Marine Algae of the Northwest Hawaiian Islands!

Reexamination of some previous collections of marine algae from the Northwest Hawaiian Islands (NWHI), also known as the Leeward Hawaiian Islands, and the addition of more recent collections have resulted in recognition of 48 taxa of Chlorophyta (green algae), with eight new records for the NWHI; 33 taxa of Phaeophyta (brown algae), with seven new records; and 124 species ofRhodophyta (red algae), ofwhich 26 are new records for the NWHI. Among the 41 new records, 14 taxa are newly reported for the entire Hawaiian archipelago. Among the new records are Nemacystus decipiens, Halimeda copiosa, and H. velasquezii and among the microscopic algae Crouania mageshimensis. Total macroscopic marine flora consists of 205 taxa, a number close to the 222 species known from Eniwetak in the northern Marshall Islands. Proportions of greens and reds in the two places are markedly different, however, with more green and fewer red species in Eniwetak. stratum and habitat from the volcanic and younger main Hawaiian Islands. The two southern islands of the northwestern group, Necker and Nihoa, are more similar to the main islands in their basalt substratum, and their marine flora may be expected to be more like those of the northernmost of the main group, Kauai and Niihau. At this time, however, there are few data for making a critical comparison owing to the poor knowledge of the marine algae of Kauai (where only a few collections have been made) and of Niihau (from which no collections are known). The new collections reported from Necker, from which only two algae were previously known, are of taxa that also occur on Kauai. The remaining nine islands, atolls, islets, pinnacles, and reefs, however, present a substantially different substratum and very little intertidal space. Their flora, therefore, was _e.xp-e.~tee_diJIe.r.ent f!:0!!! !4~Lof the southern volcanic islands with fringing -reefs that are primarily of coralline algal nature. The differing geological ages of these groups also have a bearing on the nature of the substrate. In the NWHI, a larger species list is available from the Midway Islands than from the remaining 10 islands combined. This is due, in part, to the larger size of the atoll and to the larger number of collections from the islets. 223 1 Manuscript accepted 28 October 1988. 2 Department of Botany, University of Hawaii, Honolulu, Hawaii 96822. NEW COLLECTIONS from the Northwest Hawaiian Islands, which are small islets, pinnacles, or atolls northwest of the main Hawaiian chain, have substantially added to the number of taxa previously reported from those locations (Buggeln 1965, Tsuda 1965, 1966, Balazs 1979). Opportunities to collect marine algae at these 11 locations are not numerous, and phycologists are dependent on the good nature and cooperation of biologists who are visitors for other reasons. The new collections reported upon here were made by Fred Ball, then an employee of the State of Hawaii in the Department of Land and Natural Resources, and Heather J. Fortner, who was employed on board ship for the National Marine Fisheries, and by Ira A. Levine, who was collecting bluegreen algae for a natural products study. Because of sterile specimens, not all material is reported upon here; perhaps four to six species _Lemaiu_UIlid~nii6ed. __ __ __ The coral atolls and reefs that constitute the older northwesternmost leeward Hawaiian Islands (officially known as the Northwest Hawaiian Islands [NWHI]) form a different sub-