Can trees control algal blooms – you’d be surprised

By Professor Michele Burford

Reading Time: 537 words, about 3 minutes.

Algal blooms are a major issue for water security globally and in Australia. We have seen the damage algal blooms have had on Murray-Darling Basin and the issues Florida have had with the recent ‘red tide’ epidemic. As our climate changes, we can expect more algal blooms – but is there a simple solution to help reduce these blooms?

Blue Green Algae Bloom. Photo: Sunraysia Daily.

Researchers in the Burford group have recently discovered that fallen leaves can play an important role in controlling algal blooms. The list of reasons why trees are so important to our ecosystems continues to expand.

Australian river. Photo: Michele Burford.

Summer is a time when Australian families are enjoying our waterways. Be it fishing, swimming, snorkelling, or kayaking, during summer you are likely to encounter people enjoying quality outdoor time. However, a disappointing surprise is arriving at the destination only to find signs indicating the waterways are ‘closed’, or the presence of green scums on the water surface, due to the occurrence of a blue-green algal bloom. This common ecological problem not only puts a stop to your holiday’s aquatic activity plans, but it also increases the costs of water treatment and can have major effects on the plants and animals in our waterways.

This common ecological problem not only puts a stop to your holiday’s aquatic activity plans, but it also increases the costs of water treatment and can have major effects on the plants and animals in our waterways.

Nutrients coming from the land, e.g. fertilizers, soil erosion, are a major cause of algal blooms, and planting trees along waterways is one commonly accepted way to reduce nutrient runoff. This is because trees take up nutrients from the soil in order to grow. But trees have another role, as we have recently found. Researchers in Professor Michele Burford’s research team, The Burford Group, have discovered that when leaves are wet they leach organic molecules which can inhibit blue-green algal blooms. Undertaking the research the team used a combination of novel techniques not previously applied to freshwater systems. Their findings may help explain why waterways surrounded by vegetation may have less problems with blue-green algal blooms than other waterways. This gives us a fresh perspective on trees, showing that they don’t just control algal growth by shading, they may also be chemically controlling growth.

This gives us a fresh perspective on trees, showing that they don’t just control algal growth by shading, they may also be chemically controlling growth.

Algal control through leaf leaching. Diagram: Amanda Neilen

So, can leaves from trees be used to control blooms? Certainly, planting and protecting trees along the edges of rivers, creeks, ponds and lakes is likely to be beneficial in suppressing blue-green algal blooms. Potentially chemicals within the leaves could be used as an algal control mechanism. Overall, trees have an even greater role in preserving water quality than we previously thought.

Collaborators:

This study was conducted by researchers and students at Griffith University with support from Seqwater, Healthy Land and Water, Griffith University and the Australian Research Council.

Research Publication:

This article was based on two research papers, both were published in the journal, Science of the Total Environment.

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