Of droughts and flooding rains cyanobacterial presence in NSW over the past 5 summers. BGA in NSW Lee Bowling EEP Branch 23 rd August 2012

Transcription

1 Of droughts and flooding rains cyanobacterial presence in NSW over the past 5 summers BGA in NSW Lee Bowling EEP Branch 23 rd August 212

2 Introduction Past 5 summers with extremes in weather conditions Initial 3 years of drought Past 2 summers of high rainfall and flooding in various parts of the state Looked at number and persistence of cyanobacterial blooms across these 5 years to assess whether climatic conditions impacted on bloom occurrence

3 Method Recreational alert level data (Red, Amber and Green alerts) accumulated by NSW Office of Water over the time period were assessed. Data from Office of Water, other NSW government agencies, local government and utilities. Noisy data due to variation in annual sampling effort and reporting by some data suppliers Provide general overview of cyanobacteria in NSW Assessed as Number of locations reporting alerts Cumulative weeks on alert (persistence)

4 State-wide Statewide - Locations Statewide - Cumulative weeks 14 2 Number of locations Number of weeks

5 Regional variation

6 Coastal Sydney/South Coast Total Monthly Precipitation - Sydney Nepean River at Penrith Total Monthly Rainfall (mm) Jul-7 Oct-7 Jan-8 Apr-8 Jul-8 Oct-8 Jan-9 Apr-9 Jul-9 Oct-9 Jan-1 Month/ Sydney/South Coast - Locations Apr-1 Jul-1 Oct-1 Jan-11 Apr-11 Jul-11 Oct-11 Jan-12 Apr-12 Mean Daily Discharge (ML day -1 ) /7/7 1/1/7 1/1/8 1/4/8 1/7/8 1/1/8 1/1/9 1/4/9 1/7/9 1/1/9 1/1/1 1/4/1 Date Sydney/South Coast - Cumulative weeks 1/7/1 1/1/1 1/1/11 1/4/11 1/7/11 1/1/11 1/1/12 1/4/12 Number of Locations Number of weeks

7 North-west tablelands and slopes - Barwon Total Monthly Precipitation - Moree Gwydir River at Pallamallawa Total Monthly Rainfall (mm) Jul-7 Oct-7 Jan-8 Apr-8 Jul-8 Oct-8 Jan-9 Apr-9 Jul-9 Oct-9 Jan-1 Month/ Barwon - Locations Apr-1 Jul-1 Oct-1 Jan-11 Apr-11 Jul-11 Oct-11 Jan-12 Apr-12 Mean Daily Discharge (ML day -1 ) /7/7 1/1/7 1/1/8 1/4/8 1/7/8 1/1/8 1/1/9 1/4/9 1/7/9 1/1/9 1/1/1 1/4/1 Date Barwon - Cumulative weeks 1/7/1 1/1/1 1/1/11 1/4/11 1/7/11 1/1/11 1/1/12 1/4/12 Number of Locations Number of weeks

8 Southern NSW - Murray Total Monthly Rainfall (mm) Number of locations Total Monthly Precipitation - Albury Jul-7 Oct-7 Jan-8 Apr-8 Jul-8 Oct-8 Jan-9 Apr-9 Jul-9 Oct-9 Jan-1 Month/ Murray - Locations Apr-1 Jul-1 Oct-1 Jan-11 Apr-11 Jul-11 Oct-11 Jan-12 Apr Number of weeks Mean Daily Discharge (ML day -1 ) /7/7 1/1/7 Murray River at Corowa 1/1/8 1/4/8 1/7/8 1/1/8 1/1/9 1/4/9 1/7/9 1/1/9 1/1/1 1/4/1 Date Murray - Cumulative weeks 1/7/1 1/1/1 1/1/11 1/4/11 1/7/11 1/1/11 1/1/12 1/4/

9 Far West Total Monthly Precipitation - Bourke Darling River at Bourke Total Monthly Rainfall (mm) Jul-7 Oct-7 Jan-8 Apr-8 Jul-8 Oct-8 Jan-9 Apr-9 Jul-9 Oct-9 Jan-1 Month/ Far West - Locations Apr-1 Jul-1 Oct-1 Jan-11 Apr-11 Jul-11 Oct-11 Jan-12 Apr-12 Mean Daily Discharge (ML day -1 ) /7/7 1/1/7 1/1/8 1/4/8 1/7/8 1/1/8 1/1/9 1/4/9 1/7/9 1/1/9 1/1/1 1/4/1 Date Far West - Cumulative weeks 1/7/1 1/1/1 1/1/11 1/4/11 1/7/11 1/1/11 1/1/12 1/4/ Number of Locations Number of weeks

10 Comparisons 28/9 and 211/12

11 Conclusions Coastal NSW Cyanobacterial presence showed only minor variation over the 5 years, or increased presence in wet years. Blooms in coastal areas usually associated with small reservoirs and urban water bodies, especially in Sydney and Newcastle. Rivers are short, fast flowing, so blooms in them are uncommon. Higher rainfall may actually support more blooms, as more water available, nutrient rich stormwater inflows

12 Conclusions - Tablelands and western slopes of Great Dividing Range Little difference between drought and wet years Most water bodies are large reservoirs have water, are nutrient enriched and experience blooms whether wet or dry years. Rivers with steeper gradients, fast flow not good environments to support blooms

13 Conclusions Western NSW lowland areas Reduction in cyanobacterial presence after drought broke Few standing water bodies in this part of NSW, most surface waters are rivers Cyanobacterial blooms in dry years associated with rivers as low flow Wet years mean high flows and conditions unsuited to riverine blooms.

14 Acknowledgments NSW Regional algal coordinators Warwick Mawhinney Water Environment Laboratory of NSW Office of Water All other agencies, utilities and Councils who have provided data on blooms.