Philippines - Anilao: Dive and Trek

Setting

The second dive of 30 September 2016, at the Dive and Trek private marine sanctuary at Bauan, reached by bangka outrigger beneath a steep forested headland; all 85 frames in the dive folder were reviewed, five of them topside boat and shoreline shots. It is a managed reserve and the photographs make that obvious.

General benthic features

A standing Virgin Mary figure, thickly encrusted with coralline algae and sponge, and a large submerged cross with fish shoaling around it both sit on the slope (e.g., Image 7).

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Hard coral is abundant on a gentle to moderate slope of near-continuous framework: branching and corymbose Acropora, tabular plates, foliose lettuce corals compatible with Echinopora lamellosa and Merulina, plating Montipora, massive and columnar Porites and Goniopora, brain corals, a Pachyseris-type mound, Seriatopora and Stylophora thickets, and bubble corals including a striking turquoise colony (e.g., Image 3, Image 5, Image 8, Image 9, Image 10, Image 13, Image 18, Image 20, Image 21, Image 22, Image 23, Image 24, Image 25).

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Coral cover

• Reference: Claude CV point count (this site's photos)
• Coral cover: 24% — a blind Claude computer-vision point count of 73 of Anderson's edited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.
• It is not a diver survey or a transect; it is provisional and a better model will supersede it.

Stressors

Algal overgrowth is light, but bleaching was patchy across the slope. Anderson's own frames show white-tipped branching Acropora thickets across the slope, one recorded as partially bleached, with roughly half its branch ends white; a stand of stark-white branching Acropora with its architecture still intact; a large mound-shaped colony white across its center and upper half (patchy bleaching, in the notes); a fine-branching Seriatopora (a field ID) stark white across its center with polyps still visible (recorded as dying); and a host anemone with half its crown bone-white (e.g., Image 12).

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Another fine-branching colony has a cream-pale central section that Anderson recorded as partial mortality.

Fish and other fauna

A giant clam garden is the site's strongest signal: numerous Tridacna across several size classes and species, mantles in iridescent blue, violet, green, and mottled brown, consistent with a restocking and protection program (e.g., Image 11, Image 14, Image 19).

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Habituated fish swarm divers — sergeant majors, butterflyfishes, surgeonfishes, and unicornfishes, moorish idols, redtooth triggerfish, and wrasses (e.g., Image 6).

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Anderson photographed a large black nudibranch here, with crimson gills and a violet foot margin, recorded as never before seen (e.g., Image 46, Image 49); a cream dorid boldly marked with black arches also appears in the set.

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Comparisons with other data

Reef Check surveys this sanctuary as its 'Dive and Trek Marine Sanctuary' station: its one survey, on 14 May 2014 at 5 m, recorded 70% hard coral (112 of 160 points), about two and a half years before this dive. Reef Check's Portulano Marine Sanctuary station, 1.2 km to the north, recorded 57% on the same day. Those are point-intercept transects at 5 m; the 24% here is a computer-vision index of Anderson's photographs from a dive to 26.2 m, so the difference is not a measured change.