support key ecosystem functions related to connectivity between the river and the floodplain support breeding of native fish support recruitment of juvenile life stages environmental watering will: sustain and maintain the lateral movement of fish, particularly small bodied species. extend high flow conditions and increase inundated aquatic habitat, potentially providing nursery ground for fish. affect regional differences amongst fish assemblages Lateral fish movement was high variability in fish assemblages, suggesting individual wetlands respond uniquely to environmental variables including flow in the main channel delivery of environmental water did not enhance reproduction and recruitment of carp in the studied wetlands no clear consistent pattern of movement throughout the wetlands was detected support key ecosystem functions, related to connectivity between the river and the floodplain environmental watering will: increase frog distribution, diversity and relative abundance in comparison to previous flow years increase the extent of frog habitat within each of the South Australian River reaches. Frog response frog calling and species richness was lower in summer than spring likely due to higher unregulated flows in spring however, environmental watering in summer may have maintained habitat availability for frog breeding support ecosystem functions related to environmental watering will: Coorong Ruppia the Ruppia tuberosa and fish habitat models together with the hydrodynamic model (CHM v2.1) provide a useful tool for the evaluation and
golden perch, catfish and silver perch; and the fungi Catenophlyctis and Malassizia which were found in all the larval fish species. Spawning, recruitment and origin of golden perch Hydrology From July to November 2012, flow in the lower Murray River (discharge at the South Australian border, QSA) generally reflected flow in the mid-reaches of the Murray at Euston (). In both reaches, an extended (~4 month) within-channel bank-full flow event peaked at approximately 50,000 ML day-1 in September/October 2012 before receding to approximately 20,000 ML day-1 in November 2012. Flow in the Darling River was <5,000 ML day-1 throughout this period (). Between November 2012 and March 2013, flow in the Murray River at Euston decreased to approximately 5,000 ML day-1 and flow in the Darling at Burtundy peaked at ~8,000 ML day-1 in early December 2012, but remained below 5,000 ML day-1 for the rest of the time. Flow in the Lower Murray River ranged 8–20,000 ML day-1 as a result of increasing flow from the Darling in December 2012 and water released from Lake Victoria (). Commonwealth environmental water was delivered to the SA reaches of the Murray River from October 2012–June 2013. From late October 2012 to the end of January 2013, the daily contribution of Commonwealth environmental water to flow at the South Australian border ranged ~2,000–7,300 ML, with environmental water delivery peaking at ~7,000–7,300 ML day-1 through 5–16 December 2012 (Figure 2). Details on the actual source (i.e. Lake Victoria, mid Murray River or Darling River) of this water remain unclear. Figure 19. Discharge (ML day-1) in the Murray River at the South Australian border (solid black line) and Euston (dotted black line), Darling River at Burtundy (dashed black line), Frenchman’s Creek (Lake Victoria inlet, solid red line) and Rufus River (Lake Victoria outlet, solid blue line).
10. Species and total number (standardised – 24 hour soak time) of fish captured using directional fyke nets and drum nets moving in and out of the wetland at Overland Corner over a 3-day period during each of the six phases of flow delivery. Functional groups: FD = flow dependent specialists, FG = foraging generalists, D = diadromous species, I = Invasive species (Abbreviation: Craterocephalus stercus. = Craterocephalus stercusmuscarum fulvus). EW: environmental water event. Species Common name Scientific name Functional High Receding Rising EW High EW Receding EW Low in out in out in out in out in out in out Golden perch Silver perch Unspecked hardyhead Carp gudgeon Murray rainbowfish Bony herring Flat-headed gudgeon Dwf flat-headed gudgeon Australian smelt Common carp Goldfish Eastern gambusia Redfin perch Oriental weatherloach Macquaria ambigua Bidyanus bidyanus Craterocephalus stercus. Hypseleotris spp. Melanotaenia fluviatilis Nematalosa erebi Philypnodon grandiceps Philynodon macrostomus Retropinna semoni Cyprinus carpio Carrasius auratus Gambusia holbrooki Perca fluviatilis Misgurnus anguillicaudatus FD FD FG FG FG FG FG FG FG I I I I I 4 4 11 11 18 2 1 2 85 15 2 1 37 770 32 41 107 1514 5 5 20 39 237 1 3 25 1 113 1949 16 3 2 9 72 45 7 4 70 2 4 3 94 270 25 23 3 45 4 4 4 4 21 188 291 101 2 6 137 2 10 1 8 103 453 894 372 3 37 75 1 9 1 1 48 1695 3 12 61 3 56 52 5 73 353 5 6 45 21 1 12 21 1 24 340 2 101 9 1 3 3 113 443 13 102 15 2 6 14 Total No. of species No. of native species 50 6 4 103 4 2 2536 11 7 2387 10 7 214 9 6 475 10 6 764 12 9 1956 11 7 1931 9 7 543 11 8 481 7 6 711 9 7
Comparing wetlands repeatedly sampled in spring (high and summer (environmental water) revealed that average abundance of calling males at wetlands was significantly higher in spring than in summer (p = 0.005) (Figure 36A). Average frog species call richness was also significantly higher in spring than in summer 2012 (p<0.001) (Figure 36B)(Appendix VIII). Figure 36. Mean (± Standard Error) (a) abundance and (b) species richness of calling males at wetlands (n = 9) in spring (high flows) and summer (environmental water) 2012. Comparison of environmental variables at wetlands sampled during spring (high flows) and summer (environmental water) 2012 frog surveys revealed that flow to South Australia, and emergent vegetation decreased significantly from spring to summer and air temperature increased significantly over the sampling period (Hoffmann et al. 2014). Emergent vegetation was positively correlated with flows to South Australia (r2 = 0.28, p = 0.028, n = 18). Electrical conductivity, humidity and submerged vegetation were not significantly different between spring and summer surveys. Both frog call abundance and species call richness displayed a positive relationship with emergent vegetation (Figure 37 and Figure 38). Generalised linear modelling revealed that flows to South Australia and emergent vegetation were significant predictors for frog call abundance and species call richness at wetlands (Appendix IX and Appendix X)). Overall, the included environmental variables explained 62.4% and 46.7% of the variation in frog call abundance and species richness respectively. Figure 37. Relationship between species richness of calling males and emergent vegetation (%) at wetlands in spring and summer 2012. Figure 38. Relationship between the abundance of calling males and emergent vegetation (%) at wetlands in spring and summer 2012.