The nightfish (Bostockia porosa) is a species of freshwater fish endemic to south-western Australia (meaning it is found no where else in the world!) and as the name suggests is active mostly at night. The nightfish is carnivorous and has been documented feeding on a range of taxa, including ostracods, gastropods, amphipods and even decapods (e.g. consuming parts of freshwater crayfish). The species has had limited research, with the biology of the species only being described in a paper in 1990. However, more recent broad sampling by freshwater ecologists has begun to decipher the mystery and expose the threats the nightfish faces.
A study by Beatty and colleagues published in 2014 documented large downstream movements of juvenile nightfish in tributaries of the Blackwood River (e.g. Milyeannup Brook) during November and December, as well as migration in the species being significantly associated with surface water discharge. The findings of movement predominantly in the tributaries of the Blackwood River supports earlier research by Dave Morgan and colleagues. A paper published in 2003 found increasing salinity in the Blackwood River had caused the extinction or massive decline in a number of species from the main river channel itself. Whereas the tributaries containing natural forest vegetation and lower salinity levels still contained species such as the nightfish. Although the nightfish is one of the most widespread native freshwater fish in the south-west region, salinization is an ongoing threat and is causing the decline in populations in many of the river catchments. The problem is unfortunately exacerbated by climate change in the south-west where average rainfall has declined drastically since the 1970s leading to even greater decreases in runoff/discharge and altered groundwater levels. The protection of the species in the south-west is now reliant on the preservation of high quality habitat, particularly in areas that remain uncleared, as well as the potential for intervention through the creation of artificial wetlands within the natural environment. Fun fact! The nightfish is one of several native species of fish that host the glochidia (parasitic larvae) of the native freshwater mussel (Westralunio carteri) Further reading
0 Comments
Leave a Reply. |
AuthorMy name is Garry and I am extremely passionate about the environment. I have completed my BSc. Conservation and Wildlife Biology with First Class Honours and have worked in the Environment sector since 2009. Archives
September 2019
Categories |
Photos used under Creative Commons from sean.kelleher1, BioDivLibrary, BioDivLibrary