Feather mercury concentrations and physiological condition of Great Egret and White Ibis nestlings in the Florida Everglades

Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA
Science of The Total Environment (Impact Factor: 4.1). 02/2009; DOI: 10.1016/j.scitotenv.2008.12.043
Source: PubMed


Mercury contamination in the Florida Everglades has reportedly played a role in the recent decline of wading birds, although no studies have identified a mechanism leading to population-level effects. We assessed feather mercury levels in great egret (Ardea alba; n = 91) and white ibis (Eudocimus albus; n = 46) nestlings at breeding colonies in the Florida Everglades during a year (2006) with excellent breeding conditions (characterized by hydrology leading to concentrated prey) and a year with below average breeding conditions (2007). We also assessed the physiological condition of those nestlings based on levels of plasma and fecal corticosterone metabolites, and stress proteins 60 and 70. Mercury levels were higher in both species during the good breeding condition year (great egret = 6.25 μg/g ± 0.81 SE, white ibis = 1.47 μg/g ± 0.41 SE) and lower in the below average breeding year (great egret = 1.60 μg/g ± 0.11 SE, white ibis = 0.20 μg/g ± 0.03 SE). Nestlings were in better physiological condition in 2006, the year with higher feather mercury levels. These results support the hypothesis that nestlings are protected from the harmful effects of mercury through deposition of mercury in growing feathers. We found evidence to suggest shifts in diets of the two species, as a function of prey availability, thus altering their exposure profiles. However, we found no evidence to suggest they respond differently to mercury exposure.

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    • "However, relatively few studies have focused on chicks comparing different colonies. Such studies mainly referred to herons and ibises (Abdennadher et al., 2011; Abdullah et al., 2015; Burger, 2013; Clarckson et al., 2012; Cotìn et al., 2012; Golden et al., 2003; Goutner et al., 2001; Herring et al., 2009; Kim and Oh, 2014a; Rubio et al., in press; Rumbold et al., 2001; Sepulveda et al., 1999; Spahn and Sherry, 1999), terns and gulls (Burger, 1996; García-Tarrasón et al., 2013; Kim and Oh, 2014b; Ramos et al., 2013; Sanpera et al., 2007), and pelagic birds (Blévin et al., 2013) and focused especially on Hg. Feathers are subjected to external contamination to some extent (Ek et al., 2004; Fasola et al., 1998; Hahn et al., 1993; Hollamby et al., 2006; Valladares et al., 2010). "
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    ABSTRACT: Assessing trace metal pollution using feathers has long attracted the attention of ecotoxicologists as a cost-effective and non-invasive biomonitoring method. In order to interpret the concentrations in feathers considering the external contamination due to lithic residue particles, we adopted a novel geochemical approach. We analysed 58 element concentrations in feathers of wild Eurasian Greater Flamingo Phoenicopterus roseus fledglings, from 4 colonies in Western Europe (Spain, France, Sardinia, and North-eastern Italy) and one group of adults from zoo. In addition, 53 elements were assessed in soil collected close to the nesting islets. This enabled to compare a wide selection of metals among the colonies, highlighting environmental anomalies and tackling possible causes of misinterpretation of feather results. Most trace elements in feathers (Al, Ce, Co, Cs, Fe, Ga, Li, Mn, Nb, Pb, Rb, Ti, V, Zr, and REEs) were of external origin. Some elements could be constitutive (Cu, Zn) or significantly bioaccumulated (Hg, Se) in flamingos. For As, Cr, and to a lesser extent Pb, it seems that bioaccumulation potentially could be revealed by highly exposed birds, provided feathers are well cleaned. This comprehensive study provides a new dataset and confirms that Hg has been accumulated in feathers in all sites to some extent, with particular concern for the Sardinian colony, which should be studied further including Cr. The Spanish colony appears critical for As pollution and should be urgently investigated in depth. Feathers collected from North-eastern Italy were the hardest to clean, but our methods allowed biological interpretation of Cr and Pb. Our study highlights the importance of external contamination when analysing trace elements in feathers and advances methodological recommendations in order to reduce the presence of residual particles carrying elements of external origin. Geochemical data, when available, can represent a valuable tool for a correct interpretation of the analytical results.
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    • "Stress responses on HSPs have been shown to be induced by cold and a range of other stresses (Sorensen et al., 2003; Herring et al., 2009). During the present study on dermal fibroblasts of Tharparkar and Karan-Fries cattle, a non-significant increase in the HSP70 gene expression (HSPA8, HSPA1A and HSPA2) was observed on mild cold exposure (25 1C) as compared to control (37 1C) (Figs. "
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    ABSTRACT: The present studies were conducted to investigate the difference response of dermal fibroblasts to heat stress in Tharparkar and Karan-Fries cattle. Skin is the important environmental interface providing a protective envelope to animals. In skin, dermal fibroblasts are the most regular cell constituent of dermis that is crucial for temperature homeostasis. The study aimed to examine the reactive oxygen species (ROS) formation, cytotoxicity (%) and heat shock protein 70 (HSP70) genes expression in dermal fibroblast of Tharparkar and Karan-Fries cattle and to assess whether resistance of dermal fibroblast to heat stress is breed specific. Dermal fibroblasts from ear pinna of Tharparkar and Karan-Fries cattle were exposed at 25 °C, 37 °C, 40 °C and 44 °C for 3 h to measure the ROS, cytotoxicity (%) and HSP 70 (HSPA1A, HSPA2 and HSPA8) genes expression. The results showed that ROS formation at low temperature (25 °C) decreased in both breeds as compared to control (37 °C) and the differences were significant (P<0.0001). Heat stress of 40 °C did not increase ROS formation significantly in Tharparkar but increased significantly (P<0.001) in Karan-Fries cattle. The overall cytotoxicity (%) was also found to be significantly different (P<0.001) between Tharparkar and Karan-Fries cattle, and on exposure to different temperature (P<0.001). The cytotoxicity (%) in dermal fibroblast cells of Karan fries cows were more than Tharparkar. The expression studies indicated that all HSP70 genes (HSPA8, HSPA1A and HSPA2) were up regulated at different temperature in both breeds. In Tharparkar, relative mRNA expression of HSPA8 gene was higher but HSPA1A and HSPA2 genes were low as compared to Karan-Fries cattle. At 40 and 44 °C, the relative expressions of inducible HSP 70 genes (HSPA1A and HSPA2) were higher in Karan-Fries than Tharparkar. In summary, dermal fibroblasts resistance to heat shock differed between breeds. Dermal fibroblasts of Tharparkar were observed to be more heat tolerant than crossbred Karan-Fries cattle. Study concludes that Zebu cattle (Tharparkar) dermal fibroblasts are more adapted to tropical climatic condition than crossbreed cattle (Karan-Fries). Differences exist in dermal fibroblasts of heat adapted and non-adapted cattle.
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    • "Besides nutrients , wading birds in the Everglades may transport Hg to their nesting site via guano. This is because wading birds in the Everglades prey on invertebrates and fish from the marsh and accumulate high Hg concentrations in their feathers and eggs (Herring et al., 2009). However, Hg deposition from wading bird guano in the Everglades tree island soils has not been reported. "
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    ABSTRACT: Tree islands are habitat for wading birds and a characteristic landscape feature in the Everglades. A total of 93 surface soil and 3 soil core samples were collected from 7 degraded/ghost and 34 live tree islands. The mean Hg concentration in surface soils of ghost tree islands was low and similar to marsh soil. For live tree islands, Hg concentrations in the surface head region were considerably greater than those in mid and tail region, and marsh soils. Hg concentrations in bird guano (286 μg kg(-1)) were significantly higher than those in mammal droppings (105 μg kg(-1)) and plant leaves (53 μg kg(-1)). In addition, Hg concentrations and δ(15)N values displayed positive correlation in soils influenced by guano. During 1998-2010, estimated annual Hg deposition by guano was 148 μg m(-2) yr(-1) and ∼8 times the atmospheric deposition.
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