Featured Research

from universities, journals, and other organizations

Selenium: An Insidious And Persistent Toxin With Long-Term Effects On Aquatic Wildlife

Date:
April 22, 2002
Source:
USDA Forest Service/Southern Research Station
Summary:
In an article in the April issue of Aquatic Toxicology, a USDA Forest Service researcher warns that the impacts of selenium on freshwater fish populations may become more widespread as human disturbance increases -- and that long-term effects may be underestimated.

Selenium, an essential nutrient for humans and animals, occurs as a trace element in most soils. Selenium can move into water systems when soil is disturbed by various types of development, or as a byproduct of fossil fuel combustion. When it occurs in higher than normal levels in water, selenium has been shown to cause malformations in fish and other aquatic wildlife.

In an article in the April issue of Aquatic Toxicology, a USDA Forest Service researcher warns that the impacts of selenium on freshwater fish populations may become more widespread as human disturbance increases -- and that long-term effects may be underestimated.

Dennis Lemly, Forest Service research biologist at the Southern Research Station, has spent the last two decades studying the fish in Belews Lake, North Carolina. Created in 1973 to provide cooling water for a large coal-fired power plant, the lake was contaminated by selenium in discharged wastewater.

"Belews Lake represents one of the most extensive and prolonged cases of selenium poisoning of freshwater fish in the United States," said Lemly. "It provides an excellent case study of the insidious and persistent toxicity of selenium to aquatic ecosystems."

As selenium accumulated in Belews Lake, the 20 resident species of fish started showing deformities to the spine, head, fins, and eyes. In 1986, the power plant stopped discharging wastewater into the lake. Natural recovery began, but long-term studies by Lemly and other researchers show that ill effects persist long after the source of pollution is gone.

"Selenium poisoning in fish can be invisible for a time," said Lemly, "because the primary impact is on the egg, which receives the toxin from the mother's diet. When the eggs are hatched, the developing fish metabolize the selenium. Some fish are visibly deformed, but others grow into adult fish that appear healthy yet fail to reproduce. Because there is no apparent fish kill, species can disappear before you can do anything about it."

Belews Lake was the first site to provide conclusive evidence that exposure to elevated levels of selenium -- in this case only 10 to 20 times those in nearby uncontaminated reservoirs -- causes deformities in natural populations of freshwater fish. Nineteen out of the 20 species of fish in Belews Lake disappeared over the course of four years: by 1978, only the selenium-tolerant mosquito fish remained.

Lemly conducted a follow-up study of Belews Lake in 1996, a decade after the plant quit discharging selenium-laden wastewater into the lake. He found selenium still present at a moderate risk level in the sediment of the lake. The element continued to gradually move from the sediment through the food chain, accumulating to toxic levels in fish eggs.

"Bioaccumulation in food chains causes otherwise harmless concentrations of selenium to reach toxic levels," said Lemly. "Selenium in contaminated sediments can be cycled into food chains for decades. Lessons from Belews Lake provide the foundation for protecting aquatic ecosystems as new selenium issues emerge."

At the time Belews Lake was contaminated, the irrigation of selenium-rich soils in arid regions of the American West was the other major source of selenium poisoning. New sources of selenium pollution include phosphate mining, animal feedlot waste, landfill disposal of ash from coal-fired plants, and the use of constructed wetlands to treat wastewater.

More information about the effects of selenium on the aquatic environment, as well as methods to evaluate and control it, can be found in Lemly's new book, "Selenium Assessment in Aquatic Ecosystems: A Guide for Hazard Evaluation and Water Quality Criteria," published in April 2002 by Springer-Verlag.


Story Source:

The above story is based on materials provided by USDA Forest Service/Southern Research Station. Note: Materials may be edited for content and length.


Cite This Page:

USDA Forest Service/Southern Research Station. "Selenium: An Insidious And Persistent Toxin With Long-Term Effects On Aquatic Wildlife." ScienceDaily. ScienceDaily, 22 April 2002. <www.sciencedaily.com/releases/2002/04/020419064504.htm>.
USDA Forest Service/Southern Research Station. (2002, April 22). Selenium: An Insidious And Persistent Toxin With Long-Term Effects On Aquatic Wildlife. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2002/04/020419064504.htm
USDA Forest Service/Southern Research Station. "Selenium: An Insidious And Persistent Toxin With Long-Term Effects On Aquatic Wildlife." ScienceDaily. www.sciencedaily.com/releases/2002/04/020419064504.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) — Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) — A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Coffee Then Napping: The (New) Key To Alertness

Coffee Then Napping: The (New) Key To Alertness

Newsy (Aug. 30, 2014) — Researchers say having a cup of coffee then taking a nap is more effective than a nap or coffee alone. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins