The Australian Freshwater Environment & its fish fauna A/Prof Paul Humphries School of Environmental Sciences, Charles Sturt University The Murray-Darling Basin Albury National Archives River discharges: Australia vs the world! River Danube (Welti et al. 2012) Drainage basin types in Australia • Exorheic - rain discharges to sea • Endorheic drainage is internal • Arheic - surface drainage patterns absent Source: Williams Australian Freshwater Life (1980) Freshwater lakes Few large deep lakes on Australian mainland; most are in Tasmania Australian still waters Salt lakes • Common in Australia • Resident organisms have adapted to high salinities Australian still waters Billabongs • Oxbow lakes • Occur along most meandering rivers • Link running & standing waters Swamps • Shallow sheets of standing water • Highly productive habitats • Often drained or cleared Australian flowing waters Great Dividing Range Australian flowing waters Wet-dry tropical flooddrought rivers • Kimberley to Cape York • Huge volumes of water • Often dry seasonally Australian flowing waters East & south of GDR Most diverse group Most are relatively short Many fish species migrate to sea Human impacts are high Australian flowing waters Arid-zone rivers Highly unpredictable Dry to series of waterholes Huge increase in surface area when flooding Groundwater- dependent ecosystems Source: Boulton and Brock (1999) Australia’s freshwater fish fauna Its diversity and its peculiarities Number of species by country Country Total Native Alien Extinct Brazil 2298 2281 17 0 USA 883 821 61 25 India 678 659 19 0 Cameroon 490 487 2 0 Europe 400 368 32 ? Australia 325 297 28 0 Guatemala 151 143 8 0 Vanuatu 30 29 1 0 Best predictors of number of species • Number of species related best to mean annual discharge • Then surface area Oberdorff et al., 1995 A depauperate fauna? • In total, yes. • In relation to discharge….no! • But species have to contend with much variability Discharge Speciesrichness Murray Amazon Australian freshwater fish fauna • Approx. 256 native freshwater species in Australia – >60% endemic • Gondwanan origins likely for: – Retropinnidae (smelt and grayling) – Galaxiidae (galaxiids) – Percichthyidae (cods and basses) – Ceratodidae (lungfish) – Osteoglossidae (bony tongues) Lungfish & saratoga The world 200 million years ago Australian freshwater fish fauna • Deep oceanic barrier between eastern Indonesia and Australia/New Guinea region probably prevented dispersal of: – Cypriniforms (carps, loaches, suckers) – Siluriforms (catfishes, knifefishes) Photo: Sabaj Richness 1 and 5 9 - 15 20 - 25 28 - 34 36 - 44 54 - 62 CYP W KIM 14 5 54 43 39 4442 62 41 34 28 32 37 14 40 331 11 23 23 25 20 20 36 32 41 33 9 29 15 56 W P LEB MD B PILB SG C VO R BAR K FITZ W GC BU R D EG C NEN BU LL SW W A SEQ AR N H SW V DALY SEN SEV NICH TOR R SAG STAS EKIM NEQ NTAS SEC YP AR C H N 0 500 1000 km Freshwater fish species richness by drainage basin Murray-Darling Basin species and endemism River No. of species Endemism Murray-Darling ~34 ~75% Danube 62 5% Zaire 690+ 84% Niger 134+ 5% Nile 115+ 20% Eleotridae (gudgeons) 31 spp Galaxiidae (native trout/minnows) 22 spp Rowley Nelson McDowall McDowall Percichthyidae (cods and basses) 20 spp Ryan Includes: pygmy perches (8 spp) Includes: blackfish (2 spp) Terapontidae (grunters) 25 spp Melanotaeniidae (rainbowfishes) 15 spp Clupeidae (herrings) 3 spp Lepidogalaxiidae (salamanderfish) 1 sp Pseudaphritidae (tupong/sandy) 1 sp SO, HOW DO AUSTRALIAN FISH SURVIVE SUCH A HARSH ENVIRONMENT? Aestivate = summer hibernate Diadromy: move between f/water & sea Hsien-Yung Lin, 2016 Environmental disturbance to Murray-Darling Basin rivers Barriers to fish Introduced species Chronology of freshwater fish introductions to Australia Common carp 2016 Methods for controlling carp • Commercial fishing • Recreational fishing • Active netting/electrofishing • Carp cages at fishways • Daughterless carp • Koi herpesvirus Eastern gambusia Brown trout Tilapia Russell et al. 2011 Algal blooms Flow alteration 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 J F M A M S O N D Ovens River (natural) Goulburn River (regulated) Discharge(ML.d-1) J J A Temperature depression Ovens River Goulburn River 10 12 14 16 18 20 22 24 26 28 30 21/09/2005 5/10/2005 19/10/2005 2/11/2005 16/11/2005 30/11/2005 14/12/2005 28/12/2005 11/01/2006 25/01/2006 8/02/2006 22/02/2006 8/03/2006 22/03/2006 Temperature(oC) Over-fishing Murray cod: the biggest fish in the river Thank you phumphries@csu.edu.au Rheophilia: interviews in freshwater science River Ecology Blog