Freshwater fishes of Australia

Stephanie Januchowski-Hartley

Australia!

Image credits: V Hermoso

Today’s talk!

Origins of Australia’s freshwater fishes

Biogeography of Australia’s freshwater fishes

Ecology of Australia’s freshwater fishes

Humans and freshwater fish

Credit: SRJH

Entire evolutionary history restricted to freshwater

Fossil records pre-date fragmentation of Gondwana

Few of these species in Australia

Freshwater fish origins

Primary freshwater species

Gondwanaland: geos309.community.uaf.edu

Derived from marine fishes/ ecosystems

Ancestors from tropical Indo-Pacific

Majority of Australia’s freshwater fishes

Freshwater fish originsSecondary freshwater species

Today’s talk!

Origins of Australia’s freshwater fishes

Biogeography of Australia’s freshwater fishes

Ecology of Australia’s freshwater fishes

Humans and freshwater fish

Credit: SRJH

Rainfall and catchment size influence biogeography

BiogeographyThe distribution of species through space and time

Species richness - the number of species in a defined area

driven by river discharge and perennial stream flows

Richness

Map: peter.unmack.net

Endemism - unique occurrence of a species to a single area

47% of freshwater species endemic to a single region

Driven by isolation due to aridity and drainage divides

Biogeography

Map: peter.unmack.net

Today’s talk!

Origins of Australia’s freshwater fishes

Biogeography of Australia’s freshwater fishes

Ecology of Australia’s freshwater fishes

Humans and freshwater fish

Credit: SRJH

Lepidogalaxias salamandroides (Salamanderfish)

Primary freshwater species

Endemic to peat lands between two riversMap: peter.unmack.net

Lepidogalaxias salamandroides

Inhabits small (2-600 m2) acidic ephemeral ponds

Aestivation - is a state of animal dormancy due to arid conditionsWhere are the fish?

Fishes remain in burrows

(up to 1m below) until rain returns next

yearImages: australianmuseum.net.au

Adapting to life under pressure

Performs internal fertilization

Wedged-shaped skull resists weight of wet sand

Vertebrae gaps and reduced abdominal ribs allow burrowing

Cannot move eyes; flexible vertebrae allows head to turn

Tropical river diversity

8,000 km2 supports >50% of Australia’s freshwater fish

11 rainforest endemics - perennial flow and riffle habitats

Rainforest vegetation important role in fish diets

Credit: SRJH

Kuhlia rupestris(Jungle Perch)

Feeding adaptations

Cairnsichthys rhombosomoides(Cairns rainbowfish )

Feeding adaptations!CREDIT: National Geographic

Toxotes chatareus(Seven-spot archerfish)

Amphidromy

Adult spawn in fresh waterLarvae pass to sea to feed and grow Young of year return to fresh waters

Image: hawaiiwatershedatlas.com

What are amphidromous fish adaptations?

Where would amphidromy be advantageous?

Image credit: D. Hogan

Amphidromy in Australia’s streamsAmphidromy sparse on continents

Conditions similar to island streams

Small coastal drainages poorly sampled

10 new amphidromous species recorded (2011)

many species found on nearby islands

Amphidromy in Australia’s streams

doi:10.1371/journal.pone.0026685.g002

Today’s talk!

Origins of Australia’s freshwater fishes

Biogeography of Australia’s freshwater fishes

Ecology of Australia’s freshwater fishes

Humans and freshwater fish

Credit: SRJH

Humans and fishesWhat types of human disturbances do you think could threaten

Australia’s fishes?

Thank you for listening!Related reading:

Biogeography of Australian Freshwater Fisheswww.peter.unmack.net/biogeog

Freshwater Fishes of Northeastern AustraliaPusey, Kennard and Arthington 2004

Amphidromy Links a Newly Documented Fish Community of Continental Australian Streams, to Oceanic Islands of the West

Pacificjournals.plos.org/plosone/article?id=10.1371/journal.pone.0026

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