CHAPTER 8 . Quality Status, Appropriate Monitoring and Legislation of the North Sea
175
nants concentrated in the sea surface microlayer (Hardy and Cleary 1992) is also a
strong possibility, since the toxicity of such contaminants on fish embryos has been
demonstrated (Kocan et al. 1987).
A more comprehensive survey of developmental abnormalities for all fish species
in the surface plankton (including plaice Pleuronectes platessa, sprat Sprattus sprattus,
whiting Merlangius merlangius, rockling Onos sp., flounder Platichthys flesus) was conducted in 1991 and 1992 (Cameron and von Westernhagen 1996,1997). The results show
malformation rates varying with species between 10% and 80%. Highest malformation rates were found in the plumes of the major industrialized estuaries; Weser 43%,
Rhine 29%, Thames 58%, Forth 38%. The authors consider it most likely that the abnormalities are due to anthropogenic contaminants, which have been shown to be capable of inducing such abnormalities (von Westernhagen 1988). Whether these effects
are due to parental exposure to contamination in benthic surficial sediments, or eggs
exposed at the sea surface microlayer, remains unclear, either or both routes are possible. Up to 85% of such embryonic abnormalities are known to be lethal in 5 days
(Cameron and von Westernhagen 1997). There is no evidence yet that the mortality of
fish embryos in coastal waters is affecting recruitment of fisheries, nevertheless that
must remain a principal concern.
8.6.4
UK East Coast Gradient
Deployments of "scope for growth" in mussels (Mytilus edulis) in the North Sea (1990-91)
have provided the first measurements of a pollution gradient along the UK East Coast
from the Shetland Islands to the Thames estuary (Widdows et al. 1993, 1995).
This technique measures an integration of basic physiological processes in the energy balance of the organism in terms of its potential for growth, and has been used to
measure pollution gradients for over 15 years. It has been deployed for intercomparison
with a wide range of 'other techniques in workshops organized by the IOC Group of
Experts on the Effects of Pollution (GEEP) in Norway (Widdows and Johnston 1988)
and Bermuda (Widdows et al. 1990).
During the 1990 exercise in the North Sea, scope for growth was measured at 26 sites
down the UK East Coast, then in 1991 mussels were deployed on 9 lightships off the
East Coast from the Humber to the Dover Straits. Scope for growth data from all the
sites are plotted here (Fig. 8.7) against the calculated age of North Atlantic water in the
North from a winter model simulation (van Pagee and Postma 1986). The results fall
into three groups: those for sites under the influence of estuarine water, other coastal
.... Fig. 8.6. Selected biological data from the ICES/IOC Bremerhaven Workshop indicating gradients in
pollution on a transect running northeast across the German Bight from the mouths of Elbe-Weser
estuaries (From Stebbing et al. 1992). Station numb,ers 1-9 are indicated in i and j and in Fig. 8.1b as A
to I. a to f give ecotoxicological indices of response or effec;t in the dab (Limanda limanda); a-c biochemical
indices; d mitotic abnormalities in developing elllbryos; e index of condition of cellular organelles;
f frequency of external papillomas indicating skin disease; g pooled bioassay data from a variety of
techniques following exposure to bulked microlayer and subsurface water samples; h growth data for
the copepod Tisbe battaglia exposed to surface microlayer samples; i and j morphological malformation frequencies in early developmental stages of dab (Limanda limanda). (Papers from which data
are drawn are in Stebbing et al. 1992)
175
nants concentrated in the sea surface microlayer (Hardy and Cleary 1992) is also a
strong possibility, since the toxicity of such contaminants on fish embryos has been
demonstrated (Kocan et al. 1987).
A more comprehensive survey of developmental abnormalities for all fish species
in the surface plankton (including plaice Pleuronectes platessa, sprat Sprattus sprattus,
whiting Merlangius merlangius, rockling Onos sp., flounder Platichthys flesus) was conducted in 1991 and 1992 (Cameron and von Westernhagen 1996,1997). The results show
malformation rates varying with species between 10% and 80%. Highest malformation rates were found in the plumes of the major industrialized estuaries; Weser 43%,
Rhine 29%, Thames 58%, Forth 38%. The authors consider it most likely that the abnormalities are due to anthropogenic contaminants, which have been shown to be capable of inducing such abnormalities (von Westernhagen 1988). Whether these effects
are due to parental exposure to contamination in benthic surficial sediments, or eggs
exposed at the sea surface microlayer, remains unclear, either or both routes are possible. Up to 85% of such embryonic abnormalities are known to be lethal in 5 days
(Cameron and von Westernhagen 1997). There is no evidence yet that the mortality of
fish embryos in coastal waters is affecting recruitment of fisheries, nevertheless that
must remain a principal concern.
8.6.4
UK East Coast Gradient
Deployments of "scope for growth" in mussels (Mytilus edulis) in the North Sea (1990-91)
have provided the first measurements of a pollution gradient along the UK East Coast
from the Shetland Islands to the Thames estuary (Widdows et al. 1993, 1995).
This technique measures an integration of basic physiological processes in the energy balance of the organism in terms of its potential for growth, and has been used to
measure pollution gradients for over 15 years. It has been deployed for intercomparison
with a wide range of 'other techniques in workshops organized by the IOC Group of
Experts on the Effects of Pollution (GEEP) in Norway (Widdows and Johnston 1988)
and Bermuda (Widdows et al. 1990).
During the 1990 exercise in the North Sea, scope for growth was measured at 26 sites
down the UK East Coast, then in 1991 mussels were deployed on 9 lightships off the
East Coast from the Humber to the Dover Straits. Scope for growth data from all the
sites are plotted here (Fig. 8.7) against the calculated age of North Atlantic water in the
North from a winter model simulation (van Pagee and Postma 1986). The results fall
into three groups: those for sites under the influence of estuarine water, other coastal
.... Fig. 8.6. Selected biological data from the ICES/IOC Bremerhaven Workshop indicating gradients in
pollution on a transect running northeast across the German Bight from the mouths of Elbe-Weser
estuaries (From Stebbing et al. 1992). Station numb,ers 1-9 are indicated in i and j and in Fig. 8.1b as A
to I. a to f give ecotoxicological indices of response or effec;t in the dab (Limanda limanda); a-c biochemical
indices; d mitotic abnormalities in developing elllbryos; e index of condition of cellular organelles;
f frequency of external papillomas indicating skin disease; g pooled bioassay data from a variety of
techniques following exposure to bulked microlayer and subsurface water samples; h growth data for
the copepod Tisbe battaglia exposed to surface microlayer samples; i and j morphological malformation frequencies in early developmental stages of dab (Limanda limanda). (Papers from which data
are drawn are in Stebbing et al. 1992)