### BICA01 — Cauvin Banks
**CRD page:** [Cauvin Bank and Egmont Coral Surveys (March 2015)](https://coralreefdiagnostics.com/cauvin-bank-and-egmont-)
**Date:** 2015-03-09 — **the expedition's first survey, site #1 of 109**
**GPS:** 6.80368°S, 72.38544°E · **Depth:** 28 m, a single stratum (D4)
**Frames reviewed:** 3 of 3 (the entire photographic record for this site)
**Coral cover:** 4.6% — 4 transects × 500 points = 2,000 points; per-transect 6.2 / 4.0 / 5.6 / 2.6%, **SD 1.6** · **% bleached:** 0.0%
**Algal cover:** 56.8% — sediment-laden turf (PTSTS) **22.3** · CCA (PCCATS) 15.5 · erect (PETS) 9.1 · turf (PTTS) 7.4 · macroalgae (PMTS) 2.5 · cyanobacteria (PCYTS) 0.0
**Bare substrate (PB):** 37.45% — **the highest of the 109 sites** (mean 11.2%) · non-coral invertebrates (PITS) 1.15%
**Reef type:** submerged patch reef, lagoonal (inside), exposed · **Temperature:** 28.9 °C · salinity 34 · marked `Training` · the only site in the Cauvin region

**Assemblage composition from transect data — the reef is nearly bare, and the little coral on it is the most evenly shared in the archipelago.** The transect records **eleven genera**, summing exactly to the 4.6% cover: ***Porites*** 1.45%, ***Montipora*** 1.30%, ***Pocillopora*** 0.55%, ***Acropora*** 0.35%, ***Cyphastrea*** 0.20%, ***Favites*** 0.15%, ***Goniastrea*** 0.15%, ***Leptastrea*** 0.15%, ***Stylophora*** 0.15%, ***Fungia*** 0.10% and the hydrocoral ***Millepora*** 0.05%. As a share of live coral that is *Porites* **31.5%** and *Montipora* **28.3%** — **no genus holds even a third of the assemblage.** **H′ = 1.886, Simpson (1−D) = 0.794, Pielou's J′ = 0.787.**

**The pairing of those numbers is the point.** BICA01 has the **second-lowest coral cover of the 109 sites** (4.6% vs a mean of 37.9%; only BIDI12 at 4.18% is lower) and near-lowest richness (11 genera, 103rd, mean 23.3) — yet **evenness third-highest in the dataset** (J′ 0.787 vs a mean of 0.598, behind only BINI78 and BIEA20) and **H′ above the dataset mean of 1.856** on a twentieth of the mean cover. **A thin, taxonomically diverse veneer, not a stand** — the exact inverse of BIDI11, where four genera and 75% *Porites* carried 40% cover: abundance without diversity there, diversity without abundance here.

**The benthos closes cleanly and is dominated by things that are not coral:** coral 4.6 + algae 56.8 + bare substrate 37.45 + invertebrates 1.15 = **100.00%**. Bare substrate is the dataset maximum and sediment-laden turf at 22.3% is 8th of 109 (mean 7.37%). **One-third bare, one-fifth sediment-bound turf, one-sixth CCA** — mostly open substrate under a fine algal skin, not a collapsed framework. **The 0.0% bleaching belongs with that reading, not against it: the reef is not stressed, it is sparse.**

**What the three photographs show — they corroborate the transect and add texture, nothing more.** **P3090257** is a dense low mound of bright-green strap-shaped blades — **compatible with a fleshy *Caulerpa*-type macroalga** — on open pale carbonate sand, with dark red-brown erect tufts along its left margin; **no coral in frame**. **P3090273** is a wide, dim, deep-looking view of exactly the substrate the transect describes: sediment-veneered pale carbonate with scattered dark olive erect tufts, **pink-mauve tufts compatible with articulated coralline algae**, and no coral framework. **P3090284** is the best habitat frame — low-relief pavement running to a dark blue horizon under **continuous dark turf stubble**, with **two dark surgeonfish-type acanthurids grazing over it** and a few small smooth olive-grey discs **compatible with encrusting or small massive colonies but not callable**. **Not one of the eleven transect genera can be confirmed photographically.**

**The multi-method comparison rests on two frames and is not a method test.** The table gives transect 4.6% · CoralNet 5.0% · Coralscapes 0.4% (deviation −4.2 to +0.4 pp) on **n = 2** — P3090284 was never annotated. The 5.0% is the mean of two training rounds that returned **10% and 0%**, a **200% formal-vs-informal difference — the largest of the 105 sites carrying it**. The 10% comes from **three "*Acropora*" points on P3090257 — a photograph of a green algal mound** — whose 30 points are 15 FISH, 6 Unknown, 6 Turf and 3 *Acropora*, with **no macroalgae point at all**. **CoralNet landing within 0.4 pp of the transect is arithmetic coincidence, not agreement.** Worth one line: **Coralscapes returned essentially nothing (0.4%) where the transect scored 4.6%.**

**Flags:** (1) **THREE-FRAME PHOTOGRAPHIC RECORD** — the transect data carry this description; no genus statement here derives from an image. (2) **THE MULTI-METHOD LINE RESTS ON n = 2 AND MUST NOT BE POOLED** with the n = 20+ sites; BICA01 also carries the **largest formal-vs-informal cover difference in the dataset (200%)**. (3) **ANNOTATION-PROVENANCE ARTEFACT, P3090257** — three *Acropora* points and zero macroalgae points on a *Caulerpa*-type algal mound, half the points on fish; this one frame generates the whole 10% first-training figure. (4) **Coralscapes reads 0.4% against a 4.6% transect** — anecdote about mask behaviour on sparse turf-and-sand ground, not evidence. (5) **THE 0.0% BLEACHING IS REAL BUT NOT UNIQUE** — **five other sites also read 0 on both rounds** (BIDI16, BITB40, BITB43, BIEA52, BIPB69) against a dataset mean of 9.8%. (6) **Integrity checks pass:** genus columns sum to 4.60, algal to 56.80, all four benthic totals to 100.00. (7) **HIGH EVENNESS ON ALMOST NO CORAL — Anderson's judgement needed** on whether J′ and H′ should be reported at 4.6% cover at all: *Millepora* (0.05%) and *Fungia* (0.10%) rest on one or two points of 2,000. (8) **Region name inconsistent in the supplement** — "Cauvin" in the benthic sheets, **"Calvin"** in `simplified image data`. (9) No per-frame depth. No COTS, disease or predation scars identifiable in the three frames — an absence from three photographs, not a survey result.

**Benthic data:** [Download BICA01 benthic survey data (CSV)](../benthic_data/BICA01_benthic.csv) — scleractinian cover by genus with full names, plus substrate and algal categories (bare substrate, CCA, turf, macroalgae, invertebrates), from the LOF BIOT-1 survey (Mayfield & Dempsey 2026, *Oceans*, supplemental file S1).