an extremely wide range of salinities. 

 This high degree of adaptability is a 

 definite advantage to life in the variable 

 environment of coastal and estuarine 

 waters, and it is perhaps one of the 

 means by which the neritic dinoflagel- 

 lates are able to compete successfully 

 with other organisms, such as diatoms, 

 which in general have a nnore narrow 

 range of salinity tolerance." [p. 391.] 



The author, citing Fritsch (1935), 

 mentioned that the naked dinoflagellates 

 appear to be most abundant in the open 

 ocean plankton, while the armored forms 

 are more typical of coastal and estuarine 

 regions. 



"The dinoflagellates have often been 

 credited with the ability to utilize and 

 flourish in extremely low concentra- 

 tions of nitrogen and phosphorus (Gran, 

 1926-27; Gilson, 1937). This concept 

 has stemmed largely from observations 

 that dinoflagellate maxima, intemperate 

 waters, follow the decline of the spring 

 diatom flowerings and relatively large 

 populations often persist throughout the 

 summer months when the supplies of 

 these nutrients are almost undetect- 

 able. Gran (1926-27) has proposed that 

 the dinoflagellates require less nutrition 

 for growth than the diatoms on account 

 of their relatively low rate of nnetab- 

 olism. [p. 391-392.] 



". . . dinoflagellates as a group show 

 a continuous variation in their modes 

 of nutrition from autotrophic to holozoic, 

 while mamy species are facultative, ob- 

 taining their food by either or both 

 methods (Kofoid and Swezy, 1921), . . . 

 [p. 392.] 



"In inshore waters dinoflagellates 

 are often abundant, and in many parts 

 of the world their populations may de- 

 velop bloom proportions. Here the close 

 association of the plankton with land 

 masses and the contribution of runoff 

 water to their environment provide 

 what may be considered as a natural 

 'soil extract,' and, in the vicinity of 

 heavily populated areas, frequently a 

 source of organic pollutants. As men- 

 tioned earlier, Braarud (1945) observed 

 a heavy growth of dinoflagellates in 

 the highly polluted regions of the 

 Oslofjord. Braarud and Pappas (1951) 

 later found that the addition of small 

 amounts of raw sewage to the medium 



stimulated the growth of Peridinium 

 triquetrum ." [p. 393.] 



The author suggested that growth 

 of dinoflagellates may be dependent 

 upon, or at least benefited by, the 

 previous flowering of diatoms. This 

 he suggested (citing Pearsall, 1932, 

 and Hutchinson, 1 944) as possibly caused 

 by the reduction of the concentrations 

 of one or more of the nutrients or 

 trace metals by diatoms to a level 

 favorable for dinoflagellates. On the 

 other hand, Lucas (1947, 1949) pro- 

 posed that the production of external 

 metabolites, or "ectocrines" by one 

 group of plankton organisms may bene- 

 fit the succeeding population, but in- 

 hibit competing organisms. 



"The dinoflagellates . . . possessing 

 the advantage of motility, are able to 

 maintain themselves in water of low 

 density with comparative ease and are 

 relatively independent of vertical nnix- 

 ing. ... [p. 395.] 



". . . motility provides the dinoflagel- 

 lates with an advantage in waters of 

 low nutrient content. The nonmotile 

 diatoms are dependent upon the dis- 

 solved nutrients contained in the water 

 which immediately surrounds them and 

 through which they sink (see Munk and 

 Riley, 1952). In contrast, the dino- 

 flagellates, thoughnot strong swimmers, 

 can move about for considerable dis- 

 tances and localize in the most ad- 

 vantageous depth for photosynthesis. 

 If the nutrient level of the water is 

 low, they may, by their vertical migra- 

 tions, utilize all the nutrients available 

 within the entire photic zone. Accord- 

 ing to Peters (1929) Ceratium can move 

 through 5 to 10 meters in 12 hours or 

 less." [p. 397.] 



The report contains an extensive 

 table of 21 red-water occurrences in 

 various parts of the world, including 

 some that caused nnass mortalities. 

 The author stated, ". . . one factor which 

 is alnnost universal in red water out- 

 breaks, the occurrence of a high water 

 temperature. In temperate or boreal 

 regions of the ocean, red water appears 

 to be restricted to the summer months, 

 and the notation is frequently made 

 that it is preceded by periods of un- 

 usually hot, calm weather. Along the 

 Indian coast, red water occurs during 

 the clear, hot periods between the 

 southwest and the northeast monsoons 

 (Hornell and Nayudu, 1923; Menon, 1945; 

 Bhimachar and George, 1950). Off the 

 Peruvian and Southwest African coasts 

 it appears during the southern summer 



61 



