Pest management - Ecological Applications: Toward a Sustainable World - page 148

Fig. 6.4 Chlordane,
applied as a pesticide
on land, is transported
to the Arctic via rivers
and oceanic and
atmospheric circula-
tion. A study in the
Barents Sea shows how
chlordane is biomagni-
fi ed during its passage
through the marine
food chain. Concentra-
tions in seawater are
very low. Herbivorous
copepods (that feed on
phytoplankton) have
higher concentrations
(measured in nano-
grams per gram of lipid
in the organisms), and
predatory amphipods
higher concentrations
still. The polar cod
( Boreogadus saida ),
which feeds on the
invertebrates, and cod
( Gadus morhua ), which
also includes polar cod
in its diet, show further
evidence of biomagnifi -
cation. However, it is
the higher steps in the
food chain where
biomagnifi cation is
most marked, because
the seabirds that feed
on the fi sh (black
guillemots - Cepphus
grylle ) or on fi sh and
other seabirds
(glaucous gull - Larus
hyperboreus ) have much
less ability to eliminate
the chemicals than fi sh
or invertebrates. (After
Tow n send et al., 2003,
based on data in Borga
et al., 2001.)

Concentration
of chlordanes

11.5

Copepods

21.5

Amphipods

76

Polar cod

100

Cod

292

Black guillemot

5,530

Glaucous gull

continues to kill nontarget organisms for an extended period. Other chlorinated
hydrocarbons have been developed with somewhat greater specifi city and shorter
persistence times (e.g. lindane; Table 6.1).
Organophosphates (including parathion, malathion, bidrin and azodrin) are also
nerve poisons, chemically related to the ones developed during the Second World
War. Some are very toxic to both insects and mammals but they do not persist so
long in the environment. Thus unwanted residues in crops are less of a problem