. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 67 Cnidaria (Coelenterata) Eighteen species in 11 genera of Cnidaria (hydras, jellyfish, sea anemones, and corals) are known from Johnston Atoll (Table 4). The distribution and abundance of the seven genera of coral reported by Brock, et at* (1965, 1966) are presented in Table 5. Collection sta- tions are shown in Figure 32. Two genera are quite restricted, occurring only in areas 1 and 2 near the marginal reef. The other five genera are distributed widely throughout the lagoon. Dredging operations in 1964 des
. Atoll research bulletin. Coral reefs and islands; Marine biology; Marine sciences. 67 Cnidaria (Coelenterata) Eighteen species in 11 genera of Cnidaria (hydras, jellyfish, sea anemones, and corals) are known from Johnston Atoll (Table 4). The distribution and abundance of the seven genera of coral reported by Brock, et at* (1965, 1966) are presented in Table 5. Collection sta- tions are shown in Figure 32. Two genera are quite restricted, occurring only in areas 1 and 2 near the marginal reef. The other five genera are distributed widely throughout the lagoon. Dredging operations in 1964 destroyed over 1,100 acres of reef; dredging itself destroyed 700 acres of living coral while newly deposited "coral aggregate" destroyed more than 400 acres. In addition, over 7,000 acres of reef and lagoon were more or less seriously affected by silty water. The reduction in the percentage of living coral in these silty water areas varied from none to 40 percent, with 10 percent being roughly an average figure. A parallel reduction in the number of associated invertebrate species and fish species also L^i - - ' >f.' Legend: Black - recently formed land areas. Cross hatch - areas of reef altered by recent dredging. Dots - areas of lagoon often covered by turbid water. Dense dots - area of lagoon and sea covered by very turbid water. Numbered dots - previous stations. Numbered arrows - new stations (transects) studied. Figure 32. Johnston Atoll showing invertebrate and fish collection stations, dredged areas, and the extent of silt laden water (Brock, et 1966).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smithsonian Institution. Press; National Research Council (U. S. ). Pacific Science Board; Smithsonian Institution; National Museum of Natural History (U. S. ); United States.
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