DEVELOPING A CORAL REEF FABRIC IN A HURRICANE BELT, TURKS AND CAICOS ISLANDS

A healthy Acropora palmata reef along the eastern side of Caicos Platform was directly hit by Category 4 Hurricane Ike in 2008 and then by Category 5 Hurricane Irma in 2017. This has provided an opportunity to observe reef modifications, post-storm recovery, and progressive formation of the final reefal fabric.

In 2005, the reef was a dense maze of moderate-sized A. palmata fronds reaching into the inter-tidal zone. This growing coral had recolonized an in situ stand of dead A. palmata, likely representing recovery from an A. palmata die off in the 1990s. There were no major hurricanes here between 1990 and 2008.

Storm-surge from Category-4 Hurricane Ike in September 7, 2008, turned most of the growing fronds to rubble, dropping broken pieces into the basal reefal framework and sweeping some rubble to the reef’s, platformward lee-side. The reef surface deepened to 2-3m. Small bits of living tissue on basal framework and on bits of broken coral first rapidly spread laterally coating dead coral surfaces and binding debris (years 1-2). Lateral growth rates were 15-25cm/year. Upwards growth then commenced, first as small cups and fronds and then as enlarging branching fronds (years 3-9). In these 9 years, new growth built upwards to 1.5-2.0m depth.

Storm-surge from Category-5 Hurricane Irma on September 7, 2017 stripped the growing reef and the underlying rubble from more exposed parts and redeposited this as a rubble wedge on the platformward lee-side. Over much of the reef top there is little coral rubble with living tissue from which the reef can easily regrow.

Vibrancy of fair-weather reef growth between closely spaced destructive events permits continued formation of immense amounts of coral destined to become reefal rubble characteristic of many modern and ancient reefs. In settings removed from hurricanes, the aggressive growth of Acropora palmata corals may also provide the opportunity for very thick in situ growths to rapidly form and preserve.