Oct. 18 (UPI) -- New research suggests it's possible to have too much biodiversity. In lab tests, scientists in Switzerland showed elevated levels of biodiversity can destabilize ecosystems under certain conditions.
Understandably, most research into the effects of climate change on ecological health have focused on decreased levels of biodiversity measured around the globe. The evidence on the topic is consistent. Most ecosystems host too little biodiversity, not too much.
But researchers at the University of Zurich and the Swiss Federal Institute of Aquatic Science and Technology weren't interested in most ecosystems -- or any real ecosystem, for that matter. They wanted to better understand the relationship between biodiversity and ecological stability.
In the lab, the team of ecologists created miniature ecosystem models using different combinations of six ciliates species. Ciliates are tiny protozoans that live anywhere there is water.
In sample vials, scientists mixed different numbers and combinations of ciliate species. Researchers then exposed the miniature model ecosystems to temperatures between 15 and 25 degrees Celsius. Different models were exposed to different levels of warming to approximate climate change.
A special computer algorithm and video analysis technology allowed scientists to track the different species and changing levels of biomass in each vial.
The experiments produced contradictory results. The data showed biodiversity have both a positive and negative impact on ecosystem stability.
"Ecological stability is complex and consists of various components," Frank Pennekamp, an evolutionary biologist at the University of Zurich, said in a news release. "The experiment shows how biodiversity affects the individual stability components in different ways."
Scientists identified a strong correlation between biodiversity and stable biomass production. The greater the number of species in a vial, the less biomass production fluctuated. But as temperatures increased, scientists found biodiversity put a downward pressure on biomass production. Protozoans in diverse and warming ecosystems produced less biomass.
The new study -- published this week in the journal Nature -- suggests biodiversity, under certain circumstances, can in fact limit an ecosystem's stability.
"The results make it clear that more species alone is not enough to ensure the overall stability of an ecosystem," said Florian Altermatt, professor of aquatic ecology at the Swiss Federal Institute of Aquatic Science. "In addition to a diversity of species, the species themselves must be able to react to environmental changes in a variety of ways."