162
A.R.D. Stebbing . R.1. Willows
of a threat to environmental quality than was assumed. Mechanisms to remove contaminants from monitoring programmes whose environmental threat is now known
to be minimal or inconsequential are ineffective. For example, most metals are no longer
considered to pose the threat to water quality in the North Sea, yet they are a class of
contaminants that have long featured in pollution legislation. The ICES/IOC
Bremerhaven Workshop deployed over 50 biological effects techniques on what is perhaps the most marked pollution gradient in the North Sea (Stebbing et al. 1992), but
no deleterious effects related to metals were demonstrated. Similarly, the chemical causes
of the pollution gradient identified by Widdows et al. (1995) along the UK East Coast
do not include metals. There is therefore a need to critically examine the appropriateness of chemical monitoring programmes for their purpose, since present knowledge
suggests there is redundancy. Chemical monitoring of contaminant levels that are biolog\cally insignificant, and do not cause pollution, is a waste of resources. The problem
has 'grown considerably with the number of micro-contaminants now present in the
marine environment, but which are unmonitored.
Appropriateness of chemical analyses. Regrettably environmental legislation, and
the chemical analyses to enforce it, do not necessarily relate to the same fraction, species or phase of a contaminant that is biologically available and potentially toxic. For
example, legislation for copper and cadmium relates to the concentration of the metal
in sea water, while the ionic activity of the metal determines its bioavailability and toxicity. Since a large fraction of these metals is bound to organic matter in the case of
copper (Sunda and Guillard 1976) and for cadmium to inorganic ligands (Sunda et al.
1978), the ionic fraction which is determined is only a proportion of the total present
in the environment. The problem of the biological relevance of chemical analysis can
be circumvented by monitoring bio-accumulated tissue burdens, which can be used to
predict effects (Chapman 1997) for some chemicals. Not only do the enllanced levels
ease the analytical problems, but tissue burdens are integrated over time.
Inadequacy of spatial definition in monitoring. There is a growing awareness that
contaminant behaviour in the environment does not lead inevitably to their dilution,
dispersion and/or degradation. Thus any sampling strategy should recognize those
processes that reconcentrate contaminants and to sample accordingly, particularly
when those sites are foci of biological activity. One example of importance is the potential of the turbidity maximum in estuaries to accumulate contaminants (Uncles
et al. 1988). Similarly coastal fronts have been shown to accumulate organochlorine
pesticides at the sea surface and in benthic sediments (Tanabe et al. 1991). The air-sea
interface is a well known site of contaminant accumulation (Hardy 1982), besides being one of the accumulation of sensitive early life stages of pelagic and benthic species. Thus monitoring programmes assume homogeneity in distribution, when heterogeneity is the norm.
8.4.2
Biological Monitoring
Pollution as defined (see Section 8.3.1) relates primarily to "harm to living resources
and ecological systems" due to contaminants of .various kinds. Since concern relates to
A.R.D. Stebbing . R.1. Willows
of a threat to environmental quality than was assumed. Mechanisms to remove contaminants from monitoring programmes whose environmental threat is now known
to be minimal or inconsequential are ineffective. For example, most metals are no longer
considered to pose the threat to water quality in the North Sea, yet they are a class of
contaminants that have long featured in pollution legislation. The ICES/IOC
Bremerhaven Workshop deployed over 50 biological effects techniques on what is perhaps the most marked pollution gradient in the North Sea (Stebbing et al. 1992), but
no deleterious effects related to metals were demonstrated. Similarly, the chemical causes
of the pollution gradient identified by Widdows et al. (1995) along the UK East Coast
do not include metals. There is therefore a need to critically examine the appropriateness of chemical monitoring programmes for their purpose, since present knowledge
suggests there is redundancy. Chemical monitoring of contaminant levels that are biolog\cally insignificant, and do not cause pollution, is a waste of resources. The problem
has 'grown considerably with the number of micro-contaminants now present in the
marine environment, but which are unmonitored.
Appropriateness of chemical analyses. Regrettably environmental legislation, and
the chemical analyses to enforce it, do not necessarily relate to the same fraction, species or phase of a contaminant that is biologically available and potentially toxic. For
example, legislation for copper and cadmium relates to the concentration of the metal
in sea water, while the ionic activity of the metal determines its bioavailability and toxicity. Since a large fraction of these metals is bound to organic matter in the case of
copper (Sunda and Guillard 1976) and for cadmium to inorganic ligands (Sunda et al.
1978), the ionic fraction which is determined is only a proportion of the total present
in the environment. The problem of the biological relevance of chemical analysis can
be circumvented by monitoring bio-accumulated tissue burdens, which can be used to
predict effects (Chapman 1997) for some chemicals. Not only do the enllanced levels
ease the analytical problems, but tissue burdens are integrated over time.
Inadequacy of spatial definition in monitoring. There is a growing awareness that
contaminant behaviour in the environment does not lead inevitably to their dilution,
dispersion and/or degradation. Thus any sampling strategy should recognize those
processes that reconcentrate contaminants and to sample accordingly, particularly
when those sites are foci of biological activity. One example of importance is the potential of the turbidity maximum in estuaries to accumulate contaminants (Uncles
et al. 1988). Similarly coastal fronts have been shown to accumulate organochlorine
pesticides at the sea surface and in benthic sediments (Tanabe et al. 1991). The air-sea
interface is a well known site of contaminant accumulation (Hardy 1982), besides being one of the accumulation of sensitive early life stages of pelagic and benthic species. Thus monitoring programmes assume homogeneity in distribution, when heterogeneity is the norm.
8.4.2
Biological Monitoring
Pollution as defined (see Section 8.3.1) relates primarily to "harm to living resources
and ecological systems" due to contaminants of .various kinds. Since concern relates to