FIRST POINT OUTFALL

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Monitoring Results

Indicator Bacteria

Extensive monitoring of faecal coliform bacteria in the receiving waters has been undertaken at the outlet and at adjacent beaches (MHL769 1997, MHL533 1988). The influence of the discharge at First Point could not be detected at any of the adjacent beaches (MHL533 1988). Guidelines for primary contact recreation and protection of human consumers of seafood are satisfied within 200 meters of the outfall.

Biological Communities

General findings (not necessarily related to outfall):

comparisons between sites were undertaken, but these largely represented comparisons between ‘control’ sites and few differences were found.

Methods:

Laurie, Montgomerie & Pettit (1977d) investigated phytoplankton (chlorophyll-a concentrations only - off Boulder Bay, Burwood Beach, Belmont Beach and First Point); zooplankton (off Boulder Bay, Burwood Beach, Belmont Beach and First Point); rocky bottom benthos (First Point, Little Beach Burwood Beach and Boulder Bay); rocky shore ecology (First Point, Little Cove and Little Beach); Soft bottom benthos (Belmont Beach, Burwood Beach, Stockton Beach, Dudley Beach, Merewether Beach, McMasters Beach and Avoca Beach); sandy beach fauna (Belmont Beach, Burwood Beach, Dudley Beach, McMasters Beach and Avoca Beach); fish communities (using otter trawls – Burwood Beach, Belmont Beach and McMasters Beach); and contaminants in fish (McMasters Beach and First Point).

General findings (not necessarily related to outfall):

• The benthic component of rocky bottom communities at all sites were found to be very similar.

• the rocky bottom community at Little Cove was dominated by algae.

• sponges and other sedentary animals occupied only a minor proportion of the substrate at one site (in 19m water depth).

• On vertical underwater surfaces the algae lived in three distinct zones -the upper most zone was the red algal zone characterized by Pterocladia capillacea; below this zone was an area inhabited by a variety of turfing and encrusting algae; Lithothamnion pavement formed the third and lowest zone.

• Vertical underwater faces in partial or full shade were colonized by a mixture of algae and sedentary animals.

• The percentage cover of sedentary animals increased as the light intensity decreased.

• On horizontal rocky bottoms three assemblages of algae occurred; kelp (Ecklonia radiata) forest; the assemblage of turfing algae and Lithothamnion pavement.

• Seasonal changes were observed on both vertical and horizontal rocky surfaces - the Pterocladia capillacea zone (vertical rock faces) was affected by sun or wind burn during low tide and by swell action; Ecklonia radiata forest and the assemblage of turfing algae (horizontal rocky bottoms) were affected by storm action. 

Methods:

Laxton and Laxton (1978) investigated the effects of the discharge of treated effluent from Wonga Point [see Wonga Point outfall] on the physical and biological environment. Comparisons of the benthic component of rocky bottom communities living at Wonga Point, Crackneck Point and Little Cove (First Point – prior to outfall commissioning) were undertaken using photo-quadrats.  

Laxton and Laxton (1980b) reported specifically on the rocky bottom benthic component within Little Cove. Sampling for this study, again using photo-quadrats, was carried out during February and September 1978, February 1979 and February 1980.

 Found that sewage effluent:

• increased in volume substantially in 1986

• in January, March and April 1987 small white floating particles were present in the outfall zone

• in 1987-88 effluent appeared to be severely reducing light intensity on the vertical cliff face and seabed adjacent to the outfall.

• was linked to an assemblage of filter feeding organisms developing in competition with the algae on vertical rock faces adjacent to the outfall; by 1987, these filter feeders had taken over most of the space on the construction damaged rock face adjacent to the outfall (due to presence of nutritious suspended solids in the effluent providing particulate food and by reduced light intensity at the rock face) .

• was linked to minor changes in community structure on vertical rock faces away from the outfall - the occasional inclusion of Pyura gibbosa in algal assemblages (particularly at one site approximately 200m from the outfall) and possibly increased growth of encrusting sponges.

• Overall had a limited effect on the structure of the rocky bottom benthic community. (They suggested that this effect was confined to a 10 m wide by 5 m deep section of the vertical rock face surrounding the outlet structure).

• Lincoln-Smith and Langtry (1989 –part of Laxton & Laxton 1989b) provided a statistical analysis of this rocky bottom data concluding that no effect of the outfall could be demonstrated beyond the immediate area of the discharge point and possibly at one shallow depth site.

General Findings (not necessarily related to the outfall):

• between 1982 and 1988 there were great changes in the composition and area occupied by the three algal assemblages - on horizontal rocky surfaces no change attributable to the operation of the outfall or to the discharge of effluent were detected.

Methods:

Laxton and Laxton 1989b continued studies of the sub-tidal rocky bottom communities in Little Cove.

Found that sewage effluent:

• severely reduced light intensity on the vertical cliff face and seabed adjacent to the outfall during 1987-1988.

• caused changes on the vertical cliff face close to the outfall, with a gradual increase in the cover of fauna and flora occurring on the rock surface (1997 - short turfing coralline algae and ascidians covered all of the underwater rock face);

But found no effect on:

• light intensity in these areas was back to normal in 1989 and remained high over the period 1991 to 1997

• community structure the vertical rock faces in Little Cove between 1991-1997 (away from the immediate area of the outfall) were similar to those found at the control sites at Second Point (McMasters Beach). Algal communities were particularly rich between 1993 and 1997.

Methods:

Binnie and Partners (1990) largely reiterated the findings of previous studies (both physical and biological) cited above. Laxton and Laxton (1994, 1995, 1996 and 1997) continued annual monitoring studies of the rocky bottom benthos in Little Cove. The sampling strategy for the 1991 and subsequent years surveys involved sampling at both outfall and control sites (only one control location at Second Point was used). Experimental stations at the outfall and control site were selected on the basis of similarity in topography, aspect, depth, and exposure to light and wave attack.

Found that sewage effluent:

• had a significant effect on sponges with outfall locations had a significantly greater species richness of sponge types than control locations.

But found no effect on:

• cover or numbers of individual sponges, including the two most common species Psammopemma sp. and Tedania sp.

General findings (not necessarily related to outfalls):

• no differences were found between the outfall and control sites for the diversity or abundance of kelp, algal or faunal assemblages.

Methods:

Roberts and Scanes (in press) investigated the macrobenthic assemblages living on hard substrata in shallow water kelp forests. The macrobenthic assemblages were sampled at six locations (Norah Head, North Avoca, Winnie Bay, Bangalley Head, Warriewood and Cape Banks), three of which (Norah Head, Winnie Bay and Warriewood) have ocean outfalls and the other three sites treated as controls. At each location two randomly selected sites were sampled in approximately 6-10m water depth. At each site SCUBA divers estimated abundance of macrobenthos by recording the number and percentage cover of organisms (using the point-intersect method) in 5 randomly placed quadrats (27cm²).

General findings (not necessarily related to outfall):

high proportions of green and opportunistic algae and low abundance of red and brown algae were found on settling plates at both outfall and control sites.

Methods:

McNeill (1993) investigated the recruitment of algae and invertebrates to settlement plates at three outfall (Norah Head, Weenie Bay (First Point) and Warriewood) and three control (North Avoca, Bangalley and Cape Banks) sites. Settlement plates were made of sandstone (15 cm X 15 cm X 1cm thick) and were deployed in  March 1993. Settlement plates were retrieved 12 weeks later and the percentage cover of species of algae and species and major groups of sessile invertebrates was estimated using a 100 point grid on the upper surface of the settlement plate.

Found no effect on:

• body condition, wet weight, percentage dry weight, lipid dry weight or mortality of oysters at Norah Head, Warriewood and Winnie Bay outfalls.

• trace metal levels in oysters with respect to outfall and control sites with the exception of selenium

• extractable organic halogens (EOX) in oysters between outfall and control sites.

• organochlorine pesticides in oysters deployed at the outfall sites.

General findings (not necessarily related to outfalls):

• the selenium levels found at the outfall sites were found to be similar to other EPA oyster studies and these putative outfall effects require further analysis.

Methods:

Transplanted Sydney rock oysters (Saccostrea commercialis) were also deployed at the same sites as those described by McNeill (1993).

Outfall Site

Faecal Coliform

Outfall

First Point

(Firs_7) Last updated June 2000