The river otter – sleek swimmer, audience-magnets at zoos and aquariums, whiskered diver, aquatic frolicker, correct answer to crossword puzzle clue for “playful mammal.”
And biomonitor to track toxics that damage the health of an environment or ecosystem.
North American river otters play that role because they’re “apex consumers” in the aquatic ecosystem – meaning they’re at the top of the food chain. They eat primarily aquatic animals such as fish, turtles, amphibians and crayfish.
Category Archives: Environmental toxicology
Download the free PDF. Hard copy is $47.00 from National Academies Press.
From the use of personal products to our consumption of food, water, and air, people are exposed to a wide array of agents each day–many with the potential to affect health. Exposure Science in the 21st Century: A Vision and A Strategy investigates the contact of humans or other organisms with those agents (that is, chemical, physical, and biologic stressors) and their fate in living systems. The concept of exposure science has been instrumental in helping us understand how stressors affect human and ecosystem health, and in efforts to prevent or reduce contact with harmful stressors. In this way exposure science has played an integral role in many areas of environmental health, and can help meet growing needs in environmental regulation, urban and ecosystem planning, and disaster management.
Exposure Science in the 21st Century: A Vision and A Strategy explains that there are increasing demands for exposure science information, for example to meet needs for data on the thousands of chemicals introduced into the market each year, and to better understand the health effects of prolonged low-level exposure to stressors. Recent advances in tools and technologies–including sensor systems, analytic methods, molecular technologies, computational tools, and bioinformatics–have provided the potential for more accurate and comprehensive exposure science data than ever before. This report also provides a roadmap to take advantage of the technologic innovations and strategic collaborations to move exposure science into the future.
AQUATOX is a simulation model for aquatic systems. AQUATOX predicts the fate of various pollutants, such as nutrients and organic chemicals, and their effects on the ecosystem, including fish, invertebrates, and aquatic plants. This model is a valuable tool for ecologists, biologists, water quality modelers, and anyone involved in performing ecological risk assessments for aquatic ecosystems. Although incorporating constructs from classic ecosystem and chemodynamic models, AQUATOX was developed from the beginning as an applied model for use by environmental analysts.
Release 3.1 of AQUATOX is now available. Release 3.1 contains several enhancements over previous releases that improve the model’s interface and utility. For example, the sediment diagenesis model has a “steady-state” mode that increases model speed dramatically. Other categories of refinements include floating-plants refinements, bioaccumulation and toxicity modeling improvements, and improved sensitivity and uncertainty analyses.
There has been a lot of recent press coverage about the ecotoxicology of lead shot and the benefits of alternatives. Some recent articles are:
Myra E. Finkelstein, Daniel F. Doak, Daniel George, Joe Burnett, Joseph Brandt, Molly Church, Jesse Grantham, and Donald R. Smith. (2012). “Lead poisoning and the deceptive recovery of the critically endangered California condor”. Proceedings of the National Academy of Sciences Published online before print June 25, 2012, doi: 10.1073/pnas.1203141109
Abstract: Endangered species recovery programs seek to restore populations to self-sustaining levels. Nonetheless, many recovering species require continuing management to compensate for persistent threats in their environment. Judging true recovery in the face of this management is often difficult, impeding thorough analysis of the success of conservation programs. We illustrate these challenges with a multidisciplinary study of one of the world’s rarest birds—the California condor (Gymnogyps californianus). California condors were brought to the brink of extinction, in part, because of lead poisoning, and lead poisoning remains a significant threat today. We evaluated individual lead-related health effects, the efficacy of current efforts to prevent lead-caused deaths, and the consequences of any reduction in currently intensive management actions. Our results show that condors in California remain chronically exposed to harmful levels of lead; 30% of the annual blood samples collected from condors indicate lead exposure (blood lead ≥ 200 ng/mL) that causes significant subclinical health effects, measured as >60% inhibition of the heme biosynthetic enzyme δ-aminolevulinic acid dehydratase. Furthermore, each year, ∼20% of free-flying birds have blood lead levels (≥450 ng/mL) that indicate the need for clinical intervention to avert morbidity and mortality. Lead isotopic analysis shows that lead-based ammunition is the principle source of lead poisoning in condors. Finally, population models based on condor demographic data show that the condor’s apparent recovery is solely because of intensive ongoing management, with the only hope of achieving true recovery dependent on the elimination or substantial reduction of lead poisoning rates.
News stories covering this study
- Lead acutely threatens California condor population, study says (Los Angeles Times – June 25, 2012)
- New study: Lead poisoning of condors at “epidemic proportions” (San Jose Mercury News – June 25, 2012)
- Condors threatened by ‘epidemic’ lead poisoning from hunters’ bullets (Christian Science Monitor June 26, 2012)
- California condors face lead menace (Nature Magazine – June 26, 2012)
Joel E. Pagel, Peter B. Sharpe, David K. Garcelon, Annie E. Little, Sharon K. Taylor, Kate R. Faulkner, and Carol S. Gorbics. (2012) “Exposure of Bald Eagles to Lead on the Northern Channel Islands, California.” Journal of Raptor Research 46(2):168-176. doi: http://dx.doi.org/10.3356/JRR-11-18.1
Abstract: Bald Eagles (Haliaeetus leucocephalus) were one of the upper-trophic-level avian predators on the Channel Islands, California, prior to their extirpation by 1960 caused in part by large amounts of DDT discharged into the Southern California Bight. From 2002 to 2006, 61 Bald Eagles were reintroduced onto the northern Channel Islands, as part of a 5-yr feasibility study conducted under the auspices of the Montrose Settlement Restoration Program. In December 2005, a yearling Bald Eagle female was found on Santa Rosa Island with a broken wing and elevated lead levels in her blood of 52.2 ug/dl (0.522 ppm). This incident raised concerns that lead poisoning could be a potential threat to the restoration effort and prompted further investigation. Femurs from five female and two male Bald Eagles reintroduced to the northern Channel Islands were collected postmortem for analyses of lead and other metals. Lead levels detected in femurs of these birds ranged from 0.2 to 55.0 ppm (dry weight). Lead levels in liver were also determined for two of the seven Bald Eagles. Analysis of Bald Eagle movement data from satellite telemetry transmitters suggested that eagles that spent the most time on Santa Rosa Island had the highest lead levels. The results of this study suggested that spent ammunition containing lead found in carrion (offal and entire carcasses) from deer and elk hunting on Santa Rosa Island may have been a primary source of contamination. The on-island hunt program converted to nontoxic bullets in 2007 and ended in late 2011.
Copper Opportunities: Copper Ammo Emerging as the “Bullet of Choice” among Minnesota Deer Hunters (Whitetales)
One favorite tradition among deer hunters is sharing the stories of the hunt following each year’s deer season. This year there are some new and compelling stories emerging from hunters who have switched to copper bullets for deer hunting.
Reacting with outrage to the Chicago Tribune’s investigation of the deceptive tactics that have fueled the rise of toxic flame retardants in Americans’ bodies, U.S. Senator Dick Durbin on Thursday demanded answers from two federal agencies, asking them to act aggressively to rid homes of chemicals that pose health risks but don’t stave off fires.
Read the full story at MSNBC.
The amount of plastic trash in the “Great Pacific Garbage Patch” has increased 100-fold during the past 40 years, causing “profound” changes to the marine environment, according to a new study.
Scientists from Scripps Institution of Oceanography in San Diego found that insects called “sea skaters” or “water striders” were using the trash as a place to lay their eggs in greater numbers than before.
In a paper published by the journal Biology Letters, researchers said this would have implications for other animals, the sea skaters’ predators — which include crabs — and their food, which is mainly plankton and fish eggs.
Read the full story at Environmental Health News.
Fish exposed to low levels of common flame retardants called PBDEs for most of their lives pass the chemicals – and more surprisingly, the associated toxic effects – along to their progeny. While parents’ health effects were minimal, the exposures reduced hatch rates and altered the thyroid hormone system of the next generation.
Effects were worse if the offspring were also exposed to the same low chemical levels as their parents, a situation that would mimic wild fish in a natural environment. The findings – published in the journal Environmental Science and Technology – broadly suggest that the toxic effects of PBDE exposure may magnify in subsequent generations of wild fish.
The study is important because it shows that flame retardants can trigger thyroid hormone disruption in the next generation whether or not the offspring are exposed to the chemicals.
Full citation for the research article: Yu, L, JCW Lam, Y Guo, RSS Wu, PKS Lam and B Zhou. 2011. “Parental transfer of PBDEs and thyroid endocrine disruption in zebrafish”. Environmental Science and Technology http://dx.doi.org/10.1021/es2026592.
Abstract: Polybrominated diphenyl ethers (PBDEs) have the potential to disrupt the thyroid endocrine system. The objective of the present study was to characterize the disrupting effects of long-term exposure on the thyroid endocrine system in adult fish and their progeny following parental exposure to PBDEs. Zebrafish (Danio rerio) embryos were exposed to environmentally relevant concentrations (1, 3, and 10 μg/L) of the PBDE mixture DE-71 for 5 months until sexual maturation. In the F0 generation, exposure to DE-71 significantly increased plasma thyroxine (T4) but not 3,5,3′-triiodothyronine (T3) in females. This increased T4 was accompanied by decreased mRNA levels of corticotropin-releasing hormone (CRH) and thyrotropin β-subunit (TSHβ) in the brain. The F1 generation was further examined with or without continued DE-71 treatment conditions. Exposure to DE-71 in the F0 fish caused significant increases in T4 and T3 levels in the F1 larvae and modified gene expressions in the hypothalamic–pituitary–thyroid axis (HPT axis) under both conditions. Decreased hatching and inhibition of growth in the F1 offspring were observed in the condition without DE-71 treatment. Continued DE-71 treatment in the F1 embryos/larvae resulted in further decreased hatching, and increased malformation rates compared with those without DE-71 exposure. Analysis of F1 eggs indicated that parental exposure to DE-71 could result in a transfer of PBDEs and thyroid hormones (THs) to their offspring. For the first time, we demonstrated that parental exposure to low concentrations of PBDEs could affect THs in the offspring and the transgenerational PBDE-induced toxicity in subsequent nonexposed generations.
Read the full story in the Los Angeles Times.
Mercury and PCBs contamination is widespread in sport fish in urban coastal waters across California, though mostly in moderate concentrations, a survey released Thursday by the state Water Board found.
Read the full story from Care2.
Danish wildlife researcher Christian Sonne said industrial pollutants like pesticides and flame retardants are causing some wild polar bears to experience degradation of their bones. He is a researcher at Aarhus University in the Department of the Arctic Environment. Polar bears in the East Greenland area are very polluted because they consume seal blubber containing the industrial contaminants. Last year a Canadian research study found persistent contaminants are a health hazard for polar bears in East Greenland. (This general effect has actually been known and studied for nearly two decades.)
It has been theorized that the industrial toxins get to polar bear territory in Greenland and Svalbard (east of Greenland) because that is where air and water currents join, and they move through the air and water from North America and Europe. Tragically, the last stop for the toxins is where many wild polar bears live. It’s been thought since 1993 that PCBs were negatively impacting polar bear birth rates there.
Of course, the mainstream media regularly references the threat to polar bears from global warming and the melting sea ice where they hunt and live. Climate change isn’t their only threat though, it is also poisoning from human-made chemicals.