Long hot summers in 2018 have increased occurrence of cyanobacteria blooms in lakes around the world

A number of articles have been posted on the internet about the environmental effects of a long hot summer in 2018. This article is a summary of some of those.

A link between sustained hot dry weather and outbreaks of blue green algae (cyanobacteria) in water bodies was discussed in an article at https://northsearegion.eu/canape/news/canape-the-long-hot-summer/ . “Hot weather is great – ice cream, swimming, sailing, hiking, the long hot summer has provided us many opportunities to enjoy all of these things. On the other hand, we are also experiencing the environmental affects of hot weather, which has caused particular issues in our peatland ecosystems. In the Netherlands and in the UK, our partners are struggling with cynabacteria, so-called “Blue-Green Algae” which has bloomed and rendered many areas of water unsuitable for swimming and recreation”. 

The article goes on to say “With global temperatures expected to rise due to global warming, leading to a rise in average summer water temperatures, it is inevitable that algal blooms will become more common unless we can take action to reduce the nutrient pollution in our water”.

Another article at https://www.bbc.com/news/uk-scotland-44838622 states the hot summer has lead to toxic algae in Scotland’s Lochs.

The “blue-green algae, which poses a health risk to humans and animals, has flourished during the warm spell”. Freshwater ecologist Prof Laurence Carvalho said blue-green algae had been a particular problem this summer. “Not only has it been very warm but it has also been very dry, which means they have not been flushed out of water courses by rain,” he said. It is posing a particular risk to dogs who appear to be attracted by the smell, he added.

Earlier this month a dog reportedly died from algae poisoning after drinking water from the River Conon, near Maryburgh in the Highlands. A similar incident is reported to have happened in Loch Awe in May.”

“Blue-green algae are microscopic, but clump together in visible colonies up to a few millimetres in size that can rise to the surface and form thin wispy green blooms or thick, paint-like scums. When it is ingested, it can cause damage to the liver or the nervous system in humans and animals. People who have been swimming in or have swallowed algal scum can suffer from skin rashes, eye irritation, vomiting, diarrhoea, fever and muscle and joint pain but there is no evidence of long-term effects or death among people in the UK”. “It will also help us understand the drivers of growth of these algae, such as the impact of climate change.” 

Britain has also recorded the effects of the long, hot summer on their waterways.  An article at https://www.countrylife.co.uk/nature/natures-winners-losers-summer-2018-181433 stated that “Fishermen are struggling, as the water levels in some rivers are too low for salmon and sea trout to move upstream. Similarly, hot weather can affect coarse fish through de-oxygenation of the water or the abundance of lethal algae blooms”. 

And it’s not only an issue in the northern hemisphere. An article from New Zealand https://www.nzherald.co.nz/the-country/news/article.cfm?c_id=16&objectid=11994259 explained that “a long, hot, dry summer is responsible for an algae bloom in Lake Hayes which may be toxic to humans and animals. The Otago Regional Council placed signs around the lake yesterday recommending people and dogs ”avoid contact” with the water after cyanobacteria scums, or blue-green algae, were found over the weekend. ORC environmental resource scientist Rachel Ozanne said it was ”unusual” for the algae to occur in Lake Hayes. The last known bloom there was in 1981”.

Meanwhile, the Australian Government Bureau of Metrology (http://www.bom.gov.au/climate/drought/drought.shtml) has reported that “September was Australia’s driest on record. Rainfall was very much below average nationally, and particularly low across the southern mainland”.

An article published at https://www.sbs.com.au/news/heatwaves-and-bushfires-el-nino-may-hit-australia-by-end-of-year warned “Heatwaves and bushfires are set to sting southern Australia while the nation’s north may be spared from cyclones, with a 70 per cent chance of Niño on the way. There is triple the likelihood of an Niño weather pattern bringing drier-than-normal conditions by the end of 2018, the Bureau of Meteorology warned….”.

Based on these predictions, it is probable that the issues such as the cyanobacteria blooms experienced in Europe in their recent “long, hot summer”, could soon be felt in countries such as Australia which are about to enter into the summer months.

Phoslock is one of the products that is used by Phoslock Environmental Technologies (PET) to reduce the concentration of nutrients in water. Phoslock binds excess dissolved phosphorus and renders it unavailable for consumption by cyanobacteria. Phoslock is used by water body managers as a tool to control harmful and persistent algal blooms.