On the map, zoom in and click on the dots to view underwater video at each site
Seagrass habitats within Proper Bay, Spalding Cove and around Thistle Island were dense and largely intact.
Sites at the northern end of Boston Bay and within Louth Bay are showing signs of improvement in condition compared to 2010.
Seagrass around the southern end of Boston Bay are declining in condition.
Area map
About the biounit
The Jussieu biounit extends from Cape Catastrophe including Thistle Island through to Salt Creek north of Tumby Bay (see the map). The shoreline of Jussieu is primarily orientated to the east resulting in the biounit being dominated by offshore breezes and low wave energy.
The City of Port Lincoln is the largest town on the lower Eyre Peninsula, located in the south west of the biounit and is home to approximately 15,685 people. Port Lincoln has large fishing, aquaculture and shipping industries centred around the marina and wharves. Sewage from Port Lincoln is treated at the Billy Lights Point wastewater treatment plant, which discharges nutrient rich wastewater into Proper Bay.
Parts of Port Lincoln are subject to significant stormwater flooding during high rainfall events. Poor quality stormwater enters the marine environment within Boston bay during high rainfall events.
The Tod River flows into the southern end of Louth Bay when there is sufficient rainfall. The Tod catchment is largely agricultural land where runoff can transport nutrients and sediment to the sea. EPA condition assessment shows the Tod River was in Fair condition and water quality is likely to be of poor quality when flowing to the sea.
The waters are used extensively for aquaculture, including inshore waters within Louth & Boston Bays home to Yellowtail Kingfish (Seriola lalandi) and mussels (Mytilus galloprovincialis). The deeper offshore waters are used for Southern Bluefin Tuna (Thunnus maccoyii). There are also several land based aquaculture facilities rearing abalone (Haliotis laevigata) discharging large volumes of water into the sea near Point Boston.
There are numerous embayments with shallow, warm waters which have reduced flushing with gulf waters. This is likely to result in favourable conditions for algal growth that could increase the symptoms of nutrient enrichment.
The desktop threat assessment indicated the nearshore waters in the Jussieu biounit were expected to be in Fair condition.
It is important to note that this report assessed condition of the ecosystem and that these reports do not assess the suitability or quality of waters for aquaculture food quality and fish health. For details about water quality affecting seafood quality please refer to the South Australian Seafood Quality Assurance Program (SASQAP).
In summary
Jussieu was observed to be in Good condition. Some areas had dense and intact seagrass meadows, while other areas were degraded or declining compared to the previous monitoring in 2010.
Many sites were under stress from nutrient enrichment, resulting in algal growth on the seagrass leaves (epiphytes), which if prolonged, can result in seagrass loss over time.
Findings
This program assesses the condition of habitats in waters between 2–15 m deep based on monitoring undertaken during autumn 2016. There are large areas within the biounit that are deeper than 15 m which are not included as a part of this assessment.
A total of 27 sites were monitored during autumn in 2016 to assess the condition of the biounit; 39% of habitats were seagrass, while 60% were unvegetated sand. There was only a small proportion of rocky reef (<1%) or small algae encountered.
Sites around Thistle Island and Spalding Cove maintained healthy meadows of continuous seagrass, as were found in 2010. One site at Thistle Island (m0126) showed a significant increase in seagrass cover and decrease in epiphyte load suggesting improving condition. The sites in the southernmost part of the biounit, near Thistle and Williams Islands and Memory Cove showed high phytoplankton with a pigment composition suggesting influence from nutrient rich upwelling waters originating far offshore.
Sites within Proper Bay were variable, with two sites maintaining dense and continuous seagrass, while the site east of Horse Rock (m0102) exhibited significant decrease in condition losing two thirds of the seagrass observed in 2010. All sites within Proper Bay showed high epiphyte load on seagrass and elevated phytoplankton in the water column suggesting excess nutrients.
Within Boston Bay, there was a north to south gradient in condition, with the northern sites; North Shields (m0105) increased in Posidonia spp. cover since 2010, while West Maria Point (m0107) also increased in seagrass cover and the species composition suggested recovery. The southern sites in Boston Bay showed a general pattern of decreasing condition, with reduced seagrass cover adjacent Axel Stenross (m0103), the Town Jetty (m0104), inner Boston Bay (m0106) and Billy Lights Point (m0108). This pattern was also observed inside Boston Island (m0109) and in Rotten Bay (m0110). These sites also showed elevated phytoplankton in the water column.
Louth Bay displayed a broad-scale improvement in condition with 4 of the 7 sites significantly increasing in seagrass cover compared to 2010. Additionally, Inside Bolingbroke (m0117) and outside Point Boston (m0113) both increased in Halophila spp. and Heterozostera spp. cover from less than 5% in 2010 to over 30 % in 2016, suggesting recovery from disturbance. Notwithstanding this improvement the seagrass within Louth and Peake Bays was still showing substantial symptoms of nutrient enrichment with widespread elevated epiphyte loads and high abundances of holothurians (sea cucumbers).
Broadly, sites where seagrass condition declined, there was an increase in phytoplankton. Likewise, where there has been an increase in seagrass, there was a reduction in phytoplankton, which is consistent with disturbance and recovery. Water chemistry showed that nitrogen was slightly elevated and more variable to the south of Boston Bay and within Proper Bay, when compared to Louth Bay and sites around Thistle Island.
This work demonstrates changes to the condition of nearshore habitats throughout the Jussieu biounit between 2010 and 2016. The balance in sites showing improvement compared to degradation has resulted in the biounit score remaining as good, consistent with 2010. However understanding the smaller scale drivers of change is important in the management of the system. The southern Boston Bay region is a complex mixture of many pressures, which needs more detailed scientific investigations to understand pressures impacting on condition to ensure adequate regulation and protection of the environment. The EPA is undertaking further work during 2017 and 2018 to inform management and drive changes to management of these pressures.
Pressures and management responses
Pressures
Management responses
The cumulative effect of intensive sea cage aquaculture contributes high nutrient loads into the nearshore marine waters
The PIRSA Fisheries and Aquaculture Division is responsible for the regulation of the Aquaculture industry in South Australia.
The Aquaculture (Zones–Lower Eyre Peninsula) Policy 2013 and Aquaculture (Zones–Tumby Bay) Policy 2015 limits the maximum biomass of sea cage aquaculture animals that can be grown in the zoned area and is based on a carrying capacity model to determine the suitable amount of fish for each particular region without causing adverse environmental impacts (Primary Industries and Regions SA).
When assessing an individual licence application there is also a strict set of guidelines that applies a semi-quantitative risk-based assessment, based on a nationally accredited Ecological Sustainable Development assessment framework (Fletcher et al 2004), to determine the sustainability and outcome of each individual application. PIRSA also apply guidelines to minimise environmental harm by excluding aquaculture over areas of seagrass, reef and macroalgae considered significant to local ecology.
Annual environmental monitoring program (EMP) proformas are required to be submitted by all licence holders for each licensed site for each reporting year, including all finfish sites located within the biounit. Data collected is used to adaptively manage the aquaculture industry in South Australia.
Finfish and tuna environmental monitoring programs (FEMP & TEMP) are conducted by the South Australian Research and Development Institute (SARDI). These programs involve sampling sediment adjacent to actively farmed sites and using DNA profiling to measure changes in the benthic community compared to established control sites. PIRSA Fisheries and Aquaculture, the finfish industry and SARDI determine which sites are to be sampled each year. The same group has responsibility for any follow up action that needs to occur as a consequence of poor results through the 10-point FEMP and TEMP plan of action. This sampling to date has not shown a significant difference between farmed sites and control sites within the biounit.
The EMPs for all sectors were reviewed during the development of the Aquaculture Regulations 2016 to further enhance these programs. As a result a new regional environmental monitoring program has been introduced for the Lower Eyre Peninsula region to monitor the impacts of all aquaculture activity, with the first round of sampling collected in January 2016 being currently analysed. This program is to take place over a 4-year period the monitoring is to be completed by SARDI. This monitoring program includes the dissolved nutrient outputs from the tuna and finfish industries, with results used to inform future management arrangements for these two sectors and all aquaculture activity within the biounit.
SARDI have also completed a report titled 'Carrying Capacity of Spencer Gulf: Hydrodynamic and Biogeochemical Measurement, Modelling and Performance Monitoring', which was released in 2015. This investigated the transport and fate of nutrients within this region which can be used by PIRSA to manage the location and management of sea cage aquaculture throughout the Spencer Gulf.
Nutrient loads discharged by the Port Lincoln Wastewater Treatment Plant, located at Billy Lights Point.
Until 1994, raw sewage was discharged via an outfall to Proper Bay. In 1994, SA Water commissioned the Port Lincoln Wastewater Treatment Plant (WWTP), which significantly improved the quality of the treated effluent discharged to the marine environment.
Since 2004, SA Water has further reduced nutrient loads to the marine environment by diverting a proportion of the treated effluent for reuse via the City of Port Lincoln water recycling scheme. This scheme provides water for irrigation on Council parks and reserves.
In 2014, the WWTP process aeration control was optimised to reduce the nitrogen concentration in marine discharges from the WWTP.
Tod River transports agricultural runoff with elevated nutrient and sediment loads into nearshore marine waters of Louth Bay
Eyre Peninsula NRM Board work with landholders to increase efficiency of fertiliser application; to fence off and restore riparian habitats to increase buffering capacity of riparian vegetation; and manage stock grazing pressures in riparian zones.
The Board administers the region’s Water Affecting Activity permitting program, which promotes best practice catchment management through the permitting process and ensure a minimum standard in relation to water affecting activities such as dam or watercourse crossing construction, draining or discharging water into a watercourse or excavations in a watercourse.
Fish processing facilities discharge nutrient rich effluent into the nearshore marine waters of Proper Bay
The EPA is currently working to ensure the remaining land based fish processors in the Port Lincoln region achieve compliance with the Environment Protection (Water Quality) Policy 2015 by ceasing all discharge of wastewater to the marine environment. Currently, 2 fish processors continue to discharge high salinity wastewater to the marine environment. The EPA has issued exemptions to these processors to manage this practice on a temporary basis, until a regional solution for accepting high salinity wastewater at the Port Lincoln Wastewater Treatment Plant has been determined.
The EPA is working with the industry involved, SA Water, Green Industries South Australia and the Department of Planning, Transport and Infrastructure with the aim to connect all wastewater to the local sewer network in the future.
Stormwater runoff from the Port Lincoln area, discharging nutrients and sediments to the nearshore marine waters
District Council Tumby Bay
The council completed a receiving water risk assessment as part of Stormwater Management Planning (SMP) in 2014.
Summary: Overall risks to the marine environments of the region from stormwater under existing conditions are low.
Stormwater quality improvement works are currently assessed as low priority within the SMP, and implementation in the short term will be dependent on external funding. Eyre Peninsula NRM Board are supporting Port Lincoln City Council to install water sensitive urban design infrastructure. In addition the NREP have funded and completed stormwater retention works by the Port Lincoln City Council, and actively work with the council to promote water sensitive urban design initiatives
Overflowing septic systems contribute nutrients to nearshore marine waters through shallow sub-surface or occasional overland flows.
District Council Tumby Bay
Tumby Bay Community Wastewater Management Scheme was commissioned in 1990. All township properties have been provided with approved, centralised effluent treatment and disposal.
Eyre Peninsula NRM Board
Port Lincoln City Council and District Council of Lower Eyre Peninsula to progressively connect households to sewer network where feasible.
The Jussieu biounit was in good condition. However the seagrass habitats monitored were showing the signs of excess nutrients promoting algal growth as well as loss of seagrass in some locations when compared to the previous monitoring period. Alternatively there were sties showing improvement and recolonisation from bare sand.