St. Eustatius

St. Eustatius (Statia), about 30 km² in area, sits on a relatively shallow bank that it shares with St. Kitts and Nevis, and the volcano at its southern end last erupted in the late Pleistocene or early Holocene (Wells 1988). Wells (1988) describes the flat, sandy plateau around the island as unfavorable for corals, which grow mainly on sheltered cliffs, cobble bottoms, and the lee sides of boulders. A narrow but distinct shelf at 22–30 m surrounds much of the island, and there are no extensive Acropora palmata reefs. The notable exception is the Corre Corre ridge off the southeastern point, an unbroken and exceptionally well-built algal ridge that extends roughly a kilometer up the east coast, rises over a meter above low tide, and has a near-vertical face falling to about 6 m; Wells (1988) suggests that earlier maps showing living reef all around the island may in fact refer to this ridge. The same account notes that the Windward Group islands hold fewer hermatypic coral species than the Leewards (33 against 50). Spalding et al. (2001) likewise treat Saba and St. Eustatius as steep-sided volcanoes with little reef framework but important coral communities, and note that a marine park created in 1998 protects four coastal zones on St. Eustatius that take in both reefs and shipwrecks. They estimate about 420 km² of reef for the former Netherlands Antilles, a combined figure that also covers Bonaire, Curaçao, Saba, and St. Maarten.

Souter et al. (2021) report recent trends only for the Eastern and Southern Caribbean as a whole, a subregion that groups the Lesser Antilles with Trinidad and Tobago, Aruba, Bonaire, Curaçao, and Venezuela. Across it, mean hard coral cover fell from about 26% in 1999 to 15% in 2019, the largest decline among the five Caribbean subregions, while algal cover nearly tripled between 1987 and 2019 to reach 48.3%. For the Caribbean as a whole, the same report links these losses to the 2005 mass bleaching, hurricanes, nutrient-laden, polluted coastal water, and overfishing of herbivores such as parrotfishes, and it names invasive lionfish, Sargassum influxes since 2011, and stony coral tissue loss disease (SCTLD) as newer threats; SCTLD, first seen in Florida in 2014, had been confirmed in 19 Caribbean countries and territories by October 2021. Earlier, Wilkinson (2006), drawing on the 2004 Caribbean Reefs at Risk assessment, placed the Lesser Antilles among the areas most threatened by coastal development and singled out its high islands for land-based pollution and sediment.

The St. Eustatius unit covers four dives made on 24 and 25 February 2026 in and around the St. Eustatius National Marine Park, and they are as much about man-made and mixed habitat as about natural reef. STENAPA Reef is a purpose-built artificial reef inside the park: concrete rings, arches, slabs, and steel hoops laid across a volcanic sand plain. The Chien Tong wreck is an intact steel cargo ship sitting upright on sand, with railings, masts, winch, and cargo hatches still in place. Double Wreck is a turtle-grass meadow broken by low ballast-and-rubble mounds, plus an upright anchor crusted in coral and sponge. The Ledge to Hangover is low, gorgonian-carpeted pavement stepping down to a 1.5-2 m undercut ledge.

Sponges and octocorals dominate the standing growth at every site, and stony corals are mostly small or scattered. On STENAPA Reef, sponges cover most of the structure while small young colonies settle on it, including plating corals consistent with Agaricia and lobes consistent with Porites astreoides. On the Chien Tong, sponges and hydroids crust the railings and masts, the flat decks stay bare under sediment, and young brain, maze, and star corals are just beginning to settle, most numerous in the shaded overhangs. Double Wreck's mounds hold large brain corals consistent with Pseudodiploria strigosa and giant barrel sponges, and fleshy macroalgae and turf occupy much of the hard substrate between colonies. At The Ledge, sea fans, sea plumes, and giant barrel sponges stand over long-dead framework under turf and encrusting sponge. Hard coral cover (Claude CV) ran from 2.9% at The Ledge to Hangover to 5.6% at Double Wreck, with STENAPA Reef at 4.6% and the Chien Tong wreck at 3.8%; three of the four are logged as artificial structures, so their values measure growth on built substrate rather than reef. Reef Check stations 0.7-2 km away recorded hard coral from 9.4% to 38% across surveys in 2005-2010.

In the photo review, one massive colony at Double Wreck was partly bleached on its upper half, and a computer-vision point count called 3.4% of coral points bleached at STENAPA Reef (2 of 103 photos) and 4.1% at Double Wreck (2 of 46 photos); one of the two STENAPA frames shows a marginal tissue-loss band (possible disease) rather than bleaching. At The Ledge, one massive colony shows a bright white band of freshly exposed skeleton beside a sediment-covered dead center, a tissue-loss lesion consistent with stony coral tissue loss disease (SCTLD). Invasive lionfish and invasive orange cup coral were photographed on STENAPA Reef. Wildlife is a strength: a great barracuda under the Hangover and around the Chien Tong superstructure, a green sea turtle at Double Wreck, where giant anemones host arrow crabs and cleaner shrimp, and spiny lobsters, fireworms, and a flamingo tongue across the sites.