pitt water A report to the community

A remarkable estuary under pressure

Bar-tailed godwit. Photo: Alan Fletcher This Report to the Community seeks to highlight the values and condition of the estuary, improvement works being undertaken and further actions required. While this remarkable estuary is under pressure, there are many things that can be done to ensure this natural asset continues to be enjoyed by future generations.

A haven for marine life Pitt Water - Orielton Lagoon Pitt Water and Orielton Lagoon are part of one Ramsar Site large shallow estuary, sheltered from the SCALE 1:100 000 ocean by the Seven Mile Beach spit. 5 Coal 0 kilometres More than 40 fish species are drawn to Orielton N the sheltered waters to feed on seagrass, TASMAN invertebrates and other fish. Fish frequently RICHMOND River

seen include gummy shark, eagle ray, silverfish, Frogmore Rivulet Rivulet BRINKTOP sand flathead, whiting, flounder, Australian

salmon and mullet. There are also eel, school HWY

Creek shark, seahorse, pipefish, sculptured sea moth, Duckhole RD king barracouta and silver trevally. Sorell Iron Samphire Creek Island

Rivulet

PENNA SORELL PENNA Conservation Area RD ARTHUR A rich source of food Orielton attracting birds from far away Lagoon RD HWY Seven or more speciesBelbin Rivulet of migratory birds fly from HWM Susie Islet SHARK as far away as Alaska to feed on the mudflats of Pitt Shellfish POINT Point Water and Orielton Lagoon during summer. PITT WATER MIDWAY PT

COLEBROOK The eastern curlew, which breeds in Russia and north- Woody Pittwater Island Bluff eastern China, is the largest migratoryRivulet wader to visitRD Barren Island (included in Australia. It has a long curved bill to find crabs and Nature Reserve)

other animals living in the mudflats. Barilla Bay Beach ROAD Cross Rivulet Mile LEWISHAM The estuary is the southern-most site on the East Asia Five – Australasian Flyway, a major international waterbird Barilla HWY migration corridor. CAMBRIDGE Airport Beach Mile TASMAN DODGES ACTON Seven FERRY

FREDERICK HENRY BAY

ROAD

NOTE: All boundaries follow property boundaries unless on otherwise shown. Pitt Water – Orielt A place people love to be Lagoon Nature Reserve For tens of thousands of years the estuary was the Places to view birds territory of the Moomairremener band of the Oyster Ramsar Site Bay Tribe. Other Aboriginal bands of the Big River 1 Shark Point Road, Penna tribe visited the area to harvest the rich resources. 2 Forcett Street, Sorell There are numerous middens of native oyster shells, artefacts and quarries throughout the Lagoon area. 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell Today, people enjoy fishing on the southern side of McGees Bridge and bird watching at Sorell Causeway, Forcett Street and Waterview Sanctuary. A home for unique animals Parvulastra vivipara is one of very few seastars in the world that give birth to live young. The tiny orange animal is found at only five places in south-east Pitt Water - Orielton Lagoon . Pitt Water has the largest population. Ramsar Site A rare butterfly lives in the saltmarshes – the saltbush blue or chequered blue butterfly. The larvae feed on SCALE 1:100 000 5 Rhagodia and similar saltmarsh plants in the upper Coal 0 kilometres zones of saltmarshes. Orielton N TASMAN

RICHMOND

River

Frogmore Rivulet Rivulet BRINKTOP Pitt Water - Orielton Lagoon

PittHWY Water - Orielton Lagoon Ramsar SitePitt Water - Orielton Lagoon RamsarCreek Site Duckhole SCALE 1:100Ramsar 000 5Site RD A3 5 Sorell A3 SCALE 1:100 000 Samphire Iron Creek 0 SCALE 1:100 000 5 Island A3 0 N Coal kilometres Rivulet 0 A hot spot for saltmarshN diversity PENNA Coal Orielton kilometres TASMAN Orielton N Coal kilometres SORELL TASMAN The region is one of the most significant areas C351 PENNA Conservation Orielton C351Area TASMAN of saltmarsh in Tasmania, with a great diversity RD BRINKTOP ARTHUR

C351 of plants including 10 rare species. RICHMOND Rivulet River Orielton BRINKTOP

Rivulet RICHMOND Lagoon Rivulet Frogmore River

B31 Rivulet Saltmarshes provide roosting and foraging RICHMOND Rivulet RD B31 River Frogmore HWY Rivulet habitats for birds and small animals. They also Belbin Rivulet B31 Frogmore HWY HWM Creek RD Susie Islet HWY help maintain the water quality by taking up SHARK Creek Shellfish POINT HWY nutrients and trapping sediment from waterPoint PITT WATER MIDWAY PT RD Creek BRINKTOP flowing into the estuary. Sorell COLEBROOK Duckhole Woody Iron Pittwater PENNA Sorell Island Bluff Iron

RD Duckhole Rivulet Barren Island Sorell Duckhole Creek Iron Samphire (included in CreekPENNA SamphireNature Reserve) Island Creek Island Barilla Bay RD Samphire Rivulet Beach ROAD RD Cross Rivulet IslandMile LEWISHAM Rivulet SORELL Five A9 RD Rivulet Conservation SORELL Barilla PENNA ARTHUR A9 Area Conservation SORELL ARTHUR HWY Hobart PENNA Area A9 Airport Conservation ARTHUR

PENNA CAMBRIDGE Beach RD PENNA Area Mile Orielton Lagoon RD Orielton TASMAN DODGES LagoonOrieltonHWY ACTON Seven FERRY HWY RD SHARK Lagoon POINT A nursery for commercial fish speciesHWY Shellfish Belbin Rivulet HWM Point FREDERICKSHARK HENRY HWM Susie Islet POINT The estuary is a key breeding area for several shark Belbin Rivulet BAY SusieRD Islet HWM Susiespecies Islet and a nursery for juvenile sharks, including COLEBROOK MIDWAY PT RD RD Belbin Rivulet MIDWAY PT Pittwater ROAD PITT WATER commercially harvested school shark and gummy COLEBROOK Bluff PITT RAMSAR WATERWoody site boundary MIDWAYshark. PT In 1995 Pitt Water was declared a shark refuge NOTE: All boundaries follow PITT WATERIsland Woody property boundaries unless Rivulet Barren Island and is aIsland no-takeWoody area. SHARK LEWISHAM POINT otherwise shown. Barren Island Island (included inCurrent oyster leases Rivulet Barren IslandThere are Pacific oyster farms at several locations: Nature Reserve) (included in LEWISHAM ROAD Beach RD NatureMile NatureReserve reserves Nature (includedReserve)near in Shark Point, Barilla Bay, and south and east of Rivulet Nature Reserve) COLEBROOK Places to view birds ROAD Five Woody Island.Beach Cross Barilla Bay Mile Beach Ramsar Site C334Mile B31 Rivulet BarillaGreat Bay birdwatching sites 1 Shark Point Road, Penna Barilla Bay Five C334 Cross B31 Rivulet Five C334 Rivulet A3 B31 ForcettLEWISHAM Barilla Street, Sorell Hobart Cross 2 A3 HWY BarillaAirport Hobart A3 Airport Beach 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell Barilla HWY Beach Hobart ROAD CAMBRIDGE ACTON AnHWY internationally recognisedAirport Ramsar site Mile CAMBRIDGE Mile DODGES Beach CAMBRIDGE ACTON FERRY DODGES The many values of the estuary were recognised in 1982 when much of the area FERRYDODGES TASMAN was listed as a wetland of international importance underMile the Ramsar Convention Seven FERRY TASMAN Seven TASMAN on Wetlands. The Nature Reserve protects key areas in the Ramsar site. FREDERICK HENRY Seven BAY FREDERICK HENRY ROAD FREDERICKBAY HENRY ACTON ROAD BAY

C330 C330 C330

ROAD NOTE: All boundaries follow property boundaries unless Nature Reserve otherwise shown. Nature Reserve Nature Reserve Ramsar Site Places to view birds Ramsar Site Places to view birds Ramsar Site 1 Shark Point Road, Penna Places to view birds 1 Shark Point Road, Penna 1 Shark Point Road, Penna 2 Forcett Street, Sorell 2 Forcett Street, Sorell 2 Forcett Street, Sorell 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell The condition of the estuary

Animal and plant populations vary naturally in tidal influence by levees. Nutrients from fertilisers response to changing climate and environment, but draining into the saltmarsh stimulate algal growth that at Pitt Water-Orielton Lagoon human activity near smothers the plants. Dams and reservoirs reduce the the estuary and its catchment are the main drivers of flow of freshwater and sediment into the saltmarsh. change. There are gaps in the data available and there In many areas the dominant plants have changed or are few long term records, but the overall trend of died largely due to climate change and sea level rise, declining condition is clear. Over the past few decades leaving bare ground. wildlife numbers have declined, key vegetation species have receded, and water quality has deteriorated. Fortunately, saltmarsh is returning to Orielton Lagoon following modification of the causeway to allow for tidal The area and condition of flushing, and reduced pressure from fire and grazing. saltmarsh has decreased Since 1975, 5% of the saltmarsh has been lost due to erosion resulting from sea level rise, and 18% was lost because of habitat modification and land reclamation. Nearby agricultural activity has affected the health of the saltmarsh. Large areas have been cut off from

e. a. b. d. c.

a. Round-leaved pigface b. Selliera & trailing hemichora c. Saltmarsh d. Red-necked stints feeding on the saltmarsh e. Harlequin bug on saltbush

Photos: Vishnu Prahalad % saltmarsh loss due to changes in 18 habitat and land use

% saltmarsh loss 5due to sea level rise Pitt Water - Orielton Lagoon Ramsar Site

Coal SCALE 1:100 000 0 5

Orielton kilometres TASMAN BRINKTOP RICHMOND N

River The area of seagrass has decreased Frogmore Rivulet

Aerial photography indicates that in 1970 substantial mapping by SEAMAP TasmaniaRivulet in 2005 found RD areas of seagrass were found on the northern and only small patchy areas of seagrass north of

HWY Duckholesouthern side of the causeways. Marine habitat the causeways.

Creek PENNA

Sorell Creek Rivulet Iron

RD

PENNA SORELL

RD

ARTHUR

Belbin Rivulet Orielton SHARK Lagoon POINT

COLEBROOK HWY PITT WATER Pitt Water - OrieltonMIDWAY Lagoon PT Rivulet RD Shellfish Ramsar Site Point ROAD Pittwater Cross Bluff Coal

LEWISHAM SCALE 1:100 000 Barilla Bay Rivulet 0 5

Orielton Mile Beach Barilla kilometres FiveTASMAN BRINKTOP CAMBRIDGERICHMOND HWY N

River Hobart ACTON Airport Beach Frogmore TASMAN RivuletMile

Rivulet RD Seagrass distribution in Pitt Water Orielton Lagoon in 1970. Seven HWY DODGES Duckhole 1970 seagrass FERRY

ROAD

FREDERICK HENRY Creek PENNA

BAY Sorell Creek Rivulet Iron

RD

PENNA SORELL

RD

ARTHUR

Belbin Rivulet Orielton SHARK Places to view birds Lagoon Nature Reserve POINT 1 Shark Point Road, Penna COLEBROOK Ramsar Site HWY 2 Forcett Street, SorellPITT WATER MIDWAY PT Rivulet RD 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell Shellfish Point ROAD Pittwater Cross Bluff LEWISHAM Barilla Bay Rivulet Mile Beach Barilla Five CAMBRIDGE HWY Hobart ACTON Airport Beach TASMAN Mile

2005 Seagrass distribution. Seven 2005 seagrassDODGES FERRY Sources: Rees 1996 and SEAMAP 2005 Tasmania. ROAD

Places to view birds Nature Reserve 1 Shark Point Road, Penna Ramsar Site 2 Forcett Street, Sorell 3 ‘Waterview’ Bird Santuary, Stores Lane, Sorell a. Caption here b. Caption goes here c. Caption here also

Migratory bird populations are decreasing Migratory birds are decreasing due to habitat loss along the international flyway and reduced breeding or survival of young birds. As a consequence the numbers of curlew sandpiper, eastern curlew, Pacific golden plover and double-banded plover reaching Pitt Water-Orielton Lagoon have decreased significantly since 1965. Since Pitt Water-Orielton Lagoon is an important link in the flyway, protecting it is crucial.

Eastern curlew numbers Right: Eastern curlew Photo: Alan Fletcher 250

200

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100

50

2008

2003

1998

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0 1973 Source: Birds Tasmania Birds Source:

Seastar numbers are decreasing Fish numbers appear to be decreasing The range of the live-bearing seastar has contracted While there have been no scientific studies of fish and the numbers at each site are decreasing. numbers in the estuary, there is information that suggests that the diversity and abundance of fish are Introduced species are invading decreasing. Non-native marine species such as the northern Pacific Passionate amateur naturalist and long-time resident seastar, the European shore crab, a toxic dinoflagellate of Midway Point Geoff Prestedge has noted that microalgae and some feral populations of Pacific oyster since 1975 almost all fish species have declined in have become established in the estuary. number. The banded stingaree, southern conger Kelp gulls from New Zealand and domestic ducks eel, shot-headed eel, rock ling, pipefish, soldier fish, compete for resources with native birds. Rabbits graze rock flathead, king barracouta, weedfish and smooth the saltmarsh and other coastal vegetation. Cats toadfish used to be abundant, but by 1995 were rare and dogs chase and attack birds and stock trample or not seen at all. Mr Prestedge has also observed vegetation and nests if they aren’t carefully managed. significant decreases in the abundance of a wide range of invertebrates (snails, worms, molluscs) over the Weeds such as African boxthorn and boneseed have same time period. invaded the foreshore, particularly on the northern shore between Penna and Iron Creek.

a. b. c.

a. Endemic and vulnerable Live-bearing seastar Parvulastra vivipara. Photo: G Edgar b. Wader flock. Photo: Alan Fletcher c. Saltmarsh trampled by stock. Photo: Helen Dunn Water quality and algal blooms Not so long ago there were frequent, smelly algal blooms in Orielton Lagoon. This problem was substantially alleviated when Sorell Council reduced nutrient loads flowing into the lagoon. The Midway Point sewage treatment plant was upgraded in 1992 and in 2007 effluent was diverted from the lagoon to irrigation in the Penna Reuse Scheme. In 1998 the culverts in Sorell Causeway were modified to improve tidal flows in and out of the lagoon. A study in 2005 demonstrated that the numbers and diversity of small crustaceans and worms had increased significantly, however algal blooms and occasional odours still occur in Orielton Lagoon and near Five Mile Beach, probably in response to high levels of nutrients. The oyster industry has monitored bacteria, salinity, temperature and rainfall at marine farm sites throughout the estuary since 2004. Their data show that water quality is generally good, except that faecal bacteria levels can increase after rainfall (in which case there is no harvesting). NRM South commissioned the Tasmanian Aquaculture and Fisheries Institute to monitor a broader range of parameters in five estuaries for one year. The data showed good levels of dissolved oxygen and moderate levels of turbidity, however nutrient levels were of concern. High nutrient levels can stimulate the growth of algae and algal blooms that can smother plants, consume oxygen in the water, smell and sometimes release toxins. Phosphorus levels were frequently well above threshold levels. Nitrate and nitrite levels were generally low, except for one peak considerably above the expected threshold for this type of estuary. Filamentous algae smothering saltmarsh shrubs, Coal River. Photo: Vishnu Prahalad

Good news for resident birds Birds Tasmania volunteers have been recording resident and migratory bird numbers in the estuary for decades. Thanks to their hard work we know that the numbers of pied oystercatchers, red-capped plovers and masked lapwing vary naturally among seasons, but overall have not changed significantly since 1979. Resident birds move among the estuary and other nearby sites including Pipe Clay

Lagoon, Clear Lagoon and Marion Bay depending on food resources and conditions. Pied oystercatcher numbers

250

200

Above: Pied oystercatcher 150 Photo: Alan Fletcher

100

50

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1978 1983

0 1988

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2003 2008

Source: Birds Tasmania What has caused the decline in condition?

Sediment flowing into the estuary has increased Clearing for agricultural activity in the catchment and stormwater flow in urban areas has resulted in more sediment flowing into the estuary. The upper reaches are now far shallower than they were. In the 1830s George Wray regularly sailed a 26 ton sloop called Richmond Packet between the Richmond wharf and Hobart transporting grain and other cargo. Sediment Dam construction may have contributed to the decline of seagrass by reduces fresh water flows smothering it, reducing photosynthesis. Sedimentary Craigebourne dam and other smaller farm soils near the estuary are prone to erosion, particularly dams store winter flows for summer irrigation, those on Permian mudstone or Triassic sandstone. altering the timing and size of peak flows. The causeways have altered tidal flow Almost every major creek draining into the saltmarshes has been dammed, which reduces Tidal flow into Orielton Lagoon is restricted by the frequency and volume of winter floods. Sorell Causeway, reducing flushing of nutrients and No scientific study has assessed the impacts, sediments. Incoming tides are channelled under although dams are thought to be contributing McGees Bridge into Upper Pitt Water. The Midway to the decline of saltmarsh plants, changing Point causeway alters flow into upper Pitt Water. reproduction or migration of fish such as whitebait, and accumulation of sediment in the estuary due to less frequent freshwater flushes. Urban development and agricultural activity have increased nutrient and bacteria levels Urban sources of nutrients and bacteria include stormwater and effluent from leaking septic tanks and sewage treatment plants. Nutrients can be washed out of soils cleared for pasture and crops, especially where fertiliser is applied. Soil erosion in the catchment has been linked to high phosphorus loads. People, pets and stock damage vegetation and disturb breeding birds Birds nesting on the foreshore are easily disturbed by vehicles or even people walking close to their nests; cats and dogs chase and attack birds. Walking, cycling and stock trampling can cause sustained damage to saltmarsh and other coastal vegetation. Rubbish dumping is a hazard for wildlife.

Top: Double-banded plover. Photo: Alan Fletcher a. b. a. Common greenshank. Photo: Alan Fletcher b. Building fences helps to protect saltmarsh. Photo: Andry Sculpthorpe a. Midway Point. Photo: Sorell Council b. Eroding banks at Coal River. a. Photo: Barry Hardwick c. African boxthorn invading saltmarsh. f. Photo: Andry Sculthorpe b. d. Southern Beaches Coastcare members working c. d. e. to revegetate Spectacle Islands. Photo: Gwen Egg e. Aboriginal Midden. Photo: Andry Sculthorpe f. Sorell Creek flows into Lower Pitt Water. Photo: Vishnu Prahalad Working together to a. Birds Tasmania helps students with observations. Photo: improve the condition of Andry Sculpthorpe Pitt Water-Orielton Lagoon b. Sorell Primary School a. b. working to revegetate and control weeds. Photo: Moya Sharpe The good news is that there are signs of improvement Best practice agriculture in the condition of the estuary. Recent actions have • The Coal River Products Association has been been funded by the Australian Government’s Caring trialling best practice agriculture techniques to for our Country initiative. improve soil and pasture management. Protecting shorebirds • NRM South runs sustainable farming workshops for • NRM South, Parks and Wildlife Service, Sorell Council landholders in the area.* and Birds Tasmania have built fences, controlled weeds and installed signs to protect shorebirds. Stormwater management and sewage treatment Restoring habitat • Sorell Council has installed stormwater treatment • NRM South, Sorell Council and Parks and Wildlife devices at Midway Point. NRM South and Sorell Service, Conservation Volunteers Australia and the Council have constructed a stormwater swale community have been protecting saltmarsh and at Forcett Street and prepared a Stormwater removing weeds from the foreshore.* Management Strategy.* • The Coal River Products Association has been • Southern Water is considering options to improve removing willows and African boxthorn, planting native the Sorell, Midway Point and Cambridge sewage species and building fences to protect banks and treatment plants to improve effluent quality and reduce erosion in the Coal River and the upper estuary. increase the use of effluent for irrigation. • Southern Beaches Landcare/Coastcare members Research and planning have been active, improving beach access to minimise impact on dunes, controlling weeds and • The Parks and Wildlife Service has updated the planting native species at many sites around Dodges management plan for the Pitt Water Nature Reserve. Ferry including Spectacle Islands, Red Ochre Beach, • A scientific report describing the ecological Blue Lagoon, Carlton Bluff, Samuel Thorne Reserve character of the Ramsar site has been prepared by and Jacks Flat. the Minister for Sustainability, Environment, Water, • Students from Sorell Primary School have been Populations and Communities. controlling weeds and planting native species at • NRM South prepared a Foreshore Action Plan that Waterview Sanctuary, Blue Lagoon and Park Beach. identifies key actions to protect bird nesting and * • Penna Landcare Group has been controlling African rookery sites, saltmarsh and coastal vegetation. boxthorn and boneseed in the Penna area. * Denotes projects funded by the Caring for our Country initiative. • Clarence Council plans to remove willows from Barilla Rivulet. More action is needed

Although some changes to the estuary are now • Watch birds from a safe distance (at least 50m). irreversible, there is plenty we can do to protect the Use binoculars and keep to the designated tracks. remaining values and improve the overall condition • Walk dogs on-leash so they don’t disturb birds. of the estuary. Government, community, industry and researchers each have a role to play. Here are • De-sex cats and keep them in at night. some key actions we can undertake that can make • Record and report algal blooms. a difference. • Protect coastal vegetation, reduce erosion and • Manage irrigation and other water use to minimise control invasive weeds diversion of surface water flows from the estuary. • Join a coastcare or landcare group. • Improve the performance of sewage treatment plants and septic tanks to minimise nutrients and We need to know more faecal bacteria entering the estuary. Monitoring and research is required to better • Improve the design of urban environment and understand the hydrology, sedimentation processes, stormwater treatment systems to reduce sediment water quality of the estuary and changing numbers of and nutrients flowing into the estuary in stormwater. animals and plants. • Improve pasture management and control the application of fertiliser to reduce nutrients and sediment flowing into the estuary. How you can get involved • Allow for the natural movement of saltmarsh on the If you can help out please contact NRM South landward edges in response to sea level rise. on 6221 6111 or Sorell Council on 6269 0000.

a. Pacific Golden Plover. Photo: Alan Fletcher. b. Orielton Lagoon is right on Hobart’s doorstep. Photo: Stuart Pengally c. Sorell Primary School work with Conservation Volunteers. a. b. d. Photo: Andry Sculpthorpe c. d. Conservation Volunteers clear Boxthorn from the shores of Orielton Lagoon. Photo: Andry Sculpthorpe For more information: Acknowledgements:

• The Parks and Wildlife Service management plan This report was prepared by NRM South with support for the Pitt Water Nature Reserve is available from the Australian Government’s Caring for Our at www.parks.tas.gov.au Country Initiative. • To learn more about the birds in the Pitt Water- A key reference for this report is the Pitt Water- Orielton Lagoon, contact Birds Tasmania Orielton Lagoon Ecological Character Description [email protected] prepared by Dr Helen Dunn for the Department of Sustainability, Environment, Water, Population • Contact NRM South: www.nrmsouth.org.au and Communities. or phone 6221 6111

Below: Glasswort herb, flowering. Photo: Vishnu Prahalad