3.5. Trends in Hg concentrations in L. forbesi
A summary of Hg concentrations in the different tissues
of L. forbesi from the different sampling areas and at
different seasons is presented in Table 3. The final GAM
for Hg concentrations (mg g1 dwt, log-transformed) in the
digestive gland tissue of L. forbesi explained 84% of
deviance (N ¼ 105, AIC ¼ 126.6). There was marginally
significant trend for higher values in males (P ¼ 0.038) but
this was dropped from the final model to increase sample
sizes (around 20 animals could not be sexed). The effect of
body size (DML) was highly significant (Po0.0001). Hg
concentration increased linearly with increasing DML
(Fig. 1b). There were also significant effects of season,
with values in January–April being higher than in the rest
of the year (Po0.001). Hg concentrations in the English
Channel were higher than in all other areas except the
North Sea (Po0.001).
In the case of muscle, the best model of Hg concentration
explained 85% of deviance (N ¼ 101), including a
positive linear effect of DML (Po0.001), higher concentrations
in the English Channel than in the North Sea
(P ¼ 0.011), Moray Firth (Po0.001), and North Sea
coastal waters (Po0.001), and higher concentration in
the first 4 months of the year than in the last 4 months
(Po0.001).
For gills, the best model explained 90% of deviance
(N ¼ 78), including a positive effect of DML (d.f. ¼ 2.05,
Po0.001), higher concentrations in the first 4 months of
the year than in the second and third periods (Po0.001),
and higher concentrations in the English Channel than in
the North Sea, Moray Firth, and North Sea coasts
(Po0.001 in all cases).
The best model for Hg in gonads explained 83% of
deviance (N ¼ 47) and included a weak positive effect of
DML (d.f. ¼ 1.71, P ¼ 0.031), higher values in the first 4
months of the year than the last four (Po0.001), and
higher values in the English Channel than in the North Sea
(P ¼ 0.014) and Moray Firth (Po0.001).
Finally, the best model for Hg in other tissues explained
86% of deviance (N ¼ 77) and included a positive linear
effect of DML (Po0.001), higher values in the first 4
months of the year than the last 4 (Po0.001) and higher
values in the English Channel than in the North Sea
(P ¼ 0.026), Moray Firth (Po0.001), and North Sea
coasts (Po0.001), and higher values in the Irish Sea than
in the English Channel (P ¼ 0.034).
As was apparent from the modelling results, data from
different tissues of L. forbesi give somewhat different
pictures of the geographical distribution of metal concentrations
(Fig. 2). These plots do however show that Hg
levels were consistently highest in all tissues of squid from
the English Channel. Interestingly, these squids also
displayed the lowest Cd concentrations in their tissues,
with the exception of the gonads.
3.5. Trends in Hg concentrations in L. forbesiA summary of Hg concentrations in the different tissuesof L. forbesi from the different sampling areas and atdifferent seasons is presented in Table 3. The final GAMfor Hg concentrations (mg g1 dwt, log-transformed) in thedigestive gland tissue of L. forbesi explained 84% ofdeviance (N ¼ 105, AIC ¼ 126.6). There was marginallysignificant trend for higher values in males (P ¼ 0.038) butthis was dropped from the final model to increase samplesizes (around 20 animals could not be sexed). The effect ofbody size (DML) was highly significant (Po0.0001). Hgconcentration increased linearly with increasing DML(Fig. 1b). There were also significant effects of season,with values in January–April being higher than in the restof the year (Po0.001). Hg concentrations in the EnglishChannel were higher than in all other areas except theNorth Sea (Po0.001).In the case of muscle, the best model of Hg concentrationexplained 85% of deviance (N ¼ 101), including apositive linear effect of DML (Po0.001), higher concentrationsin the English Channel than in the North Sea(P ¼ 0.011), Moray Firth (Po0.001), and North Seacoastal waters (Po0.001), and higher concentration inthe first 4 months of the year than in the last 4 months(Po0.001).For gills, the best model explained 90% of deviance(N ¼ 78), including a positive effect of DML (d.f. ¼ 2.05,Po0.001), higher concentrations in the first 4 months ofthe year than in the second and third periods (Po0.001),
and higher concentrations in the English Channel than in
the North Sea, Moray Firth, and North Sea coasts
(Po0.001 in all cases).
The best model for Hg in gonads explained 83% of
deviance (N ¼ 47) and included a weak positive effect of
DML (d.f. ¼ 1.71, P ¼ 0.031), higher values in the first 4
months of the year than the last four (Po0.001), and
higher values in the English Channel than in the North Sea
(P ¼ 0.014) and Moray Firth (Po0.001).
Finally, the best model for Hg in other tissues explained
86% of deviance (N ¼ 77) and included a positive linear
effect of DML (Po0.001), higher values in the first 4
months of the year than the last 4 (Po0.001) and higher
values in the English Channel than in the North Sea
(P ¼ 0.026), Moray Firth (Po0.001), and North Sea
coasts (Po0.001), and higher values in the Irish Sea than
in the English Channel (P ¼ 0.034).
As was apparent from the modelling results, data from
different tissues of L. forbesi give somewhat different
pictures of the geographical distribution of metal concentrations
(Fig. 2). These plots do however show that Hg
levels were consistently highest in all tissues of squid from
the English Channel. Interestingly, these squids also
displayed the lowest Cd concentrations in their tissues,
with the exception of the gonads.
การแปล กรุณารอสักครู่..
![](//thimg.ilovetranslation.com/pic/loading_3.gif?v=b9814dd30c1d7c59_8619)