The team’s findings have been published today in the journal Global Change Biology.
The scientists reported they cannot confidently predict how lakes will respond to the more frequent and intense storms that are expected in a warming world.
“If extreme weather events significantly change carbon, nutrient, or energy cycling in lakes, we better figure it out quickly,” says Jason Stockwell, an aquatic ecologist at the University of Vermont who led the new research, “because lakes can flip, like a lightbulb, from one healthy state to an unhealthy one—and it can be hard or impossible to flip them back again.”The new study focused on phytoplankton—microscopic plants commonly known as algae. Phytoplankton are of particular concern because they are the base of the food web and a critical driver of water quality.
In a search of thousands of scientific articles from around the world, the scientists found just 31 studies on 18 lakes that connected storms to freshwater lake conditions, and then to phytoplankton. Not only was the information sparse, but the few available findings were inconsistent.
It became clear that the scientific community has a poor understanding of how phytoplankton respond to storms, or how their responses may differ by storm types, across different lakes, or even at different times of year.
Dr Verburg said none of the 31 papers were about New Zealand lakes and the only related research involved a 1970s paper looking at how macrophytes were uprooted by an intense stormcausing a lake to become more turbid and stopping plants becoming reestablished.
Dr Verburg said it was known that lakes were becoming warmer in New Zealand which for deep lakes meant that typically the shallow warmer water mixed less with the deeper colder water which had flow on effects to the entire ecosystem.
“Research in this area has become urgent – lakes are definitely changing because of climate change and we need to know more about the role of storms in changing them.”
“Again that is something that needs a lot closer investigation. My fears are that the nutrient reductions being planned will not be sufficient and many lakes will become more eutrophic because of climate change effects.”Dr Verburg has applied for funding to study aspects of climate change effects on Lake Taupo. He and the other scientists involved in the review are calling for a collaborative, multi-disciplinary effort.
They suggest several research directions including integrating watershed and lake physical models with biological models to better predict phytoplankton responses to storm-induced changes to lake conditions. The scientists also recommend continued and expanded long-term lake monitoring programs, coupled with networks of electronic high-frequency sensors, to evaluate short-term changes, emergent patterns, and long-term responses of lakes and water quality to storm events.
Long before climate change became recognized as one of the world’s major problems, water scarcity was widely recognized as a challenge for humanity.Unfortunately, the rise of awareness about the challenges of climate change had a perverse result when it came to the world working collectively to reduce global water scarcity.