58 
J. M. Thomson.. 
Algae. 
The dominant species of algae in the estuary are: — 
Cystophyllnm muricatnm Enteromorpha compressa 
Chaetomorplia aera Ectocarpus confervoides 
Cladophora penicillata Viva lactuca 
Besides these, others occur, usually as isolated clumps amongst the others 
and may sometimes have been included amongst collections. (For example, 
other species of Enteromorpha may have been included amongst E. com- 
pressa.) These secondary species include: — 
Asperococcus sp. 
Calothamnium sp. 
Enteromorpha prolifera. 
Enteromorp h a i ntest i n al is 
Enter o morph a claphrata 
Enteromorpha plum osa 
Chaeto m o rp ha n i t i d u 1 a 
C a id erp a cy lin dr ace a 
Gracilaria confervoides 
M o n o sp o ra austra l is 
Polysiphonia mollis 
Zoobotrium pelucides 
Some of these are abundant elsewhere in the estuary (G. confervoides) but 
do not occur in quantity in the area investigated. 
Diatoms. 
Some colonial diatoms were present on the algae throughout the year. 
Three periods of particular abundance were noted. These occurred in 
March, May and October. From the nature of their surfaces Cystophyllnm 
and Cladophora provided the best substratum for these, while Viva was 
practically free from diatoms. From May to late July diatoms were fairly 
abundant but were very scarce in August and September. 
No identification was attempted beyond the genus. The following are 
the genera present at the three peak periods. Except from May to July 
the amount of diatoms rather rapidly fell away from the peak. 
March. 
May. 
October. 
Frustulia ( Navicula ) 
Coscinodiscus 
Synedra 
Fleur o sigma 
Bhizosolenia 
Bacillaria 
G animat oph ora 
Gam mat oph ora 
Melosira 
Lycmophora 
Melosira 
Melosira 
N it z s chia 
Striatella 
Lycmophora 
Aster ionella (?) 
The genera are listed in order of relative abundance. It is notable that the 
October increase was due almost entirely to Synedra. By November Bacil - 
laria and Melosira had disappeared and Coscinodiscus was sparingly present. 
