Fabulous Foxtail Stonewort

A Foxtail Stonewort “meadow” on the bed of Myalup Lagoon, November 2021

Here in the south-west farmers look forward to the autumn break when the first rains of the season green up pastures after our hot, dry summers, providing fresh feed for stock. But did you know the same thing happens at some of our wetlands? In this case, the new growth is a type of nutritious algae that provides food for herbivorous waterbirds.

Foxtail Stonewort (Lamprothamnium papulosum) is a type of algae that has a worldwide distribution and is common at the Yalgorup Lakes.  It is in the algal group known as charophytes, which can be considered advanced algae in that they have a more complex structure than most algae and are considered to be close relatives of modern land plants. In general, algae have a simple cell structure that cannot withstand desiccation, which is why they are commonly found as submerged plants in wetlands.

Foxtail Stonewort has some tolerance of saline water but will not thrive when the salinity approaches that of seawater. Many of the Yalgorup Lakes are very saline and so there is only a select group of lower salinity wetlands where this algae can grow. Myalup Lagoon is one such wetland at the southern end of the Lake Preston group. This wetland typically dries out at the end of summer, but as it refills in winter and spring the clear, shallow, slightly saline water provides the ideal conditions for Foxtail Stonewort “meadows” which develop on the lake bed from propagules left in the bed sediments from previous seasons.

The shallow water and dense carpets of algae provide the ideal feeding conditions for herbivorous waterbirds such as ducks and Black Swans. Foxtail Stonewort can either reproduce sexually from “seeds” known as oospores (algae don’t produce true seeds) or by vegetative reproduction from bulbils. The starchy bulbils are known to be particularly nutritious for the waterbirds and can support flocks of thousands for many months over spring and early summer.

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