Fróðskaparrit - 01.07.2004, Side 117

KYKSILVUR í FØROYUM - EIN GJØGNUMGONGD AV TØKUM DÁTUM
115
Fig. 12 Mercury in eider
in groups of adult females
(AF), adult males (AM),
juvenile females (JF) and
juvenile males (JM) are
given in mg/kg ww liver.
Under the bars are the
sampling period, the
number of individuals in
each pool (between 5 and
13) and the liver dry
weight (%) shown.
(Adaptedfrom Dam,
1998c)
quite similar in eider and shag and do not
suggest large differences in food choices,
but then only 7 out of the 40 shags analysed
were adults, and when compared to a sam-
ple of mainly adult eiders, this may skew
the picture substantially. However, the re-
sults of cadmium and copper in these
seabirds (not shown) do strongly point to a
different food source in eider than in shag,
where the copper liver concentration in ei-
der and shag were 90 mg/kg and 9 mg/kg,
and the cadmium liver concentrations were
3,3 and 0,4 mg/kg respectively. Analyses of
molluscs were part of these same investiga-
tions and particular high concentrations of
these metals were found in molluscs from
the littoral (Dam, 1998c). In the eiders, the
highest mercury and copper concentrations
were found in adult males. Especially the
copper concentrations in these adults were
high, with 394 mg/kg liver in one adult
male. Earlier studies from Svalbard re-
vealed a liver copper concentration of 1050
mg/kg in one eider and closer inspection
| 0,8
O) 0,6
*B) 0,4
I °.2
30,2 29,4 29,2 30,3 27,1 28,3 30,7
4 3 8 5 9 7 4
aug'96 jul/nov'96 jul'96 iug/nov'96 jul'96 aug'96 jul/aug'96
AF AM JF JF JM JM J
Fig. 13 Mercury in shag in groups of adult females (AF), adult males (AM), juvenilefemales (JF) and juvenile males
(JM) orjust undeterm. juveniles (J) are given in mg/kg ww liver. Under the bars are the sampling period, the number
of individuals in each pool (between 3 and 9) and the liver dry weight (%) shownJAdaptedfrom Dam, I998b).