Mark A. Pokras

Heavy metal concentrations in feathers of common loons (Gavia immer) in the Northeastern United States and age differences in mercury levels

Feathers serve as a useful, non-destructive approach for biomonitoring some aspects of environmental quality. Birds can eliminate over 90% of their body burden of mercury by sequestration in growing feathers, and they molt their feathers at least annually. Thus mercury concentrations should not vary in avian feathers as a function of age. We tested the null hypothesis that there are no age differences in the concentrations of mercury, lead, cadmium, selenium, copper, chromium and manganese in the feathers of immature and adult common loons Gavia immer from the Northeastern United States where the species is declining. Adults had significantly higher mean levels of mercury (20245 ppb) than immature loons (9677 ppb), but there were no age-related differences for other elements. Even with the small number of immatures, females had significantly higher levels of mercury than males, although the gender difference was not significant for adults.

Lead Poisoning: Using Transdisciplinary Approaches to Solve an Ancient Problem

Conservation medicine examines the linkages among the health of people, animals, and the environment. Few issues illustrate this approach better than an examination of lead (Pb) toxicity. Lead is cheap and there is a long tradition of its use. But the toxic effects of Pb have also been recognized for many years. As a result, western societies have eliminated or greatly reduced many traditional uses of Pb, including many paints, gasoline, and solders because of threats to the health of humans and the environment. Legislation in several countries has eliminated the use of lead shot for hunting waterfowl. Despite these advances, a great many Pb products continue to be readily available. For example, wildlife agencies recognize that angling and shooting sports deposit thousands of tons of Pb into the environment each year. In recent years, our knowledge of the lethal and sublethal effects of Pb has grown dramatically. This discussion reviews the effects of lead on wildlife, humans, and domestic animals. It also discusses the importance of bringing together all interest groups to find safe alternatives, to develop new educational and policy initiatives, to eliminate many current uses of Pb, and to clean up existing problems.

Mortality of common loons in New England, 1987 to 2000.

Diagnostic findings are presented on 522 common loons (Gavia immer) found dead or moribund in New England (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont, USA) between 1987 and 2000. Common loon numbers and range in New England have decreased from historic levels over the last century due to a number of proposed factors. Goals of this study were to identify and categorize causes of mortality and quantify natural versus anthropogenic causes. The majority of identifiable mortality in chicks was from intraspecific aggression (25%) and other causes of trauma (32%). Death in immature loons was primarily from fungal respiratory disease (20%) and trauma (18%). Causes of adult loon mortality differed significantly in breeding and wintering habitats. Wintering adults primarily died of trauma (17%) and infection (11%) and had significantly poorer body condition than breeding loons. In breeding adults, confirmed and suspected lead toxicosis from ingested fishing weights accounted for almost half of all mortality. Direct anthropogenic factors accounted for 52% of loon mortality in this study. Because of high carcass recovery rates, we believe these data are a good representation of loon mortality in New England. Results highlight the importance of human influences on conservation and management of the common loon in New England.

Health Risks from Lead-Based Ammunition in the Environment

Lead is one of the most studied toxicants, and overwhelming scientific evidence demonstrates that lead is toxic to several physiological systems in vertebrates, including the nervous, renal, cardiovascular, reproductive, immune, and hematologic systems (Health Risks from Lead-Based Ammunition in the Environment—A Consensus Statement of Scientists 2013). Furthermore, there is no level of lead exposure in children known to be without adverse effects [Centers for Disease Control and Prevention (CDC) 2012a, 2012b]. In light of this evidence, there is an urgent need to end a major source of lead for animals and humans: spent lead bullets and shotgun pellets. Notably, production of lead-based ammunition in the United States accounted for > 69,000 metric tons consumed in 2012; this is second only to the amount of lead used to manufacture storage batteries (U.S. Geological Survey 2013). However, there are few regulations regarding the release of lead into the environment through discharge of lead-based ammunition. For other major categories of lead consumption, such as lead batteries and sheet lead/lead pipes, environmental discharge and disposal are regulated. Therefore, lead-based ammunition is likely the greatest largely unregulated source of lead that is knowingly discharged into the environment in the United States. In contrast, the release or distribution of other major sources of environmental lead contamination (e.g., leaded gasoline, lead-based paint, lead solder) have been substantially regulated and reduced since the mid-1970s (Health Risks from Lead-Based Ammunition in the Environment—A Consensus Statement of Scientists 2013). There is a national discussion—polarized at times—of the health risks posed to humans and wildlife from the discharge of lead-based ammunition. To inform this discussion, a group of 30 nationally and internationally recognized scientists with expertise regarding lead and environmental health recently collaborated to create an evidence-based consensus statement (Health Risks from Lead-Based Ammunition in the Environment—A Consensus Statement of Scientists 2013) supporting the reduction and eventual elimination of lead released to the environment through the discharge of lead-based ammunition. The discharge of lead bullets and shotgun pellets into the environment poses significant health risks to humans and wildlife. The best available scientific evidence demonstrates that the discharge of lead-based ammunition substantially increases environmental lead levels, especially in areas with higher shooting activity (U.S. Environmetal Protection Agency 2012) and that the discharge of lead-based ammunition poses risks of elevated lead exposure to gun users (National Research Council 2012). When lead-containing bullets are used to shoot wildlife, they can fragment into hundreds of small pieces, many of which are small enough to be easily ingested by scavenging animals or to be retained in meat prepared for human consumption (Hunt et al. 2009; Knott et al. 2010; Pauli and Burkirk 2007). Consequently, lead-based ammunition may be a significant source of lead exposure in humans that regularly ingest wild game (Hanning et al. 2003; Johansen et al. 2006; Levesque et al. 2003; Tsuji et al. 2008). In addition, lead pellets and fragments have been reported in gastrointestinal tracts of hunters who consume meat from animals shot with lead-based ammunition (Carey 1977; Reddy 1985). The use of lead pellets in shotgun shells for hunting waterfowl posed a serious threat to wetland birds, and secondarily to bald eagles, in the United States, leading to the U.S. Fish and Wildlife Service’s 1991 nationwide regulations requiring use of nontoxic shotgun pellets for hunting waterfowl (Anderson 1992). However, lead poisoning from ingestion of spent lead-based ammunition fragments continues to pose a particularly serious health threat for scavenging species. These lead-containing fragments remain the principal source of lead exposure to endangered California condors and continue to prevent the successful recovery of these birds in the wild (Church et al. 2006; Finkelstein et al. 2012; Green et al. 2008; Parish et al. 2009; Rideout et al. 2012; Woods et al. 2007). Other wildlife species, such as golden eagles, bald eagles, ravens, turkey vultures, and pumas, are also exposed to the fragments of spent lead ammunition (Burco et al. 2012; Clark and Scheuhammer 2003; Craighead and Bedrosian 2008; Cruz-Martinez et al. 2012; Fisher et al. 2006; Kelly and Johnson 2011; Stauber et al. 2010; Wayland and Bollinger 1999). No rational deliberation about the use of lead-based ammunition can ignore the overwhelming evidence for the toxic effects of lead, or that the discharge of lead bullets and shot into the environment poses significant risks of lead exposure to humans and wildlife. Given the availability of non-lead ammunition for shooting and hunting (Thomas 2013), the use of lead-based ammunition that introduces lead into the environment can be reduced and eventually eliminated. This seems to be a reasonable and equitable action to protect the health of humans and wildlife.

HEMATOLOGIC AND PHYSIOLOGIC REFERENCE RANGES FOR FREE-RANGING ADULT AND YOUNG COMMON LOONS (GAVIA IMMER)

Abstract Wild common loons (Gavia immer) were captured across much of their southern North American range. Hematologic and physiologic data were collected to establish reference ranges for adults and chicks from four geographic areas: New England, Canadian Maritimes, south-central Quebec, and the Upper Great Lakes. Mean body mass and blood-glucose levels of adult loons varied among geographic regions. Chicks had lower PCV and total solids than adult loons, and also had faster heart rates and higher blood glucose levels. Although mean body mass in males was consistently greater than in females, hematologic and physiologic reference ranges between sexes were not significantly different. Geographic and age-related differences exist in common loon hematologic and physiologic reference ranges and should be considered when assessing such parameters.

Hematology and Absence of Hemoparasites in Breeding Common Terns (Sterna hirundo) from Cape Cod, Massachusetts

Abstract In June and July 1995, 98 breeding common terns (Sterna hirundo) were captured, weighed, and bled as a part of ongoing research on the population health and reproductive biology of this species of special concern. Packed cell volume, total and differential white blood cell counts, and blood smears were obtained. Blood smears from 75 terns were examined. No hemoparasites were found. There were some significant differences among hematologic parameters in birds from different islands, and between birds nesting earlier versus later in the season, but there were no significant differences associated with body mass, sex, or age. The absence of hemoparasites in the blood smears of these terns is noteworthy, especially because other studies of seabirds (including Charadriiformes) have revealed low prevalences of hematozoa.

Lead Objects Ingested by Common Loons in New England

Abstract Necropsies of Gavia immer (Common Loon) recovered lead and non-lead foreign objects from gastrointestinal tracts. Carcasses collected between 1987 and 2000 reveal that a great deal of loon mortality on lakes in New England is attributable to ingestion of lead objects. In this study, 522 carcasses were examined to inspect the types, sizes, and masses of 222 objects responsible for lead toxicosis. Most ingested lead objects were less than 2.5 cm long and weighed less than 25 g. Information on objects ingested by loons may help in development of non-toxic alternatives.

Baylisascaris larva migrans in a spider monkey (Ateles sp.)

Visceral larval migrans (VLM) in intermediate hosts caused by the raccoon nematode Bay lisascaris procyonis has been previously documented and extensively reviewed [ 5 , 61. Baylisascaris VLM has been implicated in central nervous system disease in over 40 species of mammals and birds under both natural and experimental conditions. This report documents the first spontaneous case of visceral larval migration of B. procyonis in a nonhuman primate. An encephalitis was associated with nematode larvae consistent with B. procyonis in the affected spider monkey (Ateles sp.). A unique feature of this niturally occurring case was the presence of larvae within submucosal vessels of the large intestine. This finding supports the belief that direct vascular invasion of larvae following ingestion of infective eggs is the route of Baylisascaris larval dissemination.

Emerging Zoonoses in Marine Mammals and Seabirds of the Northeast U.S.

In the Northeast United States, marine vertebrates come into contact with each other and with humans through a variety of mechanisms which allow for the transfer of pathogens from one taxa to another. Though there are many ways in which humans come into contact with infectious agents, there is an inadequate understanding of the prevalence of clinical and sub-clinical zoonotic agents in the marine vertebrates of the Northeast United States. We are strengthening our understanding of the issue by targeting marine mammals and seabirds of New England and screening normal and diseased individuals of this ecosystem to establish a baseline prevalence of zoonotic agents in this ecosystem. Samples from stranded, bycaught and wild marine mammals and seabirds have been found to be positive for our screened pathogens. Most notable are the diseases found in bycaught marine mammals as well as wild caught individuals. Our current focus is specifically on influenza A and B, brucellosis, leptospirosis, Giardia and Cryptosporidium. Samples for virology, bacterial screening and molecular screening are being archived and analyzed as practical. Our goal is to create an optimized PCR-based molecular detection protocol for the above agents

GM1-gangliosidosis in American black bears: Clinical, pathological, biochemical and molecular genetic characterization

G(M1)-gangliosidosis is a rare progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of lysosomal β-galactosidase. We have identified seven American black bears (Ursus americanus) found in the Northeast United States suffering from G(M1)-gangliosidosis. This report describes the clinical features, brain MRI, and morphologic, biochemical and molecular genetic findings in the affected bears. Brain lipids were compared with those in the brain of a G(M1)-mouse. The bears presented at ages 10-14 months in poor clinical condition, lethargic, tremulous and ataxic. They continued to decline and were humanely euthanized. The T(2)-weighted MR images of the brain of one bear disclosed white matter hyperintensity. Morphological studies of the brain from five of the bears revealed enlarged neurons with foamy cytoplasm containing granules. Axonal spheroids were present in white matter. Electron microscopic examination revealed lamellated membrane structures within neurons. Cytoplasmic vacuoles were found in the liver, kidneys and chondrocytes and foamy macrophages within the lungs. Acid β-galactosidase activity in cultured skin fibroblasts was only 1-2% of control values. In the brain, ganglioside-bound sialic acid was increased more than 2-fold with G(M1)-ganglioside predominating. G(A1) content was also increased whereas cerebrosides and sulfatides were markedly decreased. The distribution of gangliosides was similar to that in the G(M1)-mouse brain, but the loss of myelin lipids was greater in the brain of the affected bear than in the brain of the G(M1) mouse. Isolated full-length cDNA of the black bear GLB1 gene revealed 86% homology to its human counterpart in nucleotide sequence and 82% in amino acid sequence. GLB1 cDNA from liver tissue of an affected bear contained a homozygous recessive T(1042) to C transition inducing a Tyr348 to His mutation (Y348H) within a highly conserved region of the GLB1 gene. The coincidence of several black bears with G(M1)-gangliosidosis in the same geographic area suggests increased frequency of a founder mutation in this animal population.