Koh Seh’s coral survey: field measurements from 2019

What the research found

• Although published in 2025, this study measured reefs in June–September 2019. It is a local historical baseline, not a 2025 reef-health survey. PDF p.1 · PDF p.3
• The study reports 63.7% live hard-coral cover in Figure 2, rounded to 64% in the text. It recorded 409 hard-coral colonies in 14 genera and nine families. PDF p.5
• Table 1 tests did not detect differences in richness, abundance, Shannon diversity or benthic cover among the three groups. The groups were formed from coral composition; the reported PERMANOVA separation is not an independent confirmation of geographic differences. PDF p.5 · PDF p.7
• The results report no diseased corals detected in the sampled quadrats. The conclusion’s reference to a small proportion of diseased colonies conflicts with that result. PDF p.7 · PDF p.9
• The prose describes four East-zone sites, while both tables use five; table group sizes total 16. The discrepancy is retained without choosing a corrected value. PDF p.5 · PDF p.7
• The authors suggest management may contribute to reef condition. This single-island observational survey does not establish a causal effect of protection. PDF p.8 · PDF p.9

How the evidence was collected

Sixteen 50-m transects at depths of 1–2.5 m, with 11 photographed quadrats per transect: 176 photographs and 8,800 classified image points. Water variables were measured at transect ends; sediment traps were deployed for one week. Analyses grouped the sites into three coral-community zones. PDF p.3 · PDF p.4

Reported measurements

Table 1: coral communities and bottom cover

PDF p.7

SD describes variation among sites; it is not a confidence interval. None of these p-values is below 0.05. Bracketed group sizes reproduce the table despite conflicting prose.

Table 2: water conditions and sediment

PDF p.7

Letters reproduce the source’s pairwise-comparison groups. Sediment is reported in grams; it has not been converted to an areal deposition rate.

Table 3: comparison with earlier studies

PDF p.8

Koh Sdach and Koh Rong values come from cited earlier studies. They are not simultaneous surveys and cannot establish which site improved or declined.

Interpretation and uncertainty

• Local, shallow-reef sampling over one period does not represent all Cambodian reefs or interannual trends.
• The July 2025 preprint and August 2025 paper share title and authors; they are linked versions, not independent field studies.
• One indicator has printed p = 0.01 against a stated p < 0.01 rule; rounding could account for this, so the exact value needs clarification.
• Exact starting coordinates were recorded by the researchers but are not tabulated in the paper. No transect coordinates have been invented from its map.
• The three groups were derived from the coral-composition matrix and subsequently compared using that matrix. Separation should not be interpreted as independent confirmation of a pre-specified geographic hypothesis. Non-significant tests with 4–7 sites per group do not demonstrate equivalent conditions.

Original report

Read the original report · Publisher / archive copy · Download these findings (JSON)

Coverage of this account

The 11-page published paper was examined, including the reported tables and availability statement. Raw data are available by request according to the paper; they have not been obtained.

• Raw photographs, transect records and water measurements are request-only according to page 9; no author request has been sent.
• The preprint is linked bibliographically but has not been compared line by line.

How these findings are checked

Related reports

Tracing the reef evidence in Cambodia’s national assessment — see which documents share the same 2019 observations.