212 



GERBER 



CTENOPHORA 



Tentaculata 



Lobata 



One specimen preserved in the MPML reference collec- 

 tion has been identified to genus and was collected in the 

 lagoon off Enewetak Island December 28, 1975. Cteno- 

 phores were collected from the lagoon in April and 

 December 1955 (Gilmartin, 1958) and in the winters of 

 1972, 1974, and summer 1974 by Gerber (1981) but not 

 identified to species. 



MOLLUSCA 

 Gastropoda 



Two species of the holoplanktonic Thecosomata, collec- 

 tively known as pteropods, have been reported from 

 Enewetak Lagoon. Johnson (1949) and Gilmartin (1958) 

 each reported one species from Enewetak and nearby 

 Bikini, Rongelap, and Rongerik Lagoons. Pteropods were 

 collected from shallow stations at Enewetak and Majuro 

 Lagoons by Hobson and Chess (1973, 1978) but were not 

 identified further. Gerber (1981) identified two species 

 which commonly occurred in lagoon samples from shallow 

 and deep stations; they were especially common in the 

 summer months. 



Only one unidentified species of the heteropod genus 

 Atlanta was recorded by Gilmartin (1958) from Enewetak 

 Lagoon where it is not very abundant. Members of this 

 genus have been reported in low abundance in nearby 

 oceanic waters (Chiba and Hirakawa, 1972). The classic 

 taxonomic works on this and the above group have been 

 done by Tesch (1946, 1949, 1950). 



ARTHROPODA 



Crustacea 



Ostracoda 



Planktonic ostracods have been recorded from 

 Enewetak Lagoon (Gerber and Marshall, 1974; Hobson 

 and Chess, 1978; Gerber, 1981) and Majuro Lagoon (Hob- 

 son and Chess, 1973). Those recorded by Gerber (1981) 

 and most of those reported by Hobson and Chess (1973) 

 belong to the order Myodocopa, but further identification 

 was not made. Though they occur fairly regularly in net 

 collections, ostracods are represented by only a few indi- 

 viduals per sample. 



Copepoda 



Approximately 58 species of calanoid copepods have 

 been identified from Enewetak Lagoon. Johnson (1954) 

 identified the 12 most common species from Enewetak, 

 Rongelap, Rongerik, and Bikini Lagoons but unfortunately 

 did not indicate which species came from each lagoon. His 

 collections at Enewetak, Rongerik, and Rongelap Lagoons 



were made in June and at Bikini Lagoon from March to 

 May in 1946. Twelve species of calanoids were identified 

 by Gilmartin (1958) at Enewetak Lagoon from samples col- 

 lected in April, November, and December 1955; eight of 

 these species were not recorded by Johnson (1954). Two 

 plankton samples were collected at Enewetak Lagoon in 

 September 1959 and 1961 by Mahnken (1966) in conjunc- 

 tion with a detailed zooplankton study of Rongelap 

 Lagoon. He identified 25 species from Enewetak Lagoon 

 and 45 species from Rongelap Lagoon which included 

 most of the species previously reported from Enewetak. In 

 January and February 1966, Barnett (1967) studied the 

 distribution of copepods at several locations in Enewetak 

 Lagoon. He recorded about 46 species of calanoid 

 copepods, most of which also occurred in Rongelap 

 Lagoon. Gerber (1981) sampled Enewetak Lagoon during 

 January and February 1972 and 1974, respectively, and in 

 June through August 1974. He identified 45 species from 

 a mid-lagoon station; most of those species had been previ- 

 ously recorded from this lagoon. Even after these studies 

 at Enewetak, there are species of calanoid copepods which 

 have been recorded from Rongelap that have not been 

 identified from Enewetak Lagoon. Those species arc 

 Euchirella sp., Labidocera bataviae Scott, Pontella fera, 

 Pontella tenuiremis, Pontellina globosa, Pontelhpsis kraw- 

 eri. Pontelhpsis macront^x, and Undeuchaeta plumosa. At 

 Majuro Atoll Lagoon, two species of calanoid copepods 

 (Candacia discaudata and Undinula vulgaris) which also 

 occur at Enewetak Lagoon were recorded from the 

 stomach contents of fish; a third species collected there, 

 Labidocera acuta, has not been recorded from the other 

 lagoons (Hobson and Chess, 1973). In a study of the feed- 

 ing habits of various planktivorous fishes at Enewetak, 

 Hobson and Chess (1978) identified three of the large size 

 copepods to species and four others to the generic level; 

 these had been reported previously. Calanoid copepods in 

 reduced abundance were recorded by Johnson (1954) from 

 outside Bikini Lagoon, but these species were not 

 reported. Chiba et al. (1955) collected zooplankton in the 

 open ocean near Bikini Atoll and throughout the Marshall 

 Islands from May to June 1954. They presented 80 

 species of calanoid copepods, about half of which have 

 been recorded from Enewetak Lagoon; the remaining 

 species consisted of oceanic and deep water forms. There 

 are many important works dealing with the taxonomy and 

 identification of calanoid copepods which occur at 

 Enewetak Lagoon. The most important works are Bradford 

 (1974), Dakin and Colefax (1940), Delsman (1939), Frost 

 and Fleminger (1968), Giesbrecht (1889), Grice (1961), 

 Mori (1937), Scott (1909), Sewell (1929), Vervoort (1964), 

 and Wilson (1942). 



Cyclopoid copepods were first recorded from Enewetak 

 and nearby atolls by Johnson (1954) during the sampling 

 periods mentioned above. He recorded four species plus 

 two genera consisting of several unidentified species. 

 Gilmartin (1958) identified four species at Enewetak 

 Lagoon, and Mahnken (1966) identified 12 species from 

 Enewetak and five at Bikini and Rongelap Lagoons. These 



