20 intertidal benthic rransections were set up at the rocky, sandy, and mangrove muddy shore. Of 547 benthic fauna species were identified; 91 species of algae, 120 species of polychaetes, 209 species of mollusks, 83 species of crustaceans, 19 species of echinoderms, 25 miscellaneous species. Molluscs, polychaetes, algae and crustaceans comprised 91.95% of all species and were the four main groups of benthos in intertidal zone of Daya Bay.

According to faunal nature, intertidal benthos in Daya Bay can be divided into four groups: 1. Tropical-subtropical warm water species distributed in the East China Sea and the South China Sea. 2. Eurythermic-eurytopic species distributed from the Bo-Yellow Sea to the South China Sea. 3. Warm temperature species distributed in the Yellow-Bo Sea. 4. Tropical nature species distributed only in the South China Sea.

The horizontal distribution of benthos species number is more at rocky shore (316) than sandy shore (222), and more at sandy shore than mangrove muddy shore (5l); the vertical distribution of species is more at the middle tidal zone (398) than at the low tidal zone (221), and more at the low tidal zone than at the high tidal zone (36). The characteristic of the composition and distribution of benthos species is related mainly to the environmental factors of sediments form, tidal flow, current, and temperature.

The horizontal species distribution shows the effect of sediments form on benthos, the vertical species distribution shows the tidal effect on tidal to benthos, the seasonal variation of species shows the effect of temperature on benthos, the difference of species compositon between exposed, semiexposed and sheltered shore in same ecological phase shows the effect of current to benthos.