Chapter 1 



Marine Benthic Algae of Enewetak Atoll 



ROY T. TSUDA 



Marine Laboratori;, University of Guam 

 UOG Station, Mangiho. Guam 96923 



Our present knowledge of the floristics and ecology of 

 the marine benthic algae on Pacific atolls is based primarily 

 on studies conducted on Enewetak Atoll. There are more 

 species of marine benthic algae known from this atoll than 

 are known from any other Indo-Pacific atoll. 



The first published account of the marine benthic algae 

 of Enewetak appeared in Taylor's (1950b) treatise of the 

 plants of Bikini, which was part of a comprehensive study 

 of the flora and fauna of Bikini Atoll and other adjacent 

 atolls conducted in 1946 prior to the atomic bomb tests of 

 "Operation Crossroads." The phycological study was not 

 only the first for these atolls but also represented the 

 pioneering study in the Marshall Islands. Descriptive and 

 illustrative records of 57 species were included from 

 Enewetak. Three new species of the green algal genus 

 Halimeda were described based on Enewetak specimens as 

 holotypes (H, fragilis Taylor, H. gigas Taylor, and 

 H. lacunalis Taylor). 



Dawson (1957) made extensive collections of marine 

 algae on Enewetak during the summer of 1955 under the 

 auspices of the Eniwetok Marine Biological Laboratory 

 (now called the Mid-Pacific Marine Laboratory). His objec- 

 tive was to provide the laboratory with an algal reference 

 collection. The extensive collections made by Ralph F. 

 Palumbo of the Applied Fisheries Laboratory, University of 

 Washington, in relation to his radiobiological survey in the 

 Marshalls were also incorporated in the floristic account of 

 the 211 species reported by Dawson (1957). A few of 

 these species were mentioned in technical reports of the 

 U. S. Atomic Energy Commission by Palumbo (1950, 

 1955, 1959) and a later paper (Lowman and Palumbo, 

 1962). Based on the Enewetak specimens as holotypes, 

 five new red algal species were described: Antithamnion 

 percurrens Dawson, Callithamnion marshallensis Dawson, 

 Ceramium marshallense Dawson, C. sj^mpodiale Dawson, 

 and C. vagabunde Dawson. 



The first ecological study on deep water algae in an 

 atoll lagoon was conducted on Enewetak by Gilmartin 

 (1960). During 1955 and 1956, he ran a transect across 



the lagoon in waters ranging from 20 to 65 m deep and 

 recorded, as well as collected, algae he observed at the 

 various depths. A total of 87 species was reported: 16 

 species represented new records not previously reported 

 by Taylor (1950b) or Dawson (1957). 



Further algal studies which mention specimens from 

 Enewetak were mainly monographic treatments of specific 

 algae. Records of blue-green algae from Enewetak can be 

 found in monographs by Drouet and Daily (1956) and 

 Drouet (1968, 1973), who drastically revised the classifica- 

 tion scheme. Drouet's classification scheme is followed in 

 this presentation, and it is coincidental that he identified all 

 the blue-green algae reported by Taylor (1950b), Dawson 

 (1957), and Gilmartin (1960). 



Other algal genera studied include records of Halimeda 

 (Hillis, 1959), Turbinaria (Taylor, 1964), Tvdemania (Gil- 

 martin, 1966), Dawsoniella (Hollenberg, 1967), Po/ysi- 

 phonia (Hollenberg, 1968a, 1968b), Herposiphonia (Hollen- 

 berg, 1968c), Lophosiphonia (Hollenberg, 1968d), Fosliella 

 on sea urchin spines (Lawrence and Dawes, 1969), and 

 Caulerpa (Calvert et al., 1976). Poli/siphonia pentamera 

 Hollenberg (1968b) was described as a new species from 

 Enewetak Atoll. A recent study on the distribution of 

 Halimeda and T\^demania on Enewetak by Hillis-Colinvaux 

 (1977) added two more species records of Halimeda to the 

 flora. In the last chapter of the exhaustive review of 

 Halimeda by Hillis-Colinvaux (1980), the habitats occupied 

 by Halimeda at Enewetak are described in detail. In a 

 paper presented at the 63"^ Annual Meeting of the 

 Western Society of Naturalists held at the California State 

 University of Long Beach, Hillis-Colinvaux (1982) de- 

 scribed the large populations of Halimeda down to 100 m 

 and growth to over 140 m on the windward and leeward 

 outer slopes of Enewetak. The submersible "Makali'i" was 

 used for observations. 



Aside from the above papers, several ecological studies 

 mention algal species. Marsh (1970) carried out studies on 

 the primary productivity of crustose coralline algae and 

 later conducted studies on the productivity of the reef 

 community as a whole (Smith and Marsh, 1973). Other 

 studies which mention algae are those of Odum and Odum 

 (1955), Bakus (1967), Johannes et al. (1972), and Gerber 

 and Marshall (1974). Calothrix Crustacea Schousboe and 

 Thuret and Hormothamnion enteromorphoides B. and Fl. 



