Beautiful Brine Shrimp

A female brine shrimp at the northern end of Lake Preston (note the dark, egg filled “brood chamber” between her tail and abdomen)

Brine shrimp (Artemia sp.) are halophilic (salt-loving) invertebrates that are common in salt lakes, including those found in the Yalgorup Lakes system.  As part of PHCC’s current “Ramsar Project” monthly water quality assessments are being carried out at the 17 waterbodies that comprise the Yalgorup Lakes. In addition to collecting water quality data, we also take the opportunity to record any other casual observations of interest. During July and August of this year large numbers of brine shrimp were observed at the northern end of Lake Preston.

Brine shrimp can tolerate salinity of over 200 g/L which is five to six times the salinity of seawater. This is just as well for the Lake Preston population as the salinity of the lake can become this high over summer, with the salt concentrated by evaporation.  Brine shrimp feed on microscopic algae in the lake and are in turn prey to waterbirds like the Banded Stilt, although their small mass probably means they’re more of a snack to the bird than a main meal.

Their salt lake habitat is a bit unreliable as these wetlands, like many in Australia, can dry out over summer.  To overcome this brine shrimp produce eggs with a very hard coating (sometimes called “cysts”) that can survive in a dormant state in dry lake bed sediments for several years. These cysts hatch once wet conditions return.

The hardy brine shrimp eggs are therefore popular in aquaculture where harvested eggs can be stored, then added to fish tanks as required as a food source for small fish.  The tiny, newly hatched young, known as “nauplii”, make perfect food for newly hatched fish fry.  Our friends at John Tonkin College have been growing Artemia sp. from cysts as food for aqua-cultured black bream that are destined for release into the Murray River, but that’s another story….

The project work at the Yalgorup Lakes is being delivered by PHCC through funding from the Australian Government’s National Landcare Program.