Hey, what’s up with my lake?

A heron enjoys hunting in the ruddy muck. Photos by David Bell

HYDE PARK’S lakes took on an alarming hue this week, but an expert tells us it’s no cause for concern yet.

A large part of the western lake has a thick green covering and the eastern lake has a reddish crust over most of it, evocative of algal blooms of past years and leading passersby to comment their concerns about the baby ducks making their way through the muck. One park-goer worriedly stated the lake was so red it looked like a gravel road. 

But the Voice bumped into horticulturalist John Viska who said the majority of the covering wasn’t algae, but plants. 

The red matter is azolla filiculoides (water fern) and the green matter looks to be lemna minor, a duckweed that the ducks eat, with a little bit of algae floating among it. 

“They’re spontaneous germinations because the conditions are absolutely ripe,” he says. “Water temperature, mainly: As the water temperature increases they start to germinate,” likely from spores that blew in. 

Vincent mayor Emma Cole consulted the council parks team and they came to the same conclusion as Mr Viska. 

“Our parks team have reassured me the lakes are Hyde Park are in good health and pose no cause for concern,” Ms Cole says.

“The presence of these plants in our lakes do not indicate poor water quality. 

“However, the abundance of their growth may be a result of the high rainfall received over winter which may have washed extra nutrients into the lakes.

“Vincent has engaged a consultant to undertake quarterly water monitoring of the lakes and initial results indicate that the water quality is good with slightly elevated nutrients levels however, subsequent sampling is required to confirm this.

“The aquatic plants will assist in removing the excess nutrients from the water as well as provide habitat and food for our aquatic wildlife.”

Ms Cole says the plants are 

a seasonal occurrence, though we can’t recall seeing this much covering in recent years. She says the parks team will keep monitoring the lakes and take action if needed.


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