Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Herons persist in Chicago wetlands despite exposure to banned chemicals

17.01.2008
Herons nesting in the wetlands of southeast Chicago are still being exposed to chemicals banned in the U.S. in the 1970s, a research team reports. The chemicals do not appear to be affecting the birds’ reproductive success, however.

The findings appear in the current issue of the Journal of Great Lakes Research.

University of Illinois veterinary biosciences scientist Jeff Levengood led the study. Levengood, a wildlife toxicologist at the Illinois Natural History Survey, said that chemicals banned 30 years ago for their deleterious effects on wildlife are still showing up in the offspring of black-crowned night-herons in a Chicago wetland.

The researchers found PCBs and DDE in the eggs of night-herons nesting in the wetlands abutting Lake Calumet, in southeast Chicago. The Lake Calumet wetlands are surrounded by industrial developments along Lake Michigan near the Illinois-Indiana border.

The research team included scientists from the U.S. Geological Survey, the Illinois Waste Management and Research Center, and Purdue and Duke universities.

PCBs (polychlorinated biphenyls) were commonly used in electrical transformers and other industrial applications until they were banned in 1977 because of their toxicity in the environment.

DDE is a metabolic by-product of DDT (dichlorodiphenyltrichloroethane), a pesticide banned in 1972 because it was observed to kill or disrupt the reproduction of birds and other wildlife. The DDT ban is believed to have reversed the dramatic decline in the American bald eagle and the peregrine falcon in the continental U.S.

The Lake Calumet birds appear to be picking up the contamination primarily from Lake Michigan by means of an invasive fish, the alewife.

Alewives harbor comparable levels of PCBs and DDE in their tissues, Levengood said. The spawning season of the alewife in Lake Michigan coincides with the nesting season of the night-herons.

“The alewife come to shore to spawn when the first warm waters of spring run into the lake and the temperature starts to rise,” he said. “There are untold millions of these things along the (Lake Michigan) shore in April.”

On several occasions the researchers saw large numbers of night-herons – “in some cases a hundred birds or more” – along the sea walls on the southwest shore of Lake Michigan, Levengood said. “They’d be standing there peering into the water, and then they’d kind of do a belly flop into the water and grab a fish.”

The researchers collected data over two years and conducted several genetic, biochemical and reproductive analyses to determine whether the chemical exposures were adversely affecting the birds. They looked at DNA strand length (a measure of genetic damage) and oxidative stress (a contributor to aging and disease) and compared the number of eggs and the viability of the eggs and young chicks to those in other, less polluted reference colonies of black-crowned night-herons in Minnesota and Virginia.

“These were all normal compared to the reference colonies,” Levengood said.

The team found no evidence of eggshell-thinning, which is sometimes associated with exposure to DDE.

“So that’s the good news: Even though they’re getting an exposure, it’s not enough to cause problems – at least in those parameters we measured,” Levengood said.

The researchers did see an increase in some liver enzymes, he said, “but that’s not unexpected because the liver is trying to detoxify these compounds.” The long-term consequences of the rise in these liver enzymes are unknown, he said.

Populations of black-crowned night-herons in the Lake Calumet wetlands have fluctuated dramatically in the last 20 years, peaking at more than 1,500 birds in the early to mid-1990s. This population increase coincided with prolonged flooding in nearby rivers, which may have disadvantaged these short-legged herons, Levengood said.

Birders counted 447 black-crowns in Lake Calumet wetlands in 2005, the last year for which data are available.

Numbers of black-crowned night-herons and other colonial fish-eating birds had declined nationally – and in Illinois – by the 1960s. Many populations started to rebound after the ban on DDT. Illinois’ populations of black-crowned night-herons did not experience this comeback, however.

Many of the remaining heron colonies are found in or near industrial areas, Levengood said.

“Wetlands have persisted in these areas because they were out on the back 40 of some company and people generally didn’t have access,” he said. These urban industrialized sites provide needed habitat, Levengood said, but are also “contaminated and degraded.”

Urbanites are beginning to discover these areas, and want to clean them up for wildlife – and humans – to use, he said. Chicago’s Department of Environment is leading a drive to reclaim parts of the Lake Calumet wetlands, an effort that prompted the current study.

Editor’s note: To reach Jeff Levengood, call 217-333-6767; e-mail: levengoo@uiuc.edu.

Diana Yates | University of Illinois
Further information:
http://www.uiuc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Five-point plan to integrate recreational fishers into fisheries and nature conservation policy
20.03.2019 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Rain is important for how carbon dioxide affects grasslands
06.03.2019 | University of Gothenburg

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: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>