Mercury concentrations provide an indicator of marine foraging in coastal birds

The transfer of nutrients between marine and terrestrial systems has important ecological consequences, and animal movement is an important driver of nutrient transfer. Coastal birds forage in marine environments and breed in terrestrial habitats, and thus serve as vectors moving nutrients from the...

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Autores principales:	Lesley H. Thorne, Matthew Fuirst, Richard Veit, Zofia Baumann
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	Mercury Foraging Marine Terrestrial Coastal bird Ecology QH540-549.5
Acceso en línea:	https://doaj.org/article/3c8087bafaed4710b55e056fc7e28072
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spelling	oai:doaj.org-article:3c8087bafaed4710b55e056fc7e280722021-12-01T04:29:20ZMercury concentrations provide an indicator of marine foraging in coastal birds1470-160X10.1016/j.ecolind.2020.106922https://doaj.org/article/3c8087bafaed4710b55e056fc7e280722021-02-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S1470160X2030861Xhttps://doaj.org/toc/1470-160XThe transfer of nutrients between marine and terrestrial systems has important ecological consequences, and animal movement is an important driver of nutrient transfer. Coastal birds forage in marine environments and breed in terrestrial habitats, and thus serve as vectors moving nutrients from the sea to the land. However, urbanization can influence the extent to which coastal birds forage in marine or terrestrial environments due to the availability of human subsidies. Establishing a reliable and straightforward indicator of marine foraging would be useful for assessing changes in the use of terrestrial vs. marine habitats in the face of urbanization and broader environmental change, and for understanding the flow of nutrients and energy between terrestrial and marine environments. Mercury (Hg) is a highly toxic heavy metal which bioaccumulates in marine food webs, and is a potential indicator of marine foraging. Methylmercury (MeHg), is present only in aquatic ecosystems and reaches elevated concentrations in the prey species of marine birds. Thus, high concentrations of MeHg would be expected for birds foraging in marine environments in comparison to those foraging on terrestrial sources. We hypothesized that the degree of marine foraging influences Hg uptake in coastal birds. To test this hypothesis, we combined GPS tracking data with measurements of Hg concentrations in the blood of herring gulls (Larus argentatus) along an urban gradient in the northeast United States. We examined Hg concentrations for 51 individual herring gulls tracked with GPS tags at study sites representing high, medium and low degrees of urbanization. Our results showed a strong and significant positive relationship between Hg concentrations and the proportion of herring gull foraging locations occurring in offshore waters. Hg concentrations differed significantly between herring gulls whose primary foraging habitat occurred in marine vs. terrestrial environments. Gulls in more urban colonies spent less time foraging in marine environments, and had significantly lower Hg concentrations than those at the more remote study. Our results suggest that Hg concentrations in blood can be used to reflect the extent of marine foraging for animals using both marine and terrestrial habitats. Hg concentrations could be valuable monitoring tool to assess how the use of marine foraging habitats changes through time (dietary shifts) or relative to environmental change such as urbanization.Lesley H. ThorneMatthew FuirstRichard VeitZofia BaumannElsevierarticleMercuryForagingMarineTerrestrialCoastal birdEcologyQH540-549.5ENEcological Indicators, Vol 121, Iss , Pp 106922- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Mercury Foraging Marine Terrestrial Coastal bird Ecology QH540-549.5
spellingShingle	Mercury Foraging Marine Terrestrial Coastal bird Ecology QH540-549.5 Lesley H. Thorne Matthew Fuirst Richard Veit Zofia Baumann Mercury concentrations provide an indicator of marine foraging in coastal birds
description	The transfer of nutrients between marine and terrestrial systems has important ecological consequences, and animal movement is an important driver of nutrient transfer. Coastal birds forage in marine environments and breed in terrestrial habitats, and thus serve as vectors moving nutrients from the sea to the land. However, urbanization can influence the extent to which coastal birds forage in marine or terrestrial environments due to the availability of human subsidies. Establishing a reliable and straightforward indicator of marine foraging would be useful for assessing changes in the use of terrestrial vs. marine habitats in the face of urbanization and broader environmental change, and for understanding the flow of nutrients and energy between terrestrial and marine environments. Mercury (Hg) is a highly toxic heavy metal which bioaccumulates in marine food webs, and is a potential indicator of marine foraging. Methylmercury (MeHg), is present only in aquatic ecosystems and reaches elevated concentrations in the prey species of marine birds. Thus, high concentrations of MeHg would be expected for birds foraging in marine environments in comparison to those foraging on terrestrial sources. We hypothesized that the degree of marine foraging influences Hg uptake in coastal birds. To test this hypothesis, we combined GPS tracking data with measurements of Hg concentrations in the blood of herring gulls (Larus argentatus) along an urban gradient in the northeast United States. We examined Hg concentrations for 51 individual herring gulls tracked with GPS tags at study sites representing high, medium and low degrees of urbanization. Our results showed a strong and significant positive relationship between Hg concentrations and the proportion of herring gull foraging locations occurring in offshore waters. Hg concentrations differed significantly between herring gulls whose primary foraging habitat occurred in marine vs. terrestrial environments. Gulls in more urban colonies spent less time foraging in marine environments, and had significantly lower Hg concentrations than those at the more remote study. Our results suggest that Hg concentrations in blood can be used to reflect the extent of marine foraging for animals using both marine and terrestrial habitats. Hg concentrations could be valuable monitoring tool to assess how the use of marine foraging habitats changes through time (dietary shifts) or relative to environmental change such as urbanization.
format	article
author	Lesley H. Thorne Matthew Fuirst Richard Veit Zofia Baumann
author_facet	Lesley H. Thorne Matthew Fuirst Richard Veit Zofia Baumann
author_sort	Lesley H. Thorne
title	Mercury concentrations provide an indicator of marine foraging in coastal birds
title_short	Mercury concentrations provide an indicator of marine foraging in coastal birds
title_full	Mercury concentrations provide an indicator of marine foraging in coastal birds
title_fullStr	Mercury concentrations provide an indicator of marine foraging in coastal birds
title_full_unstemmed	Mercury concentrations provide an indicator of marine foraging in coastal birds
title_sort	mercury concentrations provide an indicator of marine foraging in coastal birds
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/3c8087bafaed4710b55e056fc7e28072
work_keys_str_mv	AT lesleyhthorne mercuryconcentrationsprovideanindicatorofmarineforagingincoastalbirds AT matthewfuirst mercuryconcentrationsprovideanindicatorofmarineforagingincoastalbirds AT richardveit mercuryconcentrationsprovideanindicatorofmarineforagingincoastalbirds AT zofiabaumann mercuryconcentrationsprovideanindicatorofmarineforagingincoastalbirds
_version_	1718405896969650176

Mercury concentrations provide an indicator of marine foraging in coastal birds

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