Water for Nature Environmental Watering Site Monitoring Report by Dr Anne Jensen

Transcription

1 Water for Nature Environmental Watering Site Monitoring Report by Dr Anne Jensen Pike River Floodplain, South Australian Riverland Duck Hole, Mundic Wetland and Inner Mundic Flood-runner July 2013 to June 2016 Nature Foundation SA is a not-for-profit nature charity that works to Save, Protect and Restore South Australia's natural biodiversity. Since 2008 one of our flagship programs, Water for Nature, has been delivering environmental water along the Murray River to help reduce the loss and stress to ecosystems and habitats caused by river regulation and drought. Over the last three years, our Water for Nature program has worked with 200 volunteers to deliver 4.56 gigalitres of environmental water to more than 35 wetland and floodplain sites along the Murray River. Healthy wetland and floodplain environments are important for environmental, economic, cultural and social reasons, providing an optimal environment for flora and fauna, improved water quality for human consumption and agricultural use, and opportunities for recreation and tourism. We work with private landholders, irrigators, community groups & local government on smaller sites to deliver environmental water, complementing larger government watering projects. Nature Foundation SA also works closely with the Commonwealth Environmental Water Holder to deliver environmental water. Pike River Floodplain Monitoring Report ( ) 1

2 Site name Water For Nature Environmental Watering Site Monitoring Report Reporting period July 2013 to June 2016 Date prepared August 2016 Location Pike River Floodplain, South Australian Riverland Duck Hole, Mundic Wetland and Inner Mundic Flood-runner Contact Name Water Provider Partners Duck Hole Wetland, Mundic Wetland and Inner Mundic Flood-runner are wetlands within the large Pike-Mundic floodplain on the east bank of the River Murray, straddling Weir & Lock No 5 at Paringa. Duck Hole wetland is a well-defined temporary wetland which fills seasonally at flows ~70,000 ML/d. It covers 15 ha and is fringed by black box and river coobah, as well as extensive areas of lignum. The adjacent Mundic Wetland is a higherlevel ephemeral wetland, which fills less frequently, dominated by chenopod shrubs with fringing black box. Inner Mundic Flood-runner is a high-level by-pass across the elevated floodplain between the upper and lower reaches of Mundic Creek, lined by scattered black box, filled by flows >70,000 ML/d. A natural inundation event was experienced at this wetland complex during the February 2011flood event. The natural inundation of these sites resulted in the improved health of the existing vegetation as well as the recruitment of species. However, both mature trees and flood-generated eucalypt seedlings were indicating signs of stress by NFSA Water For Nature Program Manager Natalie Stalenberg Pike River Land Management Group: Bruce Hewett; DEWNR: Brad Hollis & Sam Walters; Commonwealth Environmental Water Holder allocation to NFSA Pike River Land Management Group ; Department of Environment Water & Natural Resources; SA Water Planning Context Pike Implementation Program (2009) Pike River Floodplain Monitoring Report ( ) 2

3 Aim of watering project Key objectives Site Description Watering History Habitat Environmental watering at Pike River floodplain sites aims to: 1. improve condition of mature trees including black box (Eucalyptus largiflorens) and river coobah (Acacia stenophylla) 2. improve cover and condition of under-storey vegetation, including lignum (Duma florulenta) 3. enhance survival of seedlings arising from the 2011 flood event 4. provide food sources for waterbirds. Environmental watering at these sites has the following objectives: Duck Hole 1. improve the condition of fringing black box trees 2. increase the presence and diversity of amphibious and flood dependent species 3. increase abundance and diversity of waterbird species Mundic Wetland 1. improve the condition of fringing black box trees 2. increase the presence and diversity of amphibious and flood dependent species 3. increase abundance and diversity of waterbird species Inner Mundic Flood-runner 1. improve the condition of fringing mature black box trees The floodplain and wetland complex includes communities of red gum forest (Eucalyptus camaldulensis), black box woodland and lignum shrubland dissected by anabranches, temporary creeks, waterholes and billabongs. The vegetation communities and wetlands have suffered serious decline due to lack of flooding, drought and saline groundwater intrusion. Environmental watering can help to repair the ecosystems. The Pike-Mundic floodplain is undergoing major infrastructure projects which in future will modify the water regime to benefit regeneration of floodplain vegetation (Pike Implementation Program, due for completion in 2020). Watering commenced at Duck Hole on 13 November 2014, with 220 ML delivered in A pump was used to divert water from Mundic Channel into the feeder creek to fill the 15 ha wetland. A second fill took place in October-November Mundic Wetland was filled with 72 ML in October 2015, with a top-up of 32 ML in November Duck Hole received 271 ML and the Inner Mundic Flood-runner received 42 ML in November The Mundic wetland complex provides a diverse range of aquatic and floodplain habitats that support populations of diverse flora and fauna. Several species found on these floodplains are listed as threatened or vulnerable under the Environment Protection and Biodiversity Conservation Act 1999, including the southern bell frog (Litoria raniformis), Murray cod (Maccullochella peelii peelii) and regent parrot (Polytelis anthopeplus). The site also provides likely habitat for Murray hardyhead (Craterocephalus fluviatilis). The sites support a number of distinct vegetation communities, depending on the inundation frequency, from wetland to fringing black box woodland, then varying between lignum swamplands and chenopod shrublands as flooding frequency declines on the floodplain fringes. These communities provide resources and habitat for macropods, waterbirds, hollow-dwelling bats, mammals, frogs and reptiles, as well as species of aquatic macroinvertebrates, zooplankton and fish. This complex also provides significant feeding and breeding habitat for waterbirds, fish and other fauna. In particular, waterbirds seek refuge from drought on adjacent permanent creeks, and the temporary and ephemeral wetlands are used for breeding in times of flood. Pike River Floodplain Monitoring Report ( ) 3

4 Water Source Event details NFSA allocation from Commonwealth environmental water ; operated by Pike River Land Management Group and NFSA Water for Nature Regional Community Coordinator Craig Ferber Duck Hole Watering November 2014 delivered 220 ML; watering 19 October to 5 November 2015, delivered 271 ML Mundic Wetland Initial fill in mid-october 2015, topped up in mid-november 2015, for a total of 104 ML delivered Inner Mundic Flood-runner Site filled in mid-november 2015, 42 ML delivered Maximum area inundated (ha) Estimated area 15 ha at Duck Hole; 23 ha at Mundic Wetland, 3 ha at Inner Mundic Floodrunner Duration of the environmental watering project ( ) Duck Hole -- two seasonal waterings, in late spring through summer; Mundic Wetland and Inner Mundic Flood-runner, one seasonal watering River Murray Mundic Creek Inner Mundic Flood-runner Mundic Wetland Duck Hole Figure 1 Inundation extent at Duck Hole, Mundic Wetland and Inner Mundic Flood-runner in November 2015 Pike River Floodplain Monitoring Report ( ) 4

5 Annual Observations against key objectives (including species of conservation significance (state or Commonwealth listed threatened species, or listed migratory species) observed at the site, any breeding of frogs, birds or other prominent species observed at the site and details of any observable responses in vegetation, such as improved vigour or significant new growth) Future Watering Project not commenced (observations by PRMG & DEWNR staff) initial positive responses observed in waterbird numbers and vegetation health monitoring underway by DEWNR and Riverbush Environmental (observations by PRMG & DEWNR staff, and Riverbush Environmental) The vegetation and bird response from both Duck Hole and Mundic Wetland was significant. Many water associated plant species established, along with the presence of an array of waterbird species (DEWNR, 2015) 1. The top five waterbird species in abundance at Duck Hole were Australian Shelduck, Black-fronted Dotterel, Chestnut Teal, Grey Teal and Australian Pelican. At Mundic Wetland they were Grey Teal, Red-kneed Dotterel, Black-tailed Native Hen, Blackfronted Dotterel and Australian White Ibis (DEWNR and Riverbush Environmental Pty Ltd ). Wetland birds sighted at Duck Hole and listed under the National parks and Wildlife Act (1972) included Australian Darter, Australasian Shoveler, Freckled Duck, Intermediate Egret, Musk Duck and White-bellied Sea-eagle at Duck Hole, and Striped Honeyeater at Mundic Wetland (Riverbush Environmental Pty Ltd ). A total of 23 waterbirds were recorded at Mundic Wetland in response to the watering event. Prior to watering, Mundic Wetland had no record of waterbird species utilising the site and was dominated by the presence of woodland bird species only (DEWNR ). Species richness and abundance of waterbird response to filling of Mundic Wetland was surprising, with high use of dense vegetation in inundated area. While waders or species that are easily disturbed were readily recorded, other species may have been missed. Birds were also moving between Mundic Wetland and Duck Hole. A spike in numbers of swallows and martins indicated a food source of emerging insects from the wetland. There was a strong response from bushland birds, with breeding of several species with a conservation listing (Riverbush Environmental Pty Ltd ). Amphibious understorey plant species were dominant post-watering at all sites. At both Duck Hole and Mundic Wetland, the top five most abundant species were amphibious, a significant shift from previously dominant terrestrial species in Mundic Wetland and floodplain dependent species in Duck Hole. Duck Hole had 39 species in the dry phase (6 amphibious, 15 floodplain, 18 terrestrial), reduced to 23 species while inundated (14 amphibious, 7 floodplain, 2 terrestrial). Mundic Wetland increased from 24 (2 amphibious, 4 floodplain, 18 terrestrial) to 45 species (9 amphibious, 16 floodplain, 20 terrestrial) (DEWNR ). Mundic Wetland prior to watering consisted of terrestrial plant species dominated by Copperburr and Saltbush. However during and after the watering event, a number of important wetland and floodplain species including Nardoo, Jerry-jerry and Rosinweed were dominant across the site. A survey conducted in late May 2016 recorded 32 plant species still present at the wetland, of which 13 were wetland and floodplain species (DEWNR ). Monitor condition of site to determine need for future watering; it is likely that the wetlands will be watered by high flows in September-December Future activities coordinated by DEWNR will include watering of understorey vegetation at Inner Mundic Wetland and monitoring of tree condition at each of the wetlands. 1 Summary of Environmental Watering Event at Duck Hole, Mundic Wetland and Inner Mundic Flood-runner on the Pike Floodplain. DEWNR, Pike River Floodplain Monitoring Report ( ) 5

6 Figure 2 Pike River Land Management Group, at completion of first filling of Duck Hole wetland Figure 3 Waterbird species recorded across the Pike River floodplain during surveys from , prior to watering (Lescheid, 2015) Pike River Floodplain Monitoring Report ( ) 6

7 Figure 4 Water pumping into Duck Hole in December 2014 (left); rising levels in the wetland reach stressed river coobah and black box seedlings, but red gums are long dead (right) Figure 5 Rising water levels in Duck Hole inundate dormant lignum and stressed black box seedlings (left); Inspection by representatives from Commonwealth Environmental Water Holder s Office and Nature Foundation SA at the Duck Hole site in December 2014 (right) Figure 6 Tawny frogmouth observed on Pike River floodplain (photo supplied by Riverbush Environmental Pty Ltd (2015)2 Pike River Floodplain Monitoring Report ( ) 7