Signs of Adaptation to Climate Change

Vibrant Giant Clam. Photo ©Vatuvara Private Islands.

By Katy Miller

[Note: this is the second in a series of blogs documenting a new scientific survey of the waters and islands comprising Fiji’s Northern Lau Group]

Colourful corals cover steep and gentle sloping reefs. Vibrant giant clams sit embedded along the reef flats. Curious reef sharks cruise along the edge of the reef while juvenile parrotfish weave through branching coral colonies. Turtles make swift escapes and a school of barracuda hover over the deep. All with a visibility of 40+ metres.

School of Barracuda. Photo ©Vatuvara Private Islands.

This is only a hint of what the science team has experienced in three days of surveying the coral reefs around the two islands of Kaibu and Yacata. The sites covered have been mostly forereef habitats on the leeward side of the islands, with varying slopes and depths, and including large coral bommies, deep crevices, near vertical walls, and sandy bottoms.

Shallow lagoon patch reefs with large areas of continuous reef were dominated by sizeable colonies of branching corals, where blue sea stars and sea cucumbers nestle into the sandy bottom.

Shallow lagoon habitat. Photo ©Katy Miller.

An interesting find in amongst the lagoon habitat was a common but thermally sensitive coral called thin birdsnest coral or Seriatopora hystrix. Coral under stressful conditions such as high seawater temperature rapidly lose their characteristic coloration, in a phenomenon referred to as “coral bleaching.”

Over the past three days, the water temperatures at both the lagoon and outer fore reef sites were between 29-30 degrees Celsius. The team was surprised to see large healthy stands of the birdsnest coral in a shallow environment that is exposed to continuous high water temperatures. This suggests that some corals have adapted and were able to withstand heat stress.

Calm before the storm. Photo ©Katy Miller.

As the team came together in the evening to review our day’s findings we were notified of a cyclone development over Samoa, moving slowly towards Fiji. A cyclone in May is quite unusual for this part of the world. The Fiji Islands experience cyclones during the summer months (November to April), but this is an unexpected occurrence moving into the cooler months.

Barely 15 months after Cyclone Winston, the strongest cyclone to make landfall in the Pacific, we are now following Category 1 Cyclone Ella’s path carefully, and hoping it weakens. The looming cyclone is bringing in strong winds and ocean swell making it impossible for the team to access windward reefs. For now, the team is focusing on sheltered sites, and are keeping a close eye on the movement of Cyclone Ella.

Katy Miller is Director of the Vatuvara Foundation.


Previous blog in this series:

Exploring Coral Reefs in the Northern Lau Group

Changing Planet

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