Hawkesbury-Nepean River Environmental Monitoring Program

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Figure 6.32: Comparison of major cyanobacterial cell counts at sites N26 and N42 62 Hawkesbury Nepean River Environmental Monitoring Program: Final Technical Report
Macrophytes Large aquatic plants play an important role in the freshwater aquatic ecosystems of southeast Australia, absorbing nutrients, providing shelter for some species of fish, and creating foraging locations for others (Thiebaud and Williams 2008). Water ribbon (Vallisneria gigantea), a native to eastern Australia, is considered an indicator of good water quality and is known to be a nursery habitat for juvenile bass and a foraging habitat for adult bass (Harris 1988). Many complaints are heard in the warmer months from users of swimming, fishing and boating facilities in the Hawkesbury-Nepean River about plants that restrict the recreational use of the waterway (Thiebaud and Williams 2008). Almost invariably, the plants in question are exotic species (e.g. see Figures 6.33 and 6.34), the decomposition of which reduces water quality and aesthetic values (Thiebaud and Williams 2008). Some of these exotic species are capable of reproducing via fragmentation (Sainty and Jacobs 1981); their dispersion possibilities are therefore increased through anthropogenic means (e.g., fragments on boat motors or fishing gear). Macrophyte monitoring Williams and Thiebaud (2007) analysed changes to aquatic habitats and adjacent land use in downstream areas of the Hawkesbury-Nepean River. In that study, the presence of submerged macrophytes was mapped in early 2004 from Wisemans Ferry to Warragamba Dam. Other studies of exotic floating macrophytes are currently under way (R. Coventry, pers. comm., cited by Thiebaud and Williams 2008). However, no recent studies of the large-scale distribution of all of the three main categories of aquatic macrophytes (submerged, floating, emergent) within the river had been reported (Thiebaud and Williams 2008). Figure 6.33: Salvinia bloom at the junction of the Warragamba and Nepean Rivers, December 2006 DECC commissioned DPI Fisheries to undertake additional fieldwork to determine the current distribution of submerged, emergent and floating macrophytes in the Hawkesbury River. The fieldwork for this study was conducted in autumn and winter 2007, and the distribution of freshwater macrophytes was mapped from Warragamba Hawkesbury Nepean River Environmental Monitoring Program: Final Technical Report 63
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Hawkesbury-Nepean River Environment
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CONTENTS: BOOKLET Summary..........
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Summary Adaptive management require
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1. Introduction The Hawkesbury-Nepe
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• local government • other stak
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Sackville that have been the site o
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Long-term monitoring sites A review
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including algal blooms. This presen
Page 17 and 18: Figure 5.1: Long-term sampling site
Page 19 and 20: General observations from these gra
Page 21 and 22: Figure 5.4: Smoothed trend lines fo
Page 23 and 24: are also highly variable in terms o
Page 25 and 26: Water quality trends using statisti
Page 27 and 28: Figure 5.9: Chlorophyll-a levels ov
Page 29 and 30: al. (1999, 2004). Sydney Water rout
Page 31 and 32: N95 Edge Samples N95 Riffle Samples
Page 33 and 34: quality and macroinvertebrate commu
Page 35 and 36: Figure 6.6: Principal components an
Page 37 and 38: Figure 6.8: Average SIGNAL-SG score
Page 39 and 40: Sites upstream and downstream of da
Page 41 and 42: Figure 6.10: Multidimensional scali
Page 43 and 44: Temporal trends in AusRIVAS-based a
Page 45 and 46: Trends in periphytic diatom communi
Page 47 and 48: species did not appear in searches
Page 49 and 50: the average percentage abundances (
Page 53 and 54: . Figure 6.18: Sampling sites for f
Page 55 and 56: Hypseleotris were caught only much
Page 57 and 58: Figure 6.23: Length frequencies of
Page 59 and 60: Figure 6.24: Chlorophyll-a, total c
Page 61 and 62: Figure 6.26: Temporal differences i
Page 65 and 66: Figure 6.30: Temporal differences i
Page 67: (e.g. Merismopedia, Phormidium) hav
Page 71 and 72: • Two species of weeds, Gymnocoro
Page 73 and 74: ecord for the unregulated Colo Rive
Page 75 and 76: River has changed in the recent pas
Page 77 and 78: Maheshwari B.L., Walker K.F. and Mc
Page 79 and 80: Department of Environment and Clima
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Hawkesbury-Nepean River Environmental Monitoring Program

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