124 
a distance, and though usually well distributed through- 
out the surf there are sometimes patches where the weed 
reaches exceptional density making the water almost 
soupy. As the tide recedes, quantities of the flakes left, 
on the sand are rolled by wave action into small tubes 
which eventually collapse as they dry out. 
An examination of the flakes showed them to be 
Colpornenia simosa (Roth) Derbes and Solier. This is 
an alga which occurs commonly in the Nerang River and 
Moreton Bay, where it grows attached to rocks, oysters 
and the sea-grass Zostera marina Hooker forming irre- 
gularly rounded gas filled bladders sometimes up to 6 
inches in diameter. 
Since the species grows rarely or not at all on rocks 
exposed to the surf it seems very probable that the mater 
ial causing the nuisance, at least on the Southport and 
adjacent surfing beaches, reaches the surf via the bar of 
the Nerang River from the Nerang River estuary and the 
southern end of Moreton Bay. 
This suggestion receives added weight from the pres- 
ence on the surf beaches, during periods of heavy pollu- 
tion, of large clumps of Zosicra marina, pieces of Halo- 
phila spinulosa Bentham and other debris which could 
originate only in an estuarine locality and are not usually 
found iu such quantity on the surfing beaches. 
Another species sometimes found with the Colpo- 
menia in the siirf is Microdictyon nmbiliratnni (Velley) 
Zanardini also occurring in flakes hut differing from 
the Colpornenia in being in the form of a very fine creen 
network just discernible with the naked eve. Though 
quite common, this species is present in only negligible 
quantities compared with the Colpornenia amt It pi am* an 
insignificant part in the pollution. Like Colpornenia it, is 
a species found commonly in the Nerang River estuary 
where it is often associated with Zostera marina. 
The other species of importance in these poll-tions 
is a. green alga Enterom-orplia plumosa Kuetzing. During 
the 1952 Christmas period this was of less importance 
than Colpornenia but at times it has been known to H 
solelv responsible for very heavy pollutions. Tf occurs 
as small light green flaccid wisps 0.5-3 cm kmg. T>e 
much branched filaments are capillary throughout consist- 
ing of up to six rows of cells near the base but ending in 
a delicate tip of a single row of cells. 
Enteromorpha is a common weed on some surf-swept 
rocks on the South Queensland coast, but the species 
