Mercury levels and health parameters in the threatened Olrog’s Gull (Larus atlanticus) from Argentina

Abstract

Mercury (Hg) exposure was investigated through feathers of Olrog's Gull and related to health parameters in adults (hematocrit, total plasma proteins, morphometric measures, sex) and chicks (hematocrit, total plasma proteins, immunoglobulins G and M) from a colony located in estuary of Bahía Blanca, Argentina. Mercury concentrations were 5.50 ± 2.59 μg g⁻¹ (n = 44) in live adults, 1.85 ± 0.45 μg g⁻¹ (n = 45) in live chicks and 1.81 ± 0.41 μg g⁻¹ (n = 41) in dead chicks. Large differences were observed between live adults and live or dead chicks and small differences between live and dead chicks. In the adults, the sex of the birds was the variable that best explained Hg concentrations. Male birds had higher concentrations than females; this suggests that the clutch provides a sink for mercury during egg laying. Hg concentrations in both adults and live chicks were associated with higher hematocrits. This could be associated with upregulated erythropoiesis to compensate for increased rate of destruction of prematurely senescent, Hg-contaminated erythrocytes. Based on our results, on the levels of Hg pollution in the past in the study area, and on the dietary specialization of Olrog's Gull, we must be vigilant about potential negative effects of Hg pollution on this population and recommend continued monitoring on this threatened species.

Pattern of mercury accumulation in different tissues of migratory and resident birds: Western reef heron (Egretta gularis) and Siberian gull (Larus heuglini) in Hara International Wetland—Persian Gulf

“…Although sensitivity to methylmercury toxicity varies among different species, concentrations of Hg of 5-15 mg kg −1 in feather have been related to adverse effects on growth and reproduction of birds (Wiener et al 2003;La Sala et al 2011). Zillioux et al (1993) concluded that a threshold for major toxic effects in waterbirds is 5 mg kg −1 in liver.…”

“…This might result from a special mercury dynamic among birds that mainly is based on the balance between Hg dietary intake and the elimination of plumage during the annual molt (Monteiro and Furness 1995). Adult migratory birds can eliminate accumulated contamination in their tissues via the molting process in their overwintering areas (Furness and Camphuysen 1997;La Sala et al 2011). However, Burger and Gochfeld (2002) (stated that age can also be a factor in the accumulation of contaminant residues, although age-related differences depend on the contaminant and the species being studied.…”

Current status of the threatened Olrog’s GullLarus atlanticus: global population, breeding distribution and threats

“…Crabs, the key prey of Olrog’s Gulls on their breeding grounds (Delhey et al 2001b, Suárez et al 2011), accumulate heavy metals and organochlorine pesticides and play an important role in the transfer of persistent pollutants to higher trophic levels (Menone et al 2004, Beltrame et al 2011, Simonetti et al 2012). Mercury concentrations in Olrog’s Gulls breeding at the Isla del Puerto colony were 2–17 μg.g -1 (La Sala et al 2011), which fall within the range considered toxic to birds (Burger and Gochfeld 2002).…”

Mercury in Feathers and Blood of Gulls from the Southern Baltic Coast, Poland

“…In Greece in 2003–2009, mercury concentrations in chick feathers were between 825 and 1142 ng g −1 d.w. (Goutner et al 2013), higher than juvenile herring gulls from the Polish coast. Feathers belonging to the great black-backed gull from the Polish coast were characterized by similar concentrations to those of the black guillemot ( Cepphus grylle faeroeensis ) from the Faroe Islands (Dam et al 2004), while lower Hg T concentrations were found in covert feathers of Olrog’s gull from Bahia Blanca (Argentina) (La Sala et al 2011) and in remiges of adult Audouin’s gulls in Spain (Sanpera et al 2007). …”