1911] Michael: Chaeiognatha of tJte Sau Diego Region. 105 



ance. For example, the naupiii of Balaiius began to appear on 

 February 22nd in '07, on February 13th in '08, and on Febru- 

 ary 6th in '09. This is one of the cases where it is clear that 

 the normal sequence of events in the life-history of the organ- 

 ism is the dominant factor in determining the constitution of 

 the plankton at a definite time and place — the periodic repro- 

 duction of the Balanus causes the naupiii to appear in the plank- 

 ton at a certain time." Again (p. 296) : "Many other swarms 

 of neritic, and especially meroplanktonic, forms (such as crab 

 zoeas and fish eggs) are similarly due to the succession of stages 

 in the life history . . . ." We are therefore compelled to 

 acknowledge a very definite causal relation between rate of 

 reproduction and variations in the quantity of plankton. 



The influence of organisms on the abundance of plankton is 

 illustrated further, and from quite a different standpoint, by 

 the effects of "red- water" due to Gonyaulax, on various marine 

 animals, which is discussed by Torrey (1902) in an article en- 

 titled "An unusual occurrence of Dinoflagellata on the Cali- 

 fornia Coast.' He says (p. 187) : "It was first noticed on July 7 

 as a red streak off the mouth of San Pedro Harbor. During the 

 next few days it approached the shore, changing its shape and 

 dividing into several patches, each many acres in extent. . . . 

 The 'red-water' extended for two hundred miles at least along 

 the coast, from the region of Santa Barbara to San Diego, and 

 extended several miles to sea." On July 20 Torrey noticed a 

 "sickening odor" arising from the "red-water," and during the 

 next few days he found the following animals on the beach, 

 which were either dead or debilitated. Several hundred 

 Trachostoma arenata, many smelts, Petrolisthes cinctipes, and 

 Cancer antennaius, great numbers of Hippa analoga, a number 

 of Tevila crassatelloides, and several Mylobatis californicus, 

 Urolophus halleri, and octopi. It is also noted that "wherever 

 it [red- water] was seen the fishermen reported a scarcity of 

 food fishes." While most of the animals known to have been 

 affected are not included in what we call plankton, still it is 

 improbable that the plankton was unaffected and, if so, we must 

 acknowledge that the abundance of planldon mag be influenced 

 by the occurrence of large numbers of Gonyaulax. 



