Naturally lowering levels of algae

May 9, 2023 | WONDER | 3 minute read

If you’ve visited Holkham recently, you may have noticed some strange bags of barley straw dotted around the lake. Don’t worry – it’s for good reason! Here, Head Houseman Ryan shares the science behind the floating straw.

How does it work?

This is the annual mission of tackling the blue-green algae bloom which can be toxic and harmful to humans, dogs and waterfowl.

Pete, Roger and I have been busy transporting the barley lakeside that has been kindly bagged up by Wayne and Andrew. As the barley sits in the water, it starts to slowly decompose. During decomposition, the cellular structures of the barley break down.

The barley breaks down faster in warmer and more aerated water so this time of year is ideal to begin the process. After a few weeks of being in the lake, the bacterial dominant breakdown becomes fungal dominant which leads to the rotting of the barley. As the fungus eats away at the barley, it releases Humic Acid which leeches into the surrounding water.

Once it reacts with the aerated water’s oxygen and sunlight, it becomes increasingly unstable and forms a superoxide radical, hydrogen peroxide.

Hydrogen peroxide is a powerful algaecide, but when slowly produced in this naturally forming way it has no ill effect on the aquatic life in the lake. It is, however, still strong enough to battle the blooms of algae.

Why do we need to do this?

The reason we battle the algal blooms is that they place a huge stress on our lake’s ecosystem; when the algae dies and decomposes, the bacteria that break it down have to consume oxygen to do so. This leaves in the lake for the fish and can potentially be fatal to many species that depend on the lake.

Hopefully by the time the summer, Outlaw half triathlon and Festival of Sport are here, the lake will have a lower level of algae and having used a natural method the water quality will be all the better for it!