Relationship between small fish abundance and flow regimes in Eastern Mt Lofty Ranges

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RESEARCH AREA
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This weeks featured research article has just been published in Hydrological Sciences Journal by Aquasave (Nature Glenelg Trust), Museum and Art Gallery of the Northern Territory, and University of Łόdź researchers and examines modelling techniques with the aim of identifying significant relationships between the abundance of a native small bodied fish (Galaxias olidus sensu lato) and components of flow regimes representative of temporary streams of the Eastern Mount Lofty Ranges. Relationships were tested based on 1-year and 3-year antecedent flow metrics representing flow regime between 2001 and 2013, and for 0+ (recruits), 1+ and 2+ (survivors) year age groups. The research showed that increases in the abundance of G. olidus were linked to metrics that represent greater water availability and the persistence of water across the year (annual total duration of bank-full flows, and total duration of zero flow in the low flow season), whereas recruitment was more strongly linked to longer term 3‑year metrics (number of years with zero-flow spells in the transition from the high flow season (HFS) to the low flow season (LFS), and number of years with two or more freshes in the transition from the LFS to the HFS). The research also found an unexpected negative relationship between the abundance of adults and average daily flow in the transition from the LFS to the HFS which is expected to increase both habitat and food availability and promote higher abundance. Researchers theorise that this may be due to the remobilisation of nutrients and deterioration of water quality during these break of season flows and/or the dispersal/displacement of fish which may act to distribute individuals and reduce abundances in monitored pools. The study emphasises the importance of restoring natural periods of low flow over the summer and autumn months, and supports the principals informing the current program to restore low flows across the Eastern and Western Mount Lofty Ranges. The study concludes that the study has successfully demonstrated a modelling approach that will allow further description of flow-ecology relationships that can be used to inform programs aimed to promote native fish communities across the study region. The paper can be downloaded here (or email jennie.fluin@sa.gov.au for a copy).