Table 53 and in Fig. iJi. The niunber of stations was reduced from eight 

 in 1929 to six in 1930; Stations 82, 68, and 75 were abandoned, and 

 Station 72 was substituted for Stations 68 and 75 (Fig, 1), The month 

 of April is poorly represented by stations because the regular program 

 was not begun until May, but none of the succeeding periods is represented 

 by less than four stations. 



The diatoms were rather abundant in April, and increased 

 rapidly in May, reaching a spring maximum of I80 thousand units per 

 liter in the last half of the month. During June there was a marked 

 declini?, and the low point of the season was reached in early July, 

 The counts remained low in late July and early August. In late 

 August the diatoms began to increase toward the autumn maximum, which 

 came in late September. The maximum count of 2k2 thousand units is 

 probably higher than it should be, because of a local aggregation of 

 Stephanodiscus at one station. In early October there was a second 

 major decline to 12li thousand units per liter. Thus, the diatoms ex- 

 hibited two periods of abundance, the first in spring (late May), and 

 the second in autumn (late September) , 



The green algae were present Only in traces in April, They 

 increased somewhat in May, but declined in June almost to the vanishing 

 point. In July there was a marked increase to 39 thousand units per 

 liter. The increase during August was slight, but in September they 

 again increased rapidly, reaching the maximum of 99 thousand units in 

 late September, Following this there was a sharp decline to 60 thousand 

 in the first few days of October, Disregarding the small increase of 

 greens in May, this group had one period of abundance, which began in 

 July and r eached its culmination in September, 



The blue-green algae were very rare at the beginning of the 

 season, increased slightly in May, and became rare again in late June. 

 In July and August, they increased rapidly, reaching a count of 71 

 thousand units in late August, The count remained at this level in 

 early September, but rose sharply to the season's maximum of 2.03 thousand 

 units in the latter part of that month. As the season closed the count 

 was still high, having declined very little from the maximum. Thus, the 

 blue-green had only one period of tT'e^t abundance, and this came in 

 autumn. 



The plankton was dominated by diatoms during the first three 

 months of the season. In July, all three groups were about equally 

 abundant, and in August, diatoms were outnumbered by both greens and 



156 



