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![Stable isotopes in feathers and blood as a tool to investigate diet and mercury dynamics of seabirds için kapak resmi Stable isotopes in feathers and blood as a tool to investigate diet and mercury dynamics of seabirds için kapak resmi](/client/assets/cf6e192b74af2810/ctx/images/no_image.png)
Stable isotopes in feathers and blood as a tool to investigate diet and mercury dynamics of seabirds
Başlık:
Stable isotopes in feathers and blood as a tool to investigate diet and mercury dynamics of seabirds
Yazar:
Bearhop, Stuart, author.
ISBN:
9780438059283
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (169 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: Bob Furness.
Özet:
1. The extent of freshwater feeding by cormorants shot at inland fisheries was examined using stable isotope signatures of feathers. Isotopic analyses indicate that at the time of shooting the diet of most birds comprised entirely freshwater prey. Cormorants moved inland gradually as winter progressed, but once established they appeared to have fed at freshwater sites throughout the autumn and winter. 2. Temporal and spatial variation in the diet of great skuas was assessed using stable isotope and conventional dietary analyses. Significant differences in delta15N of the feathers of St Kilda chicks suggested shifts in trophic level and conventionally collected dietary data corresponded to this. Likewise significant differences in delta15N of chick feathers between colonies were supported by pellet and regurgitate data. A significant increase in delta13C at St Kilda during 1996 suggested increased primary production, which was in accordance with continuous plankton recorder surveys made m they area. 3. The influences of lipid and uric acid upon and values of great skua blood were investigated. No differences between the isotope signatures of adult blood before and after washing with hot chloroform were detected. However the values of chick blood were higher after the chloroform treatment. Washing chick blood must therefore remove a substance from chick blood that is isotopically light and that is not present in adult blood in large amounts. Uric acid is known to occur in high concentrations in the blood of chicks due to high rates of protein catabolism associated with growth. It seems likely that high uric acid levels may influence values in chick blood. 4. Routine haematological investigations were carried out on 102 adult great skuas in the wild. No sex or age related differences were detected in any of the parameters measured. There are few sets of haematological reference ranges published for seabirds in the northeastern Atlantic. Given recent pollution threats in this region, the reference ranges presented for this species could be a valuable tool in future conservation efforts. 5. The relationships between two red blood cell paramters (haematocrit and MCV) and aspects of breeding performance in the great skua were investigated. Male MCVs were significantly correlated with hatch date and the MCVs of both sexes were correlated with fledging success. No correlations existed between these breeding parameters and haematocrit. Since males provision females they probably influence breeding performance via foraging abilities, whereas m females nutritional investment may be more important. We conclude that MCV is a useful measure of condition in birds. 6. Mercury concentrations, together with 15deltaN and delta13C, were determined in body feathers of northern fulmars and great skuas. Additionally selected flight feathers of great skuas were also analysed. No relationships between mercury concentrations and isotope signatures of feathers were detected. This suggests that mercury concentrations and stable isotope values in feathers are uncoupled. Correlations among flight feathers suggest that stable isotope analyses may provide a means of investigating moult in birds. 7. Biomagnification of mercury was investigated via combined mercury and stable isotope analysis of the blood and feathers of great skua chicks. There were significant correlations between and mercury concentrations in the blood of chicks from two northeast Atlantic colonies. The correlations were not as good in chick feathers and blood therefore may be a better monitoring unit than feathers. Adult blood was also assessed and in terms of biomonitoring may provide an index of mercury accumulation over the whole breeding season. 8. A wide range of parameters thought to contribute to intra-specific variation in mercury levels were investigated using blood and feathers of adult great skuas as sampling units. Trophic effects were demonstrated in the blood and feathers of adult great skuas, but these were relatively minor compared to the effect of foraging area. It was concluded that there are a number of interacting factors determining intra-specific variability in mercury concentrations and that the relative importance of each factor is variable both spatially and temporally. 9. The dynamics of mercury in the blood and feathers of great skuas during moult was too complex to be modelled by simple pharmacokinetic models. A post dosing study concluded that during moult mercury elimination from the blood might conform to a three compartment model rather than the two compartment model previously suggested for birds. In terms of biomonitoring, blood mercury concentrations possibly reflect intake since cessation of the previous moult and feather mercury concentrations reflect intake over the same penod as the blood at the time of their growth. In addition clear evidence was found for differences in physiology affecting mercury concentrations measured in tissues.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684705.1) | 684705-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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