Scientists who monitored skuas in Adélie Land and the Kerguelen Islands for ten years have found when these seabirds exhibit high mercury levels in their blood, their breeding success decreases.
The researchers from the Centre d'Etudes Biologiques de Chizé and from the Littoral, Environnement et Sociétés Laboratory (CNRS / Université de La Rochelle) say that this is the first time that toxicological measurements have been combined with a population study carried out over such a long period in the Antarctic and Subantarctic.
art of the mercury from industrial and domestic activities (burning of hydrocarbons and coal) is transported to the Arctic and Antarctic by winds. This mercury of anthropogenic origin, together with naturally occurring mercury, enters the food chain. A heavy metal, mercury is a powerful endocrine disruptor that can inhibit the production of hormones for reproduction. In the Polar Regions, many seabirds such as skuas were known to accumulate this toxic element at high levels in their tissues. However, the long-term effects on their populations had not yet been assessed.
For the first time, the researchers have carried out a ten-year population study of two seabird species: brown skuas living in the Kerguelen Islands (Subantarctic) and south polar skuas living in Adélie Land (Antarctica). Skuas are migratory birds that feed essentially on penguin eggs and chicks, as well as fish. These formidable predators, which live for up to 25 to 30 years, accumulate mercury in their tissues.
South polar skua (Catharacta maccormicki) defending its breeding site in Adélie Land. Mercury contamination affects the fecundity of this seabird. © Samuel Blanc / www.horizonspartages.fr
The researchers first captured around a hundred south polar skuas and brown skuas and took blood samples to measure their mercury levels. The birds were then ringed and released. For ten years, the scientists returned to the nesting sites in order to observe their breeding success. Skuas can rear one to two chicks per year.
The first finding was that mercury levels in brown skuas were three times higher than in south polar skuas. The researchers showed that, in both species, the higher the mercury levels in the birds, the fewer chances they had of breeding successfully and especially of rearing their chicks. Unexpectedly, it is in the least contaminated species, the south polar skua, that the effects of mercury are the most obvious. This could be due to the fact that, in Adélie Land, the more severe environmental conditions, combined with the increasing presence of other pollutants (pesticides, PCBs), magnify the impact of mercury contamination.
These findings show that pollutants that accumulate in the Polar Regions are an important threat to biodiversity. Modelling by the researchers indicates that, if mercury contamination continues to increase, skua populations could decline in the long term. The scientists call for further toxicological and demographic studies on other southern species. In addition, they are carrying out similar studies to measure the effects on bird populations of 'conventional' pollutants such as pesticides and other heavy metals, as well as new molecules such as perfluorinated compounds that are also accumulating in the Antarctic.
Citation: Demographic responses to mercury exposure in two closely-related Antarctic top predators. Goutte A., Bustamante P., Barbraud C., Delord K., Weimerskirch H., Chastel O.. Ecology, Ecology April 2014, DOI: 10.1890/13-1229.1
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Sexual Fantasies: Threesomes Are Normal, Golden Showers Not So Much
- The Vampire Deer Of Afghanistan
- Cui Bono? B-corporations And The University
- Information-Theoretic Security: Creating 21st Century Cryptography Standards
- Okay With Disgusting Images? You Vote This Way 95 Percent Of The Time
- Resveratrol Reverses Benefits Of Exercise - Study
- Aging Brains Aren't Necessarily Declining Brains
- "Trouble is without citations this article reads like a slew of anecdotes. It begins promisingly..."
- "Do you work for Hank? Or do you just parrot his line of bullshit, and try to legitimize it with..."
- "Yes, that is why I wrote it that way, precisely because they are all watching the thinker...."
- "Sort of. As foreign countries go I have most affection for Great Britain. I have much..."
- Two-faced anti-GMO groups: Block crop and food innovations then claim Big Ag prevents GMO innovations
- Why support erodes for GMO labeling (Hint: It’s not because of spending by Big Ag)
- Genetic “hall of mirrors” with large palindromes, yet smaller: What’s mighty about the mouse
- Gut bacteria an easy scapegoat for disease, but connections hard to prove
- Vermont Rube Goldberg-like GMO labeling law exempts GMO filled natural supplements
- Downside to GMOs: Yields have become so good, they exceed processing capacity
- More penalties on the way for hospitals that treat the poor? New U-M study suggests so
- Cancer cell fingerprints in the blood may speed up childhood cancer diagnosis
- Study of Chile earthquake finds new rock structure that affects earthquake rupture
- Tracking a gigantic sunspot across the Sun
- Massive geographic change may have triggered explosion of animal life
Books By Writers Here