Publication year: 2007-01-01

Publication title: Polychlorinated biphenyls, DDT, polybrominated diphenyl ethers, and organic pesticides in United Kingdom harbor seals (Phoca vitulina) - mixed exposures and thyroid homeostasis. Environmental Toxicology and Chemistry, 26 (5).

Publication authors: Hall, A.J. & Thomas, G.O.

Publication editors: Sea Mammal research Unit (CMRU)

Blubber samples were collected from harbour seals ( Phoca vitulina ) from five populations around the UK coast: the Wash, southeast England; St Andrews Bay, southeast Scotland; the Moray Firth, northeast Scotland; Orkney, north Scotland; and Islay and Jura, southwest Scotland. These populations were selected following differential mortality during the 2002 phocine distemper epidemic in order to determine whether contaminant concentrations had influenced mortality rates associated with that disease.

Sampling was undertaken over eight field trips between January and October 2003. Four of these field trips (24 January 2003 and 06, 11 and 25 March 2003) were to the St Andrews Bay site, while the remaining sites were each visited once for a period of several days, as follows: Moray Firth, 22 April 2003 to 24 April 2003; Orkney, 02 June 2003 to 06 June 2003; Islay and Jura, 12 September 2003 to 19 September 2003; and the Wash, 24 October 2003 to 26 October 2003. Sixty animals were sampled: 10 from each population except the Wash, from which 20 samples were taken.

The seals were captured on land, hauled out with the use of hand-held hoop nets, or caught at sea in tangle nets deployed from boats. One dead seal was also included in the analysis. After capture, the seals were weighed and sedated, and classified as adult or juvenile on the basis of mass and body length measurements. Animals greater than 110 cm standard body length (nose to tail) were considered to be adult and those between 100 and 110 cm as juvenile. Animals less than 100 cm were excluded from the study.

Blubber biopsy samples were collected from each animal and stored at -20 °C, then extracted using the Soxhlet method. Lipid content was determined gravimetrically while Gas Chromatography-Mass Spectrometry (GC-MS) was used to determine wet weight concentrations of contaminants per lipid proportion of the sample. Methods and analyses are detailed in Hall and Thomas (2007) and references therein.

The data were submitted to BODC in .xls files containing sample metadata and concentrations of individual contaminants in blubber samples taken from each animal. Concentrations of standard combinations of congeners were also included. Data received by BODC were transferred into a template whose form had been agreed between BODC and the data originator. The data were then loaded to the BODC database using established BODC data banking procedures. The site name 'Abertay' provided in the originator's data file was changed to 'St Andrews Bay' to maintain consistency with Hall and Thomas (2007). Each field trip was assigned an identifier by BODC, which links the field trip information to the data.No changes were made to the data during loading. Each contaminant concentration was mapped to an appropriate parameter code with exception of standard combinations of congeners.

All values are wet weight concentrations per lipid proportion in the blubber of harbour seals. Note that the number of decimal places for a particular contaminant may vary between individuals. The originator has stated that, given the magnitude and biological significance of the concentrations, it is valid to round all values to one decimal place for the sake of consistency, should data users wish to do so.

Instrument(s) used to collect data: gas chromatograph mass spectrometers.