PLANTATION POINT OUTFALL

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Monitoring Results

Indicator Bacteria

Results from Laxton & Laxton (1987b) suggest that sites as close as 100m from the outfall satisfied faecal coliform bacterial criteria for primary contact recreation and human consumption of fish. It was not known, however, if the outfall was discharging at the times of sampling.

Biological Communities

May (1981 & 1985)

Found that sewage effluent:

  • caused a decline in the species numbers with some species (including Griffithsia monilis, Lophosiphonia reptabunda and Polysiphonia sp.) not recorded after the opening of the sewage outlet, whilst others disappeared later (Ectocarpales complex and Sphacelaria tribuloides) or were present less often (Ceramium sp.).

  • increased the abundance of other species (Amphiroa anceps, Hildenbrandia sp., Porphyra columbina, Ralfsia sp. and Ulva lactuca) or appeared during one year only (Cystophora moniliformis, Dictyota dichotoma, Petrospongium rugosum in 1977-78; Martensia elegans and Scytosiphon lomentaria in 1978-79).

Found no effect on:

  • the abundance of fifteen species over the period of the study (May 1985).

Methods:

ay (1981 & 1985) investigated the intertidal flora before and after the commissioning of the outfall.

Underwood et al (1990)

Found that sewage effluent:

  • increased the cover of encrusting coralline algae at Plantation Point compared to other locations.

  • increased the density of adult and juvenile kelp (Ecklonia radiata) at Plantation Point compared to other locations.

  • increased coverage of ephemerous filamentous algae and decreased the cover of encrusting coralline algae at Plantation Point compared to other locations.

But found no effect on:

  • the number of species of intertidal macrobenthos between Plantation Point and other locations.

  • the most abundant intertidal gastropods (Austrocochlea constricta, Bembicium nanum, Cellana tramoserica, Nerita atramentosa and Nodilittorina unifasciata) between Plantation Point and other locations.

  • the density of the barnacle Chamaesipho tasmanica among locations.

  • the number of species of subtidal macrobenthos between Plantation Point and other locations.

  • the cover of sponges or Zonaria/Lobophora (a complex of foliose macroalgae) between Plantation Point and other locations.

  • the kelp habitat between Plantation Point and other locations with the exception of the urchin Heliocidaris erythrogramma.

  • the densities of the four most abundant macroinvertebrates (Australium tentoriforme [gastropod], Brachidontis hirsutus [mussel], Centrostephanus rodgersii [urchin] and a mixture of species of sea anenomes) within the Barrens habitat between Plantation Point and the other locations.

  • the amount of bare space available at Plantation Point compared to other locations.

  • the cover of encrusting coralline algae at Plantation Point relative to the other locations within the Fringe habitat.

General findings (not necessarily related to the outfall):

  • there is small scale patchiness in the percentage cover of Chamaesipho tasmanica, but Plantation Point does not differ significantly from the other locations in the cover of barnacles in the midshore zone.

  • there are significant differences between locations in the percentage cover of foliose algae but there is no pattern to indicate that Plantation Point is different to other places in the Bay.

  • there is small scale patchiness in the percentage cover of encrusting algae but Plantation Point does not differ significantly from the other locations.

  • Heliocidaris was not found at Plantation Point, Cresswell or Honeymoon Bay [and is therefore unlikely to be an outfall effect].

Methods:

Underwood et al (1990) surveyed the intertidal and subtidal macrobenthos living on rocky substrata at Plantation Point. Rocky intertidal habitats were sampled at six locations around Jervis Bay (Plantation Point, Honeymoon Bay, Montagu Roadstead, Green Point, Cresswell and Murrays Beach). At each location, three or four zones from the top to the bottom of the shore were identified depending on topography and types of benthic organisms present. Subtidal habitats were surveyed at five sites (Plantation Point, Honeymoon Bay, Green Point, Crewel and Murrays Beach). Major habitats sampled consisted of “Fringe”, “Kelp Forest” and “Barrens”.

Underwood et al (1992)

Found that sewage effluent:

  • increased the cover of foliose algae in the Barrens habitat was Plantation Point compared to other locations.

But found no effect on:

  • any intertidal macrobenthic component

General findings (not necessarily related to the outfall):

  • More juvenile kelp plants were found at Plantation Point, but this may be due to the exposed location of Plantation Point relative to most of the other sublittoral habitats in Jervis Bay.

Methods:

Underwood et al (1992) repeated (with some modifications) their earlier (1990) studies on intertidal and subtidal macrobenthos on rocky substrata at Plantation Point.

TEL (1992)

General findings (not necessarily related to the outfall):

  • Reefs inside the Bay showed marked differences in abundance and species richness.

  • Plantation Point (along with Montague Head) often ranked low in terms of species richness and fish abundance, while Green Point (and, to a lesser extent Murray’s Point) often ranked high.

Methods:

TEL 1992 conducted two visual surveys of reef fish communities at five reefs inside the Bay and four reefs outside the Bay in October 1988 and August 1990. These studies were designed to provide baseline data in relation to a possible ocean discharge in the vicinity of Jervis Bay and prior to a possible augmentation of the Plantation Point discharge.

CSIRO (1994)

General findings (not necessarily related to the outfall):

  • No organochlorine pesticides were found in red morwong and mercury levels in red morwong were below the NHMRC maximum recommended levels (now superseded by the National Food Authority’s (Anon 1992) maximum recommended levels).

Methods:

CSIRO (1994) collected fish for a study of bioaccumulation of pesticides (in muscle tissue) and trace elements (mercury in liver tissue). Red morwong (Cheilodactylus fuscus) were collected from two sites, Green Patch and Plantation Point (ten individuals from each site).

WBM (1993a)

General findings (not necessarily related to the outfall):

  • there was considerable variation in the fish communities present at different reefs. Green Point was the richest reef (in terms of abundance and number of species), Murrays Point was the poorest reef and Plantation Point ranked moderately.

  • no organochlorine pesticides or PCBs were detected in any of the samples (both liver and muscle) analysed.

  • trace elements in fish were detected in concentrations similar to those found at unpolluted sites near Sydney.

  • with the exception of arsenic, all concentrations of trace metals were below the National Food Authority’s (NFA) standards. No conclusion could be made on the compliance of arsenic since reliable methods of determination of inorganic arsenic (on which the NFA standards are based) were not available.

  • trace elements in turban shell gastropods from sites at Plantation Point actually had lower levels of most trace elements, while Green Point and Montague Point [putative reference locations] had the highest concentrations of most trace elements.

Methods:

WBM (1993a) surveyed rocky reef communities and investigated bioaccumulation of contaminants in fish in Jervis Bay. The same five rocky reef sites surveyed by TEL (1992) were also surveyed by WBM (1993a). WBM (1993a) also investigated bioaccumulation of organochlorine pesticides and trace elements in 3 species of fish from Plantation Point and in turban shell gastropods (Astraea tentoriiformis [probably = Australium tentoriforme]) from Plantation Point and 3 reference reefs. At the time of WBM’s studies, the discharge at Plantation Point had been augmented (early 1992) with effluent from the St Georges Basin STP. Average annual discharge rates had increased from 16L/s to 32L/s and in March 1992 phosphorus stripping had been introduced to the Huskisson STP. The net result of augmentation and phosphorus stripping was to decrease the phosphorus load from the Plantation Point discharge by 60%.

WBM (1993a) also investigated contaminants in Red Morwong (Cheilodactylus fuscus), Blue Groper (Achoerodus viridis), and Rock Cale (Crinodus lophodon) from Plantation Point (3 individuals of each of the fish species).

Smith (1994)

General findings (not necessarily related to the outfall):

  • this study found no consistent difference between sites closest to the outfall and more distant sampling locations and consequently no outfall effect was suggested. These results were judged to indicate that natural environmental factors were more influential than low-volume tertiary treated effluent from the outfall in determining patterns of community structure in the holdfast community within Jervis Bay.

Methods:

Smith (1994) looked at kelp holdfast communities near Plantation Point outfall. Differences in faunistic patterns at 6 sites (3 close to the outfall and 3 control sites) were investigated in the winters of 1990 and 1991.

Outfall Site

Sea Urchin

Faecal Coliform

Red Morwong

Limpets

Kelp

Ulva

Plantation Pt. 

  

(Plan_7) Last updated June 2000