EPOW - Ecology Picture of the Week

Explanation:   We are standing on the edge of a large, very shallow lake in arid southeastern Australia.  This lake bed is often dry.  When full it is the destination of boaters and fishers.  But today the air wreaks of decaying fish and the putrid waters have receded well into the lake basin interior. 

This is Lake Hindmarsh, fed by the Wimmera River from the highlands of western Victoria.  The lake is usually a playa with no permanent outlet, but after several consecutive wet years -- which occur only every two decades or so -- it overflows into Outlet Creek and into the adjacent Lake Albacutya in the Wimmera Basin.  When full, Hindmarsh is the largest inland freshwater lake in Victoria, with 4 miles (6.4 km) of beach.  This massive carp dieoff was likely from a local, periodic drought.   

When it has water, Hindmarsh provides habitat for several species of game and nongame fish including redfin, golden perch, freshwater catfish, tench, goldfish, and many carp, as well as freshwater crayfish or yabbies.  The golden perch and freshwater catfish enter from the Wimmera River where they have been stocked for many years.  Golden perch and freshwater catfish are listed as vulnerable species under the Australian Flora and Fauna Guarantee Act of 1988.

Hindmarsh is one of many wetlands and lakes in the Murray-Darling River Basin that are of local importance for recreation, fishing, and agricultural irrigation, and of international importance for wetland habitat conservation.  However, most of the river and lake wetlands in this region have suffered degradation of their habitats from multiple causes, including water diversion, introduction of effluents from surrounding agricultural and livestock fields, introduction of exotic fish and aquatic plant species, and rising saline groundwater.