Mercury accumulation in the food web of the Scotia Sea, Southern Ocean
The aim of the work presented in this thesis was to understand processes of bioaccumulation and biomagnification of mercury (Hg) in a Southern Ocean (SO) food web, and to evaluate the effect of organism size and habitat in Hg accumulation during the last decade. To do this, tissues of various specie...
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University of St Andrews
2024
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Online Access: | https://hdl.handle.net/10023/30006 https://doi.org/10.17630/sta/945 |
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ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/30006 2024-06-23T07:45:58+00:00 Mercury accumulation in the food web of the Scotia Sea, Southern Ocean Seco, José Pereira, Eduarda Brierley, Andrew Fundação para a Ciência e Tecnologia 156 2024-06-06T19:58:33Z https://hdl.handle.net/10023/30006 https://doi.org/10.17630/sta/945 en eng University of St Andrews The University of St Andrews Universidade de Aveiro https://hdl.handle.net/10023/30006 https://doi.org/10.17630/sta/945 Thesis Doctoral PhD Doctor of Philosophy 2024 ftstandrewserep https://doi.org/10.17630/sta/945 2024-06-12T00:00:17Z The aim of the work presented in this thesis was to understand processes of bioaccumulation and biomagnification of mercury (Hg) in a Southern Ocean (SO) food web, and to evaluate the effect of organism size and habitat in Hg accumulation during the last decade. To do this, tissues of various species occupying different trophic levels were analysed in samples collected over various sampling years (2006/07 and 2016/17) from areas with distinctive environmental characteristics. Different accumulation patterns were found: Antarctic krill juveniles had higher Hg concentrations than adults; in squid, Hg concentration increased with individual size in one species (Alluroteuthis antarcticus), decreased in another (Galiteuthis glacialis), and in another still, there was no obvious relationship (Bathyteuthis abyssicola); for myctophid fish there was a consistent increase of Hg concentration with fish size, with the exception of Electrona antarctica females. Proportions of organic Hg also varied between trophic groups, from relatively low (15-37%) in krill to virtual 100% in all myctophid tissues. Regarding Hg tissue allocation, squid muscle was the tissue that had highest Hg, followed by digestive gland and gills. Myctophids’ Hg concentrations were higher in the liver and heart than in muscle or gills. Geographic differences in Hg concentration in krill were found, with individuals from the South Orkney having Hg levels 5 to 7 times higher than South Georgia: this geographic variation was not found in myctophids. As expected, when evaluating Hg along the food web, POM spell out had the lowest Hg levels, followed in increasing concentration by zooplankton, squid, myctophid, notothenid fish and seabirds. Predators exhibited variability in Hg levels which corresponding to the trophic level of their diets, with lower G15N levels corresponding to lower Hg concentrations. The mid food web groups (squid and myctophids) showed a decreasing trend in Hg level over the last decade, but that difference was not reflected in top ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctic Krill Antarctica antarcticus Scotia Sea Southern Ocean University of St Andrews: Digital Research Repository Antarctic Scotia Sea Southern Ocean |
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Open Polar |
collection |
University of St Andrews: Digital Research Repository |
op_collection_id |
ftstandrewserep |
language |
English |
description |
The aim of the work presented in this thesis was to understand processes of bioaccumulation and biomagnification of mercury (Hg) in a Southern Ocean (SO) food web, and to evaluate the effect of organism size and habitat in Hg accumulation during the last decade. To do this, tissues of various species occupying different trophic levels were analysed in samples collected over various sampling years (2006/07 and 2016/17) from areas with distinctive environmental characteristics. Different accumulation patterns were found: Antarctic krill juveniles had higher Hg concentrations than adults; in squid, Hg concentration increased with individual size in one species (Alluroteuthis antarcticus), decreased in another (Galiteuthis glacialis), and in another still, there was no obvious relationship (Bathyteuthis abyssicola); for myctophid fish there was a consistent increase of Hg concentration with fish size, with the exception of Electrona antarctica females. Proportions of organic Hg also varied between trophic groups, from relatively low (15-37%) in krill to virtual 100% in all myctophid tissues. Regarding Hg tissue allocation, squid muscle was the tissue that had highest Hg, followed by digestive gland and gills. Myctophids’ Hg concentrations were higher in the liver and heart than in muscle or gills. Geographic differences in Hg concentration in krill were found, with individuals from the South Orkney having Hg levels 5 to 7 times higher than South Georgia: this geographic variation was not found in myctophids. As expected, when evaluating Hg along the food web, POM spell out had the lowest Hg levels, followed in increasing concentration by zooplankton, squid, myctophid, notothenid fish and seabirds. Predators exhibited variability in Hg levels which corresponding to the trophic level of their diets, with lower G15N levels corresponding to lower Hg concentrations. The mid food web groups (squid and myctophids) showed a decreasing trend in Hg level over the last decade, but that difference was not reflected in top ... |
author2 |
Pereira, Eduarda Brierley, Andrew Fundação para a Ciência e Tecnologia |
format |
Doctoral or Postdoctoral Thesis |
author |
Seco, José |
spellingShingle |
Seco, José Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
author_facet |
Seco, José |
author_sort |
Seco, José |
title |
Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
title_short |
Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
title_full |
Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
title_fullStr |
Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
title_full_unstemmed |
Mercury accumulation in the food web of the Scotia Sea, Southern Ocean |
title_sort |
mercury accumulation in the food web of the scotia sea, southern ocean |
publisher |
University of St Andrews |
publishDate |
2024 |
url |
https://hdl.handle.net/10023/30006 https://doi.org/10.17630/sta/945 |
op_coverage |
156 |
geographic |
Antarctic Scotia Sea Southern Ocean |
geographic_facet |
Antarctic Scotia Sea Southern Ocean |
genre |
Antarc* Antarctic Antarctic Krill Antarctica antarcticus Scotia Sea Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Krill Antarctica antarcticus Scotia Sea Southern Ocean |
op_relation |
https://hdl.handle.net/10023/30006 https://doi.org/10.17630/sta/945 |
op_doi |
https://doi.org/10.17630/sta/945 |
_version_ |
1802643261214425088 |