Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mercury in dolphins: Study compares toxin levels in captive and wild sea mammals

22.05.2012
Amid growing concerns about the spread of harmful mercury in plants and animals, a new study by researchers from The Johns Hopkins University and The National Aquarium has compared levels of the chemical in captive dolphins with dolphins found in the wild. The captive animals were fed a controlled diet, while the wild mammals dined on marine life that may carry more of the toxic metal.
The study found lower levels of mercury in the captive animals, particularly compared to wild dolphins tested off the Atlantic and Gulf coasts of Florida, a state that is in the path of mercury-laden fumes from power plants. The aquarium dolphins are fed smaller fish from North Atlantic waters, where mercury pollution is less prevalent.

The findings were published in a recent issue of Science of the Total Environment.

Although these results represent a significant case study, the research focused on a small number of animals, and Edward Bouwer, chair of the Department of Geography and Environmental Engineering at Johns Hopkins and supervisor/co-author of the study, cautioned against drawing wide-ranging conclusions from the research.

"This is just one snapshot, one puzzle piece," said Bouwer. "What we'd like to do now is repeat this project with aquariums in other parts of the world. The goal is to get a clearer comparison of mercury-related health risks facing dolphins both in captivity and in the wild. This type of research can give us hints about how the type of diet and where it originated can affect mercury-related health problems in captive dolphins, compared to their cousins in the wild."

Public health officials are concerned about human consumption of mercury, particularly in a form called methylmercury, because it can damage the brain and other parts of the nervous system, especially in young children. Dolphins that ingest too much methylmercury can suffer similar harm.

Mercury is emitted as a gas from coal- and oil-fired power plants. Some makes its way into the ocean, where bacteria turn it into methylmercury, which moves up the food chain. Eventually, it turns up in the large fish that serve as dinner for wild dolphins. Once ingested, the heavy metal makes its way into the animals' bloodstream, where it can begin to damage the nervous system.

With this in mind, the Johns Hopkins and National Aquarium researchers wanted to investigate mercury exposure differences between captive and wild dolphins whose diets came from different regions. The team collected blood samples from seven aquarium dolphins, ages 2 to 38, and tested them for mercury, methylmercury and a third chemical, selenium, which appears to help ward off the toxic effects.

The researchers compared their results against those derived from wild dolphin blood samples collected in earlier capture-and-release studies conducted in the waters off Charleston, S.C.; Indian River Lagoon on Florida's Atlantic coast; and Sarasota, on Florida's Gulf Coast.

"While mercury levels in the wild dolphins off South Carolina were slightly higher than those in the National Aquarium dolphins, readings from the dolphins off the Florida coasts were significantly higher," said Yongseok Hong, postdoctoral fellow in the Department of Geography and Environmental Engineering in Johns Hopkins' Whiting School of Engineering and lead author of the study.

"The difference in mercury exposure was attributed to differences in the dolphins' diets," he said. "The aquarium dolphins were fed a consistent level of small fish–capelin and herring–that were caught in North Atlantic waters off Newfoundland and New England. Lower levels of mercury are expected in these waters, compared to the waters off Florida."

Leigh Clayton, the National Aquarium's director of animal health, said the team members who care for the aquarium's dolphins were enthusiastic about contributing to this study because it gave them a chance to more fully evaluate the food that the team feeds to its marine mammals.

"It is important that we gain a better understanding of the mercury levels in the North Atlantic food chain in order to ensure we're providing the best diet possible to our dolphins," Clayton said. "The research we have done with Johns Hopkins has provided helpful information for our marine mammals team and allows us, at this time, to have confidence that our current fish food sources do not have excessively elevated mercury levels."

Last December, after the study was conducted, the U.S. Environmental Protection Agency adopted strict standards aimed at reducing the release of toxic air pollution from coal- and oil-fired power plants, a key source of mercury contamination in sea water.

Co-authors of the study were Clayton; Sue Hunter, the National Aquarium's director of animal programs and marine mammals; and Erik Rifkin, of the National Aquarium Conservation Center. Three high school students -- Amelia Jones, Sara Hamilton and Debbie Brill -- helped with sample analysis.

Funding for the research was provided by the National Aquarium and by the Center for Contaminant Transport Fate and Remediation at The Johns Hopkins University.

Color digital images available; contact Phil Sneiderman or Kate Hendrickson
Related links:
Johns Hopkins Department of Geography and Environmental Engineering: http://engineering.jhu.edu/~dogee/

National Aquarium: http://www.aqua.org/

Phil Sneiderman | EurekAlert!
Further information:
http://www.jhu.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>