St. Eustatius - Double Wreck
Part of the regional summary: St. Eustatius
More about this place: Sint Eustatius on Wikipedia
More info
Leeward Caribbean Islands (NOAA CRW virtual station)A turtle-grass meadow broken by low ballast-and-rubble mounds, all that is left of the wrecks, plus an upright anchor. The mounds hold brain and star coral heads and barrel sponges; an arrow crab shelters under a sponge and a cleaner shrimp sits on an anemone, along with a green turtle and a barracuda. Wreck and artificial-structure site: this cover value counts coral growing on man-made structure (steel, concrete, wreck debris) and the bottom around it, so it isn't comparable with natural-reef cover, although it is counted in the St. Eustatius regional mean, which pools three artificial structures and one natural reef.
Een veld van schildpadgras, onderbroken door lage heuvels van ballast en puin, het enige wat er van de wrakken over is, plus een rechtopstaand anker. Op de heuvels groeien hersen- en sterkoraalkoppen en tonsponzen; een pijlkrab schuilt onder een spons en een poetsgarnaal zit op een anemoon, samen met een soepschildpad en een barracuda. Wrak- en kunstconstructielocatie: deze bedekkingswaarde telt koraal dat groeit op door mensen gemaakte constructies (staal, beton, wrakresten) en de bodem eromheen, en is dus niet vergelijkbaar met de bedekking van natuurlijke riffen, hoewel ze wel meetelt in het regionale gemiddelde van St. Eustatius, dat drie kunstmatige constructies en één natuurlijk rif samenvoegt.
AI translation of this summary; the English is authoritative.
Seven independent survey stations shown with the program’s logo — click one to see how far it is from this site.
Three other CRD dive sites with their own pages within 5 km shown in orange — click a marker to open its page.
These are unedited originals; edited versions will replace them.
12 of the 50 photographs on this page are shown beside the text that discusses them under "Site description" below.
Site description
Setting
A mixed seagrass, patch-reef, and sponge-garden habitat; no recognizable hull remains, and what is left of the wrecks is a scatter of low ballast-and-rubble mounds and an upright anchor, its chain running away across the seagrass. Visibility is workable but hazy/particulate throughout, consistent with a site with fine sediment and seagrass nearby (e.g., Image 7).
General benthic features
Low coral/rock outcrops rising from the seagrass are thickly colonized by sponges: a prominent cluster of bright yellow tube sponges, red and orange encrusting sponges, pale blue-gray vase-type sponges, and a green branching gorgonian/sea rod, with a small mustard-hill-type coral head (olive-green encrusting mounds) and a khaki brain/star coral head nearby (e.g., Image 3, Image 26).
A separate pair of large barrel sponges (one with a striped fish sheltering in its mouth, plus sergeant majors and a spotted trunkfish/boxfish visible) frames a cleaning-station-like scene with schooling reef fish; black wire coral and a small round dark sponge sit at their base (e.g., Image 36, Image 39).
One frame shows a solitary massive star-coral colony (tan, evenly pored, healthy-looking) on the seabed among rubble and low-growing sponges (e.g., Image 31).
Coral cover
- Reference: Claude CV point count (this site's photos)
- Coral cover: 5.6% — a blind Claude computer-vision point count of 46 of Anderson's unedited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.
Stressors
One massive colony is partly bleached on its upper half, pale cream-white above normal tan tissue (e.g., Image 51), and a computer-vision point count called 4.1% of coral points bleached (2 of 46 photos); no disease or physical damage was seen on the coral colonies photographed.
Fish and other fauna
A green sea turtle is visible cruising over a seagrass meadow in hazy blue-green water in the opening frame (e.g., Image 27).
Macro frames show a yellowline arrow crab (Stenorhynchus seticornis) with long banded legs sheltering under an orange encrusting sponge, an aggregation of long-spined black brittle stars densely packed together in a crevice, and a Pederson/spotted cleaner shrimp (cf. Periclimenes) perched on the pale lavender-tipped tentacles of a corkscrew or giant anemone (e.g., Image 1, Image 17, Image 23).
A great barracuda swims low over the seagrass in a separate frame, with a diver's fin visible at the frame edge (e.g., Image 8).
Comparisons with other data
Hoeksema et al. (2022) surveyed this site (Double Wreck), 0.04 km from the pin. Within 5 km, seven independent stations (Reef Check and XL Catlin Seaview Survey) recorded station-year means of 0.7–38% hard coral cover between 2005 and 2013; the nearest of these, XL Catlin Seaview Survey at transect 25015, 1.06 km away, read 2.0% in 2013.
CV model comparison
More info
A few colony-focused photos raise the mean; the median is the typical photo. No computer-vision method yet estimates coral cover accurately on new images, so treat this as indicative rather than a measurement; it is revised as the methods improve.More info
DINOv3 and CoralSCOP were run on the same photos and are listed for comparison. No diver transect exists for this trip, so agreement between the rows is not accuracy, and no computer-vision method yet estimates coral cover accurately on new images; treat every row as indicative.| Method | Hard coral cover (%) | Photos (n) ± SE |
|---|---|---|
| In-house DINOv3 | 15.6 | n = 46 · SE 1.1 |
| CoralSCOP unedited | 26.1 | n = 46 · SE 2.3 |
| Claude | 5.6 | n = 46 · SE 1.5 |
The two computer-vision methods disagree by 10.5 pp (15.6–26.1%) and read 10.0–20.5 pp above Claude's blind point count (5.6%); the headline is Claude's blind point count because no transect or manual count exists here.
See a more detailed, stand-alone version of this table.
Independent surveys nearby
| Agency / program | Year(s) | Stations / distance | Link |
|---|---|---|---|
| Reef Check | 2005–2010 | 5 stations, 1.48–4.31 km | Records ↓ |
| XL Catlin Seaview Survey | 2013 | 2 stations, 1.06–1.07 km | Records ↓ |
Coral Reef DiagnosticsYear-average (illustrative only, programs differ)Within 5 km, 7 independent survey stations recorded hard coral cover in 17 surveys between 2005 and 2013. Of the 4 stations surveyed in more than one year, 3 declined (by 1.0–20 points) and 1 increased (by 14 points) between their first and latest surveys. The longest record, Barracuda Reef Line 1 (Reef Check, 1.48 km away), went from 28% in 2005 to 26% in 2010 (mean of 2 surveys). The most recent nearby survey is from 2013, so these values predate recent heat stress. This site's own estimate (5.6%) sits within the range of these station-year means up to 2 km away (0.7–28%); the methods differ, so the comparison is context, not a like-for-like test.
Collected by other programs using different methods (Reef Check uses point-intercept transects; the XL Catlin Seaview Survey uses photo-transects with automated image annotation), so these are context for the figures above, not a like-for-like comparison. Where a station was surveyed more than once, the cell shows either the range of its values or, as a single value, the mean of surveys made in one year. Station names are not dive-site names.
| Agency | Site / location | Date | Hard coral cover (%) | Distance | Link |
|---|---|---|---|---|---|
| Reef Check | Barracuda Reef Line 1 | 2005–2010 | 11–28% (range of yearly means; 6 surveys) | 1.48 km | — |
| Reef Check | Barracuda Reef Line 2 | 2005–2007 | 24–25% (2 surveys) | 1.48 km | — |
| Reef Check | Mushroom Garden Line 1 | 2005–2009 | 9.4–33% (4 surveys) | 2.58 km | — |
| Reef Check | Mushroom Garden Line 2 | 2005–2007 | 24–38% (2 surveys) | 2.58 km | — |
| Reef Check | Twin Sisters | 2009 | 16% | 4.31 km | — |
| XL Catlin Seaview Survey | transect 25015 | 2013 | 2.0% | 1.06 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 25016 | 2013 | 0.7% | 1.07 km | doi:10.14264/uql.2019.930 |
Data & links
All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and the organizations named in the data sources above.
© Coral Reef Diagnostics.
References
- Hoeksema BW, van der Loos LM, van Moorsel GWNM (2022). Coral diversity matches marine park zonation but not economic value of coral reef sites at St. Eustatius, eastern Caribbean. Journal of Environmental Management 320:115829. DOI
- Gonzalez-Rivero M, et al. (2019). Seaview Survey photo-quadrat and image classification dataset. The University of Queensland (UQ eSpace) data collection. DOI