral and reef fish species, and help reseed adjacent reefs.

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