42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



living Foraminifera in June and August in Todos Santos Bay, Calif., 

 and he believed that these maxima were in response to the abundance 

 of phytoplankton in late spring and summer. Parker and Athearn 

 (1959) found the largest living population in Poponesset Bay, Mass., 

 in June and suggested that this maximum might be related to maxi- 

 mum temperature because Myers (1935) and Bradshaw (1955) 

 have shown that some species of foraminifers increase reproduction 

 rates at higher temperatures. 



Riley (1959) has shown that although there is a 20-fold variation 

 in chlorophyll, the amount of organic matter in surface waters of 

 L.I.S. varies within narrow limits. If the Foraminifera are indiscrimi- 

 nate feeders, and depend either directly or indirectly on organic mat- 

 ter in the water column, then the amount of food available is the 

 same throughout the year. On the other hand if they depend on the 

 phytoplankton either directly or indirectly, then their food will vary 

 seasonally. 



In L.I.S. the phytoplankton have a large midwinter flowering in 

 February and March, several irregular summer flowerings, and in 

 some years a large autumn flowering. The zooplankton have maxima 

 in late spring and late summer. The Foraminifera were not abundant 

 in March, and the next sampling time was in June. Therefore, if a 

 late-spring increase had occurred it would not have been detected. 

 Likewise, no samples were taken in July and August, and so it is not 

 known whether or not the Foraminifera maintained their June maxi- 

 num throughout the summer. In October 1961 Eggerella advena 

 had a significant maximum, whereas none occurred in early autumn 

 1962. No data are available concerning possible phytoplankton flow- 

 erings during the autumns of 1961 and 1962. 



The maximum temperature in L.I.S. occurs in August and the 

 minimum in January or February. The temperature in June and 

 October is about 16-18°C, the former being one month prior to the 

 maximum and the latter one month after it. 



The seasonal maxima obtained in this study are based on sampling 

 times which are widely spaced. It may be said that the abundance of 

 Foraminifera in October 1961 and June 1962 correlates in a general 

 way with times of maximum temperature and with the increase of 

 zooplankton in late summer and late spring, which in turn is correlated 

 with the phytoplankton cycle. Until information regarding the feed- 

 ing habits and importance of temperature for the species in question 

 are available, these variables cannot be evaluated. 



