North American Lakes 'Jellify' as Calcium Levels Decline

Your lakes may be turning into jelly. Scientists have found that as calcium levels continue to decline in soft-water lakes, certain organisms are also disappearing and being replaced by jelly-like creatures.

Due to prolonged periods of acid rain and timber harvesting, may soft-water lakes in North America are experiencing declining calcium levels. This, in turn, has caused ecosystems to shift. The animals that have calcium requirements, such as the water flea Daphnia, are being replaced by other animals.

"Calcium is an essential nutrient for many lake-dwelling organisms, but concentrations have fallen so low in many lakes that keystone species can no longer survive," said Adam Jeziorski, one of the lead authors of the new study, in a news release. "Conditions now favor animals better adapted to lower calcium levels, and these changes can have significant ecological and environmental repercussions."

In order to better understand this shift, the scientists examined tiny fossils from lake sediments. This allowed them to determine the pre-impact conditions of the lakes as the calcium decline began before monitoring programs were put into place. Using this method, the researchers reconstructed the environmental conditions of the past 150 years.

"Lake sediments act like a history book of past changes in a lake, recording what happened before the problem was identified," said John Smol, one of the researchers. "Jelly-clad invertebrates have been increasing in an alarming number of lakes. This is likely a long-term effect of acid rain on forest soils, logging and forest regrowth."

In the end, the researchers found that many lakes that they studied had passed critical thresholds. In fact, many jelly-clad invertebrates were taking the place of those that needed calcium. This has important implications for lake biology, since it can alter food webs and can also clog water intakes.

The findings are published in the journal Proceedings of the Royal Society B.