J. Widdows et al., SCOPE FOR GROWTH AND CONTAMINANT LEVELS IN NORTH-SEA MUSSELS MYTILUS-EDULIS, Marine ecology. Progress series, 127(1-3), 1995, pp. 131-148
Mussels Mytilus edulis, collected from 26 coastal sites from the Shetl
and Islands to the Thames estuary and 8 offshore Light vessels, were u
sed to monitor changes in environmental quality along the North Sea co
astline of the UK (July 1990 and August 1991). The combined measuremen
ts of the stress response, scope for growth (SFG), and chemical contam
inants in the tissues of mussels were able to detect, quantify and ide
ntify some of the major toxicants causing the observed pollution effec
ts. SFG declined from north to south, reflecting both the major inflow
of clean water from the North Atlantic via the north of Scotland, and
the overall increase in environmental contamination with increasing u
rbanisation and industrialisation towards the south. There were coasta
l regions (e.g. Humber-Wash area and the Thames estuary) as well as sp
ecific sites (e.g. Ythan, Montrose, Blyth, Teesmouth, Whitby) which sh
owed markedly reduced SFG. Using experimentally derived tissue concent
ration-response relationships it was shown that at over half the sites
the reduced SFG could be entirely explained by the recorded concentra
tions of contaminants in the tissues. At the majority of sites, a larg
e contribution towards the observed decline in SFG was caused by toxic
(mainly polyaromatic) hydrocarbons, largely reflecting urbanisation a
nd shipping activity. in addition, reductions in SFG appear to be part
ially explained by the accumulation of significant amounts of 'polar o
rganic compounds' and tributyltin. At no sites were metals accumulated
to concentrations that could cause a significant reduction in SFG. At
those sites with a large 'unexplained component' to the very low SFG
values, there was a significant correlation between this 'residual une
xplained toxicity' and concentrations of organochlorines in the mussel
s. More research on the toxicity of these organochlorine compounds to
mussels is needed.