MARINE BIOLOGICAL STATION AT PORT ERIN. 35 
Bay, we find that the monthly averages (see fig. 9) for 
the total plankton begin low in January and February, 
rise in March and still more in April, reach the 
maximum in May, drop rapidly through June, July and 
August to the summer minimum, rise a little in 
September and October to form the autumnal maximum, 
and fall again in November and December to the mid- 
winter minimum. The autumnal maximum is always 
’ 
97 


°o 
a ) 


07.08 ,09 


08,09 

TERE 
RANARAN 
KANSAS 

2 


he & SG CRRA CAG ER Bee ees 
SAT AY 2 Gh EE EO. St SSS SSS 
QIN RT EESRRERERES EN FOR Se Ses 


97,08,09 
PT RANAN ANS 
ENS 
ANS 
08,09 

0%, 09 


PESOS OS 


RATES SS ANNA 
NIST SS SEATS ES 
SHEERS SESECCUL ARN 
NSS 
SRERAWABAT 
08, 
Folk 
N 
N 
mw 
NN 

= 
af 
= 
5 
a 
¥ 

Fie. 9. Diagram of average haul of Plankton per month in the three 
years (1907-09) separately and combined. The black columns show 
most clearly the changes throughout the year. 
much less than the vernal. Both are caused by a very 
marked increase in the Phyto-plankton, chiefly Diatoms, 
and the species which are the most abundant and 
characteristic at the two seasons are for the most part 
distinct. In summer when the Phyto-plankton is 
practically absent, the Zoo-plankton reaches its 
pene ATS Oe TD 
