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Monitoring Results
Indicator Bacteria
Faecal
coliform results indicated that the disinfection had been successful in
ensuring that levels were well below NHMRC guidelines for recreational use at
the two locations on Racecourse Beach that were tested and are regularly used
for bathing.
Biological Studies
Found that
sewage effluent:
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Changed the
number of species of intertidal flora at the outfall (some increased some
decreased). Of the 31 species
recorded in 1974, nine (Centroceras
clavulatum, Cladophora repens, Codium cuneatum, Griffithsia monilis,
Helminthocladia dotyi, Jania sp., Padina
fraseri, Plocamium cartilagineum
and Rhodymenia australis) did
not occur after the commissioning of the outfall. A further three species
(Ceramium sp., Nemalion multifidum and Phyllospora
comosa) of the original 31 were not recorded after the 1975-76 period.
Splachnidium rugosum was present
less often during the later years. Two
species (Bangia fuscopurpurea
and Enteromorpha intestinalis)
appeared soon after the sewage outfall was commissioned and remained
throughout the period of study. Chaetomorpha
aerea appeared later. Some species (e.g. Calothrix
crustacea, Dictyota dichotoma and Lophosiphonia
reptabunda) appeared in only one year. Eighteen species occurred
throughout the study period: 12 of these showed no obvious change in
abundance, while four (Enderachne
binghamiae, Laurencia brongniartii, L. filiformis and Sargassum
lophocarpum) decreased in abundance; and two (Ralfsia
sp. and Porphyra
columbina) increased in abundance. Ulva
lactuca was common on much of the headland prior to the installation
of the outlet and retained its position near the outlet pipe throughout
the period of study. Gelidium
pusillum did not appear until October 1978, but by June 1979 was the
dominant plant nearest the outfall.
Methods
May
investigated the intertidal floras before and after the commissioning of the
outfall in September 1975.
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