01/02/2007 | by admin
FOUR YEARS AFTER THE LEAKING OIL TANKER PRESTIGE WENT DOWN OFF GALICIA, TONY BUTT EXAMINES ITS EFFECTS ON THE BAY OF BISCAY.
The significant problems we face cannot be solved at the same level of thinking we were at when we created them. – Albert Einstein
On 19th November 2002, thirty miles off the Costa da Morte,
Spain, the single-hulled supertanker Prestige broke in half and
sank, distributing 60,000 tonnes of heavy fuel oil all along the
Atlantic coastlines of Spain, Portugal and France.
Perhaps I ought to apologise for harping back to some
disaster that happened over three years ago; one that perhaps
we’d all be better off forgetting. Now that we can surf again,
the fishermen can fish and everybody can get on with their
lives, why dwell on it?
Well, the answer is, if I could have written this article three
years ago, when the Prestige was hot news, I would have. But it
was just too early. You see, the overall effects of large oil spills
such as the Prestige take years, if not decades, to develop. It is
only by studying them for many years afterwards that we can
begin to understand their effects.
The Prestige oil spill was an environmental catastrophe of the
highest order. Its consequences were far-reaching and profound,
affecting every single member of the coastal community;
human and non-human. The fishermen couldn’t fish for
months; the ‘percebeiros’ (those intrepid and uniquely Galician
collectors of shellfish) couldn’t work, and we, the surfers,
couldn’t even go in the water. In fact, just to get near it one
would sometimes to cross a stinking black mass of crude oil. I
remember paddling out at a beach almost a thousand kilometres from where the Prestige went down, more than a year after it
happened, and coming out covered in brown-black stains. The
list of consequences, immediate or delayed, goes on.
Now, just over three years later, it seems the whole episode
has been almost forgotten – as if there had been a huge fuss for
nothing. Presumably, the remaining 37,000 tonnes of fuel still
leaking out of the ship, 4,000 metres down, has miraculously
disappeared. It must have because Repsol YPF, the state-owned
oil company ‘contracted’ by the Spanish government to suck
the oil out with robots and giant pipelines, didn’t need to do
it. Presumably, all the remaining oil under the rocks along
the Galician shoreline has also miraculously disappeared. In
fact, according to official government reports, the coastline of
Galicia has made a “complete recovery”.
But that’s governments for you. Of course Galicia’s
coastline hasn’t got over the Prestige disaster. Even though the
initial, direct physical impacts are now almost imperceptible,
the indirect, long-lasting and extensive impacts haven’t ceased.
In fact, it’s absurd to say that the entire coastal system has made
a ‘complete recovery’ in such a short space of time.
Scientists are intensively studying the long-term effects of
the Prestige and other oil spills. Two important coastal biology
studies have recently appeared in the scientific literature, one
about the Prestige – the first of its kind so far – the second about
the Exxon Valdez, now seventeen years in the past and from which
a considerable amount of data is now available. Both these
catastrophes happened in coastal areas of outstanding natural
beauty, high productivity and high biodiversity. It is ironic
that most large oil spills seem to happen on some of the most
pristine coastlines in the world. Sadly, it follows that these
areas automatically become the best ‘natural laboratories’ for
studying the long-term impacts of such events.
PRELIMINARY STUDY OF THE PRESTIGE
Just by looking at the state of the coastline after the Prestige spill,
any fool could tell it would take a miracle for the effects to go
away immediately, despite the heavily-censored Spanish news
reports. After a year, people were just beginning to get the first
ideas of the overall impact on the ecosystem. Then it was really
too early to tell, but now, just over three years later, some of
the first proper results have emerged concerning the Prestige and
its effects on the ecosystem.
Biologists Rosario de la Huz and colleagues from the
University of Vigo have just published an extensive study into the
biological impacts of the spill on the coastline of Galicia. Their
work, covering the entire Galician coast, focused on 18 sandy
beaches. They compared data on the diversity and abundance of
six categories of small animals from September 1996 (before
the spill) until May 2003 (after the spill). The species, termed
macrofauna, were grouped into six taxonomic categories,
including marine and semi-terrestrial crustaceans and insects.
These are considered good examples of species that can be greatly affected by a coastal contamination event, in addition to
occupying a relatively low level in the food pyramid.
During their post-spill survey in May 2003, the first thing
the Huz team did was to write down their initial observations.
There was, they noted, a considerable amount of oil in the
sediment on all the beaches studied (no surprises there). In
fact, on 10 of the 18 beaches the sand was not even visible
beneath a thick carpet of black oil. The next thing they did was
to count the number of different species present, and compared
this with data already available from September 1996. A highly
significant decrease in the number of species (effectively, the
biodiversity) was observed on all but one of the beaches, in
some cases up to two thirds of the species having disappeared.
They then counted, for each taxonomic group, the total
population of individual animals per square metre of beach
area. This was also found to have decreased considerably.
Perhaps the most surprising result was that, in addition to
the oil itself directly affecting the biology, the actual cleaning
of the beaches (a secondary consequence of the oil spill) did
just as much damage, if not more, as the Prestige. This wasn’t
new; in fact it had already been noted from previous spills
such as the Exxon Valdez. The main reason for the damage is that
vigorous cleaning of the beach removes every last trace of
vegetable matter. Algal wrack (a type of seaweed) for example,
is used by the macrofauna as food and shelter, particularly on
the dry beach and right on the water’s edge. If the macrofauna
cannot live, then, obviously, neither can the larger creatures
that depend on the macrofauna for food. And if they can’t live,
neither can the bigger ones who depend on them for food. And
so on up the food pyramid.
After rigorous statistical testing, Huz and colleagues
considered that their conclusions (basically, that the ecosystem
has seriously been affected by both the oil itself and the
cleaning of the beaches) were trustworthy, despite the
difficulty in distinguishing changes due to the oil spill from
those due to natural variability. They were worried that, since
one set of measurements was taken in the spring (May 2003)
and the other in the autumn (September 1996), the natural
seasonal variation between these two times of year might have
influenced the results. Therefore, they performed a special
check to estimate this natural variation, which was then
subtracted from the total effects of the spill. The results still
indicated a major effect on the ecosystem, so their conclusions
were deemed reliable.
BACK TO THE FUTURE: THE EXXON VALDEZ
On 24th March 1989, the Exxon Valdez went aground on Bligh Reef,
Prince William Sound, Alaska. As a result, 42,000 tonnes of crude
oil seriously contaminated at least 2,000km of pristine Alaskan
coastline. The case of the Exxon Valdez is now the most highly studied
example of long-term effects from large oil spills. The extensive
results published over the last 17 years on the biological effects
of the Exxon Valdez can be useful for seeing what lies in store for the
Galician coastline. By the way, if you think this is irrelevant because
there are no surfing waves in Prince William Sound, think again.
The oil reached the Kodiak Archipelago, where there are good
waves and a thriving surf community.
Charles Peterson and colleagues from the University of North
Carolina have published a comprehensive review of all the work
done in the last 17 years on the ecotoxicological effects of the
Exxon Valdez oil spill. After reviewing the vast literature now available,
Peterson points out that the seriousness of the event was grossly
underestimated at the time. The indirect consequences (termed
‘cascade’ effects) are only now becoming apparent, all these years
later. He stresses that the current procedures for assessing how
the ecosystem will respond to traumatic contamination events,
including oil-tanker accidents, are still inadequate. This is mainly
because these procedures do not account for some of the indirect,
delayed impacts. Peterson concludes with a list of ‘what we
thought then’ and ‘what we know now’ about various aspects of
the spill. These are summarised as follows:
• It was thought that most of the oil on most shorelines would
be degraded rapidly. Now we know that it degrades at varying
rates, with oil stuck under the surface being protected from the
usual effects of physical disturbance, photolysis (degradation by
sunlight) and oxygenation (degradation by exposure to the air).
Therefore, the oil may persist for many years. A lot of oil having
been protected from the elements in this way can still be found on
rocky beaches several years after a spill.
• We already knew that sea
birds and marine mammals died
of short-term, acute exposure,
mostly due to (a) corrosion of
the skin and protective coatings
leading to hypothermia, and
(b) ingestion of the fuel leading
to direct damage to internal
organs. Scientists also had a
vague idea that the poison would work its way up the food
pyramid, eventually reaching the top-level predators, including
us. However, that was still a little naïve. It is now known that the
health of the animals themselves, not just whether they live or
die, can affect the ‘health’ of the entire ecosystem. For example, in
a contaminated environment, the breeding and raising of young
is seriously hindered, particularly in socially organised animals.
This then affects the whole species, which, in turn, affects other
species above and below it in the food pyramid.
• It was thought the impacts on the coastline, including
the ecosystem, were exclusively associated with the presence
of the oil itself, directly poisoning or physically encumbering
most forms of life. Now we know that the frantic cleaning of
the beaches after an oil spill can cause just as much, if not more
damage. Moreover, repeated clean-up operations tend to set back
any ecosystem recovery already under way. This is a surprising
result and quite difficult to believe. It means that having clean,
sandy beaches for the tourists to lie on, or for us surfers to walk
across, after a spill, might come at the price of causing even
more damage to the ecosystem. Would it be better to just leave
the oil there?
The importance of the long-term health of the affected species is worth thinking about. The study pointed out that most
some of the worst affected were those socially organised species
such as dolphins and sea otters. It turns out that their health,
or correct functioning, is important to the whole ecosystem
and therefore (presumably) important to us and other top-level
occupants. A major coastal contamination event like the Prestige
would be to dolphins or sea otters as horrific as, say, Chernobyl
or Bhopal was to the unfortunate people affected by those
disasters. Both were events where people didn’t just die, but
where entire societies – even more that just one generation – still
have to live with cancers and other diseases.
All in all, the study of Dr. Peterson and colleagues shows
that these kinds of catastrophes never turn out to be simpler to
deal with than we thought they would be. They always turn out
to be more complicated. This phenomenon is partly due to our
own wishful thinking, and partly due to the sad fact that the
very people responsible for these disasters are those controlling
Studies into the Exxon Valdez and the Prestige oil spills are beginning
to show that, by abusing the environment in this way, we are
slowly but relentlessly weakening the biodiversity of the planet.
The term ‘ecocide’ is now commonly being used to describe
our gradual extermination of the planet’s species and, as a result,
the eventual depletion of our own resource base. Many modern
scientists and philosophers, including the brilliant Jared Diamond
(author of the award-winning Guns, Germs and Steel), suggest that
ecocide has now become a more realistic threat to human society
than, say, nuclear war.
We humans have spent thousands of years, generation after
generation, adapting to the environment. The reason we are able
to adapt to it is because it changes slower than we do. However,
now that we have the technology to catastrophically change our
environment over an extremely short length of time, we are actually
putting the planet in extreme peril. Wisdom with hindsight is easy,
but learning from our mistakes is essential if we are to survive.
Tony Butt completed
a PhD in Physical
Oceanography at the
Centre for Marine
Studies, University of
He now lives and
continues his research
in Northern Spain.