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Journal ArticleDOI

Mercury in Feathers of Little Egret Egretta garzetta and Night Heron Nycticorax nycticorax Chicks and in Their Prey in the Axios Delta, Greece

TL;DR: Night heron chick feathers, freshwater fish and dragonfly larvae could be used to monitor mercury contamination in this region, but use of bird feathers alone could give misleading results if changes in diet occurred.
Abstract: Mercury concentrations were measured in feathers of little egret and night heron chicks and in their prey in the Axios Delta, Greece. Significantly higher concentrations occurred in night heron than in little egret in 1993. In the night heron the mercury content of feathers was negatively correlated to the size of chicks, possibly due to inhibition of growth. Mercury concentrations were higher than reported for heron feathers in seriously polluted sites in North America and Japan, but the toxic hazard is unclear. Diets differed considerably between the two species due to use of different foraging habitats and this seems responsible for different mercury contents of feathers. Mercury concentrations in the pumpkinseed sunfish Lepomis gibbosus, goldfish Carrassius auratus, and in dragonfly Odonata larvae were the highest among the prey categories. Frogs and water beetles Dytiscidae had moderate concentrations whereas saltwater fish and terrestrial prey had very low mercury concentrations. The implication is that the deltaic marshes are the habitat most polluted with mercury. Night heron chick feathers, freshwater fish and dragonfly larvae could be used to monitor mercury contamination in this region, but use of bird feathers alone could give misleading results if changes in diet occurred.

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Citations
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Journal ArticleDOI
TL;DR: The study supports the fact that marine pelagic prey are important for estuarine seabirds because they provide a food resource with lower contamination levels and may have a wider application in similar seabird species and coastal environments.
Abstract: We assessed mercury levels in the feathers of little tern (Sternula albifrons) chicks from hatching to fledging and in their prey captured by adults in three main foraging habitats: lagoon, salinas, and adjacent sea. These data were used to model mercury concentration in chick feathers through food ingestion, in order to explore the effects that changes in diet would have on the mercury burden of chicks as they aged. The mercury concentration in feathers of chicks raised in sandy beaches was higher than in those raised in salinas. Lagoon prey had a significantly higher mercury concentration (0.18 ± 0.09 μg g−1 dry weight [d.w.]) than prey from salinas and the adjacent sea (both 0.06 ± 0.03 μg g−1 d.w.). In relation to prey species group, mercury content was significantly higher for bottom fish (0.17 ± 0.10 μg g−1 d.w.) than for pelagic (0.08 ± 0.06 μg g−1 d.w.), euryhaline fish (0.04 ± 0.02 μg g−1 d.w.), and crustacea (0.08 ± 0.03 μg g−1 d.w.). To understand the importance of mercury content of each prey group, we ran several theoretical scenarios assuming that chicks were fed on only one species at a time. Considering a diet restricted to lagoon (mostly benthic) prey, A- and B-chicks may encounter health problems with an excess of mercury. On the contrary, a diet restricted to marine (mostly pelagic) prey would decrease the mercury concentration in chick feathers; the fast growth rate and the related mercury dilution effect in little tern chicks seem to decrease mercury levels in their feathers. Our study supports the fact that marine pelagic prey are important for estuarine seabirds because they provide a food resource with lower contamination levels. This model may have a wider application in similar seabird species and coastal environments.

15 citations


Cites background from "Mercury in Feathers of Little Egret..."

  • ...In chicks \5 days of age, mercury levels were related not only to items delivered by their parents (Goutner and Furness 1997) but...

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  • ...In chicks \5 days of age, mercury levels were related not only to items delivered by their parents (Goutner and Furness 1997) but also to mercury burdens present in their eggs (transmitted from their female parents [Becker et al. 1993])....

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01 Jan 2009
TL;DR: In this paper, the authors determine any local effect of coal-fired power plants on total mercury concentrations in wetland sediment and tadpole samples, and find that coal-fire power plants are not significantly affecting mercury concentration in surrounding wetlands.
Abstract: There have been contradictory reports of the relative proportion of mercury from coal-fired power plants that deposits locally. Our objective was to determine any local effect of coal-fired power plants on total mercury concentrations in wetland sediment and tadpole samples. Four power plants and 45 wetlands were selected for study. Total mercury concentrations were determined in 75 sediment samples (range: 8–82 ng/g dry weight) and 100 bullfrog (Lithobates catesbeiana) and green frog (Lithobates clamitans) tadpoles (range: 5–318 ng/g wet weight). Tadpole and sediment total mercury did not significantly vary by power plant or distance from the plant. Only one power plant had a significantly greater concentration of total mercury in sediment downwind compared to upwind wetlands. A similar (but non-significant) trend was found for tadpole total mercury surrounding the same plant. Tadpole total mercury was negatively correlated with both tadpole weight and total length. Tadpole and sediment total mercury concentrations were not significantly correlated with one another. The results of the current study suggest that coal-fired power plants are not significantly affecting mercury concentrations in surrounding wetlands.

14 citations

01 Jan 2008
TL;DR: The conservation of freshwater habitats alongside the enforcement for less intensive agricultural practices at rice fields is considered essential for heron protection in the Axios delta.
Abstract: Habitat use, abundance and changes in number of herons were studied in the Axios Delta during a year cycle. At least seven different man-made and natural habitat types were distinguished in an area of 99.06 km 2 ; rice fields (44.5% of the study area), seacoast (20.6%), salt marshes (19.0%) and fresh water habitats (2.5%). Nine heron species were recorded (five breeding, two wintering and two staging). Little egret was the most opportunistic species using almost equivalently all habitat types. Great white and grey herons mostly exploited the salt marshes and seacoast. Squacco, purple and night herons exploited rice fields, especially during the chick-rearing period (May-June). Fresh water marshes were valuable for almost all species, particularly during the breeding season. Canals were occasionally attractive to heron species, especially in the spring. Interspecific competition may occur in the feeding areas and especially in the freshwater marshes, but both, biological and behavioural segregation among the species probably reduced the negative effects. The conservation of freshwater habitats alongside the enforcement for less intensive agricultural practices at rice fields is considered essential for heron protection in the Axios delta.

14 citations


Cites background from "Mercury in Feathers of Little Egret..."

  • ...Additionally, species such as those previously mentioned have been studied as bioindicators of mercury (Goutner & Furness, 1997; Goutner et al., 2001a) and organochlorines (Albanis et al., 1996)....

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Journal ArticleDOI
TL;DR: Purple heron eggs and nestling feathers have demonstrated their usefulness as bioindicators for pollution in the river biota; feathers in particular show pollutant impacts on a strict local basis.
Abstract: The Flix reservoir, in the low course of the Ebro River, contains thousands of tons of polluted sediments, accumulated from the activities of a chemical factory. An ongoing project is working toward removing these pollutants. Piscivore birds like the purple heron (Ardea purpurea) may be useful bioindicators, so eggs and nestling feathers were sampled during the 2006–2008 breeding seasons at three localities: a reference site situated upstream and two potentially affected by the toxic muds; one at the focal area and one at a distal area, the Ebro Delta. The samples were analyzed for isotopic signatures of 15N and 13C and concentrations of heavy metals and selenium. Baseline nitrogen signatures were higher in riverine sites than in the delta. Nitrogen together with carbon signatures adequately discriminated riverine and deltaic ecosystems. Mercury levels are highly influenced by the polluted sediments at Flix and pose potential risks for the birds, as they are among the highest ever recorded in heron species. Selenium and copper concentrations probably derive from other sources. Except for mercury, heavy metals and selenium levels were below toxic levels. Purple heron eggs and nestling feathers have demonstrated their usefulness as bioindicators for pollution in the river biota; feathers in particular show pollutant impacts on a strict local basis. A long series of study years is necessary in dynamic ecosystems such as this, so continued monitoring of the heron population at Flix is advisable to trace the effects of the toxic muds, particularly during their removal, because of the high levels of mercury detected.

11 citations


Cites background from "Mercury in Feathers of Little Egret..."

  • ...…(Boncompagni et al. 2003) and Hong Kong (Connell et al. 2002) or several heron species from China (Burger and Gochfeld 1993) and even higher than those reported for little egret and night heron feathers in the Axios Delta, Greece (Goutner and Furness 1997) and northern Italy (Fasola et al. 1998)....

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  • ...Finally, it should be noted that mercury levels found in nestling feathers at Flix are far higher than the ones found for little egret in Pakistan (Boncompagni et al. 2003) and Hong Kong (Connell et al. 2002) or several heron species from China (Burger and Gochfeld 1993) and even higher than those reported for little egret and night heron feathers in the Axios Delta, Greece (Goutner and Furness 1997) and northern Italy (Fasola et al. 1998)....

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  • ...2002) or several heron species from China (Burger and Gochfeld 1993) and even higher than those reported for little egret and night heron feathers in the Axios Delta, Greece (Goutner and Furness 1997) and northern Italy (Fasola et al....

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References
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Book
01 Jan 1973

2,885 citations

Journal ArticleDOI
TL;DR: A review of the available information on global Hg cycling shows that the atmosphere and surface ocean are in rapid equilibrium; the evasion of Hg0 from the oceans is balanced by the total oceanic deposition of hg(II) from the atmosphere as mentioned in this paper.

1,027 citations

Journal ArticleDOI
TL;DR: It is concluded that significant physiological and biochemical responses to such exposure conditions occur at dietary metal concentrations insufficient to cause signs of overt toxicity, particularly important are reproductive effects which include decreased egg production, decreased hatchability, and increased hatchling mortality.

795 citations


"Mercury in Feathers of Little Egret..." refers background in this paper

  • ...…to be much more sensitive to mercury toxicity than are seabirds, and experimental studies resulting in tissue concentrations of mercury similar to those reported here led to reduced chick growth, impaired brain development and lesions in nerve tissues (Heinz 1979; Scheuhammer 1987; Thompson 1996)....

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  • ...Terrestrial and freshwater birds appear to be much more sensitive to mercury toxicity than are seabirds, and experimental studies resulting in tissue concentrations of mercury similar to those reported here led to reduced chick growth, impaired brain development and lesions in nerve tissues (Heinz 1979; Scheuhammer 1987; Thompson 1996)....

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BookDOI
01 Jan 1993
TL;DR: In this paper, birds are used as indicators of change in water quality and change in marine prey stocks in the tropics of the world, and as monitors of radionuclide contamination.
Abstract: Can birds be used to monitor the environment? Environmental change. Birds as monitors of radionuclide contamination. Birds as indicators of change in water quality. Birds as monitors of pollutants. Seabirds as indicators of change in marine prey stocks. Migrants as monitors of change in the tropics. An integrated approach to assessing environmental changes affecting birds. Synthesis and future prospects.

733 citations


"Mercury in Feathers of Little Egret..." refers background or methods or result in this paper

  • ...In waterbirds, the feeding habits have a strong influence on mercury content of feathers (Hoffman and Curnow 1979; Doi et al.1984; Braune 1987; Furness 1993), so these differences can be attributed to the fact that the two species have different diets, use different foraging habitats, and will switch diet according to prey availability....

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  • ...Although it is expected that mercury content in chick feathers may vary a little with age (Furness 1993), absence of this relationship in 1994 might be attributable to the type of sample containing ages of limited spectrum in comparison to the sample of 1993....

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  • ...found in previous studies of bird feathers (Burger 1993; Furness 1993)....

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  • ...Measurements made were of total mercury, though we assume that this was all methylmercury as found in previous studies of bird feathers (Burger 1993; Furness 1993)....

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  • ...In waterbirds, the feeding habits have a strong influence on mercury content of feathers (Hoff- man and Curnow 1979; Doiet al.1984; Braune 1987; Furness 1993), so these differences can be attributed to the fact that the two species have different diets, use different foraging habitats, and will…...

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