Southern pygmy perch watering requirements study
|Full Title||A monitoring program to determine the watering requirements of floodplain populations of the southern pygmy perch, Nannoperca australis, in Barmah-Millewa Forest|
|Contact Person||Rick Stoffels|
|Funding Body||Goulburn Broken CMA|
|Duration||Jan 2014 - June 2018|
|Collaborators||Yorta Yorta Nations Aboriginal Corporation|
The pygmy perch has undergone a dramatic decline in NE Victoria over the last 15 years (now ‘Vulnerable’ (VIC) or ‘Endangered’ (NSW)). Despite this species’ attractive appearance, its ecology is poorly understood. Anecdotal evidence implies this species may experience high productivity rates on floodplains of NE Victoria, particularly in wetlands containing submerged macrophytes. Indeed, it is possible that this habitat type may be very important to the regional viability of this species, but scientific tests of this hypothesis are yet to be carried out.
If submerged macrophyte beds of floodplain wetlands are a pivotal habitat for this species, floodplain watering regime will likely have a large impact on regional population viability. Interestingly, the greatest declines of this species have been observed during the ‘Millenium Drought’ (2000-2010), during which overbank flows into wetlands were rare. Taken together, the anecdotal evidence implies this species may be a good ‘indicator species’; an indicator of the efficacy of floodplain environmental water allocations (EWAs) in NE Victoria.
This projects launches a monitoring programme to feed into the adaptive management of flows at the Barmah-Millewa Icon Site. If pygmy perch are dependent on slow- or zero-flow habitats containing submerged macrophytes, then the Millenium Drought could have resulted in very large-scale habitat loss for this species. Large-scale recovery would then be dependent on individuals recolonising localities from certain ‘source’ populations, which may be separated by 10’s to 100’s of kilometres. It follows that recolonisation of floodplain areas like Barmah-Millewa may be slow. Therefore, the aim is to set up a monitoring programme that is cost-effective, yet of an appropriate duration (5 years) to detect recovery of a rare species following a period of decline. Further, our aim is not merely to monitor changes in abundance at Barmah-Millewa alone, but also to structure sampling in a way that our knowledge of their specific habitat requirements will be improved. Accordingly, under this project we will replicate a spatially-stratified annual census on the Ovens Floodplain, in addition to the Barmah-Millewa Forest. This replication will:
- Improve our chances of detecting regional recovery of this species following the drought, especially given the Killawarra Forest area was, prior to the Millenium Drought, a productive habitat for this species.
- Substantially improve the power of our inferences concerning the effect flooding characteristics (e.g. magnitude, frequency) have on the population dynamics of this species.
- Substantially improve the power of our inferences concerning the habitat requirements of this species.
Across Barmah-Millewa Forest (Murray Floodplain) and Killawarra Forest (Warby-Ovens NP, Ovens Floodplain):
- Determine the effect of floodplain inundation on pygmy perch population structure (including abundance and size composition);
- Determine the wetland habitat characteristics—water quality and habitat structure—that affect pygmy perch distribution and abundance on the floodplain.