Freshwater Fish (lecture 2) Flashcards
freshwater fish
occupy freshwater habitat for a significant part of lofe cycle
freshwater evolutionary perspective
only four fish follow it (lungfish, north and south saratoga, and salamanderfish)
-all evolved in freshwater
Gwandan relic(only live in freshwater)
lungfish, saratoga, and salamander
Marine colonizer(marine ancestors)
catfish, eel, rainbowfish, galaxiids, blackfish, lampreys, and murray cod
reason for few Australian species
-fish need water(Australia is highly variable and pretty dry and arid)
-runoff (low runoff since Australia is 80% arid)
-not looking hard enough
(neglected group of Australia wildlife)
-not looking in the right places (KImbley region have found incredibly new species, but not visited)
types of habitats
torresian, eyrean, bassium
torresian
- monsoonal, warm
- north coast
- wet/dry season
- wide flood plain
eyrean
- arid, ephemeral bodies water bodies
- inland
- source on West of Great Divide
- fluctuating, unpredictable levels
- warm, slow and turbid
- massive floodplain
- salt lakes
bassium
- high rainfall, cooler, permanent water
- east coast
- source on East of Great Divide
- fall rapidly to the sea
- clear and cool
- relatively stable flow
- mountain lakes
Australia’s hydrologic background (time series of flow)
gauged streams
- nationally-80% of stream do not flow continuously over time
- victoria-50%
much greater percentage in ungauged catchments
high inter-annual variability in duration of zero flows
challenging environment for fish to persist in
many exploit refuges
Australia’s specie richness of freshwater fish compared to the rest of the world
- low
- 206 exclusively freshwater native species
- about 70% endemic, especially in Tasmania, south-west WA and the Kimberly region
- 71 non freshwater dependent species
- 26 exotic or introduced species
migration patterns during life cycle
diadromous
-anadromous, catadromous,
amphidromous
obligate freshwater
-potamodromous
diadromous
- using two different habitats
- fresh and salt water
anadromous
-type of diadromous
-sea to stream
-spends adult life in marine then move to freshwater to spawn
-ex.
lampreys, Tas whitebait
catadromous
-type of diadromous
-stream to sea
-spend adult life in freshwater then moves to marine to spawn
-ex.
eel, barramundi
amphidromous
-type of diadromous
-non-breeding migration, both ways
-dont move to spawn, but move to take on new food source
-ex.
Australian bass
potamodromous
-type of obligate
-freshwater migration
-dont experience environment stress from salt to freshwater
-move during spawn
-ex.
silver perch
threatening procesess
habitat change and introduction of exotic species
habitat change
- river regulation
- salinisation, pollution, and eutrophication
river regulation
a habitat change
dams
- Australia has variable rainfall
- used for human
consumptions
barriers from moving to freshwater
-lead to fragment
population (higher chance of extinction)
prohibits the nutrients for down stream food chains
alter flow regimes
high flows occur in the summer instead of the environmental spring due to dams
-effects fish spawn
cutting down brush
- bringing more salt to the surface
- loss of habitat
salinisation, pollution and eutrophication
- a habitat change
- 95% of Australia’s original wetlands degraded or lost due to rural development and mining
- particularly severe in heavily populated coastal areas and farming areas
- salinisation is caused by land clearing resulting in a rise of the salt-laden water table
- agricultural chemicals
introduced or exotic species
trout, mosquito fish, and carp
trout
- introduce specie
- introduce for angling to feel like the old country
- preservation of trout fishery is strong
- predators of native fish
mosquito fish
- introduce specie
- used for mosquito control but failed
- competes with natives
carp
- accidental
- number one pest
- impact debated
- bottom feeder
- destructs habitat beds
- shear biomass
