Transcript Oxley Creek
MONIT ORING PROG RA M How Healthy is Moreton Bay, and its Rivers and Creeks? Adrian Jones & Ivan Holland Angela Grice, Francis Pantus, Dan Wruck & Bill Dennison CRC for Coastal Zone Estuary & Waterway Management Outline • Background • Pressures • Impacts • Response • Ecosystem Health Monitoring • Oxley Creek • Health of the rivers • Health of Moreton Bay Bribie Island Caboolture River Pine River Moreton Island Redcliffe Brisbane River Oxley Creek Moreton Bay North Stradbroke Island Logan River • Moreton region has 2 million people and is the fastest growing region in the country • Moreton Bay receives input from Brisbane, Logan, Caboolture and Pine Rivers • The Brisbane River has the - largest catchment of all regions - highest population density - highest sewage inputs Rivers and Bay are important to us … Trawling Fishing at Luggage Pt Outfall Waterskiing Swimming Port of Brisbane … and everyone else! Population Growth is a major pressure Population expansion in the region over the past half century is one of the most rapid in the world and provides one of the major pressures to ecosystem health Sewage discharges concentrated in Brisbane River & Bramble Bay • Largest sewage discharge = Luggage Pt. at mouth of Brisbane R. • Oxley Creek = second largest • 3 significant discharges into Bramble Bay and Hayes Inlet from Pine Rivers, Redcliffe and Brisbane City • Multiple minor discharges scattered throughout tidal reaches Land area 000’s ha 300 200 land-use 100 1860 Fertilizer 000’s t yr-1 Increasing Sown pasture Cropped land 20 15 1900 1940 1980 and fertilizer N P K application 10 5 1910 1950 1990 Urban areas are the largest source of Turbidity TSS (kg ha-1 yr-1) 1000 800 600 400 200 0 Residence time affects dilution of nutrients & sediments • Residence times are highly variable • Rivers have the longest residence time • Short residence times near inlets • Bramble Bay has the longest residence time within the bay Rivers receive inputs from a variety of point and non point sources • Primary inputs are nutrients (nitrogen & phosphorus) and suspended solids Sewage Outfall Golf course fertiliser runoff and gravel extraction plant Sewage Treatment Plant Industry Outfall Grazing - manure Aquaculture Degraded waterways stimulates study • Concern about impacts of expanding population • Moreton Bay study “Moreton Bay and its waterways will, by 2020, be a healthy ecosystem supporting the livelihoods and lifestyles of residents and visitors” To protect and restore waterways STRATEGY Stormwater Quality Improvement Device Sewage Treatment Upgrades MONITORING RESEARCH Riparian Rehabilitation Monitoring & Research • Essential tools for effective preservation and remediation of waterways • Determines ecological outcomes of nutrient removal from sewage, stormwater controls and other management actions Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya • the extent of sewage plumes Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya • the extent of sewage plumes • nutrient responses of phytoplankton communities Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya • the extent of sewage plumes • nutrient responses of phytoplankton communities • occurrence of nuisance macroalgae e.g. sea lettuce Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya • the extent of sewage plumes • nutrient responses of phytoplankton communities • occurrence of nuisance macroalgae e.g. sea lettuce • status of turtles and dugongs Monitoring Ecosystem Health Indicators of Ecosystem Health • loss or recovery of seagrasses, mangroves and corals • outbreaks of Lyngbya • the extent of sewage plumes • nutrient responses of phytoplankton communities • occurrence of nuisance macroalgae e.g. sea lettuce • status of turtles and dugongs • water quality – phytoplankton biomass – nitrogen and phosphorus – turbidity Oxley Creek • Oxley Creek drains an area of 260 km2 • It originates at Mt Perry south of Ipswich near Flinder’s Peak • Variety of land uses • The catchment contains the endangered Anglestemmed Myrtle (Austromyrtus gonoclada) Historically, Oxley Creek was cleaner • “ …During summer holidays, as school boys, we had regularly swum and fished in the creek.” • “….in spawning times…. The mullet would jump out of the water…” • “It was always muddy but not as bad as it is today.” Oxley Creek is biologically important Wading Birds Dingo Fruit Bat Colony Wading Birds Oxley Creek has recreational value Boats moored on creek Canoeing on Oxley Creek Oxley Creek is Very Turbid Sand Extraction Oxley Creek is Rich in Nutrients Inala STP Causing algal blooms downstream Oxley Creek is Rich in Nutrients Oxley Creek receives nutrients from the influx of the Brisbane River Oxley Ck STP • 2nd largest STP Impacts on Oxley Creek High faecal coliforms indicates contamination by faeces 5000 4000 3000 2000 high 1000 0 0 10 20 30 Distance Upriver (km) Low dissolved oxygen restricts aquatic life Oxley Creek Dissolved oxygen (%) Faecal coliforms (CFU/100mL) Oxley Creek 80 60 40 20 0 0 10 20 Distance Upriver (km) 30 Community Involvement • • • • Wetland restoration Weed eradication Riparian regeneration Water quality monitoring Healthy riparian zone at upper Oxley Creek School students monitoring water quality River estuaries: moderately to highly degraded • • • • • • Nutrients & sediments from forestry, agricultural and urban areas Algal booms, high nutrients Nutrient uptake means no sewage nitrogen impact on Deception Bay Caboolture River Urbanised & agricultural catchment Aquaculture prominent Very turbid Logan River • • • Highly turbid Extensive vegetation cleared 10x more N • • Urbanised & industrial catchment High turbidity & nutrients Pine River • • • • Brisbane River Moderate degradation High degradation Extremely degraded Very high nutrient loadings Too turbid for phytoplankton Long residence time Bremer River Rivers are nutrient over-enriched • High concentrations of nutrients often results in blooms of single species – reducing diversity Phytoplankton bloom in Caboolture River Aquatic weed bloom in upper Brisbane River Jellyfish bloom in response to high plankton biomass in Pine River Benthic microalgal bloom on Brisbane River sediment River Estuaries Report Card 2000 Bribie Island Caboolture River Moreton Island Caboolture River Redcliffe Pine River North Stradbroke Island Brisbane River Pine Rivers D Brisbane River D Worsened Unchanged Bremer River Logan River Logan River C F D Improved A excellent B good C fair D poor F fail River estuaries Moreton Bay Highly impacted river estuaries Pristine and diverse marine environments Monitoring has identified zones of impacts Oxley Ck Historically the Western Bay was relatively pristine Within Moreton Bay, dugongs, sea turtles and extensive seagrass beds were once present on the urbanised western shores, but are now largely restricted to the well flushed eastern regions. What are the impacts on Moreton Bay? • Sediments – 50,000 truck loads of mud into Brisbane River every year • Nutrients – 500 olympic swimming pools of treated sewage effluent every day – 1/3 Brisbane River flow is sewage effluent • Lyngbya – 3000 football fields of seagrass covered by Lyngbya in Moreton Bay Sewage Plume Mapping identifies zones of human impact • Macroalgae takes up sewage nutrients • Chambers deployed around bay and rivers • Allows mapping of extent of sewage plume Plume mapping technique identifies different nutrient sources • Highest sewage concentration is in middle reaches of the rivers due to inputs and lack of tidal flushing • Plume concentrated in western bay • Sewage plume from rivers is seasonally variable September 1997 March 1998 June 2000 Monitoring affects management decisions Sediments impact West Moreton Bay Suspended sediment concentration (mg L-1) Sediment thickness (mm) model output simulating May 96 flood With sediments come nutrients % Mud Total N (mg L-1) Sediment re-suspension Bramble Bay Nearbed wave Water depth (m) velocities (cm s-1) wind waves and tidal currents 40 30 Wind 20 Tide 10 0 8.5 7.5 6.5 5.5 January 20 January 27 February 3 Sediments affect seagrass distribution Suspended solids Seagrass distribution Sediments affect seagrass distribution • Reduced water clarity in Waterloo Bay due to river inputs and resuspension • Last remaining healthy seagrass beds in Western Moreton Bay • Sensitive region with variable water quality Seagrass loss has occurred due to Logan River plume Macleay Is Russell Is Logan R • First seagrass loss in 1992 • Recovery 1994-1998 • Disappeared since 1998 1989 1996 Seagrass loss is ongoing • • • • • Deception Bay (97) Long Island (92, recover 98) Behm’s Creek (96) Northern Broadwater (00) Lyngbya majuscula bloom Loss reduces habitat Are sediments affecting corals too? • Scoping surveys shown dramatic shift from dead to live coral cover with distance from mainland in Waterloo Bay • Intensive survey will be conducted each winter Favia speciosa. Waterloo Bay Excessive nutrients cause algal blooms Ulva bloom Algal bloom 1000 ML per day Bramble Bay is nutrient laden • Phytoplankton blooms • Mangroves full with nutrients • Sediments release nutrients Phytoplankton Mangroves Phytoplankton levels Lyngbya majuscula • • • • • Toxic marine cyanobacterium Naturally occurring but proliferated in N. Deception Bay Bulldozers needed to remove rotting, stinking mass Human health problems Ecosystem health problems – seagrass loss, repels fish Lyngbya has rapid growth Lyngbya at Amity & Moreton Banks • • • • Occurs naturally on reefs and seagrass beds Large amounts at Moreton / Amity Banks last summer Potential threat to main dugong & turtle grazing areas Less toxic than in Deception Bay, oyster impact unknown Soils samples collected from various sites in the Pumicestone Passage and Deception Bay region Mangrove Intact pine forest Cleared pine forest Melaleuca Canal development Coffeerock Sandstone Point Shirley Creek Eastern & Northern Moreton Bay Best in the Bay Clean, clear water No algal blooms Eastern & Northern Moreton Bay B-/A • Most pristine area of Moreton Bay • extensive seagrass beds, mangroves, & coral reefs supporting huge diversity of marine life • dugongs, turtles, whales, dolphins, fish • Excellent water quality • Tidal flushing – 1 day Turtles and dugongs Dugongs and turtles now concentrated on Eastern side Dugongs • Population ~ 900 • 7 deaths since Jun 99 Turtles • Population > 10,000 • Green Turtle Fibropapilloma Disease • 70% affected in S. Bay • 40% affected in Peel Is. & reefs • 20% affected at Moreton Banks Moreton Bay Report Card 2000 Northern Bay • Well-flushed by oceanic waters Worsened A • Intact denitrification Northern Deception Bay • D Eastern Banks • Well-flushed B- B • High sediment nutrients Central Bay • Lyngbya outbreak Southern Deception Bay • • • • • A excellent B good C fair D poor F fail • Lyngbya • Declining seagrass Bramble Bay Improved • Extensive seagrass beds supporting dugongs & turtles No improvement • No seagrass recovery • High turbidity Unchanged D • Muddy sediments • Relatively good water quality F Southern Bay Sewage inputs High nutrients and turbidity Waterloo Bay Ulva blooms • Some coral Historical seagrass loss • Stable seagrass beds High sediment nutrient • Stormwater control fluxes C+ • • • • C- Extensive mangrove forests Sewage inputs Seagrass losses Lack of mangrove recovery from hail damage Communication • • • • • • • Quarterly newsletters Annual report card Healthy Waterways website Coastal CRC website Scientific papers Scientific reports Monitoring Technique Video www.botany.uq.edu.au/marbot/ (research) www.healthywaterways.qld.gov.au (management) www.coastal.crc.org.au/ehmp (monitoring)