490 EIGHTH PACIFIC SCIENCE CONGRESS 



poor flora of the Marshall Islands. Besides these, only scattered papers 

 or fragmentary floristic accounts exist, even for such scientifically ad- 

 vanced regions as the Philippines and the Hawaiian Islands. 



Not only are these floristic accounts few and incomplete, but many 

 of them lack any consideration of ecological data. Furthermore, nu- 

 merous problems of nomenclature remain, as well as errors in identi- 

 fication, such that many species are recorded under different names in 

 different areas while unlike species are often incorrectly identified under 

 a single name. 



Thus, it must be admitted that our present knowledge of the ma- 

 rine algae of the Indo-Pacific region is hardly sufficient to permit us 

 to attempt to deduce many conclusions regarding distribution, either 

 specific or general. 



Despite these difficulties and shortcomings the present study of the 

 marine flora of Nhatrang Bay has revealed some interesting facts re- 

 garding distribution which may aid in the thinking in this symposium. 



Firstly, of the 224 species known at Nhatrang, about 40% are com- 

 mon ones which are cosmopolitan, pan-tropical or known to be of wide- 

 spread occurrence in warm seas. From this group of species of broad 

 tolerances little can be deduced as to the affinities of the Nhatrang 

 flora with floras of other regions. 



Secondly, our general lack of knowledge of tropical algae is de- 

 monstrated in the rather large proportion of new or little known spe- 

 cies at Nhatrang (25%). About 7% represent undescribed plants or 

 species referred with doubt to described ones, while about 40 species, 

 or 18%, are hitherto recorded from only one or tw^o other localities. 

 It is particularly noteworthy that of these latter localities a number are 

 very remote from Vietnam, as for example, Easter Island, Juan Fer- 

 nandez Islands, Tahiti, South India, The Virgin Islands, The Gulf of 

 California, Mauritius, The Canary Islands, Hawaii, New Caledonia, 

 and even Senegal. 



It is from among the remaining 35% of the species, whose distri- 

 butions are somewhat better known and apparently more restricted, 

 that the more interesting correlations may be sought. 



In the immediate vicinity of the Institut Oceanographique the most 

 prevalent marine environments are sheltered ones in which the off-shore 

 islands serve as protection from surf-engendering sea-swell. These quiet 

 waters are subject to intense isolation, which accounts for relatively high 

 temperatures, and for diurnal warming of up to 3°C. It is in these 

 quiet lagoon and bay-shore habitats that the greatest proportion of pari- 

 tropical species occurs. It is also there that nearly all of the species 

 which are of occurrence in Indonesia or in the tropical Indian Ocean 



