Camp pond had completely dried up
as of July 12, 2006
Credit: U of Alberta
In yet one more harbinger that global climate change has accelerated in the Arctic, shallow ponds that served the tundra as biological “hotspots” and bird habitat for millennia have suddenly shrank or disappeared under the withering summer sun.
Some ponds that existed as permanent features for more than 1,000 years on Cape Herschel of Ellesmere Island in far northeastern Canada abruptly evaporated in a season or two, according to a new study, Crossing the final ecological threshold in high Arctic ponds, published July 2 in the online edition of Proceedings of the National Academy of Science.
“The final ecological threshold for these aquatic ecosystems has now been crossed: complete desiccation,” wrote Marianne Douglas, Professor of Earth and Atmospheric Science and Director of the Canadian Circumpolar Institute at the University of Alberta, and John Smol, Professor of Biology at Queen’s University, in the study’s abstract.
“It was quite shocking to see some of our largest study ponds dry up by early summer,” said Douglas.
They blamed the changes on warmer and drier conditions that shifted the ratio of evaporation to precipitation.
“These shallow ponds, which dot the Arctic landscape, are important indicators of environment change and are especially susceptible to the effects of climate change because of their low water volume,” the authors said in a story about the findings.
Douglas and Smol have been studying about 40 unique ponds periodically for the past 24 years, collecting data on water quality and water levels in nine different seasons between 1983 and 2006.
“Collectively, this data represents the longest record of systematic limnological (the science of the properties of fresh water) monitoring from the high Arctic,” they wrote.
Unlike many other Arctic ponds in tundra zones, these ponds were underlain by granite and appeared remarkably stable. Still, over the years, they found evidence of increasing evaporation relative to precipitation, and changes in water chemistry, that suggested warming temperatures. But nothing prepared the scientists for what they discovered when they returned to the tundra in July 2006.
Dr. Marianne Douglas in the high Arctic
(with Greenland in the background).
Credit: University of Alberta
Several of the main ponds had gone dry. Others had shrunk.
“The desiccation of small, shallow sites is certainly of ecological and environmental significance; however, what is especially worrisome is that many of the disappearing ponds are of considerable size,” they wrote in the study.
“For example, one of our main sampling sites is Camp Pond. During earlier periods of higher water levels (i.e., the 1970s and 1980s), it typically had dimensions of 20 m by 40 m and even larger during wetter years, yet it was completely dry by July 12, 2006.
“Cape Herschel Lagoon, a substantial water body of 160 m by 35 m and 1 m deep in the 1980,
has only a small shallow puddle of water (23 m 11 m, and 10 cm deep) left in one basin when we sampled it on July 13, 2006.”
The ecological ramifications of these changes are likely severe and will be felt throughout the Arctic ecosystem, says Douglas. It would affect waterfowl habitat and breeding grounds, invertebrate population dynamics and food for insectivores and drinking water for animals, to name only a few.
“These surface water ponds are so important because they are often hotspots of biodiversity and production for microorganisms, plants and animals in this otherwise extreme terrestrial environment.” said Douglas.
“The final ecological threshold for an aquatic ecosystem is loss of water,” Smol added in a release. “These sites have now crossed that threshold.”