Environmental Engineering Reference
In-Depth Information
CHAPTER SEVEN
Detecting ecological effects of pollutants
in the aquatic environment
ALASTAIR GRANT
Introduction
In the marine environment a widely used definition of pollution is the 'intro-
duction by man, directly or indirectly, of substances or energy into the marine
environment (including estuaries) resulting in deleterious effects such as harm to
living resources, hazards to human health, hindrance of marine activities,
including fishing, impairing quality for use of sea-water and reduction of
amenities' (GESAMP
1982
my emphasis). The increasing sophistication of
analytical chemical methods means that we can detect contamination by a
wide range of chemicals in almost any aquatic environment (see
Chapter 5
). But
the rational regulation of direct contaminant discharges to the environment
and the setting of priorities for dealing with contaminants arising from diffuse
sources requires us to be able to identify the subset of cases of contamination
where deleterious effects are, or may be, occurring. There has been consider-
able recent improvement in methods for prospective risk assessment methods
that allow an assessment of whether particular concentrations of a substance
might cause ecological effects in the field. For example, the development of
species sensitivity distributions has given greatly improved information on
whether the sensitivity of standard laboratory test organisms reflects the
sensitivity of the much wider range of organisms that occur in the field (see,
e.g., Maltby et al.
2005
), and there is discussion of risk assessment methods
elsewhere in this volume (
Chapters 5
and
9
). However, determining whether an
individual substance actually is having deleterious effects on the ecology at any
particular location remains a major challenge for ecotoxicology.
The aim of this chapter is to review recent advances in methods for detecting
ecological effects of pollutants at field sites, and discuss the reasons why it is
often difficult to do better than detecting areas where there is severe ecological
damage. I will also review some examples from the literature, including my
own work, where it has proved possible to detect subtle ecological changes due
