Change to coral communities along a gradient of increasing exposure to a mud-discharging river in the Enipein Catchment, Pohnpei, Micronesia were quantified by the two principal authors (PICRC) using video transects at 5 sites, each with 3 replicate stations. Site 1 was closest to the river mouth and Site 5 farthest away (just under 2 km).
For each of 75 20 m transects, 200 sample points were generated by stopping the video every 2-3 s and identifying benthos under 5 fixed sample points on the screen (40 frames per transect). Cover was estimated for the benthos categories: abiotic substrata were recorded as carbonate (consolidated, including crustose coralline algae), mud (only used so thick no other substratum was visible), sand or rubble. Hard corals (scleractinia) were identified to the genus level where possible; corals in the Faviidae and Fungiidae were recorded to the family level; the three most abundant Porites taxa were recorded separately (massive Porites, Porites cylindrica, and Porites rus); unidentfied corals were grouped together - 24 species were identified. Other benthic groups recorded were: the calcareous green alga Halimeda, other macroalgae, soft corals, the calcareous hydrozoan Millepora, and sponges.