A.R.D. Stebbing . R.I. Willows
physical and chemical environmental effects that modify contaminant bioavailability
and impact are integrated by such indices. A suite of four techniques have been advocated by the North Sea Task Force, and were tested with many others on the same pollution gradient in the German Bight (Stebbing et al. 1992).
Environmental quality: chemical factors or biological targets? The benefits of
measuring the impact of pollutants on biological targets is obvious, since they relate
directly to the most commonly used criteria for environmental quality, where biological activity, richness and diversity are the standard. The argument that the detection of
toxic effects implies that damage is done, and that their use cannot be preventative, is
not the case where techniques utilize adoptive responses to toxic exposure. To monitor
chemical factors, rather than biological targets (Holdgate 1979; Stebbing 1996) implies
that the causal relationship between each is sufficiently adequate to predict one from
the other. Such comprehensive knowledge of environmental processes (Table 8.1) is
unlikely to be attained in the medium term. Besides which, the burden of monitoring
has grown to the extent that, logistically, target monitoring is the only way to manage
the task cost-effectively. In the past, biological techniques lacked the sensitivity and
reproducibility required, but this is no longer the case, in that a suite of techniques is
now available that potentially fulfil the necessary criteria.
It has never been suggested that biological techniques should be used alone. Their
role is as an initial monitor and surveillance of water quality, that can then be used to
direct subsequent analytical effort to establish the chemical cause(s). Used alone, biological monitoring techniques are of limited utility because:
a they typically do not identify the specific cause of the toxic effect detected. Specific
indicators like imposex in gastropods for TBT are rare,
b only representative species can be used from a limited number of communities
to represent whole ecosystems. Extrapolation between species is not straightforward,
c the availability of species and use of biological techniques may be seasonal, or may
not cover the geographic range to be investigated,
d few techniques have been used widely enough for rigorous protocols to be established, and problems of reproducibility of results between laboratories resolved,
e only in recent times have a range of biological techniques achieved the necessary
sensitivity with reproducibility and precision.
Over the last decade the advantages and disadvantages of chemical versus biological monitoring have been debated within international bodies, such as ICES and IOC.
The adoption of research developments in biologically-based indices have been held
back by the commitment to legislation expressed predominantly in chemical terms.
Nevertheless the rationale for biologicai monitoring has a logical appeal that is gradually winning support, as concern over the effectiveness of chemical monitoring and its
cost-effectiveness have risen, while the rigour of improved biological techniques has
been repeatedly demonstrated (Bayne et al. 1988; Addison and Clarke 1990; Stebbing
et al. 1992; Wharfe and Tinsley 1995).
physical and chemical environmental effects that modify contaminant bioavailability
and impact are integrated by such indices. A suite of four techniques have been advocated by the North Sea Task Force, and were tested with many others on the same pollution gradient in the German Bight (Stebbing et al. 1992).
Environmental quality: chemical factors or biological targets? The benefits of
measuring the impact of pollutants on biological targets is obvious, since they relate
directly to the most commonly used criteria for environmental quality, where biological activity, richness and diversity are the standard. The argument that the detection of
toxic effects implies that damage is done, and that their use cannot be preventative, is
not the case where techniques utilize adoptive responses to toxic exposure. To monitor
chemical factors, rather than biological targets (Holdgate 1979; Stebbing 1996) implies
that the causal relationship between each is sufficiently adequate to predict one from
the other. Such comprehensive knowledge of environmental processes (Table 8.1) is
unlikely to be attained in the medium term. Besides which, the burden of monitoring
has grown to the extent that, logistically, target monitoring is the only way to manage
the task cost-effectively. In the past, biological techniques lacked the sensitivity and
reproducibility required, but this is no longer the case, in that a suite of techniques is
now available that potentially fulfil the necessary criteria.
It has never been suggested that biological techniques should be used alone. Their
role is as an initial monitor and surveillance of water quality, that can then be used to
direct subsequent analytical effort to establish the chemical cause(s). Used alone, biological monitoring techniques are of limited utility because:
a they typically do not identify the specific cause of the toxic effect detected. Specific
indicators like imposex in gastropods for TBT are rare,
b only representative species can be used from a limited number of communities
to represent whole ecosystems. Extrapolation between species is not straightforward,
c the availability of species and use of biological techniques may be seasonal, or may
not cover the geographic range to be investigated,
d few techniques have been used widely enough for rigorous protocols to be established, and problems of reproducibility of results between laboratories resolved,
e only in recent times have a range of biological techniques achieved the necessary
sensitivity with reproducibility and precision.
Over the last decade the advantages and disadvantages of chemical versus biological monitoring have been debated within international bodies, such as ICES and IOC.
The adoption of research developments in biologically-based indices have been held
back by the commitment to legislation expressed predominantly in chemical terms.
Nevertheless the rationale for biologicai monitoring has a logical appeal that is gradually winning support, as concern over the effectiveness of chemical monitoring and its
cost-effectiveness have risen, while the rigour of improved biological techniques has
been repeatedly demonstrated (Bayne et al. 1988; Addison and Clarke 1990; Stebbing
et al. 1992; Wharfe and Tinsley 1995).