The Jellification of North Temperate Lakes

PEARL Paleoecological Environmental Assessment and Research Laboratory
Department of Biology, Queen's University, Kingston ON, Canada, K7L 3N6
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The Jellification of North Temperate Lakes
Lakes turning to jelly?
Research team identifies new environmental threat for boreal lakes
Kingston, ON ­ A widespread environmental change occurring in softwater lakes of North America (and likely
elsewhere) has been detected by researchers from Queen's University, the University of Cambridge and York
University, working with scientists from other Canadian universities and government laboratories. The team has
identified a biological shift in many temperate, soft­water lakes in response to declining calcium levels (a legacy
of acid rain and timber harvesting). Reduced calcium availability is hindering the survival of aquatic organisms
with high calcium requirements (a case of "aquatic osteoporosis"), leading to the rising dominance of nutrient­
poor, jelly­clad animals.
"We are seeing the jellification of many lakes," notes Queen's post­doctoral fellow Adam Jeziorski, one of the
lead authors of the study. "Calcium is an essential nutrient for many lake­dwelling organisms, but concentrations
have fallen so low in many lakes that keystone species can no longer survive" he says. "The old guard is no
longer competitive; conditions now favour animals better adapted to lower calcium levels, and these changes can
have significant ecological and environmental repercussions."
The study is published today in the prestigious journal Proceedings of the Royal Society B.
The researchers documented how changes in lakewater calcium concentrations have altered the invertebrate
communities of lakes, mainly through the widespread replacement of the water flea, Daphnia (a key component
of many aquatic food webs) with Holopedium glacialis, a jelly­clad competitor.
As lakewater calcium decline began before monitoring programs were in place, indirect means were required to
determine pre­impact conditions. The study of tiny fossils and other indicators in the sediment accumulated at the
bottom of lakes allowed Queen's researchers to compare the communities identified in water monitoring
programs with those present prior to the onset of acid deposition. Modelling techniques allowed the
determination of the mechanism underlying the changes through time. Prof. John Smol, Canada Research Chair
in Environmental Change and co­director of Queen's Paleoecological Environmental Assessment and Research
Laboratory (PEARL), and his colleagues, examined environmental trends over the past ~150 years. "Lake
sediments act like a history book of past changes in a lake" says Smol "they are like the black boxes on aircraft,
recording what happened before a problem is identified." Their study showed that jelly­clad invertebrates, which
have lower nutrient content than native species and can even clog water filters, have been increasing in an
alarming number of lakes. Linking the problem to the long­term effects of acid rain on forest soils, as well as to
logging and forest re­growth, the lower calcium levels of these lakes are a long­term change. "This has important
management implications," says Dr. Jeziorski. "It was a combination of paleoecological research, long­term
monitoring, and modeling that helped to identify the underlying mechanisms," he adds.
"This is all very worrisome," concludes Dr. Smol, "The good news is that we are able to identify one of the
effects of reduced lakewater calcium levels. The bad news is that many lakes have passed critical thresholds, and
we have been reduced to the role of a spectator as these changes continue to unfold. Once again we see that there
are many unexpected consequences of our actions ­ and they are mostly negative."
The research was supported primarily by grants from the Natural Sciences and Engineering Research Council of
Canada, as well as funding from the Ontario Ministry of the Environment and Climate Change.
Also on the team are: Andrew Tanentzap (University of Cambridge); Norm Yan and Allegra Cairns (York
University); Jennifer Korosi (University of Ottawa); Michael Arts (Ryerson University), Bill Keller (Laurentian
University); and Andrew Paterson, Michelle Palmer, James Rusak and Ron Ingram (Ontario Ministry of the
Environment and Climate Change).
PLEASE NOTE: A PDF copy of the study can be obtained from the Journal ­ Proceedings of the Royal Society
B, or contact Dr. John Smol at smolj@queensu.ca for a copy. High resolution images are available upon request.
Contact:
Rosie Hales or Anne Craig
News and Media Services
Queen's University
Kingston, Ontario, Canada
Anne 613­533­2877 anne.craig@queensu.ca
Rosie 613­533­6000 x77513 rgh3@queensu.ca
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Contact Information for authors:
John P. Smol
Paleoecological Environmental Assessment and Research Lab
(PEARL)
Department of Biology, Queen's University
Kingston, ON, Canada
Tel: (613) 533­6147 smolj@queensu.ca
Adam Jeziorski
Paleoecological Environmental Assessment and Research Lab
(PEARL)
Department of Biology, Queen's University
Kingston, ON, Canada
Tel: (613) 533­6000 x77337 adam.jeziorski@queensu.ca
Andrew Tanentzap
Ecosystems and Global Change Group
Department of Plant Sciences, University of Cambridge
Cambridge, United Kingdom
Tel: +44 1223 748 982 ajt65@cam.ac.uk
Norman Yan
Department of Biology, York University
Toronto, ON, Canada
Andrew Paterson
Ontario Ministry of the Environment
Dorset Environmental Science Centre
Dorset, ON, Canada
Michelle Palmer
Ontario Ministry of the Environment
Environmental Monitoring and Reporting Branch
Toronto ON, Canada
Jennifer Korosi
Department of Biology
University of Ottawa
Ottawa, ON, Canada
James Rusak
Ontario Ministry of the Environment
Dorset Environmental Science Centre
Dorset, ON, Canada
Michael Arts
Department of Chemistry and Biology
Ryerson University
Toronto, ON, Canada
Tel: (416) 979­5000 x3147 michael.arts@ryerson.ca
Wendel (Bill) Keller
Cooperative Freshwater Ecology Unit
Laurentian University
Sudbury, ON, Canada
Ron Ingram
Allegra Cairns
Ontario Ministry of the Environment
Dorset Environmental Science Centre
Dorset, ON, Canada
Department of Biology
York University
Toronto, ON, Canada
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