MERCURY AND PERSISTENT ORGANIC POLLUTANT CONCENTRATIONS IN AFRICAN FISH EAGLES, MARABOU STORKS, AND NILE TILAPIA IN UGANDA

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Measurement of metal concentrations in feathers of bird-vehicle collisions, Sabzevar, Iran

The purpose of the present study is to compare the concentrations of lead, copper, and zinc in feathers of birds struck in collisions with vehicles. Two main assumptions were investigated: that there is a significant difference between species with different diets and that large and old species have higher concentrations of lead than small and young species because of their longer life span and longer exposure time to pollutants. Mean concentrations were obtained for lead 0.122, 0.006, 0.007, 0.010, and 0.014, for copper 0.718, 0.783, 0.530, 0.853, and 0.793, and for zinc 0.891, 0.940, 0.787, 0.932, and 1.003 in house sparrow (Passer domesticus), tree sparrow (Passer montanus), European roller (Coracias garrulus), Little bittern (Ixobrychus minutus), and Levant sparrowhawk (Accipiter brevipes), respectively. The results showed that there were no significant differences in the concentrations of the studied elements between species with different diets and as well as between large and small size or juveniles and adults; thus, the two hypotheses were rejected. The concentrations of the studied elements were lower than the "negative effects" threshold values suggested by previous studies; thus, they are not likely to pose a serious threat to the selected species. However, it is important to include not only other non-essential elements in future studies but also larger sample sizes. It is also noteworthy that this is the first study to determine the concentration of metals in two of the species, Coracias garrulous and Accipiter brevipes.

Reconstructing avian mercury concentrations through time using museum specimens from New York State

We examined how variation in MeHg concentrations through time is reflected in birds, a taxon commonly used as a biological indicator of ecosystem health. Using museum specimens collected from 1880 to 2016, we measured feather MeHg concentrations in six species of birds that breed in New York State and have distinct dietary and habitat preferences. We predicted that MeHg concentrations in feathers would mirror Hg emission patterns in New York State and increase through time until 1980 then decrease thereafter in response to increased regulation of anthropogenic Hg emissions. We found that MeHg concentrations increased with δ¹⁵N, and that MeHg feather concentrations for some individuals from four of the six species examined exceeded concentrations known to cause negative sublethal effects in birds. In contrast to our prediction, MeHg concentrations in feathers did not parallel global or local Hg emissions through time and varied by species, even after controlling for possible changes in diet and habitat. MeHg concentrations varied substantially within species and individual specimens, suggesting that high within-individual variation in feather MeHg concentrations caused by spatiotemporal variation in molt, environmental Hg exposure, or mobility decoupling Hg uptake from breeding sites, may obscure trends in MeHg through time. Our study provides a unique assessment of feather MeHg in six species not typically analyzed using this retrospective approach.

Sex-associated differences in trace metals concentrations in and on the plumage of a common urban bird species

Urban areas encompass both favorable and stressful conditions linked with human activities and pollution. Pollutants remain of major ecological importance for synanthropic organisms living in the city. Plumage of urban birds harbour trace metals, which can result from external deposition or from internal accumulation. External and internal plumage concentrations likely differ between specific trace metals, and may further differ between males and females because of potential sex-linked differential urban use, physiology or behaviour. Here, we measured the concentrations in four trace metals (cadmium, copper, lead and zinc) in both unwashed and washed feathers of 49 male and 38 female feral pigeons (Columba livia) from Parisian agglomeration. We found that these concentrations indeed differed between unwashed and washed feathers, between males and females, and for some metals depended on the interaction between these factors. We discuss these results in the light of physiological and behavioural differences between males and females and of spatial repartition of the four trace metals in the city.

Feathers as a biomonitoring tool of polyhalogenated compounds: a review

Feathers have many advantages that make them an excellent nondestructive tool for monitoring polyhalogenated compounds (PHCs). This paper proposes a review on the PHCs in feathers and factors influencing the pollutant load. Special attention has given to external contamination and the main analytical methods used to detect these compounds in feathers. Some authors have found strong and significant correlations between the concentrations of PHCs in feathers and internal tissues, providing positive expectations for their future use in the field of ecotoxicology. However, changes in diet, time elapsed between the previous molt period and sampling, sample size, and/or external contamination have been suggested as possible causes to explain the lack of correlations reported in some studies. Further studies with newly grown feathers and blood samples would be required in order to clarify this issue. Although atmospheric deposition has been reported as cause of external contamination, preening oil seems to be the most relevant factor contributing to this process. Unfortunately, washing techniques tested to date are not able to effectively remove the surface contamination from barbs and shafts, and therefore, it is necessary to develop methods able to discriminate between internal and external contamination. Finally, in this review, deposition rate is proposed as a measurement unit, as this allows comparisons between different parts of the same feather, as well as between different feathers.

Assessment of heavy metals in water samples and tissues of edible fish species from Awassa and Koka Rift Valley Lakes, Ethiopia

The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard.

Contrasting levels of heavy metals in the feathers of urban pigeons from close habitats suggest limited movements at a restricted scale

Despite restrictions in emissions, heavy metals may remain a major environmental issue due to their numerous sources and their persistence. Here, we assessed current levels of 4 metals (Copper, Cadmium, Lead, Zinc) in the feathers of 91 feral pigeons (Columba livia) from 7 sites in the urbanized region of Paris. Elements were detected in all pigeons, indicating that metals persist in urbanized areas. The ratio between metal concentrations in the feathers vs. in the environment calculated using data from other studies was 2-90 times higher for cadmium than for other metals, underlying its ecological importance. Concentrations in the feathers depended on locality, suggesting that pigeons remain in local habitats at this restricted scale, as expected from previous observations. Overall, our study suggests that urban feral pigeons may represent a good model system for metal biomonitoring.

Mercury in white stork (Ciconia ciconia) chick feathers from northeastern Mediterranean areas in relation to age, brood size, and hatching order

Mercury (Hg) levels in white stork (Ciconia ciconia) feathers collected in the mid-1990s from five northeastern Mediterranean (Greece) areas varied, with mean ranges between 301 ng g(-1) dry weight (dw) (Pinios River) and 1911 ng g(-1) dw (Sperchios Delta). A significant increase of Hg levels in chick feathers with age (surrogated by bill size) was found in the Evros and Pinios River areas, a nonsignificant increase in the Amvrakikos Gulf and the Epirus Region, and a marginally significant decrease in the Sperchios Delta area. For combined data of 1993 and 1995, Hg concentrations did not differ significantly in relation to hatching order among broods but differed significantly in relation to brood size being higher in 4-chick broods than those in 3-chick broods. All 10 areas formed 4 groups with levels mutually significantly different. Highest levels were detected in the Evros, Axios, and Sperchios riverine areas, whereas the lowest levels occurred at Drama plain, which lacks large water bodies in its vicinity. Levels were lower than those associated with intoxication to other ciconiiform species.

Pathology and toxicology findings for search-and-rescue dogs deployed to the September 11, 2001, terrorist attack sites: initial five-year surveillance

A long-term surveillance study was conducted on 95 search-and-rescue (S&R) dogs deployed to the September 11, 2001, terrorist attack sites; an additional 55 nondeployed S&R dogs served as controls. After 5 years of surveillance, 32% of the deployed dogs have died and 24% of the nondeployed dogs. The mean age at the time of death in these 2 groups of dogs is not significantly different. Causes of death in both groups of dogs include inflammatory, degenerative, and proliferative conditions. No primary pulmonary tumors have been identified to date nor has any significant level of toxicant been found in the tissues from these dogs using assays for general organic compounds and metals or, specifically, for polychlorinated biphenyls. However, significant numbers of both deployed and nondeployed dogs have evidence of inhaled matter as demonstrated by the presence of anthracotic pigments or refractile particulate matter in pulmonary tissue. Although S&R activities in response to the 9/11 terrorist attacks exposed dogs to a wide variety of potentially toxic compounds, to date, these dogs do not appear to suffer from higher mortality or increased pulmonary disease compared with nondeployed dogs. To the authors' knowledge, the current survey represents the first long-term and large-scale survey of the pathology and toxicology of S&R dogs deployed to a major disaster site.

Environmental pollutants in endangered vs. increasing subspecies of the lesser black-backed gull on the Norwegian Coast

Organochlorine (OC) residues were measured in eggs and blood of different subspecies of the lesser black-backed gull, Larus fuscus, on the Norwegian coast: a) increasing L. f. intermedius in the North Sea; b) endangered L. f. fuscus near the Arctic Circle; c) L. f. fuscus and greyish-mantled gulls, with a L. f. intermedius appearance, in the Barents Sea region. The dominating OCs in lesser black-backed gulls were polychlorinated biphenyls (PCB) and p,p'-dichlorodiphenyldichloroethylene (DDE). DDE and beta-hexachlorocyclohexane (beta-HCH) residues were higher in L. f. fuscus compared to L. f. intermedius and greyish-mantled birds in the Barents Sea region. In the latter area, blood residues of PCB and DDE in lesser black-backed gulls were as high as in great black-backed gulls, Larus marinus, while in the other regions they were lower. The higher DDE residues in endangered L. f. fuscus compared to increasing L. f. intermedius and greyish-mantled birds, which are invading northern Norway, suggest that OCs may have played a role in the population decline of L. f. fuscus, possibly in combination with nutrient stress.

Suggested guidelines for use of avian species as biomonitors

An animal's suitability as a biomonitor of environmental change can be determined by biological, reproductive and ecological characteristics determined at the class, order and species level. The animal's habitat where the research is to be performed and the form, function and structure of the environmental change being studied within that habitat also determines suitability. Non-threatened populations of large, non-migratory, long-lived, seasonally-breeding tertiary avian predators, whose dietary preferences are narrow and known, can be useful as monitors of environmental chemical contaminants. If chemicals are being monitored, a quantifiable endpoint effect must be demonstrated in the species, or a similar species under experimental laboratory conditions. Logistical and economic issues as well as public and regulatory authority acceptance should also be considered when assessing the suitability of a species as a biomonitor.