Indonesia - Komodo NP: Siaba Besar

Setting

Coral extended down to 20-22 m. On the first dive (19 January), visibility was 10 m and the water 26-27°C. On the second dive (26 January), visibility was 10 m, with a very mild current.

General benthic features

Acropora formed large, very old colonies (e.g., Image 1).

1

Stylophora, Seriatopora, Pachyseris, and numerous other lettuce corals were present. The coral assemblage at 5-10 m was particularly rich. Merulina, plating Acropora, bottlebrush Acropora, and Anacropora were present; the water was murky with a high sediment load, many corals were feeding, and there was some Acropora mortality. Enormous, ancient sheets of Pachyseris grew at 15-20 m (e.g., Image 2).

2

Pocillopora was notably absent. Large areas were dominated by Acropora (e.g., Image 5).

5

Fluorescent green Stylophora was very common at the site. Some Fungia, Pavona, and massive Porites (though not a major framework builder) were present; fish life was diverse, but average fish size was small (e.g., Image 3).

3

Soft corals and sea anemones were beautiful, though this was definitely a hard coral-dominated site. Zoanthids and corallimorphs were common. At least five species of soft coral were present. Pocillopora verrucosa finally appeared at the end of the dive, at 6 m. No Pocillopora damicornis or Pocillopora acuta was seen. On the second dive (26 January), the corals included Pocillopora verrucosa, Seriatopora hystrix, Stylophora pistillata, Seriatopora caliendrum, Acropora (diverse and abundant), Pachyseris (dominant in places), and Pavona (including a very large colony). The site was dominated by hard coral and punctuated by large, sandy patches. There were many large, foliaceous coral colonies, only one of which was Pachyseris. Cabbage and lettuce corals grew among many huge branching Acropora colonies. Also recorded were Pavona, large colonies compatible with Euphyllia on the sand (e.g., Image 16, Image 24, Image 51), one Culcita, several species of Galaxea (all small), Montipora, several species of brain coral, Hydnophora, finger Porites, and small massive Porites (uncommon); Pocillopora acuta was notably absent.

162451

Coral cover

• Reference: Claude CV point count (this site's photos)
• Coral cover: 53% — a blind Claude computer-vision point count of 121 of Anderson's edited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table. Anderson's notes call the hard coral cover absolutely stunning.
• Diversity and cover were very high at 10 m.

Stressors

There was some Culcita damage, though not much. Anderson's log also notes some Acropora mortality: on the first dive, white sections of branches within otherwise pigmented staghorn thickets are recent mortality, cause not stated (e.g., Image 5).

Fish and other fauna

Several large green turtles were seen, one of which may have been pregnant. Anderson's notes also list pregnant turtles. Garden eels lived in an interesting sand apron. Tiny nudibranchs were seen. A small NBS anemone, some algae in the sand, Dictyota, and some Acropora colonies were also seen. A tiny frogfish and a small mantis shrimp peering out of its burrow (Image 44) were in the sandy area, where we spent the last third of the dive.

44

The second dive turned up 5-6 large turtles, several sharks resting on the sand, a nurse shark, and a cuttlefish.

Comparisons with other data

Reef Check surveyed a station named Siaba Besar (Sector 1), 1.65 km away. Within 5 km, six independent stations (Reef Check and WWF-US / WWF-Indonesia) recorded station-year means of 8.8–51% hard coral cover between 2016 and 2020; the nearest, Reef Check at Mawan (Sector 1), 0.34 km away, read a mean of 10% in 2020.

Dive record

The first visit was dive 1 of 19 January 2019 (trip dive 1). It ran from 7:28 to 8:33. Maximum depth was 19.2 m, and the dive lasted 65 minutes. The breathing gas was 33% oxygen. The average water temperature was 26.8°C. It was the first dive of the trip, at a site well known for hard coral. The return visit was dive 3 of 26 January 2019 (trip dive 30), from 15:20 to 16:26 (66 min). Maximum depth was 16.2 m. The average water temperature was 26.9°C. The breathing gas was 30% oxygen. It was our second dive at this amazing site.

Other notes

The most common soft coral, logged in the water as Sinularia, appears in the photographs as lavender, leathery colonies with smooth, finger-like lobes, compatible with Sinularia (e.g., Image 6).

6

The photographs show at least two other foliaceous forms: dense stands of thin, upright, contorted fronds with fine ridges parallel to their margins (e.g., Image 13, Image 42), and mounds of thin, frilly plates with a rough, granular surface (e.g., Image 49).

134249