UK National Marine Monitoring Programme - Second ... - JNCC - Defra

2.3 Monitoring of biological effects
Biological effects measure the response of
organisms to contaminants, rather than the levels
of the contaminants themselves. Biological effects
monitoring thus might give a clearer picture of the
health and quality of the marine environment. Some
techniques are pollutant specific (e.g. imposex in
dogwhelks due to tributyl tin (TBT) pollution), and
some are more general measures (e.g. fish disease
studies).
2.3.1 Benthic macrofauna
Benthic macrofauna are the animals living within
(infauna) or on (epifauna) the surface of the
sediments. Benthic organisms are effectively sessile
so act as integrators of the effects of environmental
stresses, whether natural, like salinity changes, or
anthropogenic. Benthic communities have long
been studied as a measure of environmental quality
(Holme and McIntyre, 1971).
2.3.2 Oyster embryo bioassay
Young oysters undergo intense cellular activity
during the early stages of development. The
presence of contaminants in the surrounding
environment adversely affects development of
their normal shape. Embryos are exposed to
environmental and clean water samples and their
development is compared. The difference gives a
measure of overall water quality.
2.3.3 Fish disease studies
Sampling and disease reporting followed protocols
set up by the International Council for the Exploration
of the Seas (ICES) (Bucke et al., 1996). Target fish
species are dab (L. limanda) and cod (Gadus morhua)
for offshore locations and the European flounder (P.
flesus) for inshore or estuarine stations. Fish were
examined for both externally visible diseases and
internal diseases. Internal lesions indicating exposure
to contaminants include foci of cellular alteration
(FCA), and benign and malignant tumours.
2.3.4 Imposex studies
The imposex condition has been strongly linked
with the presence of organotins in the environment
(Gibbs et al., 1987). Imposex is an abnormality
in gastropod molluscs in which male sexual
characteristics are imposed on the genital systems
of females. The female develops a penis and a vas
deferens, which may block the genital opening
so that egg capsules cannot be laid. Affected
populations gradually decline and may become
eliminated.
2.3.5 The mixed function oxidase test
(EROD)
EROD or Ethoxyresorufin-O-deethylase activity
provides an indication of the presence of a range of
organic contaminants in fish. When absorbed, these
contaminants induce synthesis of enzymes known
as the cytochrome P450 group. Cytochrome
P4501A1 (CYP1A1) is the terminal component and
EROD activity is CYP1A1 dependent.
2.3.6 Metallothionein
Marine organisms produce metallothioneins (MT)
to convert the toxic forms of some metals into less
toxic, bound forms. The bound forms can then be
safely stored and may be excreted. The presence of
MT indicates exposure to these metals, rather than
any impact of exposure on the well-being of the
animal. MT is usually measured in the liver of fish
(and related organs in invertebrates), as the liver
normally contains the highest concentrations of
inducing metals.
2.3.7 DNA adducts
DNA adducts are formed when reactive chemicals
bind to DNA. The presence of DNA adducts
is linked to PAH exposure and the presence of
cancerous growths in fish liver.
2.4 Indicators
Indicators summarise complex information or raw
data and can be used to assess the effectiveness of
alternative policy options and keep policy makers
and the public better informed. Under the NMMP,
the MEMG has been developing indicators for
hazardous substances, eutrophication and litter,
as part of a wider initiative to develop a suite of
marine indicators to report on the state of the
UK marine environment and to measure changes.
Some of these indicators have been used for the
first time in this report.
2.4.1 Indicators of chemical quality
• Concentrations of hazardous substances
compared to Environmental Quality
Standards (EQSs)
EQSs are concentrations below which a substance is
not believed to be detrimental to aquatic life. These
were originally developed for the EC Dangerous
Substances Directive (76/464/EEC). The concept
is now well established and is incorporated into
the Water Framework Directive (2000/60/EC).
EQSs are derived using acute toxicity tests on
organisms at different trophic levels. To provide a
safety factor, the EQS is set substantially below the
concentration observed to have a toxic effect on
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