Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

North America's northernmost lake affected by global warming

27.09.2007
Analyses conducted by researchers from Université Laval’s Center for Northern Studies reveal that the continent’s northernmost lake is affected by climate change.

In an article to be published in the September 28 edition of Geophysical Research Letters, the international research team led by Université Laval scientists Warwick Vincent and Reinhard Pienitz reports that aquatic life in Ward Hunt Lake, a body of water located on a small island north of Ellesmere Island in the Canadian Arctic, has undergone major transformations within the last two centuries. The speed and range of these transformations—unprecedented in the lake’s last 8,000 years—suggest that climate change related to human activity could be at the source of this phenomenon.

The researchers’ conclusions are based on the analysis of a sediment core extracted in the center of Ward Hunt Lake in August 2003. This 18 centimeter long sediment core containing algae pigments and diatom remnants was used by the researchers as a biological archive in order to determine the diversity and abundance of aquatic life-forms in the lake over the last 8,450 years.

Analysis of the deepest layers of sediment revealed a very small number of algae as well as only minor variations in concentration. However, the top two centimeters of the core, which correspond to the last 200 years, showed abrupt changes in the lake’s algae population: during that period, chlorophyll a concentration, a pigment found in every species in the lake, increased by a factor of 500. A type of diatom typical of very cold environments also made its first appearance during the same period. “The absence of diatoms and the low pigment concentration below the top 2.5 centimeters of the core suggest that the lake was permanently frozen in the past,” explains lead author and Center for Northern Studies researcher Dermot Antoniades.

Located on the 83rd parallel in the Quttinirpaaq (meaning “top of the world” in Inuktitut) National Park, Ward Hunt Island is completely surrounded by ice. The lake itself is permanently covered by a 4-meter layer of ice, except for a small peripheral zone that thaws out during a few weeks every summer. “This is of course an extreme environment for living organisms, but our data indicate that current conditions make the lake a more favorable location for algae growth than it was in the past,” points out Antoniades. “We cannot claim with certainty that these changes were brought on by human activity, but natural variations observed over the last millennia were never so abrupt and extensive,” concludes the researcher.

In addition to Antoniades, Vincent, and Pienitz, the article is co-authored by Catherine Crawley from the University of Toronto, Marianne Douglas from the University of Alberta, Dale Andersen from the Center for the Study of Life in the Universe (USA), Peter Doran at the University of Illinois in Chicago (USA), Ian Hawes from the National Institute of Water and Atmospheric Research (New Zealand), and Wayne Pollard from McGill University.

This study was conducted as part of the ArcticNet program, which brings together scientists and managers in the natural, human health and social sciences with their partners in Inuit organizations, northern communities, federal and provincial agencies and the private sector to study the impacts of climate change in the coastal Canadian Arctic.

Jean-François Huppé | EurekAlert!
Further information:
http://www.ulaval.ca

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

The material that obscures supermassive black holes

26.09.2017 | Physics and Astronomy

Ageless ears? Elderly barn owls do not become hard of hearing

26.09.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>