The Accumulation, Storage and Elimination of Metals and Organochlorines in the Great Skua Catharacta skua skua and Metal Accumulation in Atlantic Procellariiformes

Muirhead, Sandra Jayne (1986) The Accumulation, Storage and Elimination of Metals and Organochlorines in the Great Skua Catharacta skua skua and Metal Accumulation in Atlantic Procellariiformes. PhD thesis, University of Glasgow.

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The concentrations of metals and organochlorines (DDE and polychlorinated biphenyls) were measured in tissues of seabirds from the North and South Atlantic in order to examine possible differences between north and south populations. The seabirds were collected from the islands of Foula (Shetland), St. Kilda (Outer Hebrides) and Gough (Tristan da Cunha), the species investigated being the Great skua Catharacta skua skua and C. s. hamiltoni and several North and South Atlantic Procellariiformes. The North Atlantic Great Skua C. s. skua was of special interest for two reasons as it is a top marine predator and the birds were of known age. Great Skua tissues and feathers were analysed in order to compare the inter-organ distribution of the essential metals copper, zinc, and the essential metalloid selenium, with two chemically related metals, mercury and cadmium, which have no known physiological function. Eggs, liver, muscle and body fat were analysed for organochlorines. Concentrations of metals were determined in the liver and kidney of South and North Atlantic Procellariiformes and Great Skuas to indicate levels of potential pollutants and to compare concentrations in pelagic seabirds north-east Atlantic with the South Atlantic. The metals cadmium, copper, and zinc were determined by atomic absorption spectrophotometry (AAS); mercury by cold-flame AAS and mercury/hydride/AAS; selenium by instrumental neutron activation analysis and organochlorines by electron-capture gas chromatography. In the individual tissues of the Great Skua correlations were found between DDE and PCB's for both whole tissue and lipid concentrations. DDE levels were found to have declined in the eggs and tissues of the Great Skua between 1971 and 1983, but this was not found for PCB concentrations. The South Atlantic Procellariiformes accumulate high concentrations of the potentially toxic metals cadmium and mercury, the highest levels for cadmium being found in the kidney and for mercury in the liver (up to 148mug g-1 wet weight cadmium in the kidney and up to 271mug g-1 wet weight mercury in the Wandering Albatross Diomedea exulans). North Atlantic Procellariiformes contained lower concentrations of cadmium in the kidney (up to 25mug g-1 Cadmium wet weight in the Fulmar Fulmarus glacialis) which may be a consequence of diet, those birds taking a higher proportion of squid in their diet (several of the South Atlantic species) having higher cadmium concentrations than birds feeding mainly on other food sources (all of the North Atlantic birds). Squid may form a potential source of metals for the Procellariiformes as cephalapods are known to accumulate metals in the digestive gland. Many of the seabirds showed correlations between kidney cadmium and zinc concentrations, and liver and kidney cadmium concentrations. Accumulation of zinc and cadmium together suggests the existence of a possible detoxification mechanism involving zinc and metallothionein, but the correlation does not exist for all birds accumulating high cadmium concentrations. The normal distribution of some of the data suggests that there may be metabolic regulation of cadmium. The North Atlantic Great Skua shows strong relationships between most of the metals and between renal and liver cadmium concentrations. However, no correlation between age and accumulation of any of the metals was shown. Correlations of selenium and mercury concentrations in the liver indicate, as with zinc and cadmium, a possible protective role by selenium. Levels of PCBs and DDE in muscle and body fat all correlate with each other and vary greatly between individuals, suggesting individual variation in excretion rates, feeding habits or distribution in winter. Mercury levels in primary feathers indicate the concentration of mercury in the bloodstream at the time of feather formation, reflecting in turn either environmental levels at the time of feather formation or the moblisation of tissue mercury and its excretion via the feather. Mercury concentrations in the primary feathers of several species decline from primary one to primary ten, with the levels being higher in South Atlantic seabirds. No significant differences were found in mercury concentrations between present day and museum samples of feathers of the Great Skua. Great skuas from the South Atlantic have significantly higher renal cadmium concentrations than North Atlantic Great Skuas. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Zoology, Ecology, Biogeochemistry, Toxicology
Date of Award: 1986
Depositing User: Enlighten Team
Unique ID: glathesis:1986-77364
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jan 2020 11:53
Last Modified: 14 Jan 2020 11:53

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