Extremists on both sides are often disparaging about their opposite
numbers. Ecologists may be considered somehow inferior on account of their
ignorance of chemistry, while biochemists get reputations as heartless exploiters
of living organisms incapable of recognising anything more sophisticated
than a homogenate. Both caricatures are unfair, and it seems the time is
right for at least a partial reconciliation, and to make what could even
become a recog nised field in biology: molecular ecology.

The first steps towards such a new specialism have already been taken.
For instance, we now know that chemical messengers play an important role
in aquatic environments.

Salmon are a classic example; returning across thousands of kilometres
of ocean, these fish home in on their river of birth by detecting its characteristic
odour in the estuary outflow. They must smell their way home by detecting
specific molecules, of course, and though we do not know exactly what these
chemicals are they can apparently influence salmon at dilutions which homeopathic
practitioners would be proud of. Action at extremely low concentration is
a feature of many hormones and intracellular messengers, but it is remarkable
to see its parallel in the open environment.

The courtship of newts, characterised by the lashing and fanning tails
of ardent males in ponds and ditches every spring, also has meaning in molecular
terms. The water current generated by these vigorous actions carries with
it testosterone released from the male cloaca, and is recognised by interested
females as an indisputable sign of maleness. Hormones, it seems, are not
confined to working within organisms.

Yet another aspect of molecular ecology in aquatic environments is highlighted
by analysis of dissolved organic matter (DOM), which often amounts to a
greater mass per unit volume than all the living organisms put together.
One component of DOM in both salt and freshwater habitats turns out to be
free DNA. It remains to be seen whether DNA features in this context as
just another potential nutrient, or whether genetic information is available
in this reservoir for organisms equipped to exploit it. Bacteria have recently
been shown to have DNA receptors on their external surfaces; here surely
is an area meriting greater attention from, among others, those planning
the release of genetically engineered organisms into the environment.

Although most obvious in water, molecules are undoubtedly also important
in terrestrial ecosystems, as a means of communication or as chemical defences
in everything from slugs to slime moulds.

A second and increasingly important topic of molecular ecology is the
study of DNA. DNA fingerprinting has received great media attention in the
context of forensic investigation and paternity suits. Less well known is
the expanding use of the method in the study of populations of wild animals.

Initial work with DNA probes has concentrated on relationships within
social groups, and in particular the question of parentage and whether apparently
pair- bonded female birds ever cheat on their mates. Evidently they quite
often do, and chicks do not always have the same male parent that regularly
attends the nest.

Already that method is addressing problems in other areas of ecology.
Foremost among these is likely to be population genetics, with new and more
comprehensive answers to questions about gene flow, genetic drift and population
isolation.

Beyond that, DNA may provide a living record of historical events including
clues about the establishment of existing distribution and abundance patterns.
At present, DNA probes give no information on adaptive features. An exciting
possibility is that future probes will highlight features which have been
selected, say, for survival in a particular kind of environment.

Certainly the pressure to bridge the gap between molecular genetic and
ecological understanding of living creatures willL increase, if only because
we are on the threshold of an era in which genetically engineered organisms
will feature ever more highly as escapees into the world around us.

Molecular ecology is already with us, and certain to raise its profile
in the coming years. Needless to say, animals will still eat each other,
as well as plants. And there will still be competition and all the other
things about which traditional ecology will have lots more to say. Any attempt
to reduce ecology to molecules has no place in these new developments, but
at least ecologists and biochemists may begin talking to each other again.
That would be a start.

Trevor Beebee lectures in biochemistry at the University of Sussex,
but nonetheless takes a great interest in the ecology of free-living amphibia.

No doubt many of a Green persuasion will celebrate this turn of events
as a vindication of long-pressed arguments, though it is of course no such
thing. Economics, not environmental issues, have done the damage and there
is no reason, on the basis of this particular decision, to believe that
Greenpolitik has spread its roots at Westminster. Moreover, an important
and as yet unresolved question may be deferred again as a consequence of
these events: what will be the best way of meeting Britain’s energy requirements
in the 21st century in an environmentally-friendly way? Here, then, is a
heretical approach based on past and likely future consequences of the power
game for one of Britain’s most endangered animals: the natterjack toad.
This admittedly narrow view may be less absurd that it seems at first sight.
Complex issues are often enlightened by consideration of the particular,
and what matters to these small amphibians very probably impacts upon much
else besides.

Natterjacks like to live on the barren heathlands of southern and eastern
England, and on the sandy shores of the north-west coast. Their first taste
of power came many decades ago, in the form of sulphur dioxide emitted from
fossil-fuelled stations of the Industrial Revolution. They weren’t impressed;
ponds in their heathland habitats turned out to be as susceptible as the
lakes and rivers of southern Norway and Scotland to the arrival of the acid
rains, and changed from neutral to vinegar within less than a hundred years.
This acidification – attested to by analysis of diatoms and soot particles
in ponds which were inhabited by natterjacks earlier this century, but which
are now deserted – kills spawn and tadpoles and thus must have committed
whole populations of natterjacks to oblivion. Natterjacks are now virtually
extinct on heathland, thanks in no small part to round one of the power-production
business.

Some of the last refuges of natterjacks around the Irish Sea coast may
be about to witness the second round of this sorry tale. In this part of
Britain the toads live within a few hundred metres of the seashore, and
many of the remaining populations rely on temporary pools flushed out by
occasional winter high-tides to breed successfully. Such tidal flushing
is vital to the subsequent survival of tadpoles; it is now under threat
from another plan for generating power at sites where perhaps 20 per cent
of Britain’s surviving natterjacks still live. Barrages currently proposed
for the Duddon estuary in Cumbria and for the Solway would eliminate tidal
flushes in these crucial areas altogether, with disastrous consequences
for the natterjacks there. It is as if, with malice aforethought, the power
generators were hell-bent on finishing an extinction process so successfully
initiated on the heathlands.

So much for the two most widely discussed alternatives to nuclear power;
what, now, about the devil itself? Interestingly, its connection with natterjacks
has been of the opposite kind. The Irish Sea coast is, of course, home to
one of Britain’s most notorious installations, the Sellafield reprocessing
plant. One thing that visitors to this establishment rarely get to see is
Britain’s only nature reserve dedicated entirely and specifically to natterjack
toads. Now, this reserve exists because it was expedient for British Nuclear
Fuels to create it when it wanted to develop another area in which natterjacks
previously lived. Irrespective of motive, though, the results have been
spectacularly good and the population of these endangered toads living in
the shadow of Sellafield has become one of the most thriving in Britain.

Nor does the good news stop at the site boundary; the public perception
of nuclear power is such that areas for some miles around are effectively
blighted for development. These include some of Cumbria’s most attractive
coastline, especially the vast sand-dune peninsulas of the Ravenglass estuary.
You’ve probably guessed by now that natterjacks thrive here too; it’s questionable,
though, whether the developers would have left them so conspicuously alone
if the Drigg nuclear waste dump wasn’t next door.

There can’t be much doubt as to which type of energy source natterjack
toads would vote for, given the choice. But, of course, this is only the
tip of several icebergs; natterjacks were not the only sufferers from the
acidification of heathland ponds, nor will they face extinction alone if
the barrages go up in our most beautiful estuaries. We all know only too
well, perhaps ad nauseam, the possible dangers from nuclear power and would
be insane to ignore them. What would be a greater folly, though, is to opt
for developments which will certainly cause damage, as an emotive reaction,
against ones which have only an awful potential to do so. Surely the mature
view is to proceed along a dangerous path with care rather than along a
disastrous one in mindless terror, and in no circumstances to follow any
route dictated primarily by economic considerations.

Trevor Beebee works in the School of Biological Sciences at the University
of Sussex.